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Zhang, J., Blackmer, A. M., Kyveryga, P. M., Van De Woestyne, B. and Blackmer, ...... Bai, L. P., Sui, F. G., Ge, T. D., Sun, Z. H., Lu, Y. Y. and Zhou, G. S. 2006.




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PEDOSPHERE
An International Peer-Reviewed Journal
(ISSN 1002-0160; Bimonthly)
 HYPERLINK "http://pedosphere/issas.ac.cn" http://pedosphere/issas.ac.cn; www.elsevier.com/locate/pedosphere
Contents and Abstracts
1991(1)-2009(6)

Zhang, Y. L., Fan, J. B., Wang, D. S. and Shen, Q. R. 2009. Genotypic differences in grain yield and physi ological nitrogen use efficiency among rice cultivars. Pedosphere. 19(6): 681--691.
ABSTRACT: Efficient use of N in agricultural practice can increase yield, decrease production costs and reduce the risk of environmental pollution. Effects of N fertilizer application rates on grain yield and physiological N use efficiency (PE) in relation to the accumulation and redistribution of biomass and N in rice (Oryza sativa L.) cultivars were studied at two experimental farms of Nanjing Agricultural University, Nanjing, China in 2004. Three high N use efficiency (NUE) rice cultivars (Wuyunjing 7, Nanguang, and 4007) and one low NUE rice cultivar (Elio) with similar growth patterns were studied under seven N rates (0, 60, 120, 180, 240, 300 and 360 kg ha-1). Grain yield increased with the N application rate and attained plateau at 180 kg N ha-1 for rice cultivars at each site. Increasing N rate decreased PE for biomass and grain yield. Grain yield and PE of Elio were about 20% and 18% lower than those of high NUE cultivars. Differences in biomass, N accumulation and N redistribution were observed at the post-heading stage among rice cultivars with differing NUEs. The less reproductive tillers of Elio resulted in less demand for C and N during grain filling, thus leading to lower PE of Elio compared with the high NUE rice cultivars.

Li, D. J. and Wang, X. M. 2009. Nitric oxide emission following wetting of dry soils in subtropical humid forests. Pedosphere. 19(6): 692--699.
ABSTRACT: Information about soil nitric oxide (NO) emissions from subtropical forests is quite limited, and even less is known about the pulse emission of NO when wetting soils after a long period of dryness. In this study, we measured NO fluxes following wetting of dry soil in a broadleaf forest and a pine forest in subtropical China. Large pulses of NO fluxes were observed after soil wetting in both forests. NO fluxes increased significantly within 0.5 h following wetting in both forests and reached peak 1 h and 4 h after soil wetting in the pine forest and the broadleaf forest, respectively. In the broadleaf forest, averaged peak flux of NO pulses was 157 ng N m–2 s–1, which was 8 times the flux value before wetting, and in the pine forest, the averaged peak flux was 135 ng N m–2 s–1, which was 15.5 times the flux value before wetting. The total pulses-induced NO emissions during the dry season were roughly estimated to be 29.4 mg N m–2 in the broadleaf forest and 22.2 mg N m–2 in the pine forest or made up a proportion of 4.6% of the annual NO emission in the broadleaf forest and 5.3% in the pine forest.

Tang, L., Zhu, Y., Liu X. J., Tian, Y. C., Yao, X. and Cao, W. X. 2009. Simulation model for photosynthetic production in oilseed rape. Pedosphere. 19(6): 700--710.
ABSTRACT: Photosynthetic production is a major determinant of final yield in crop plants. A simulation model was developed for canopy photosynthesis and dry matter accumulation in oilseed rape (Brassica napus) based on the ecophysiological processes and using a three-layer radiation balance scheme for calculating the radiation interception and absorption by the layers of flowers, pods, and leaves within the canopy. Gaussian integration method was used to calculate photosynthesis of the pod and leaf layers, and the daily total canopy photosynthesis was determined by the sum of photosynthesis from the two layers of green organs. The effects of physiological age, temperature, nitrogen, and water deficit on maximum photosynthetic rate were quantified. Maintenance and growth respiration were estimated in determining net photosynthetic production. Partition index of the shoot in relation to physiological development time was used to calculate shoot dry matter from plant biomass and shoot biomass loss because of freezing was quantified by temperature effectiveness. Testing of the model for dynamic dry matter accumulation through field experiments of different genotypes, sowing dates, and nitrogen levels showed good fit between the observed and simulated data, with an average root mean square error of 10.9% for shoot dry matter. Thus, the present model appears to be reliable for the prediction of photosynthetic production in oilseed rape.

Ma, T., Zhou, C. H. and Cai, Q. G. 2009. Modeling of hillslope runoff and soil erosion at rainfall events using cellular automata approach. Pedosphere. 19(6): 711--718.
ABSTRACT: A novel quantitative cellular automata (CA) model that simulates and predicts hillslope runoff and soil erosion caused by rainfall events was developed by integrating the local interaction rules and the hillslope surface hydraulic processes. In this CA model, the hillslope surface was subdivided into a series of discrete spatial cells with the same geometric features. At each time step, water and sediment were transported between two adjacent spatial cells. The flow direction was determined by a combination of water surface slope and stochastic assignment. The amounts of interchanged water and sediment were computed using the Chezy-Manning formula and the empirical sediment transport equation. The water and sediment discharged from the open boundary cells were considered as the runoff and the sediment yields over the entire hillslope surface. Two hillslope soil erosion experiments under simulated rainfall events were carried out. Cumulative runoff and sediment yields were measured, respectively. Then, the CA model was applied to simulate the water and soil erosion for these two experiments. Analysis of simulation results indicated that the size of the spatial cell, hydraulic parameters, and the setting of time step and iteration times had a large impact on the model accuracy. The comparison of the simulated and measured data suggested that the CA model was an applicable alternate for simulating the hillslope water flow and soil erosion.

Ren, H. Y., Zhuang, D. F., Singh, A. N., Pan, J. J., Qiu, D. S. and Shi, R. H. 2009. Estimation of As and Cu contamination in agricultural soils around a mining area by reflectance spectroscopy: A case study. Pedosphere. 19(6): 719--726.
ABSTRACT: Concentrations of Iron (Fe), As, and Cu in soil samples from the fields near the Baoshan Mine in Hunan Province, China, were analyzed and soil spectral reflectance was measured with an ASD FieldSpec FR spectroradiometer (Analytical Spectral Devices, Inc., USA) under laboratory condition. Partial least square regression (PLSR) models were constructed for predicting soil metal concentrations. The data pre-processing methods, first and second derivatives ((FD and SD), baseline correction (BC), standard normal variate (SNV), multiplicative scatter correction (MSC), and continuum removal (CR), were used for the spectral reflectance data pretreatments. Then, the prediction results were evaluated by relative root mean square error (RRMSE) and coefficients of determination (R2). According to the criteria of minimal RRMSE and maximal R2, the PLSR models with the FD pretreatment (RRMSE = 0.24, R2 = 0.61), SNV pretreatment (RRMSE = 0.08, R2 = 0.78), and BC-pretreatment (RRMSE = 0.20, R2 = 0.41) were considered as the final models for predicting As, Fe, and Cu, respectively. Wavebands at around 460, 1 400, 1 900, and 2 200 nm were selected as important spectral variables to construct final models. In conclusion, concentrations of heavy metals in contaminated soils could be indirectly assessed by soil spectra according to the correlation between the spectrally featureless components and Fe; therefore, spectral reflectance would be an alternative tool for monitoring soil heavy metals contamination.

Huang, Q. R., Hu, F., Huang, S., Li, H. X., Yuan, Y. H., Pan, G. X. and Zhang, W. J. 2009. Effect of long-term fertilization on organic carbon and nitrogen in a subtropical paddy soil. Pedosphere. 19(6): 727--734.
ABSTRACT: A long-term experiment beginning in 1981 in Jinxian County of Jiangxi Province, subtropical China, was conducted in a paddy field under a double rice cropping system with four different fertilization regimes, including 1) no fertilizer as control (CK), 2) balanced chemical N, P, and K fertilizers (NPK), 3) organic manure using milk vetch and pig manure in the early and late rice growing season, respectively, (OM), and 4) balanced chemical fertilizers combined with organic manure (NPKM). Samples (0--17 cm) of the paddy field soil, which was derived from Quaternary red clay, were collected after the late rice harvest in November 2003 for determination of total organic carbon (TOC) and total nitrogen (TN) and fractions of organic C and N. Results showed that TOC and TN in the NPKM and OM treatments were significantly higher than those in other two treatments (CK and NPK). Application of organic manure with or without chemical fertilizers significantly increased the contents of all fractions of organic C and N, whereas chemical fertilizer application only increased the contents of occluded particulate organic C (oPOC) and amino acid N. In addition, application of organic manure significantly enhanced the proportions of free particulate organic carbon (fPOC) and oPOC in total C, and those of amino sugar N and amino acid N (P < 0.01) in total N. In contrast, chemical fertilizer application only increased the proportions of oPOC and amino acid N (P < 0.05). There were no significant differences in either contents or proportions of soil organic C and organic N fractions between the NPKM and OM treatments. These indicated that organic manure application with or without chemical fertilizers played the most significant role in enhancing soil organic C and N quantity and quality in the paddy field studied.

Jiang, J. P., Xiong, Y. C., Jiang, H. M., Ye, D. Y., Song, Y. J. and Li, F. M. 2009. Soil microbial activity during secondary vegetation succession in semiarid abandoned lands of Loess Plateau. Pedosphere. 19(6): 735--747.
ABSTRACT: To show the vegetation succession interaction with soil properties, microbial biomass, basal respiration, and enzyme activities in different soil layers (0--60 cm) were determined in six lands, i.e., 2-, 7-, 11-, 20-, 43-year-old abandoned lands and one native grassland, in a semiarid hilly area of the Loess Plateau. The results indicated that the successional time and soil depths affected soil microbiological parameters significantly. In 20-cm soil layer, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), MBC/MBN, MBC to soil organic carbon ratio (MBC/SOC), and soil basal respiration tended to increase with successional stages but decrease with soil depths. In contrast, metabolic quotient (qCO2) tended to decrease with successional stages but increase with soil depths. In addition, the activities of urease, catalase, neutral phosphatase, ²-fructofuranosidase, and carboxymethyl cellulose (CMC) enzyme increased with successional stages and soil depths. They were significantly positively correlated with microbial biomass and SOC (P < 0.05), whereas no obvious trend was observed for the polyphenoloxidase activity. The results indicated that natural vegetation succession could improve soil quality and promote ecosystem restoration, but it needed a long time under local climate conditions.

Wang, J. H., Lu, X. G., Jiang, M., Li, X. Y. and Tian, J. H. 2009. Fuzzy synthetic evaluation of wetland soil quality degradation: A case study on the Sanjiang Plain, Northeast China. Pedosphere. 19(6): 756--764.
ABSTRACT: Wetland soil quality degradation caused by large-scale agricultural reclamation on the Sanjiang Plain of Northeast China has been widely reported. A relative soil quality evaluation (RSQE) model and a projection pursuit evaluation (PPE) model based on real-coded accelerating genetic algorithm were introduced to evaluate quality variations in top layers of the main wetland soils on the Sanjiang Plain in 1999 and 2003, respectively. As soil quality degradation boundaries were vague, this study established two fuzzy synthetic evaluation (FSE) models based on the original data and criteria used in the RSQE and PPE models. The outputs of the two FSE models were obtained by choosing two fuzzy composite operators M ('",(") and M (" ,•"). Statistical analysis showed that the results of the FSE, RSQE, and PPE models were correlated. In particular, outputs of the FSE model using M (" ,•") were significantly correlated with those of the RSQE model with r = 0.989 at P < 0.01. Compared with RSQE and PPE models, the FSE model may be more objective in showing soil quality variations and was closer to the natural situation, showing the feasibility and applicability of the FSE model in evaluating soil quality degradation. However, the choice of composite operator was of critical importance. The study of wetland soil quality degradation on the Sanjiang Plain was of scientific and practical significance for protection and management of soils and for sustainable development of agriculture in this area in the future.

Xu, H., Yang, L. Z., Zhao, G. M., Jiao, J. G., Yin, S. X. and Liu, Z. P. 2009. Anthropogenic impact on surface water quality in Taihu Lake region, China. Pedosphere. 19(6): 765--778.
ABSTRACT: Taihu Lake region is one of the most industrialized areas in China, and the surface water is progressively susceptible to anthropogenic pollution. The physicochemical parameters of surface water quality were determined at 20 sampling sites in Taihu Lake region, China in spring, summer, autumn, and winter seasons of 2005--2006 to assess the effect of human activities on the surface water quality. Principal component analysis (PCA) and cluster analysis (CA) were used to identify characteristics of the water quality in the studied water bodies. PCA extracted the first three principal components (PCs), explaining 80.84% of the total variance of the raw data. Especially, PC1 (38.91%) was associated with NH4-N, total N, soluble reactive phosphorus, and total P. PC2 (22.70%) was characterized by NO3-N and temperature. PC3 (19.23%) was mainly associated with pH and dissolved organic carbon. CA showed that streams were influenced by urban residential subsistence and livestock farming contributed significantly to PC1 throughout the year. The streams influenced by farmland runoff contributed most to PC2 in spring and winter compared with other streams. PC3 was affected mainly by aquiculture in spring, rural residential subsistence in summer, and livestock farming in fall and winter seasons. Further analyses showed that farmlands contributed significantly to nitrogen pollution of Taihu Lake, while urban residential subsistence and livestock farming also polluted water quality of Taihu Lake in rainy season. The results would be helpful for the authorities to take sound actions for an effective management of water quality in Taihu Lake region.

Shi, G. T., Chen, Z. L., Xu, S. Y., Yao, C. X., Bi, C. J. and Wang, L. 2009. Salinity and persistent toxic substances in soils from Shanghai, China. Pedosphere. 19(6): 779--789.
ABSTRACT: Some farmland soils in Shanghai had high salinity levels, suggesting secondary salinization of the soils. The soil problems in Shanghai were studied, including the salinity and nitrate nitrogen (NO3--N) concentrations, heavy metal pollution characteristics, and organochlorine pesticide (OCP) residual levels and polycyclic aromatic hydrocarbon (PAH) contents. Accumulation of NO3--N in vegetable soils was the most significant among different functional soils. Heavy metal pollution was significant in the samples collected from the sewage-irrigated land and roadside. The identification of the metal sources through multivariate statistical analysis indicated that Pb, Zn, Cu and Cr in urban soils were from the traffic pollutants; excessive application of fertilizer and irrigation were the main reasons for the metal pollution in agricultural soils; Ni in the observed soils was controlled by parent soils. OCPs could still be detected in farmland soils but degraded greatly in last 20 years after prohibition of their usage. PAHs with 2--3 rings were the main components in industrial soils. The concentrated PAHs in the investigated soils were likely from petroleum and coal combustion.

Lin, J. S., Shi, X. Z., Lu, X. X., Yu, D. S., Wang, H. J., Zhao, Y. C. and Sun, W. X. 2009. Storage and spatial variation of phosphorus in paddy soils of China. Pedosphere. 19(6): 790--798.
ABSTRACT: Due to the growing concern about the agricultural phosphorus (P) losses pollution, an in-depth understanding of P in paddy soils of China would be helpful in providing a national perspective of the environmental impact of P cycling and fertility on China’s farms. In this study, we evaluated the P storage and the P density of paddy soils in China, characterized the spatial variations of P among the subgroups of paddy soils and soil regions in China, and evaluated the P data using GIS-based analysis, which included a newly compiled 1:1 M digital soil map of China, and using 1 490 soil profiles. The available and total P densities of paddy soils were 6.7 and 698.5 g m-3, respectively. Overall in China, the total P storage within 1 m of paddy soils was estimated to be 330.1 Tg. The P density of paddy soils varied substantially with subgroups due to the different soil water regimes such as groundwater table and soil drainage. The P availability in paddy soils, especially in surface layer, was higher in high temperature and precipitation areas. Further research is needed to examine more anthropogenic impact factors, such as increasing use of chemical fertilizer.

Jin, Z., Dong, Y. S., Qi, Y. C. and Domroes, M. 2009. Precipitation pulses and soil CO2 emission in desert shrubland of Artemisia ordosica on the Ordos Plateau of Inner Mongolia, China. Pedosphere. 19(6): 799--807.
ABSTRACT: Precipitation is the major driver of ecosystem functions and processes in semiarid and arid regions. In such water-limited ecosystems, pulsed water inputs directly control the belowground processes through a series of soil drying and rewetting cycles. To investigate the effects of sporadic addition of water on soil CO2 efflux, an artificial precipitation event (3 mm) was applied to a desert shrub ecosystem in the Mu Us Sand Land of the Ordos Plateau in China. Soil respiration rate increased 2.8--4.1 times immediately after adding water in the field, and then it returned to background level within 48 h. During the experiment, soil CO2 production was between 2 047.0 and 7 383.0 mg m-ð2. In the shrubland, soil respiration responses showed spatial variations, having stronger pulse effects beneath the shrubs than in the interplant spaces. The spatial variation of the soil respiration responses was closely related with the heterogeneity of soil substrate availability. Apart from precipitation, soil organic carbon and total nitrogen pool were also identified as determinants of soil CO2 loss in desert ecosystems.

Jin, J., Wang, G. H., Liu, X. B., Liu, J. D., Chen, X. L. and Herbert, S. J. 2009. Temporal and spatial dynamics of bacterial community in the rhizosphere of soybean genotypes grown in a black soil. Pedosphere. 19(6): 808--816.
ABSTRACT: The dynamics of rhizosphere microbial communities is important for plant health and productivity, and can be influenced by soil type, plant species or genotype, and plant growth stage. A pot experiment was carried out to examine the dynamics of microbial communities in the rhizosphere of two soybean genotypes grown in a black soil in Northeast China with a long history of soybean cultivation. The two soybean genotypes, Beifeng 11 and Hai 9731, differing in productivity were grown in a mixture of black soil and siliceous sand. The bacterial communities were compared at three zone locations including rhizoplane, rhizosphere, and bulk soil at the third node (V3), early flowering (R1), and early pod (R3) stages using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) of 16S rDNA. The results of principal component analyses (PCA) showed that the bacterial community structure changed with growth stage. Spatially, the bacterial communities in the rhizoplane and rhizosphere were significantly different from those in the bulk soil. Nevertheless, the bacterial communities in the rhizoplane were distinct from those in the rhizosphere at the V3 stage, while no obvious differences were found at the R1 and R3 stages. For the two genotypes, the bacterial community structure was similar at the V3 stage, but differed at the R1 and R3 stages. In other words, some bacterial populations became dominant and some others recessive at the two later stages, which contributed to the variation of the bacterial community between the two genotypes. These results suggest that soybean plants can modify the rhizosphere bacterial communities in the black soil, and there existed genotype-specific bacterial populations in the rhizosphere, which may be related to soybean productivity.

Zhu, H. W., Wang, Y. J., Zhou J., Jiang, J., Li, C. B., Zhou, D. M. and Friedman, S. P. 2009. Wien Effect characterization of interactions between ions and charged sites on clay surfaces of variable-charge soils. Pedosphere. 19(5): 545--553.
ABSTRACT: To investigate the interactions of oppositely charged sites on the surfaces of variable-charge soil particles with cations and anions, and to evaluate the mean Gibbs free binding and adsorption energies of various cations on particles of red soil and latosol, clay fractions smaller than 2 µm were separated from samples of the two variable-charge soils. Ferric oxides were removed from part of the clay fractions, which were then saturated with various chlorides (NaCl, KCl, CaCl2, CdCl2 or LaCl3). Electrical conductivities (EC) of dilute suspensions of the original and of the iron oxides-free clay fractions in deionized water were measured with the SHP-2 short high-voltage pulse apparatus, which enables measurement of the Wien effect at field strengths (E) from 14 to 250 kV cm-1. The Wien effect (EC-E) curves revealed EC increases of red soil suspensions between 14 to 200 kV cm-1, of 8.3, 8.4, 12.1, 5.9, and 1.2 µS cm-1 for NaCl, KCl, CaCl2, CdCl2, and LaCl3, respectively, reflecting the differing interactions with the various cations and chloride. The EC increments with the iron-free red soil suspensions were higher, being 29.7, 17.2, and 15.3 µS cm-1 for NaCl, CaCl2, and CdCl2, respectively. In the natural latosol suspensions the EC increments were practically zero, whereas in the iron-free fractions there were significant EC increments of 10.3, 5.7, 5.0, and 1.6 µS cm-1 for NaCl, CaCl2, CdCl2, and LaCl3, respectively.

Li, M. Y., Zhang, J., Lu, P., Xu, J. L. and Li, S. P. 2009. Evaluation of biological characteristics of bacteria contributing to biofilm formation. Pedosphere. 19(5): 554--561.
ABSTRACT: Biofilm-associated microorganisms play crucial roles in terrestrial and aquatic nutrient cycling and in the biodegradation of environmental pollutants. Biofilm formation was determined for a total of 18 bacterial isolates obtained from the biofilms of wastewater treatment systems and of little carpolite in soil. Among these isolates, seven showed strong biofilm-forming capacity. The phylogenetic affiliation of the isolates showing high biofilm formation capacity was determined through 16S rDNA sequencing and the isolates were grouped into 7 bacterial species including Pseudomonas sp., Pseudomonas putida, Aeromonas caviae, Bacillus cereus, Pseudomonas plecoglossicida, Aeromonas hydrophila, and Comamonas testosteroni. The biofilm-forming capacity was closely related with flagella, exopolysaccharide, and extracellular protein. According to the coefficient of determination, the relative importance of the five biological characteristics to biofilm formation was, in order from greatest to least, exopolysaccharide > flagella > N-acyl-homoserine lactones (AHLs) signaling molecules > extracellular protein > swarming motility.

Zeng, H. A. and Wu, J. L. 2009. Sedimentary records of heavy metal pollution in Fuxian Lake, Yunnan Province, China: Intensity, history, and sources. Pedosphere. 19(5): 562--569.
ABSTRACT: This study focused on the concentration change of heavy metals of sediment cores in heavily polluted north area and less polluted middle area of Fuxian Lake in Southwest China. On the basis of the analysis of Cu, Ni, Ti, V, Pb, Cd, and Zn concentration-depth profiles, the pollution history of heavy metals was studied using 137cesium (137Cs) dating. The sources of heavy metals were distinguished by normalization of their profiles to aluminum and analysis of heavy metal concentrations of potential source materials. Geoaccumulation index (Igeo) was used to quantify their contamination intensity. The results showed that all the heavy metals found in the Fuxian Lake sediments originated naturally before 1980s. Cu, Ni, Ti, and V were still mainly natural in the north lake after 1980s, Cu, Ni, Ti, V, and Pb were mainly natural in the middle lake at all time, but the concentrations of Pb and Zn in the north lake were influenced by industrial wastes from the phosphorus fertilizer factory and cement plants. In all the lake, the contaminations of Cd and Zn were the results of agricultural cultivation using a large amount of fertilizers and the atmospheric fallouts of dusts from cement plants. At present, the geoaccumulation indices showed that the Fuxian Lake sediments were moderately to strongly polluted by Cd in the middle lake, and unpolluted to moderately polluted by Pb and Zn and strongly polluted by Cd in the north lake. Moreover, the pollution intensities of Cd, Zn, and Pb have been increased since 1980s.

Wang, Y., Du, S. T., Li, L. L., Huang, L. D., Fang, P., Lin, X. Y., Zhang, Y. S. and Wang, H. L. 2009. Effect of CO2 elevation on root growth and its relationship with indole acetic acid and ethylene in tomato seedlings. Pedosphere. 19(5): 570--576.
ABSTRACT: A hydroponic experiment was carried out to study the effect of elevated carbon dioxide (CO2) on root growth of tomato seedlings. Compared with the control (350 ¼L L-1), CO2 enrichment (800 ¼L L-1) significantly increased the dry matter of both shoot and root, the ratio of root to shoot, total root length, root surface area, root diameter, root volume, and root tip numbers, which are important for forming a strong root system. The elevated CO2 treatment also significantly improved root hair development and elongation, thus enhancing nutrient uptake. Increased indole acetic acid concentration in plant tissues and ethylene release in the elevated CO2 treatment might have resulted in enhanced root growth and root hair development and elongation.

Hou, X. W., Wu, J. J., Xu, J. M. and Tang, C. X. 2009. Interactive effects of lead and bensulfuron-methyl on decomposition of 14C-glucose in paddy soils. Pedosphere. 19(5): 577--587.
ABSTRACT: Little information is available on the interactive effects of inorganic and organic pollutants on carbon utilization by soil microorganisms. This study examined the effects of two common soil pollutants, lead (Pb) and bensulfuron-methyl herbicide (BSM), on decomposition of an adscititious carbon source (14C-glucose). Two contrasting paddy soils, a silty clay soil and a clay loam soil were incubated with different concentrations and combinations of pollutants for 60 days. Orthogonal rotatable central composite design was adopted to design the combinations of the pollutant concentrations so that rate response curves could be derived. Rapid decomposition of 14C-glucose occurred in the first three days for both soils where no Pb or BSM was added (control). Overall, 63%-64% of the added 14C-glucose was decomposed in the control over the 60-day incubation. The addition of Pb or BSM significantly decreased the decomposition of 14C-glucose during the first week but increased the decomposition thereafter; as a result, the percentages of 14C-glucose decomposed (57%-77%) over the 60-day period were similar to or higher than those of the control. Application of the pollutants in combination did not further inhibit decomposition compared with the control. Overall, decomposition rates were lower in the silty clay soil than in the clay loam soil, which was related to the soil texture, cation exchange capacity, and pH. The relationship between the decomposition rates and the pollutants could be well characterized by the quadratic regression orthogonal rotation model. The results indicated that the initial antagonistic effects of the pollutants followed by the synergistic effects on microbial activity might result from changes of the concentrations of the pollutants.

Fares, A., Safeeq, M. and Jenkins, D. M. 2009. Adjusting temperature and salinity effects on single capacitance sensors. Pedosphere. 19(5): 588--596.
ABSTRACT: Several newly developed capacitance sensors have simplified real-time determination of soil water content. Previous work has shown that salinity and temperature can affect these sensors, but relatively little has been done to correct these effects. The objectives of this study were to evaluate the effect of media temperature and salinity on the apparent water content measured with a single capacitance sensor (SCS), and to mitigate this effect using a temperature dependent scaled voltage technique under laboratory conditions, a column study was conducted containing two media: pure deionized water and quartz sand under varying water contents (0.05 to 0.30 cm3 cm-3) and salinity (0 to 80 mmol L-1). Media temperature varied between 5 and 45 oC using an incubator. The SCS probes and thermocouples were placed in the middle of the columns and were logged at an interval of 1 minute. There was strong negative correlation between sensor reading and temperature of deionized water with a rate of -0.779 mV °C-1. Rates of SCS apparent output were 0.454 and 0.535 mV oC-1 for air in heating and cooling cycles, respectively. A similar positive correlation with temperature was observed in sand at different water contents. The SCS probe was less sensitive to temperature as salinity and water content increased. Using a temperature-corrected voltage calibration model, the effect of temperature was reduced by 98%. An analytical model for salinity correction was able to minimize the error as low as 2% over the salinity level tested.

Li, Q., Jiang, Y., Liang, W. J., Wang, H. and Jiang, S. W. 2009. Nematode diversity in phaeozem agroecosystems of Northeast China. Pedosphere. 19(5): 597--605.
ABSTRACT: The diversity and distribution patterns of soil nematode communities in phaeozem agroecosystems of Northeast China were assessed to evaluate nematode taxonomic diversity and functional diversity in relation to climatic condition and soil characteristics in human modified landscape. Along the latitudinal gradient, soil samples were collected from north (Hailun) to south (Gongzhuling) down to a depth of 100 cm with intervals of 0--20, 20--40, 40--60, 60--80, and 80--100 cm. The nematode abundance and taxonomic diversity (generic richness) were lower at Hailun than at other sites, and higher values of evenness were observed at Hailun and Harbin than at Dehui and Gongzhuling. Nematode faunal analysis revealed that soil food web at Hailun was successionally more mature or structured, and the environment little disturbed, while at Harbin and Gongzhuling, the soil food web was degraded with stressed environment. The environmental variables relevant in explaining the patterns of nematode distribution and diversity in phaeozem agroecosystems, using canonical correspondence analysis (CCA), were the mean annual temperature, total nitrogen, electrical conductivity, mean annual precipitation, and other soil properties. Among these variables, the mean annual temperature was a relatively important factor, which could explain 29.05% of the variations in nematode composition.

Ning, P., Wang, H. B., Pan, B., Bart, H.-J. and Yang, M. 2009. Isolation and sorption behavior of humic acid from Zhongdian peat of Yunnan Province, China. Pedosphere. 19(5): 606--614.
ABSTRACT: The Zhongdian swamp meadow in Zhongdian, China is well known as “Shangri-la”, where the peat has never been studied for its potential to interact with pollutants. Humic acid (HA) was extracted from Zhongdian peat using two methods, namely sodium pyrophosphate extraction (SPE) and dilute base extraction (DBE), and characterized for its functional groups and sorption property. The HAs extracted by both methods contained several active functional groups and had large external specific surface areas. The adsorption mechanism of methylene blue onto HAs was interpreted as Langmuir sorption. SPE-HA showed higher sorption capacity because of its larger specific surface area, whereas the extraction yield of DBE-HA was twice that of SPE-HA. Kinetics modeling indicated that the sorption of methylene blue was a two-component first order reaction. The component with the higher rate constant also showed higher sorption capacity. No pH effect was observed for methylene blue sorption on HA in our experimental design, and the sorption decreased as the temperature increased.

Mao, L. J., Mo, D. W., Yang, J. H. and Shi, C. X. 2009. Geochemistry of trace and rare earth elements in red soils from the Dongting Lake area and its environmental significance. Pedosphere. 19(5): 615--622.
ABSTRACT: Trace element (TE) and rare earth element (REE) contents in red soils from the Dongting Lake area of China were determined to understanding the provenance and weathering characteristics of the red soils. The results showed similar REE distribution patterns among red soils from the Dongting Lake area, Xiashu loess from Zhenjiang, loess and the Pliocene red soil from the Loess Plateau. These patterns implied a similar provenance from dust-storms, except for red soil R5 which formed by bedrock weathering and had significant light REE (LREE) enrichment and heavy REE (HREE) depletion due to longer weathering periods and higher intensity of weathering. Trace element, especially the Rb/Sr and Li/Ba ratios, and REE, especially the LREE/HREE ratio and ´Eu could trace weathering intensity. Higher Rb/Sr, Li/Ba, and LREE/ HREE ratios and negative Eu anomalies were present in the red soil from the Dongting Lake area. The weathering intensity was in the decreasing order of R5 in the Dongting Lake area > red soil from the Dongting Lake area (including reticulate red soil, weak reticulate red soil, and homogeneous red soil formed by dust storms) > Xiashu loess from Zhenjiang > Loess-paleosol and Pliocene red soil from the Loess Plateau. Variations in the TE and REE contents of soil could be effectively used to study the provenance and the weathering intensity.

Wang, J. H., Ding, H., Lu, Y. T. and Shen, G. Q. 2009. Combined effects of cadmium and butachlor on microbial activities and community DNA in a paddy soil. Pedosphere. 19(5): 623--630.
ABSTRACT: Due to frequent soil Cd contamination and wide use of butachlor in China, there is a need to assess their combined toxicity to soil microorganisms. The combined effects of cadmium (Cd, 10 mg kg-1 soil) and herbicide butachlor (10, 50, and 100 mg kg-1 soil) on enzyme activities and microbial community structure in a paddy soil were assessed using the traditional enzyme assays and random amplified polymorphic DNA (RAPD) analysis in this study. The results showed that urease and phosphatase activities were significantly reduced by high butachlor concentration (100 mg kg-1 soil). When the concentrations of Cd and butachlor added were at a ratio of 1:10, urease and phosphatase activities were significantly decreased whereas enzyme activities were greatly improved at the ratio of 1:5, which indicated that the combined effects of Cd and butachlor on soil urease and phosphatase activities depended largely on their addition concentration ratios. Random amplified polymorphic DNA (RAPD) analysis showed loss of original bands and appearance of new bands when compared with the control soil. Random amplified polymorphic DNA fingerprints suggested substantial differences between the control and treated soil samples, with apparent changes in the number and size of amplified DNA fragments. The addition of high concentration butachlor and the combined impacts of Cd and butachlor significantly affected the diversity of the microbial community. These results suggest that RAPD analysis in conjunction with other biomarkers such as soil enzyme parameters would prove a powerful ecotoxicological tool. Further investigations should be carried out to understand the clear link between RAPD patterns and enzyme activity.

Khan, M. J. and Jones, D. L. 2009. Effect of composts, lime and diammonium phosphate on the phytoavailability of heavy metals in a copper mine tailing soil. Pedosphere. 19(5): 631--641.
ABSTRACT: Soil samples from a historic copper mine tailing site at the Parys Mountain, North Wales (UK) were amended with green waste compost (GC), GC+30% sewage sludge (GCS), lime and diammonium phosphate (DAP), to determine the effect of amendments on DTPA- and Ca(NO3)2-extractable metals in the mine tailing and on the phytoavailability of heavy metals by a lettuce (Lactuca sativa L.). Both compost were added at the rate of 10% by weight, lime was added as calcium carbonate equivalent (pH = 7) and DAP at a 2 300 mg kg-1 soil level. The experiment was arranged in randomised complete design with three replicates in pots under control environment. Addition of lime resulted in the largest reduction in metal extractability with DTPA and Ca(NO3)2 and phytoavailability of Cu, Fe and Zn while DAP was effective in lowering Pb extractability and phytoavailability. With exception of Zn, all other metals extracted decreased with time after amendment applications. The distribution of heavy metals between and within the four procedures of potentially bioavailable sequential extraction (PBASE) procedure varied significantly (P < 0.001). Stronger relationships were noted between the metals extracted with PBASE SE1 and Cu, Pb (P < 0.01) and Fe (P < 0.001) in the lettuce. These results indicate that addition of lime is sufficient to restore the vegetative cover to a high metal mines wastes while DAP is good for stabilizing Pb, but its detrimental role on plant growth and the risk associated with presence of N in DAP (through N leaching) may restrict its chances for remediation of contaminated sites.

Wang, E. D., Little, B. B., Williams, J. A. and Yu, Y. 2009. Simulation of hail and soil type effects on crop yield losses in Kansas, USA. Pedosphere. 19(5): 642--653.
ABSTRACT: Computer simulation was used for predictive analysis of the effects of weather and soil type on crop yield in the U.S. crop insurance program. The Environmental Policy Integrated Climate (EPIC) model was modified to include hail weather events, which completed the modifications necessary to simulate the four most frequent causes of crop yield loss (hail, excessive wet, excessive cold, and excessive dry) associated with soil type in Kansas, USA. At the region level, per hectare yields were simulated for corn, wheat, soybean, and sorghum. We concluded that it was possible to predict crop yields through computer simulation with greater than 93% accuracy. The hail damage model test indicated EPIC could predict hail-soil-induced yield losses reasonably well (R2 > 0.6). The investigation of soil type influence on dryland sorghum and wheat production indicated that Wymore silty clay loam soil and Kenoma silt loam produced the highest sorghum yields statistically; Kuma silt loam, Roxbury silt loam, Crete silty clay loam, and Woodson silt soils produced the second highest sorghum yields statistically; and Richfiled silt loam, Wells loam, and Canadian sandy loam produced the lowest sorghum yields. By contrast, wheat production showed less sensitivity to soil type variation. The less sensitive response of wheat yields to the soil type could be largely due to the unconsidered small-scale variability of soil features.

Azeez, J. O. 2009. Effects of nitrogen application and weed interference on performance of some tropical maize genotypes in Nigeria. Pedosphere. 19(5): 654--662.
ABSTRACT: Low soil nitrogen and weed infestations are some of the major constraints to maize production in Nigeria. The development of tropical maize genotypes with high and stable yield under low nitrogen (N) condition and weed interference is very important since access to these improved genotypes may be the only choice of many small scale farmers. A split-split plot experiment in a randomized complete block design with three replicates was established at two sites with different agroecological zones in Nigeria, Ikenne (Typic Paleudalf) and Shika (Typic Tropaquept), in 2002 and 2003 rainy seasons to investigate the responses of four maize genotypes (Oba super II, Low N pool C2, TZB-SR, and ACR 8328 BN C7) to N fertilizer applied at four rates, 0, 30, 60, 90 kg N ha-1, and three weed pressure treatments, no weed pressure (weekly weeding), low weed pressure (inter-row weekly weeding), and high weed pressure (no weeding throughout the growing season). Growth and yield parameters of maize and weeds were taken at flowering and harvest. The results indicated that there was a significant reduction in maize leaf area, leaf area index, and photosynthetically active radiation due to weed interference at both sites. The application of nitrogen at 90 kg N ha -1 significantly increased maize leaf area. Reductions in maize growth and yield parameters at flowering and harvest were significant due to weed interference at both Ikenne and Shika, thus showing that the reductions in maize growth and yield parameters due to weed interference were not ecological zone specific even though weed species and their seed banks may differ. Ameliorative management options could thus be the same in the two agroecological zones. Application of 90 kg N ha-1 led to a significant increase in maize grain yield at Shika while there was no fertilizer effect at Ikenne on grain yield. There was no significant difference between the 60 and 90 kg N ha-1, suggesting that 60 kg N ha-1 could be a possible replacement for the higher fertilizer rate at least for the identified maize genotypes. Low weed pressure treatment led to 26% and 35% reductions in maize grain yield at Ikenne and Shika, respectively while 22% and 51 % reductions, respectively, were observed due to high weed pressure treatment. Generally, maize grain yield was higher at Ikenne than Shika. The maize genotypes Low N pool C2 and ACR 8328 BN C7 performed better than other genotypes at Ikenne while the maize genotype Oba super II had the best performance at harvest at Shika. Application of nitrogen increased weed biomass at flowering at Ikenne. The maize grain yield was highest in the N-efficient genotypes, Oba super II and Low N pool C2; while the susceptible genotype TZB-SR had the least yield at Shika. There existed a negative and significant correlation between maize grain yield and weed biomass at both sites studied.

Wang, M. Y., Hu L. B. ,Wang, W. H., Liu, S. T., Li, M. and Liu, R. J. 2009. Influence of long-term fixed fertilization on diversity of arbuscular mycorrhizal fungi. Pedosphere. 19(5): 663--672.
ABSTRACT: Diversity of arbuscular mycorrhizal fungi (AMF) was investigated in a field that had received long-term fixed fertilization (LFF) for 26 years. There were a total of 12 treatments in triplicates with different amounts of manure, urea, calcium phosphate, and potassium chloride. Rhizosphere soil samples of maize and wheat grown in the experimental field in Shandong Province, China, were collected in September 2003 and May 2004, respectively. Arbuscular mycorrhizal fungal spores were isolated and identified using morphological characters. Mycorrhizal colonization percentage, spore density (SD), species richness (SR), relative abundance (RA), and Shannon-Weiner index (SWI) were determined. Nineteen recognized species of AMF belonging to 5 genera were identified. Long-term fixed fertilization significantly influenced colonization percentage, SR, SD, and species diversity of AMF. The adaptability of AMF to soil fertility was different among species. Species richness and SD of AMF in maize and wheat rhizosphere soils were the highest in the nonfertilization treatment (control) and lowest in the high manure + high nitrogen treatment (M2N2). The SWI decreased as the fertilization level increased except in the low manure treatment (M1) on maize. Compared with the other treatments, treatment M2N2 significantly reduced SD of Glomus, and the high manure + low nitrogen treatment (M2N1) significantly retarded sporulation of Scutellospora. Manure treatments stimulated sporulation of Glomus mosseae. Spore density of G. mosseae was higher in the high nitrogen + phosphorus + potassium treatment (N2PK) than in the high nitrogen + phosphorus treatment (N2P) and the high nitrogen + potassium treatment (N2K). The SD of S. pellucida was higher in Treatment N2K than Treatments N2PK and N2P. In conclusion, long-term fixed fertilization, especially with high levels of manure and N, decreased SR, SD, and colonization and changed the species composition of AMF.

Sun, Z. X., Zheng, J. M. and Sun, W. T. 2009. Coupled effects of soil water and nutrients on growth and yields of maize plants in a semi-arid region. Pedosphere. 19(5): 673--680.
ABSTRACT: Interaction between soil water and nutrients plays an important role in sustainable crop management in semi-arid environments. On the basis of a field experiment conducted from 2000 to 2003, this study examined the coupled effects of irrigation and fertilizers on maize growth and yield in a semi-arid region of northeastern China. In terms plant productivity, nitrogen fertilizer had the most significant effect followed by irrigation and phosphate levels. The combined application of nutrients and irrigation exerted a synergistic effect on the grain yield of maize plants. Regression analysis indicated that optimal levels of nitrogen and phosphate, in addition to adequate irrigation, could greatly improve the efficiency of grain production. Similarly, optimization of soil nutrient availability substantially increased water use efficiency. These suggested that for the most efficient and sustainable crop production, irrigation and nutrient management should be based on a quantitative understanding of water/nutrients interaction, particularly in semi-arid and arid regions.

Lai, D. Y. F. 2009. Methane dynamics in northern peatlands: A review. Pedosphere. 19(4): 409--421.
ABSTRACT: Northern peatlands store a large amount of carbon and play a significant role in the global carbon cycle. Owing to the presence of waterlogged and anaerobic conditions, peatlands are typically a source of methane (CH4), a very potent greenhouse gas. This paper reviews the key mechanisms of peatland CH4 production, consumption and transport and the major environmental and biotic controls on peatland CH4 emissions. The advantages and disadvantages of micrometeorological and chamber methods in measuring CH4 fluxes from northern peatlands are also discussed. The magnitude of CH4 flux varies considerably among peatland types (bogs and fens) and microtopographic locations (hummocks and hollows). Some anthropogenic activities including forestry, peat harvesting and industrial emission of sulphur dioxide can cause a reduction in CH4 release from northern peatlands. Further research should be conducted to investigate the influence of plant growth forms on CH4 flux from northern peatlands, determine the water table threshold at which plant production in peatlands enhances CH4 release, and quantify peatland CH4 exchange at plant community level with a higher temporal resolution using automatic chambers.

Yang, Y. G., Jin, Z. S., Bi, X. Y., Li, F. L., Sun, L., Liu, J. and Fu, Z. Y. 2009. Atmospheric deposition-carried Pb, Zn, and Cd from a zinc smelter and their effect on soil microorganisms. Pedosphere. 19(4): 422--433.
ABSTRACT: Dust emissions from smelters, as a major contributor to heavy metal contamination in soils, could severely influence soil quality. Downwind surface soils within 1.5 km of a zinc smelter, which was active for 10 years but ceased in 2000, in Magu Town, Guizhou Province, China were selected to examine Pb, Zn, and Cd concentrations and their fractionation along a distance gradient from a zinc smelter, and to study the possible effects of Pb, Zn, and Cd accumulation on soil microorganisms by comparing with a reference soil located at a downwind distance of 10 km from the zinc smelter. Soils within 1.5 km of the zinc smelter accumulated high levels of heavy metals Zn (508 mg kg-1), Pb (95.6 mg kg-1), and Cd (5.98 mg kg-1) with low ratios of Zn/Cd (59.1--115) and Pb/Cd (12.4--23.4). Composite pollution indices (CPIs) of surface soils (2.52--15.2) were 3 to 13 times higher than the reference soils. In metal accumulated soils, exchangeable plus carbonate-bound fractions accounted for more than 10% of the total Zn, Pb, and Cd. The saturation degree of metals (SDM) in soils within 1.5 km of the smelter (averaging 1.25) was six times higher than that of the reference soils (0.209). A smaller soil microbial biomass was found more frequently in metal accumulated soils (85.1--438 µg C g-1) than in reference soils (497 µg C g-1), and a negative correlation (P < 0.01) of soil microbial biomass carbon to organic carbon ratio (Cmic/Corg) with SDM was observed. Microbial consumption of carbon sources was more rapid in contaminated soils than in reference soils, and a shift in the substrate utilization pattern was apparent and was negatively correlated with SDM (R = -0.773, P < 0.01). Consequently, dust deposited Pb, Zn, and Cd in soils from zinc smelting were readily mobilized, and weredetrimental to soil quality mainly in respect of microbial biomass.

Lamsal, S., Bliss, C. M. and Graetz, D. A. 2009. Geospatial mapping of soil nitrate-nitrogen distribution under a mixed-land use system. Pedosphere. 19(4): 434--445.
ABSTRACT: Mapping the spatial distribution of soil nitrate-nitrogen (NO3-N) is important to guide nitrogen application as well as to assess environmental risk of NO3-N leaching into the groundwater. We employed univariate and hybrid geostatistical methods to map the spatial distribution of soil NO3-N across a landscape in northeast Florida. Soil samples were collected from four depth increments (0--30, 30--60, 60--120 and 120--180 cm) from 147 sampling locations identified using a stratified random and nested sampling design based on soil, land use and elevation strata. Soil NO3-N distributions in the top two layers were spatially autocorrelated and mapped using lognormal kriging. Environmental correlation models for NO3-N prediction were derived using linear and non-linear regression methods, and employed to develop NO3-N trend maps. Land use and its related variables derived from satellite imagery were identified as important variables to predict NO3-N using environmental correlation models. While lognormal kriging produced smoothly varying maps, trend maps derived from environmental correlation models generated spatially heterogeneous maps. Trend maps were combined with ordinary kriging predictions of trend model residuals to develop regression kriging prediction maps, which gave the best NO3-N predictions. As land use and remotely sensed data are readily available and have much finer spatial resolution compared to field sampled soils, our findings suggested the efficacy of environmental correlation models based on land use and remotely sensed data for landscape scale mapping of soil NO3-N. The methodologies implemented are transferable for mapping of soil NO3-N in other landscapes.

Cai, W. M., Yao, H. Y., Feng, W. L., Jin, Q. L., Liu, Y. Y., Li, N. Y. and Zheng, Z. 2009. Microbial community structure of casing soil during mushroom growth. Pedosphere. 19(4): 446--452.
ABSTRACT: The culturable bacterial population and phospholipid fatty acid (PLFA) profile of casing soil were investigated at different mushroom (Agaricus bisporus) cropping stages. The change in soil bacterial PLFAs was always accompanied by a change in the soil culturable bacterial population in the first flush. Comparatively higher culturable bacterial population and bacterial PLFAs were found in the casing soil at the primordia formation stage of the first flush. There was a significant increase in the ratio of fungal to bacterial PLFAs during mushroom growth. Multivariate analysis of PLFA data demonstrated that the mushroom cropping stage could considerably affect the microbial community structure of the casing soil. The bacterial population increased significantly from casing soil application to the primordia formation stage of the first flush. Casing soil application resulted in an increase in the ratio of gram-negative bacterial PLFAs to gram-positive bacterial PLFAs, suggesting that some gram-negative bacteria might play an important role in mushroom sporophore initiation.

Durán Zuazo, V. H., Rodríguez Pleguezuelo, C. R., Arroyo Panadero, L., Martínez Raya, A., Francia Martínez, J. R. and Cárceles Rodríguez, B. 2009. oil conservation measures in rainfed olive orchards in south-eastern Spain: Impacts of plant strips on soil water dynamics. Pedosphere. 19(4): 453--464.
ABSTRACT: Sloping and mountainous olive production systems are widespread, occupying large parts of the Mediterranean landscape prone to water erosion. Soil erosion, runoff, and soil water content patterns over a three-year period were monitored in erosion plots on a mountainside with rainfed olive (Olea europaea cv. Picual) trees under: 1) non-tillage with barley strips of 4 m width (BS); 2) non-tillage with native vegetation strips of 4 m width (NVS); and 3) non-tillage without plant strips (NT). The erosion plots, located in Lanjaron (Granada, south-eastern Spain), on a 30% slope, were 192 m2 in area. For assessing soil water dynamics in real-time and near-continuous soil water content measurements, multisensor capacitance probes were installed in the middle of plant strips and beneath the olive tree at five soil depths (10, 20, 30, 50, and 100 cm). The highest erosion and runoff rates were measured under NT, with a mean of 17.3 Mg ha-1 year-1 and 140.0 mm year-1, respectively, over the entire study period. The BS and NVS with respect to the NT reduced erosion by 71% and 59% and runoff by 95% and 94%, respectively. In general, greater available soil water content was found under BS than NVS and NT, especially beneath the olive tree canopies. These results supported the recommendation of non-tillage with barley strips in order to reduce erosion and to preserve soil water for trees in traditional mountainous olive-producing areas, where orchards cover vast tracts of land.

Li, F. H. and Keren, R. 2009. Calcareous sodic soil reclamation as affected by corn stalk application and incubation: A laboratory study. Pedosphere. 19(4): 465--475.
ABSTRACT: A laboratory lysimeter experiment was conducted to investigate the effects of forage corn (Zea mays L.) stalk application on the CO2 concentration in soil air and calcareous sodic soil reclamation. The experimental treatments tested were soil exchangeable sodium percentage (ESP) levels of 1, 11, and 19, added corn stalk contents of 0 to 36 g kg-1, and incubation durations of 30 and 60 days. The experimental results indicated that corn stalk application and incubation significantly increased CO2 partial pressure in soil profile and lowered pH value in soil solution, subsequently increased native CaCO3 mineral dissolution and electrolyte concentration of soil solution, and finally significantly contributed to reduction on soil sodicity level. The reclamation efficiency of calcareous sodic soils increased with the added corn stalk. When corn stalks were added at the rates of 22 and 34 g kg-1 into the soil with initial ESP of 19, its ESP value was decreased by 56% and 78%, respectively, after incubation of 60 days and the leaching of 6.5 pore volumes (about 48 L of percolation water) with distilled water. Therefore, crop stalk application and incubation could be used as a choice to reclaim moderate calcareous sodic soils or as a supplement of phytoremediation to improve reclamation efficiency.

Arain, M. B., Kazi, T. G., Jamali, M. K., Baig, J. A., Afridi, H. I., Jalbani, N. and Sarfraz, R. A. 2009. Comparison of different extraction approaches for heavy metal partitioning in sediment samples. Pedosphere. 19(4): 476--485.
ABSTRACT: Three extraction methods, ultrasonic assisted extraction (USE), microwave assisted extraction (MSE), and conventional single extraction (CSE), in conjunction with the modified three-stage BCR sequential extraction procedure (SEP) were applied to examine the contents of Cd, Cu, Cr, Ni, Pb and Zn from lake sediment samples, to know whether these techniques can reduce extraction time and improve reproducibility. The SEP and developed alternative single extraction methods were validated by the analysis of certified reference material BCR 601. By the use of optimized sonication and microwave conditions, steps 1, 2 and 3 of the BCR sequential extraction methods (excluding the hydrogen peroxide digestion in step 3, which was not performed with sonication and microwave) could be completed in 15--30 min and 60--150 s, respectively. The recoveries of total extractable metal contents in BCR 601, obtained by three single extractions ranged from 93.3%--102%, 88.9%--104% and 81.2%--96.2% for CSE, USE and MSE, respectively. The precision of the single extraction methods was found in the range of 3.7%--9.4% for all metals (n = 6).

Wang, Y. Q., Zhang, X. C., Zhang, J. L. and Li, S. J. 2009. Spatial variability of soil organic carbon in a watershed on the Loess Plateau. Pedosphere. 19(4): 486--495.
ABSTRACT: Soil organic carbon (SOC) has great impacts on global warming, land degradation and food security. Classic statistical and geostatistical methods were used to characterize and compare the spatial heterogeneity of SOC and related factors, such as topography, soil type and land use, in the Liudaogou watershed on the Loess Plateau of North China. SOC concentrations followed a log-normal distribution with an arithmetic and geometric means of 23.4 and 21.3 g kg-1, respectively, were moderately variable (CV = 75.9%), and demonstrated a moderate spatial dependence according to the nugget ratio (34.7%). The experimental variogram of SOC was best-fitted by a spherical model, after the spatial outliers had been detected and subsequently eliminated. Lower SOC concentrations were associated with higher elevations. Warp soils and farmland had the highest SOC concentrations, while aeolian sand soil and shrublands had the lowest SOC values. The geostatistical characteristics of SOC for the different soil and land use types were different. These patterns were closely related to the spatial structure of topography, and soil and land use types.

Wu, F. Z., Yang, W. Q., Wang, K. Y., Wu, N. and Lu, Y. J. 2009. Effect of stem density on leaf nutrient dynamics and nutrient use efficiency of dwarf bamboo. Pedosphere. 19(4): 496--504.
ABSTRACT: The monthly dynamics of nitrogen (N) and phosphorus (P) concentrations and stocks in leaves, resorption efficiency, and resorption proficiency, as well as leaf-level use efficiency, nutrient productivity, and mean residence time were studied to understand the effect of stem density of dwarf bamboo (Fargesia denudata Yi) on leaf-level N and P use efficiency in three dwarf bamboo stands with different stem densities under bamboo-fir (Picea purpurea Mast.) forest over one growing period in the Wanglang National Nature Reserve, Sichuan, China. Dwarf bamboo density had little effect on the dynamics pattern of both N and P concentrations, stocks, resorption efficiency, and resorption proficiency, but strongly affected their absolute values and leaf-level use efficiency. Higher density stands stored more nutrients but had lower concentrations. There was a clear difference in the resorption of limiting nutrient (N) and non-limiting nutrient (P) among the stands. Phosphorus resorption efficiency, N resorption proficiency, and P resorption proficiency increased with increase of stem density, but no significant variation of N resorption efficiency was found among the stands. Moreover, the higher density stands used both N and P more efficiently with higher N productivity and higher P mean residence time, respectively. Higher P productivity was found in the lower density stands, but there was no clear variation in the N mean residence time among stands. These suggested that the higher density stands may have more efficient strategies for utilizing nutrients, especially those which are limiting.

Abe, S. S., Oyediran, G. O., Masunaga, T., Yamamoto, S., Honna, T. and Wakatsuki, T. 2009. Soil development and fertility characteristics of inland valleys in the rain forest zone of Nigeria: Mineralogical composition and particle-size distribution. Pedosphere. 19(4): 505--514.
ABSTRACT: The particle-size distribution and mineralogical composition of the clay ( 2 mm) increased, whereas the proportion of silt and clay (< 0.053 mm) decreased under RNT, indicating a better soil structure that will prevent erosion. RNT helped to control leaching and significantly improved total N, P, K and organic matter in soil. The highest crop yields were found under RNT system every year, and total crop yields were higher under conventional paddy-upland rotation tillage (CR) than under FPF, except in 2003 and 2006 when serious drought occurred. RNT was proven to be a better tillage method for lowland rice-based cropping system.

Shen, R. Y., Luo, Y. M., Feng, S., Zhang, G. Y., Wu, L. H., Li, Z. G., Teng, Y. and Christie, P. 2009. Benzo[a]pyrene and phenanthrene in municipal sludge from the Yangtze River Delta, China. Pedosphere. 19(4): 523--531.
ABSTRACT: To evaluate the contaminated conditions of benzo[a]pyrene (B[a]P) and phenanthrene (PA) in sludge and to ascertain whether B[a]P limit for land application of sludge exists, the contents of B[a]P and PA in 46 sludge samples from 15 cities in the Yangtze River Delta area of China were determined using high performance liquid chromatography (HPLC) coupled with a fluorescence detector after ultrasonic extraction and silica gel cleanup. B[a]P contents ranged from non-detectable to 1.693 mg kg-1 dry weight DW, averaged 0.402 mg kg-1 (DW), and were < 1.0 mg kg-1 DW in most of the sludge samples. PA was found in all the sludge samples analyzed; its contents ranged between 0.028 and 1.355 mg kg-1 DW, with an average value of 0.298 mg kg-1 DW. Most of the sludge samples contained < 0.5 mg kg-1 DW PA. All 46 municipal sludge samples analyzed in this study showed B[a]P contents < 3.0 mg kg-1 DW, which is the limit value for sludge applied to agricultural lands in China. The contents and distributions of B[a]P and PA in municipal sludge were related to sludge types, sources and treatment technologies, along with the physical and chemical properties of these pollutants.

Liu, H. J., Zhang, Y. Z., Zhang, X. L., Zhang, B., Song, K. S., Wang, Z. M. and Tang, N. 2009. Quantitative analysis of moisture effect on black soil reflectance. Pedosphere. 19(4): 532--540.
ABSTRACT: Several studies have demonstrated that soil reflectance decreases with increasing soil moisture content, or increases when the soil moisture reaches a certain content; however, there are few analyses on the quantitative relationship between soil reflectance and its moisture, especially in the case of black soils in northeast China. A new moisture adjusting method was developed to obtain soil reflectance with a smaller moisture interval to describe the quantitative relationship between soil reflectance and moisture. For the soil samples with moisture contents ranging from air-dry to saturated, the changes in soil reflectance with soil moisture can be depicted using a cubic equation. Both moisture threshold (MT) and moisture inflexion (MI) of soil reflectance can also be determined by the equation. When the moisture range was smaller than MT, soil reflectance can be simulated with a linear model. However, for samples with different soil organic matter (OM), the parameters of the linear model varied regularly with the OM content. Based on their relationship, the soil moisture can be estimated from soil reflectance in the black soil region.

Wang, Z. Q., Wu, L. H., Animesh, S. and Zhu, Y. H. 2009. Phytoremediation of rocky slope surfaces: Selection and growth of pioneer climbing plants. Pedosphere. 19(4): 541--544.
ABSTRACT: ÿShort communication, without abstract ÿ

Tian, D. L., Yan, W. D., Fang, X., Kang, W. X., Deng, X. W. and Wang, G. J. 2009. Influence of thinning on soil CO2 efflux in Chinese fir plantations. Pedosphere. 19(3): 273--280.
ABSTRACT: Forest management is expected to influence soil CO2 efflux (FCO2) as a result of changes in microenvironmental conditions, soil microclimate, and root dynamics. Soil FCO2 rate was measured during the growing season of 2006 in both thinning and non-thinning locations within stands ranging from 0 to 8 years after the most recent thinning in Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) plantations in Huitong Ecosystem Research Station, Hunan, China. Soil temperature and moisture were also measured to examine relationships between FCO2 and soil properties. Forest thinning resulted in huge changes in FCO2 that varied with time since cutting. Immediately following harvest (year 0) FCO2 in thinning area increased by about 30%, declined to 20%--27% below pre-cutting levels during years 4--6, and recovered to pre-cutting levels at 8 years post-cutting. A similar temporal pattern, but with smaller changes, was found in non-thinning locations. The initial increase in FCO2 could be attributed to a combination of root decay, soil disturbance, and increased soil temperature in gaps, while the subsequent decrease and recovery to the death and gradual regrowth of active roots. Strong effects of soil temperature and soil water content on FCO2 were found. Forest thinning mainly influenced FCO2 through changes in tree root respiration, and the net result was a decrease in integrated FCO2 flux through the entire felling cycle.

Fernández, J. M., Senesi, N., Plaza, C., Brunetti, G. and Polo, A. 2009. Effects of composted and thermally dried sewage sludges on soil and soil humic acid properties. Pedosphere. 19(3): 281--291.
ABSTRACT: The effect of annual additions of composted sewage sludge (CS) and thermally dried sewage sludge (TS) at 80 t ha-1 on soil chemical properties was investigated for three years in a field experiment under semiarid conditions. Humic acids (HAs) isolated by conventional procedures from CS, TS, and unamended (SO) and sludge amended soils were analysed for elemental (C, H, N, S and O) and acidic functional groups (carboxylic and phenolic) and by ultraviolet-visible, Fourier transform infrared and fluorescence spectroscopies. With respect to CS, TS had similar pH and total P and K contents, larger dry matter, total organic C, total N and C/N ratio and smaller ash content and electrical conductivity. Amendment with both CS and TS induced a number of modifications in soil properties, including an increase of pH, electrical conductivity, total organic C, total N, and available P. The CS-HA had greater O, total acidity, carboxyl, and phenolic OH group contents and smaller C and H contents than TS-HA. The CS-HA and TS-HA had larger N and S contents, smaller C, O and acidic functional group contents, and lower aromatic polycondensation and humification degrees than SO-HA. Amended soil-HAs showed C, H, N and S contents larger than SO-HA, suggesting that sludge HAs were partially incorporated into soil HAs. These effects were more evident with increasing number of sludge applications.

Laveuf, C., Cornu, S., Baize, D., Hardy, M., Josiere, O., Drouin, S., Bruand A. and Juillot, F. 2009. Zinc redistribution in a soil developed from limestone during pedogenesis. Pedosphere. 19(3): 292--304.
ABSTRACT: The long-term redistribution of zinc in a naturally zinc-enriched soil during pedogenesis was quantified based on mass balance calculations. According to their fate, parent limestones comprised three zinc pools: zinc bound to calcite and pyrite-sphalerite grains, zinc bound to phyllosilicates and zinc bound to goethite in the inherited phosphate nodules. Four pedological processes, i.e., carbonate dissolution, two stages of redox processes and eluviation, determined the redistribution of Zn during pedogenesis. The carbonate dissolution of limestones released Zn bound to calcite into soil solution. Due to residual enrichment, Zn concentrations in the soil are higher than those in parent limestones. Birnessite, ferrihydrite and goethite dispersed in soil horizon trapped high quantities of Zn during their formation. Afterwards, primary redox conditions induced the release of Zn and Fe into soil solution, and the subsequent individualization of Fe and Mn into Zn-rich concretions. Both processes and subsequent aging of the concretions formed induced significant exportation of Zn through the bottom water table. Secondary redox conditions promoted the weathering of Fe and Mn oxides in cements and concretions. This process caused other losses of Zn through lateral exportation in an upper water table. Concomitantly, eluviation occurred at the top of the solum. The lateral exportation of eluviated minerals through the upper water table limited illuviation. Eluviation was also responsible for Zn loss, but this Zn bound to phyllosilicates was not bioavailable.

Hao, X. Z., Zhou, D. M., Huang, D. Q., Cang, L., Zhang, H. L. and Wang, H. 2009. Heavy metal transfer from soil to vegetable in southern Jiangsu Province, China. Pedosphere. 19(3): 305--311.
ABSTRACT: Vegetable fields in peri-urban areas receive large amounts of extraneous heavy metals because of rapid urbanization and industrialization in China. The concentrations of Cu, Zn, and Pb in 30 soil samples and 32 vegetable samples, collected from 30 different sites in southern Jiangsu Province of China, were measured and their transfer from soil to vegetable was determined. The results showed that the soil samples had wide ranges of pH (4.25--7.85) and electrical conductivity (EC) (0.24--3.42 dS m-1). Among the soil samples, there were four soil samples containing higher Cu and two soil samples containing higher Zn concentrations than those specified in the Chinese Soil Environmental Quality Standard II. However, no vegetable sample was found to contain a high level of Cu or Zn. In contrast, one vegetable sample contained 0.243 mg Pb kg-1 FW, which was above the Chinese Food Hygiene Standard, whereas the corresponding soil Pb concentration was lower than the Chinese Soil Environmental Quality Standard II. The transfer coefficients of Cu of all vegetable samples exceeded the suggested coefficient range, implying that extraneous Cu had high mobility and bioavailability to vegetables. There was no significant correlation between extractable soil heavy metal concentrations with four kinds of extractants and soil pH, EC, heavy metal concentrations in vegetables and soils, except that soil pH correlated well with the extractable soil Cu, Zn, and Pb concentrations with 1.0 mol L-1 NH4NO3. Moreover, diethylenetriamine pentaacetic acid (DTPA) extraction method was a more efficient method of extracting heavy metals from the soils independent of soil pH and EC than other three methods used.

Sant’anna, S. A. C., Fernandes, M. F., Ivo, W. M. P. M. and Costa, J. L. S. 2009. Evaluation of soil quality indicators in sugarcane management in sandy loam soil. Pedosphere. 19(3): 312--322.
ABSTRACT: An important factor for the sustainability of soils highly susceptible to degradation is the use of monitoring tools that promptly and realistically reflect changes imposed on soil by different cropping systems. To select soil quality indicator variables in sugarcane (Saccharum officinarum L.) production areas that fulfill the criteria of sensitivity to management practices and between-season consistency in the management discrimination, ten composite soil samples (0--10 cm) were collected in July 2005 (rainy season) and again in March 2006 (dry season) from areas under cultivation of organic sugarcane (OS), green sugarcane (GS), burned sugarcane (BS) and from an adjacent native forest (NF) area at Usina Triunfo, Boca da Mata, Alagoas, Brazil. Microbial biomass-C (MBC), total organic C (TOC), soil enzyme activity expressed as the rate of fluorescein diacetate (FDA) hydrolysis, mean weight diameter of water-stable soil aggregates (MWD), and percentage of water-stable macroaggregates (PWSA) were analyzed. Although MBC and TOC were higher in NF than in the cultivated areas, no differences were observed in these C pools between the three sugarcane systems. The response of FDA to the site management was dependent on the sampling time. In the rainy period, the activity followed the order: NF > OS > GS > BS, whereas in the dry season, only NF differed from the other treatments. Irrespective of the sampling time, MWD and PWSA decreased in the order NF > OS = GS > BS. The variables MWD and PWSA are quite sensitive for discriminating between site management histories regardless the sampling season.

Fan, M. S., Li, Z., Wang, F. M. and Zhang J. H. 2009. Growth and phosphorus uptake of oat (Avena nuda L.) as affected by mineral nitrogen forms supplied in hydroponics and soil culture. Pedosphere. 19(3): 323--330.
ABSTRACT: Plants show different growth responses to N sources supplied with either NH4+ or NO3-. The uptake of different N sources also affects the rhizosphere pH and therefore the bioavailability of soil phosphorus, particularly in alkaline soils. The plant growth, P uptake, and P availability in the rhizosphere of oat (Avena nuda L.) grown in hydroponics and in soil culture were investigated under supply with sole NH4+-N, sole NO3--N, or a combination. Sole NO3--fed oat plants accumulated more biomass than sole NH4+-fed ones. The highest biomass accumulation was observed when N was supplied with both NH4+-N and NO3--N. Growth of the plant root increased with the proportion of NO3- in the cultural medium. Better root growth and higher root/shoot ratio were consistently observed in NO3--fed plants. However, root vigor was the highest when N was supplied with NO3-+NH4+. NH4+ supply reduced the rhizosphere pH but did not affect P uptake by plants grown in soils with CaHPO4 added as P source. No P deficiency was observed, and plant P concentrations were generally above 2 g kg-1. P uptake was increased when N was supplied partly or solely as NO3--N, similarly as biomass accumulation. The results suggested that oat was an NO3--preferring plant, and NO3--N was essential for plant growth and the maintenance of root absorption capacity. N supply with NH4+-N did not improve P nutrition, which was most likely due to the absence of P deficiency.

Karimov, A., Qadir, M., Noble, A., Vyshpolsky, F. and Anzelm, K. 2009. Development of magnesium-dominant soils under irrigated agriculture in southern Kazakhstan. Pedosphere. 19(3): 331--343.
ABSTRACT: Irrational irrigation practices in the Arys Turkestan Canal command area in the southern part of Kazakhstan have led to the formation of soils with poor physical and chemical properties. To study whether irrigation and leaching practices and/or groundwater rise have contributed to the accumulation of Mg2+ on the cation exchange complex of these soils, historical changes in soil and groundwater quality were used as source data and the Visual MINTEQ model was applied to analyze the chemical composition of water and soils in the study area. The imposed irrigation regime and the leaching of light sierosem soils led to the dissolution and subsequent leaching of inherent gypsum and organic matter from the soil profile. Further, the domination of bicarbonate in the irrigation water promoted weathering of the carbonate minerals present as calcite. The higher concentrations of Mg2+ in comparison to Ca2+ in the irrigation water resulted in the replacement of Na+ by Mg2+ on the cation exchange complex. In the lower part of the command area, shallow groundwater has contributed to the accumulation of Na+ and to a large extent of Mg2+ on the cation exchange sites.

Subedi, M., Hocking, T. J., Fullen, M. A., McCrea, A. R., Milne, E., Wu, B. Z. and Mitchell, D. J. 2009. Use of farmers’ indicators to evaluate the sustainability of cropping systems on sloping land in Yunnan Province, China. Pedosphere. 19(3): 344--355.
ABSTRACT: Diversity in the biophysical and socio-economic attributes of agricultural systems makes them uniquely niche based. Farmers are expert in local biophysical and socio-economic situations and can contribute in developing pragmatic indicators of agro-environmental development. During evaluation of an agricultural research project in Yunnan, China, local farmers were capable of evaluating the effects of modified technologies on existing cropping systems and discussed their attitudes to the interventions using their own indicators. Farmers’ response can be grouped into seven major aspects: i) effects on income, ii) effects on production resources, iii) effects on crop management, iv) existing local knowledge about the technology, v) availability of inputs, vi) access to information, and vii) socio-economic conditions of farming households. Farmers concluded that environmental conditions in the experimental catchment in comparison to an adjacent untreated catchment were better in terms of soil and water losses, vegetation cover and natural resources, infrastructures and catchment management, use of environmentally-friendly technologies, and crop productivity. Success in soil and water conservation programmes depends on the efforts of the farmers and other local users and their greater involvement helps to identify more pragmatic indicators. Furthermore, it increases ownership of the programme, enhances interactions with the project scientists, increases farmers’ awareness of agro-environmental problems and their possible consequences. These development will enable scientists to develop better targeted interventions and increase the likelihood of adoption of tested technologies by local communities. The use of paired adjacent catchments improved evaluation activities and is proposed as good practice for future catchment improvement programmes.

Chen, Y. F., Liu, Y. S., Wang, J., Yan, J. P. and Guo, X. D. 2009. Land use changes of an aeolian-loessial soil area in Northwest China: Implications for ecological restoration. Pedosphere. 19(3): 356--361.
ABSTRACT: China has experienced dramatic land use changes over recent decades, with marked environmental and socio-economic consequences. Hengshan County, located in the aeolian-loessial area of Northwest China, was investigated to illustrate land use changes and their implications for environmental and long-term rural economic development. The farmland in Hengshan County significantly decreased during 1990--2003, whereas forest land and grassland increased. The conversion rates of farmland, orchard land, forest land and construction land varied markedly among different periods: 1990--1995, 1995--2000 and 2000--2003. Conversion of orchard land, grassland and construction land was dominant in 1990--1995, whereas the conversion of farmland to forest land mainly occurred in 2000--2003. The results suggested a profound transition in institutional policy and political economy of land management, including implementation of integrated soil erosion control projects, adoption of a market-oriented economy and the ‘Grain-for-Green’ policy, during this period in China. To achieve long-term sustainable land use in Hengshan County, efforts should aim at increasing off-farm income of rural families as well as establishing land-economizing mechanisms to promote land productivity, in addition to conservation measures.

Chi, B. L., Bing, C. S., Walley, F. and Yates, T. 2009. Topographic indices and yield variability in a rolling landscape of western Canada. Pedosphere. 19(3): 362--370.
ABSTRACT: Understanding the relationships between topographic indices and crop yield variability is important for soil management and crop production in rolling landscape. Two agricultural fields at Alvena and Hepburn, Saskatchewan, Canada were selected to examine how topographic indices were related to wheat yield under two topographic and weather conditions in the Canadian prairies. The landscapes of the two sites are classified as hummocky and the dominant soil type is an Aridic Ustoll. The relationships among yield, topography, soil, and weather were analyzed using wheat (Triticum aestivum L.) grain yield from Alvena in 2001 (dry year) and 2004 (wet year) and from Hepburn in 1998 (dry year). Topographic/soil indices included relative elevation, wetness index, upslope length, curvature, soil organic matter, and soil moisture storage before seeding. The results indicated that, in the dry years, the correlation coefficients between upslope length and grain yield were 0.79 for the typical rolling landscape (Alvena) in 2001 and 0.73 for shallow gentle rolling landscape (Hepburn) in 1998. In the wet year (2004), the relationships between yield and topographic/soil attributes were not as strong as in dry years. Therefore, upslope length was the best yield indicator for the two landscapes in dry years, whereas no topographic indices were highly correlated to crop yield in wet years. Those topographic indices seemed useful in identifying the yield variability and delineating the proper management zone.

Yang, S. Z., Jin, H. J., Wei, Z., He, R. X., Ji, Y. J., Li. X. M. and Yu, S. P. 2009. Bioremediation of oil spills in cold environments: A review. Pedosphere. 19(3): 371--381.
ABSTRACT: Oil spills have become a serious problem in cold environments with the ever-increasing resource exploitation, transportation, storage, and accidental leakage of oil. Several techniques, including physical, chemical, and biological methods, are used to recover spilled oil from the environment. Bioremediation is a promising option for remediation since it is effective and economic in removing oil with less undue environmental damages. However, it is a relatively slow process in cold regions and the degree of success depends on a number of factors, including the properties and fate of oil spilled in cold environments, and the major microbial and environmental limitations of bioremediation. The microbial factors include bioavailability of hydrocarbons, mass transfer through the cell membrane, and metabolic limitations. As for the environmental limitations in the cold regions, the emphasis is on soil temperatures, freeze-thaw processes, oxygen and nutrients availability, toxicity, and electron acceptors. There have been several cases of success in the polar regions, particularly in the Arctic and sub-Arctic regions. However, the challenges and constraints for bioremediation in cold environments remain large.

Li, J. X., Zhang, W. X., Liao, C. H., Yang, Y. P. and Fu, S. L. 2009. Responses of earthworms to organic matter at different stages of decomposition. Pedosphere. 19(3): 382--388.
ABSTRACT: This study was conducted to examine the responses of earthworms to soil organic matter and litter at different decomposition stages and their contributions in litter decomposition processes in southern subtropical areas of China. Two plantations were selected as the study sites: Site I was dominated by the exotic endogeic earthworm species Ocnerodrilus occidentalis; Site II was dominated by epigeic species Amynthas corticis. After the fallen litter and earthworms were removed or expelled, four treatments were set up as: reserving the top soil (0--5 cm, equal to H layer) (H), removing the top soil and adding fresh litter (Le), removing the top soil and adding semi-decomposed litter (Li), and a control with no top soil nor any litter (CK). Five randomized blocks that were enclosed with nylon nets on the top were set up in each site, and then the four treatments were arranged randomly in each block. After 2-3 months, earthworms were collected using the formalin method. The results showed that Ocnerodrilus occidentalis preferred Treatment H, though it was found in Treatments Le and Li as well; Amynthas corticis preferred Treatment Li, though sometimes it also appeared in Treatment H; and Amynthas sp., another epigeic species, was mainly present under Treatment Le and only appeared in Treatment H occasionally. These findings confirmed that earthworm species belonging to different ecological groups had different responses to organic matter at different decomposition stages. The impacts of earthworm communities dominated by O. occidentalis mainly appeared at the later periods of litter decomposition.

Liu, J., Han, Y. and Cai, Z. C. 2009. Decomposition and products of wheat and rice straw from a FACE experiment under flooded conditions. Pedosphere. 19(3): 389--397.
ABSTRACT: Winter wheat and rice straw produced under ambient and elevated CO2 in a China rice-wheat rotation free-air CO2 enrichment (FACE) experiment was mixed with a paddy soil at a rate of 10 g kg-1 (air-dried), and the mixture was incubated under flooded conditions at 25 oC to examine the differences in decomposition as well as the products of crop residues produced under elevated CO2. Results showed that the C/N ratio and the amount of soluble fraction in the amended rice straw grown under elevated CO2 (FR) were 9.8% and 73.1% greater, and the cellulose and lignin were 16.0% and 9.9% lesser than those of the amended rice straw grown under ambient CO2 (AR), respectively. Compared with those of the AR treatment, the CO2-C and CH4-C emissions in the FR treatment for 25 d were increased by 7.9% and 25.0%, respectively; a higher ratio of CH4 to CO2 emissions induced by straw in the FR treatment was also observed. In contrast, in the treatments with winter wheat straw, the CO2-C and CH4-C productions, the ratio of straw-induced CH4 to CO2 emissions, and the straw composition were not significantly affected by elevated CO2, except for an 8.0% decrease in total N and a 9.7% increase in C/N ratio in the wheat straw grown under elevated CO2. Correlation analysis showed that the net CO2-C and CH4-C emissions from straw and the ratio of straw-induced CH4 to CO2 emissions were all exponentially related to the amount of soluble fraction in the amended straw (P < 0.05). These indicated that under flooded conditions, the turnover and CH4 emission from crop straw incorporated into soil were dependent on the effect of elevated CO2 on straw composition, and varied with crop species. Incorporation of rice straw grown under elevated CO2 would stimulate CH4 emission from flooded rice fields, whereas winter wheat straw grown under elevated CO2 had no effect on CH4 emission.

Ashraf, M, Rahmatullah, Maqsood, M. A., Kanwal, S., Tahir, M. A. and Ali, L. 2009. Growth responses of wheat cultivars to rock phosphate in hydroponics. Pedosphere. 19(3): 398--402.
ABSTRACT: Screening cultivars to grow under conditions of low phosphorus (P) availability and utilize P efficiently from compounds of low solubility in soils may be beneficial to overcome poor plant growth in P-deficient soils. The growth behavior and P utilization efficiency of seven wheat cultivars grown in hydroponics were studied, using rock phosphate as P source. The wheat cultivars grown for 30 days were significantly different in biomass accumulation, P uptake and P utilization efficiency. The dry matter production of all the cultivars was significantly correlated with P uptake, which in turn correlated to the drop in the root medium pH. The ranking of wheat cultivars on the basis of dry matter yield, P uptake and P utilization efficiency was Zamindar 80 > Yecora > C 271 > WL 711 > Barani 83 > PARI 73 > Rohtas. The cultivar Zamindar 80 appeared to possess the best growth potential in P-deficient soils.

Shi, L., Wang, Y. H., Nian, F. Z., Lu, J. W., Meng, J. L. and Xu, F. S. 2009. Inheritance of boron efficiency in oilseed rape. Pedosphere. 19(3): 403--408.
ABSTRACT: Field experiments were conducted to study the inheritance of boron efficiency in oilseed rape (Brassica napus L.) by evaluating the boron (B) efficiency coefficient (BEC, the ratio of the seed yield at below the critical boron level to that at the boron-sufficient level) with 657 F2:3 lines of a population derived from a cross between a B-efficient cultivar, Qingyou 10, and a B-inefficient cultivar, Bakow. Qingyou 10 had high BEC as well as high seed yield at low available soil B. On the contrary, Bakow produced low seed yield at low B status. Boron deficiency decreased the seed yield of the F2:3 lines to different extents and the distribution of BEC of the population showed a bimodal pattern. When the 657 F2:3 lines were grouped into B-efficient lines and B-inefficient lines according to their BEC, the ratio of B-efficient lines to B-inefficient lines fitted the expected ratio (3:1), indicating that one major gene controlled the B-efficiency trait. 127 F2:3 lines selected from the population at random, with distribution of BEC similar to that of the overall population, were used to identify the target region for fine mapping of the boron efficiency gene.

Zhu, Z. L., Zhang, L. H., Zhang, H., Qiu, Y. L., Zhang, R. H. and Zhao, J. F. 2009. Extraction of cadmium from sewage sludge using polyepoxysuccinic acid. Pedosphere. 19(2): 137--142.
ABSTRACT: Polyepoxysuccinic acid (PESA), as an environmental benign biodegradable chelant, was used to remove heavy metals from the sewage sludge of Shanghai Taopu Wastewater Treatment Plant. The extraction of cadmium (Cd) from sewage sludge using aqueous solution of PESA was studied. It was found that PESA was capable of extracting Cd from the sludge, and the extraction efficiency was dependent on both pH and the concentration of the chelating reagent. The extraction efficiency decreased gradually with increasing of pH, whereas the dependency on pH decreased as the concentration of PESA increased. In the case of the high PESA to total metal ratio, e.g., 10:1, the extraction efficiency reached above 70% within the pH range from 1 to 7. The highest extraction efficiency obtained in the experiment was 78ÿ. By comparing the contents of the heavy metals in sewage sludge before and after the extraction, it was found that the extracted Cd came mainly from the four fractions: acid-soluble, reducible, oxidizable, and water-soluble fractions.

Mench, M. and Bes, C 2009. Assessment of the ecotoxicity of topsoils from a wood treatment site. Pedosphere. 19(2): 143--155.
ABSTRACT: A series of 9 soil samples were taken at a timber treatment site in SW France where Cu sulphate and chromated copper arsenate (CCA) have been used as wood preservatives (Sites P1 to P9) and one soil sample was collected at an adjacent site on the same soil type (Site P10). Copper was a major contaminant in all topsoils, varying from 65 (Soil P5) to 2600 mg Cu kg-1 (Soil P7), exceeding background values for French sandy soils. As and Cr did not accumulate in soil, except at Site P8 (52 mg As kg-1and 87 mg Cr kg-1) where CCA-treated posts were stacked. Soil ecotoxicity was assessed with bioassays using radish, lettuce, slug Arion rufus L., and earthworm Dendrobaena octaedra (Savigny). There were significantly differences in lettuce germination rate, lettuce leaf yield, radish root and leaf yields, slug herbivory, and earthworm avoidance. An additional bioassay showed higher negative impacts on bean shoot and root yields, Rhizobium nodule counts on Bean roots, and guaiacol peroxidase activity in primary Bean leaves for soil from Site P7, with and without fertilisation, than for soil from Site P10, despite both soils having a similar value for computed free ion Cu2+ activity in the soil solution (pCu2+). Beans grown in soil from Site P7 that had been fertilised showed elevated foliar Cu content and phytotoxic symptoms. Soils from Sites P7 (treatment plant) and P6 (storage of treated utility poles) had the highest ecotoxicity, whereas soil from Site P10 (high organic matter content and cation exchange capacity) had the lowest. Except at Site P10, the soil factor pCu2+ computed with soil pH and total soil Cu could be used to predict soil ecotoxicity.

Wang, G. H., Jin, J., Liu, J. J., Chen, X. L., Liu, J. D. and Liu, X. B. 2009. Bacterial community structure in a Mollisol Under long-term natural restoration, cropping, and bare fallow history estimated by PCR-DGGE. Pedosphere. 19(2): 156--165.
ABSTRACT: Soil microbial biomass and community structures are commonly used as indicators for soil quality and fertility. A investigation was performed to study the effects of long-term natural restoration, cropping, and bare fallow managements on the soil microbial biomass and bacterial community structures in depths of 0--10, 20--30, and 40--50 cm in a black soil (Mollisol). Microbial biomass was estimated from chloroform fumigation-extraction, and bacterial community structures were determined by analysis of 16S rDNA using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Experimental results showed that microbial biomass significantly declined with soil depth in the managements of restoration and cropping, but not in the bare fallow. DGGE profiles indicated that the band number in top 0--10 cm soils was less than that in depth of 20--30 or 40--50 cm. These suggested that the microbial population was high but the bacterial community structure was simple in the topsoil. Cluster and principle component analysis based on DGGE banding patterns showed that the bacterial community structure was affected by soil depth more primarily than by managements, and the succession of bacterial community as increase of soil depth has a similar tendency in the three managements. Fourteen predominating DGGE bands were excised and sequenced, in which 6 bands were identified as the taxa of Verrucomicrobia, 2 bands as Actinobacteria, 2 bands as ±-Proteobacteria, and the other 4 bands as ´-Proteobacteria, Acidobacteria, Nitrospira, and unclassified bacteria. In addition, the sequences of 11 DGGE bands were closely related to uncultured bacteria. Thus, the bacterial community structure in black soil was stable, and the predominating bacterial groups were uncultured.

García, I., Diez, M., Martín, F., Simón, M. and Dorronsoro, C. 2009. Mobility of arsenic and heavy metals in a sandy-loam textured and carbonated soil. Pedosphere. 19(2): 166--175.
ABSTRACT: The continued effect of the pyrite-tailing oxidation on the mobility of arsenic, lead, zinc, cadmium, and copper was studied in a carbonated soil under natural conditions, with the experimental plot preserved with a layer of tailing covering the soil during three years. The experimental area is located in Southern Spain and was affected by a pyrite-mine spill. The climate in the area is typically Mediterranean, which determines the rate of soil alteration and element mobility. The intense alteration processes that occurred in the soil during three years caused important changes in its morphology and a strong degradation of the main soil properties. In this period, lead concentrated in the first 5 mm of the soil, with concentrations higher than 1 500 mg kg-1, mainly associated to the neoformation of plumbojarosite. Arsenic was partially leached from the first 5 mm and mainly concentrated between 5--10 mm in the soil, with maximum values of 1 239 mg kg-1; the retention of arsenates was related to the neoformation of iron hydroxysulfates (jarosite, schwertmannite) and oxyhydroxides (goethite, ferrihydrite), both with a variable degree of crystallinity. The mobility of Zn, Cd, and Cu was highly affected by pH, producing a stronger leaching in depth; their retention was related to the forms of precipitated aluminium and, in the case of Cu, also to the neoformation of hydroxysulfate.

Yang, X. H., Wang, F. M., Huang, J. F., Wang, J. W., Wang, R. C., Shen, Z. Q. and Wang, X. Z. 2009. Comparison between radial basis function neural network and regression model for estimation of rice biophysical parameters using remote sensing. Pedosphere. 19(2): 176--188.
ABSTRACT: The radial basis function (RBF) emerged as a variant of artificial neural network. Generalized regression neural network (GRNN) is one type of RBF, and its principal advantages are that it can quickly learn and rapidly converge to the optimal regression surface with large number of data sets. Hyperspectral reflectance (350 to 2 500 nm) data were recorded at two different rice sites in two experiment fields with two cultivars, three nitrogen treatments and one plant density (45 plants m-2). Stepwise multivariable regression model (SMR) and RBF were used to compare their predictability for the leaf area index (LAI) and green leaf chlorophyll density (GLCD) of rice based on reflectance (R) and its three different transformations, the first derivative reflectance (D1), the second derivative reflectance (D2) and the log-transformed reflectance (LOG). GRNN based on D1 was the best model for the prediction of rice LAI and GLCD. The relationships between different transformations of reflectance and rice parameters could be further improved when RBF was employed. Owing to its strong capacity for nonlinear mapping and good robustness, GRNN could maximize the sensitivity to chlorophyll content using D1. It is concluded that RBF may provide a useful exploratory and predictive tool for the estimation of rice biophysical parameters.

Lu, X. K., Mo, J. M., Gundersern, P., Zhu, W. X., Zhou, G. Y., Li, D. J. and Zhang, X. 2009. Effect of simulated N deposition on soil exchangeable cations in three forest types of subtropical China. Pedosphere. 19(2): 189--198.
ABSTRACT: The effects of simulated nitrogen (N) deposition on soil exchangeable cations were studied in three forest types of subtropical China. Four N treatments with three replications were designed for the monsoon evergreen broadleaf forest (mature forest): control (0 kg N ha-1 year-1), low N (50 kg N ha-1 year-1), medium N (100 kg N ha-1 year-1) and high N (150 kg N ha-1 year-1), and only three treatments (i.e., control, low N, medium N) were established for the pine and mixed forests. Nitrogen had been applied continuously for 26 months before the measurement. The mature forest responded more rapidly and intensively to N additions than the pine and mixed forests, and exhibited some significant negative symptoms, e.g., soil acidification, Al mobilization and leaching of base cations from soil. The pine and mixed forests responded slowly to N additions and exhibited no significant response of soil cations. Response of soil exchangeable cations to N deposition varied in the forests of subtropical China, depending on soil N status and land-use history.

Zhang, H. M., Wang, B. R., Xu, M. G. and Fan, T. L. 2009. Crop yield and soil responses to long-term fertilization on a red soil in southern China. Pedosphere. 19(2): 199--207.
ABSTRACT: A 15-year fertilization experiment with different applications of inorganic N, P and K fertilizers and farmyard manure (M) was conducted to study the yield and soil responses to long-term fertilization at Qiyang, Hunan Province, China. Average grain yields of wheat and corn (1 672 and 5 111 kg ha-1, respectively) for the treatment NPKM were significantly higher than those (405 and 310 kg ha-1) of the unfertilized control and single inorganic fertilizer treatments. Compared with the corresponding initial values of the experiment, all treatments showed a yield decline of 9 to 111 kg ha-1 year-1 in wheat and 35 to 260 kg ha-1 year-1 in corn, respectively, and a significant pH decline of 0.07 to 0.12 pH year-1, except for the treatments PK and NPKM. After long-term fertilization, the soil organic C, soil available P, exchangeable Ca2+ and Mg2+ and available Cu2+ and Zn2+ contents were higher in the treatment NPKM than in the treatments applied with inorganic fertilizer only. Compared to the treatment NPK, the treatment NPKM, where manure partially replaced inorganic N, had a positive impact on arresting the decline of soil pH. This improved grain yields of wheat and corn, suggesting that application of NPK fertilizer in combination with farmyard manure is important to maintain soil fertility and buffering capacity in red soil.

Long, X. H., Chi, J. H., Liu, L., Li, Q. and Liu, Z. P. 2009. Effect of seawater stress on physiological and biochemical responses of five Jerusalem artichoke ecotypes. Pedosphere. 19(2): 208--216.
ABSTRACT: Three treatments consisting of 0%, 15%, and 30% seawater were investigated to analyse the ecotypic variabilities among five populations of Jerusalem artichoke (Helianthus tuberosus) regarding their responses to seawater stress under a hydroponic culture system. Analyses were done 2, 4, and 6 days after treatments. The 15% and 30% seawater treatments reduced the growth rates of roots and shoots of H. tuberosus populations. The activities of superoxide dismutase, peroxidase, and catalase majored in the leaves were stimulated under the seawater stress. The electrolyte leakage and malondialdehyde contents of the leaves were also stimulated owing to seawater stress. The contents of proline and soluble-sugars in the leaves increased significantly with increasing seawater concentrations. The concentrations of Na+, K+, and Cl- in the aerial parts and roots increased with an increase in the seawater concentration throughout the experimental period. There were ecotypic differences among the five populations of H. tuberosus as evidenced by the analyses of the above items in both aerial parts and roots under seawater treatment. The magnitude of the ecotypic variance components indicated that a substantial proportion of the total variation for these physiological and biochemical responses were owing to ecotype, indicating the possibility of improvement through hybridization and selection.

Stavi, I., Lavee, H., Ungar, E. D. and Sarah, P. 2009. Ecogeomorphic feedbacks in semiarid rangelands: A review. Pedosphere. 19(2): 217--229.
ABSTRACT: The ecogeomorphic processes occurring on semiarid rangelands are reviewed, with emphasis on the source-sink relations and positive feedback loops that existed between shrub patches and intershrub areas, and the way livestock presence affected these interactions. Compared with intershrub areas, the shrub patches had a higher soil porosity, infiltration capacity, water-holding capacity, hydraulic conductivity, structural stability, and organic matter content, and lower bulk density. These differences derived from a host of processes whose intensity was less in the shrub patches, including raindrop impact, mechanical crust formation, overland water flow, soil erosion, evaporative moisture loss, and flock trampling. There was also greater shading of the soil surface; soil and litter deposition; water accumulation; microbial, fungal, and mesofaunal activities in the shrub patches. The overland flow of water carried soil and litter from the intershrub areas to the shrub patches and resulted in microtopographic modifications that tended to strengthen these source-sink relations. Grazing had an impact on these processes, not only at the shrub-intershrub scale but also within the intershrub areas, through the creation of highly compacted trampling routes. The combined role of the above ecogeomorphic processes was to maintain the rangeland’s functionality. Without these inter-relationships, water loss, soil erosion, and nutrient depletion would occur at the hillside scale, causing degradation of the landscape.

Deng, X. W., Han, S. J., Hu, Y. L. and Zhou, Y. M. 2009. Carbon and nitrogen transformations in surface soils under Ermans birch and dark coniferous forests. Pedosphere. 19(2): 230--237.
ABSTRACT: Soil samples were taken from an Ermans birch (Betula ermanii)-dark coniferous forest (Picea jezoensis and Abies nephrolepis) ecotone growing on volcanic ejecta in the northern slope of Changbai Mountains of Northeast China, to compare soil carbon (C) and nitrogen (N) transformations in the two forests. The soil type is Umbri-Gelic Cambosols in Chinese Soil Taxonomy. Soil samples were incubated aerobically at 20 °ðC and field capacity of 700 g kg-1 over a period of 27 weeks. The amount of soil microbial biomass and net N mineralization were higher in the Ermans birch than the dark coniferous forest (P < 0.05), whereas the cumulative C mineralization (as CO2 emission) in the dark coniferous forest exceeded that in the Ermans birch (P < 0.05). Release of the cumulative dissolved organic C and dissolved organic N were greater in the Ermans birch than the dark coniferous forest (P < 0.05). The results suggested that differences of forest types could result in considerable change in soil C and N transformations.

Xu, J. L., Wu, J., Wang, Z. C., Wang, K., Li, M. Y., Jiang, J. D., He, J. and Li, S. P. 2009. Isolation and characterization of a methomyl-degrading Paracoccus sp. mdw-1. Pedosphere. 19(2): 238--243.
ABSTRACT: Methomyl, an extremely toxic pesticide, is widely used in agriculture. A strain named mdw-1 capable of degrading methomyl rapidly was successfully isolated from activated sludge in this study. It could utilize methomyl as the sole carbon or nitrogen source. The optimal temperature and medium pH for its growth and methomyl biodegradation were 30 ºC and 7.0, respectively. It was identified as a Paracoccus sp. according to its morphological features, physiological and biochemical characteristics, and phylogenetic analysis based on the sequence of 16S rDNA. Gas chromatography-mass spectrometry (GC-MS) analysis showed that methomyl could be completely transformed to S-methyl-N-hydroxythioacetamidate in 10 h of incubation with the isolate mdw-1.

Zhou, W. J., Zhang, Y. Z., Wang, K. R., Li, H. S., Hao, Y. J. and Liu, X. 2009. Plant phosphorus uptake in a soybean-citrus intercropping system in the red soil hilly region of South China. Pedosphere. 19(2): 244--250.
ABSTRACT: A field microplot experiment was conducted in the red soil hilly region of South China to evaluate plant phosphorus (P) uptake under soybean and citrus monoculture and the soybean-citrus intercropping system using the 32P tracer technique. P fertilizer was applied at three depths (15, 35, and 55 cm). The experimental results showed that the planting pattern and 32P application depth significantly affected the characteristics of P uptake by soybean and citrus. Under the soybean-citrus intercropping system, considerable competition was observed when the 32P fertilizer was applied to the topsoil (15 cm); therefore, the 32P recovery rate declined by 41.5% and 14.7% for soybean and citrus, and 32P supplying amount of topsoil to soybean and citrus decreased by 346.8 and 148.1 mg plot-1, respectively, compared to those under the monoculture. However, 32P recovery of soybean was promoted when 32P fertilizer was applied to the deeper soil layers (35 and 55 cm) under soybean-citrus intercropping. Under the soybean monoculture, 32P fertilizer could hardly be used by soybean when 32P fertilizer was applied at the 55 cm depth or below, with the recovery rate being less than 0.1%; it was up to 0.253% by soybean under intercropping. The higher P recovery of soybean under soybean-citrus intercropping when P was applied in the deeper soil layers was because part of the P nutrient that the citrus absorbed from the deeper soil layers could be released into the topsoil and then it could be used by the soybean.

Xue, W. B., Yi, A. H., Zhang, Z. Q., Tang, C. L., Zhang, X. C. and Gao, J. M. 2009. A new competitive adsorption isothermal model of heavy metals in soils. Pedosphere. 19(2): 251--257.
ABSTRACT: A new competitive adsorption isothermal model (CAIM) was developed for the coexistent and competitive binding of heavy metals to the soil surface. This model extended the earlier adsorption isothermal models by considering more than one kind of ion adsorption on the soil surface. It was compared with the Langmuir model using different conditions, and it was found that CAIM, which was suitable for competitive ion adsorption at the soil solid-liquid surface, had more advantages than the Langmuir model. The new competitive adsorption isothermal model was used to fit the data of heavy metal (Zn and Cd) competitive adsorption by a yellow soil at two temperatures. The results showed that CAIM was appropriate for the competitive adsorption of heavy metals on the soil surface at different temperatures. The fitted parameters of CAIM had explicit physical meaning. The model allowed for the calculation of the standard molar Gibbs free energy change, the standard molar enthalpy change, and the standard molar entropy change of the competitive adsorption of the heavy metals, Zn and Cd, by the yellow soil at two temperatures using the thermodynamic equilibrium constants.

Wu, Q. B., Wang, X. K. and Ouyang, Z. Y. 2009. Soil organic carbon and its fractions across vegetation types: Effects of soil mineral surface area and microaggregates. Pedosphere. 19(2): 258--264.
ABSTRACT: Soil organic carbon (SOC) can act as a sink or source of atmospheric carbon dioxide; therefore, it is important to understand the amount and composition of SOC in terrestrial ecosystems, the spatial variation in SOC, and the underlying mechanisms that stabilize SOC. In this study, density fractionation and acid hydrolysis were used to assess the spatial variation in SOC, the heavy fraction of organic carbon (HFOC), and the resistant organic carbon (ROC) in soils of the southern Hulun Buir region, northeastern China, and to identify the major factors that contribute to this variation. The results showed that as the contents of clay and silt particles (0--50 µm) increased, both methylene blue (MB) adsorption by soil minerals and microaggregate contents increased in the 0--20 and 20--40 cm soil layers (P < 0.05). Although varying with vegetation types, SOC, HFOC, and ROC contents increased significantly with the content of clay and silt particles, MB adsorption by soil minerals, and microaggregate content (P < 0.05), suggesting that soil texture, the MB adsorption by soil minerals, and microaggregate abundance might be important factors influencing the spatial heterogeneity of carbon contents in soils of the southern Hulun Buir region.

Xu, S. Y., Chen, Y. X., Lin, K. F., Chen, X. C., Lin, Q., Li, F. and Wang, Z. W. 2009. Removal of pyrene from contaminated soils by white clover. Pedosphere. 19(2): 265--272.
ABSTRACT: Phytoremediation has been used as an emerging technology for remediation of soil contamination with polycyclic aromatic hydrocarbons (PAHs), ubiquitous persistent environmental pollutants derived from natural and anthropogenic processes, in the last decade. In this study, a pot experiment was conducted to investigate the potential of phytoremediation of pyrene from spiked soils planted with white clover (Trifolium repens) in the greenhouse with a series of pyrene concentrations ranging from 4.22 to 365.38 mg kg-1. The results showed that growth of white clover on pyrene-contaminated soils was not affected. The removal of pyrene from the spiked soils planted with white clover was obviously higher than that from the unplanted soils. At the end of the experiment (60 d), the average removal ratio of pyrene in the spiked soils with white clover was 77%, which was 31% and 57% higher than those of the controls with or without micobes, respectively. Both roots and shoots of white clover took up pyrene from the spiked soils and pyrene uptake increased with the soil pyrene concentration. However, the plant-enhanced dissipation of soil pyrene may be the result of plant-promoted microbial degradation and direct uptake and accumulation of pyrene by white clover were only a small part of the pyrene dissipation. Bioconcentration factors of pyrene (BCFs, ratio of pyrene, on a dry weight basis, in the plant to that in the soil) tended to decrease with increase in the residual soil pyrene concentration. Therefore, removal of pyrene in the contaminated soils was feasible using white clove.

Montagne, D., Cornu, S., Le Forestier, L. and Cousin, I. 2009. Soil drainage as an active agent of recent soil evolution: A review. Pedosphere. 19(1): 1--13.
ABSTRACT: While research on pedogenesis mainly focuses on long-term soil formation and most often neglects recent soil evolution in response to human practices or climate changes, this article reviews the impact of artificial subsurface drainage on soil evolution. Artificial drainage is considered as an example of the impact of recent changes in water fluxes on soil evolution over time scales of decades to a century. Results from various classical studies on artificial drainage including hydrological and environmental studies are reviewed and collated with rare studies dealing explicitly with soil morphology changes, in response to artificial drainage. We deduce that soil should react to the perturbations associated with subsurface drainage over time scales that do not exceeding a few decades. Subsurface drainage decreases the intensity of erosion and must i) increase the intensity of the lixiviation and eluviation processes, ii) affect iron and manganese dynamics, and iii) induce heterogeneities in soil evolution at the ten meter scale. Such recent soil evolutions can no longer be neglected as they are mostly irreversible and will probably have unknown, but expectable, feedbacks on crucial soil functions such as the sequestration of soil organic matter or the water available capacity.

Bai, S. B., Wang, J., Lü, G. N., Zhou, P. G., Hou, S. S. and Xu, S. N. 2009. GIS-based and data-driven bivariate landslide-susceptibility mapping in the Three Gorges area, China. Pedosphere. 19(1): 14--20.
ABSTRACT: A detailed landslide-susceptibility map was produced using a data-driven objective bivariate analysis method with datasets developed for a geographic information system (GIS). Known as one of the most landslide-prone areas in China, the Zhongxian-Shizhu Segment in the Three Gorges Reservoir region of China was selected as a suitable case because of the frequency and distribution of landslides. The site covered an area of 260.93 km2 with a landslide area of 5.32 km2. Four data domains were used in this study, including remote sensing products, thematic maps, geological maps, and topographical maps, all with 25 m× 25 m pixels. Statistical relationships for landslide susceptibility were developed using landslide and landslide causative factor databases. All continuous variables were converted to categorical variables according to the percentile divisions of seed cells, and the corresponding class weight values were calculated and summed to create the susceptibility map. According to the map, 3.6% of the study area was identified as high-susceptibility. Extremely low-, very low-, low-, and medium-susceptibility zones covered 19.66%, 31.69%, 27.95%, and 17.1% of the area, respectively. The high- and medium-hazardous zones are along both sides of the Yangtze River, being in agreement with the actual distribution of landslides.

Ghosh, S., Wang, Z. Y., Kang, S., Bhowmik, P. C. and Xing, B. S. 2009. Sorption and fractionation of a peat derived humic acid by kaolinite, montmorillonite, and goethite. Pedosphere. 19(1): 21--30.
ABSTRACT: Sorption of humic acid (HA) on mineral surfaces has a profound interest regarding the fate of hydrophobic organic contaminants (HOCs) and carbon sequestration in soils. The objective of our study is to determine the fractionation behavior of HA upon sorption on mineral surfaces with varying surface properties. HA was coated sequentially on kaolinite (1:1 clay), montmorillonite (2:1 clay), and goethite (iron oxide) for four times. The unadsorbed HA fractions were characterized by elemental analysis, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), and solid state 13C nuclear magnetic resonance spectroscopy (NMR). The mineral-HA complexes were characterized by DRIFT. Polarity index [(N+O)/C] revealed higher polarity of the unadsorbed HA fractions after coating on kaolinite, reflecting that relatively higher polarity fractions of HA remain unadsorbed. Sorption of aliphatic alcohol fraction along with carbohydrate was prominent on kaolinite surface. DRIFT results of the unadsorbed HA fractions indicated more sorption of aliphatic moieties on both kaolinite and montmorillonite. DRIFT results of the unadsorbed HA fractions after sorption on kaolinite and goethite showed the sorption of the proteinaceous fractions of HA. The HA fractions obtained after coating on goethite showed significant sorption of carboxylic moieties. The results mentioned above comply reasonably well with the DRIFT spectra of the mineral-HA complexes. 13C NMR results showed higher sorption of anomeric C on kaolinite surface. Higher sorption of paraffinic fraction was observed on montmorillonite. NMR data inferred the sorption of carboxylic moieties on goethite surface. Overall, this study showed that aliphatic moieties of HA preferentially sorbed on kaolinite and montmorillonite, while carboxylic functional groups play a significant role in sorption of HA on goethite. The sorbed fractions of HA may modify the mineral surface properties, and thus, the interaction with organic contaminants.

Wang, W., Feng, J. and Oikawa, T. 2009. Contribution of root and microbial respiration to soil CO2 efflux and their environmental controls in a humid temperate grassland of Japan. Pedosphere. 19(1): 31--39.
ABSTRACT: Soil CO2 efflux, root mass, and root production were investigated in a humid temperate grassland of Japan over a growing season (Apr. to Sep.) of 2005 to reveal seasonal changes of soil CO2 efflux, to separate the respective contributions of root and microbial respiration to the total soil CO2 efflux, and to determine the environmental factors that control soil respiration. Minimal microbial respiration rate was estimated based on the linear regression equations between soil CO2 efflux and root mass at different experimental sites. Soil CO2 efflux, ranging from 4.99 to 16.29 ¼mol CO2 m-2 s-1, depended on the seasonal changes in soil temperature. The root mass at 0--10 cm soil depth was 0.82 and 1.27 kg m-2 in Apr. and Sep., respectively. The root mass at 0--10 cm soil depth comprised 60% of the total root mass at 0--50 cm soil depth. The root productivity at 0--30 cm depth varied from 8 to 180 g m-2 month-1. Microbial and root respiration rates ranged from 1.35 to 5.51 and 2.72 to 12.06 ¼mol CO2 m-2 s-1, respectively. The contribution of root respiration to the total soil CO2 efflux averaged 53%, ranging from 33% to 72%. The microbial respiration rate was exponentially related to soil temperature at 10 cm depth (R2 = 0.9400, P = 0.002, n = 6), and the root respiration rate was linearly related to the root production at 0--30 cm depth (R2 = 0.6561, P = 0.042, n = 6).

Scalenghe, R. and Ferraris, S. 2009. The first forty years of a Technosol. Pedosphere. 19(1): 40--52.
ABSTRACT: Soil formation is often a very slow process that requires thousands and even millions of years. Human influence, occasionally on a par with the function of climate or geological forces, can accelerate the process and can be viewed as a distinct soil forming factor. This paper describes a soil, Haplic Regosol, in which anthrosolization dominates the soil forming process. Man-made soils, Technosols, were stabilized with techniques of ecological engineering (crib walls). We measured the main soil properties and focused on the movement of water (the reduction of soil weight is the key factor in stabilizing these calcschists). The newly deposited debris, sheltered by anthropic interventions, after four years differentiated an A/C profile while after forty years differentiated an O/A/AB/Bw/BC/C profile. Our results indicate that colonization by plants and the consequent success of vegetation establishment is influenced mainly by control of the factor of pedogenesis ‘topography’ and by the ability of these Technosols to retain nutrients.

Yang, M., Shi, L., Xu, F. S., Lu, J. W. and Wang, Y. H. 2009. Effects of B, Mo, Zn, and their interactions on seed yield of rapeseed (Brassica napus L.). Pedosphere. 19(1): 53--59.
ABSTRACT: A field experiment was conducted to study the effects of boron (B), molybdenum (Mo), zinc (Zn) and their interactions on seed yield and yield formation of rapeseed (Brassica napus L. var. Huashuang 4). Application of B fertilizer to a sandy soil increased the seed yield by 46.1% compared to the control and also created a considerably higher seed yield than the two treatments solely applying Mo and Zn fertilizers, which suggested that B was a main constraint for the seed yield of Huashuang 4 in this experiment. The effect of B fertilizer on the seed yield was attributed to an increase in the number of seeds per silique and siliques per plant. The combined application of B with Mo or Zn resulted in higher seed yield than the application of B, Mo or Zn alone, and the seed yield of the B+Mo+Zn treatment was the highest in all treatments, 68.1% above the control. Dry matter accumulation of seed followed a typical S-shaped curve and it was higher in plants supplied with B than in plants without B. A small but significant increase in the seed oil content and an improvement in the oil quality were also observed in all treatments compared with the control. These results suggested that optimal micronutrient application could provide both yield and quality advantages for rapeseed in poor soil.

Romar, A., Gago, C., Fernández-Marcos, M. L. and Álvarez, E. 2009. Influence of Fluoride addition on the composition of solutions in equilibrium with acid soils. Pedosphere. 19(1): 60--70.
ABSTRACT: Atmospheric emissions of fluoride from an aluminium smelter-alumina refinery located on the northern coast of Galicia, NW Spain, increase the content of fluorine in soils and vegetation in the vicinity of the complex. The effects of the addition of fluoride solutions on the chemical properties of soil samples from the area surrounding the complex were investigated in laboratory experiments. Addition of fluoride to soils resulted in increases in pH and concentrations of Fe, Al, and organic matter in the equilibrium solutions and decreases in concentrations of Ca, Mg, and K. No consistent effects were observed on the Cu, Mn, or Zn concentrations. Most of the Al in solution was bound to organic matter. Within the fraction “labile aluminium,” the concentration of Al-OH complexes decreased and the Al-F complexes increased, especially AlF3 and AlF4-, which are less toxic than Al3+ and Al-OH species.

Gao, J. Q., Ouyang, H., Xu, X. L., Zhou, C. P. and Zhang, F. 2009. Effects of temperature and water saturation on CO2 production and nitrogen mineralization in alpine wetland soils. Pedosphere. 19(1): 71--77.
ABSTRACT: Relationships between carbon (C) production and nitrogen (N) mineralization were investigated in two alpine wetland soils of the Tibetan Plateau using laboratory incubation under different temperatures (5, 15, 25, and 35 ºC) and water saturation (noninundation and inundation). A significant positive relationship was found between CO2 production and N mineralization under increasing temperatures from 5 to 35 ºC with the same water saturation condition in the marsh soil (r2 > 0.49, P < 0.0001) and the peat soil (r2 > 0.38, P < 0.002), and a negative relationship with water saturation increasing at the same temperature, especially 25 and 35 ºC, in the marsh soil (r2 > 0.70, P < 0.009) and the peat soil (r2 > 0.61, P < 0.013). In conclusion, temperatures and water saturation could regulate the relationship between CO2 production and net N mineralization in the Tibetan alpine marsh and peat soils.

Abarchi, I., Zhang, Z. Y., Vanlauwe, B., Guo, X. P., Wang, W. M., Ong’or, B T. I. and Timbely, D. 2009. Effects of plant age and rock phosphate on quality and nutrient release of legume residue. Pedosphere. 19(1): 78--85.
ABSTRACT: An incubation experiment was carried out on plateau and slope fields to investigate the effect of plant age and rock phosphate (RP) on the organic resource (OR) quality and available N and P release of the legume residues, including standing biomass and surface litter. The legumes, Mucuna pruriens (L.) and Lablab purpureus (L.), were treated with or without Togo rock phosphate (RP) and were sampled at 12, 18, 24 and 30 weeks after planting. Results showed that the application of RP significantly affected the P content of the legume residues on the plateau field for the first 18 weeks, but not the other OR quality parameters, nor their N mineralization, or P release parameters. Although application of RP led to higher P contents in both legumes on the plateau field, the P contents were still far below those observed on the slope field. For both species, the biomass age appeared to have a major impact on their N, P, and polyphenol contents, but not on the lignin content. At 24 weeks, both legume N and P contents dropped to about half their values at 12 weeks of age. Residue age also significantly affected N mineralization both with and without RP addition and the net Olsen-P with RP addition. The younger residues generally led to higher N mineralization and net Olsen-P content than the older residues. The best immediate responses to herbaceous legume addition were expected from younger materials, but often at the cost of the total biomass produced and the possibility to produce seeds. The production of seeds, however, could be potentially implemented on a small area of legumes, thus invariably allowing for maturity and seed production.

Wang, B., Lai, T., Huang, Q. W., Yang, X. M. and Shen, Q. R. 2009. Effect of N fertilizers on root growth and endogenous hormones in strawberry. Pedosphere. 19(1): 86--95.
ABSTRACT: Endogenous hormones play an important role in the growth and development of roots. The objective of this research was to study the effect of four types of N fertilizer on the root growth of strawberry (Fragaria ananassa Duchesne) and the endogenous enzymes of indole-3-acetic acid (IAA), abscisic acid (ABA), and isopentenyl adenosine (iPA) in its roots and leaves using enzyme-linked immunosorbent assay. Application of all types of N fertilizers significantly depressed (P d" 0.05) root growth at 20 d after transplanting. Application of organic-inorganic fertilizer (OIF) as basal fertilizer had a significant negative effect (P d" 0.05) on root growth. The application of OIF and urea lowered the lateral root frequency in strawberry plants at 60 d (P d" 0.05) compared with the application of two organic fertilizers (OFA and OFB) and the control (CK). With the fertilizer treatments, there were the same concentrations of IAA and ABA in both roots and leaves at the initial growth stage (20 d), lower levels of IAA and ABA at the later stage (60 d), and higher iPA levels at all seedling stages as compared to those of CK. Thus, changes in the concentrations of endogenous phytohormones in strawberry plants could be responsible for the morphological changes of roots due to fertilization.

Deng, J. S., Wang, K., Li, J. and Deng, Y. H. 2009. Urban land use change detection using multisensor satellite images. Pedosphere. 19(1): 96--103.
ABSTRACT: Due to inappropriate planning and management, accelerated urban growth and tremendous loss in land, especially cropland, have become a great challenge for sustainable urban development in China, especially in developed urban area in the coastal regions; therefore, there is an urgent need to effectively detect and monitor the land use changes and provide accurate and timely information for planning and management. In this study a method combining principal component analysis (PCA) of multisensor satellite images from SPOT (systeme pour l'observation de la terre or Earth observation satellite)-5 multispectral (XS) and Landsat-7 enhanced thematic mapper (ETM) panchromatic (PAN) data, and supervised classification was used to detect and analyze the dynamics of land use changes in the city proper of Hangzhou. The overall accuracy of the land use change detection was 90.67% and Kappa index was 0.89. The results indicated that there was a considerable land use change (10.03% of the total area) in the study area from 2001 to 2003, with three major types of land use conversions: from cropland into built-up land, construction site, and water area (fish pond). Changes from orchard land into built-up land were also detected. The method described in this study is feasible and useful for detecting rapid land use change in the urban area.

Wang, Q. J., Horton, R. and Fan, J. 2009. An analytical solution for one-dimensional water infiltration and redistribution in unsaturated soil. Pedosphere. 19(1): 104--110.
ABSTRACT: Soil infiltration and redistribution are important processes in field water cycle, and it is necessary to develop a simple model to describe the processes. In this study, an algebraic solution for one-dimensional water infiltration and redistribution without evaporation in unsaturated soil was developed based on Richards equation. The algebraic solution had three parameters, namely, the saturated water conductivity, the comprehensive shape coefficient of the soil water content distribution, and the soil suction allocation coefficient. To analyze the physical features of these parameters, a relationship between the Green-Ampt model and the algebraic solution was established. The three parameters were estimated based on experimental observations, whereas the soil water content and the water infiltration duration were calculated using the algebraic solution. The calculated soil water content and infiltration duration were compared with the experimental observations, and the results indicated that the algebraic solution accurately described the unsaturated soil water flow processes.

Fang, Y. T., Yoh, M., Mo, J. M., Gundersen, P. and Zhou, G. Y. 2009. Response of nitrogen leaching to simulated nitrogen deposition in disturbed and mature forests of southern China. Pedosphere. 19(1): 111--120.
ABSTRACT: Current nitrogen (N) leaching losses and their responses to monthly N additions were investigated under a disturbed pine (Pinus massoniana) forest and a mature monsoon broadleaf forest in southern China. N leaching losses from both disturbed and mature forests were quite high (14.6 and 29.2 kg N ha-1 year-1, respectively), accounting for 57% and 80% of their corresponding atmospheric N inputs. N leaching losses were substantially increased following the first 1.5 years of N applications in both forests. The average increases induced by the addition of 50 and 100 kg N ha-1 year-1 were 36.5 and 24.9 kg N ha-1 year-1, respectively, in the mature forest, accounting for 73.0% and 24.9% of the annual amount of N added, and 14.2 and 16.8 kg N ha-1 year-1 in the disturbed forest, accounting for 28.4% and 16.8% of the added N. Great N leaching and a fast N leaching response to N additions in the mature forest might result from long-term N accumulation and high ambient N deposition load (greater than 30 kg N ha-1 year-1 over the past 15 years), whereas in the disturbed forest, it might result from the human disturbance and high ambient N deposition load. These results suggest that both disturbed and mature forests in the study region may be sensitive to increasing N deposition.

Ma, J. H., Chu, C. J., Li, J. and Song, B. 2009. Heavy metal pollution in soils on railroad side of Zhengzhou-Putian section of Longxi-Haizhou Railroad, China. Pedosphere. 19(1): 121--128.
ABSTRACT: The pollution status and horizontal distribution of heavy metals (Ni, Pb, Cr, Zn, Cu, and Cd) in the soil on railroad side along the Zhengzhou-Putian section of Longxi-Haizhou Railroad were studied by collecting soil samples along a sampling section perpendicular to the railroad at the distances of 0, 10, 20, 30, 50, 100, 200, 300, and 500 m from the railroad edge. The concentrations of heavy metals in the sampling soils were higher than those of the control site. The concentrations of Pb, Zn, and Cd were found to be the highest in the soils at the railroad edge, and then decreased with increasing distance from the railroad. The highest concentrations of Ni, Cr, and Cu in soils were located at about 10--30 m from the railroad. Compared with the single factor pollution index (SFPI) of heavy metals calculated for the control site, the average SFPI from the sampling sites decreased in the order of Cr > Cd > Pb > Zn > Ni > Cu. There were notable negative correlations between the integral pollution index (IPI) of soil heavy metals at all sampling sites and the distances from the railroad. According to three IPIs calculated from the background values of heavy metals in och-aquic Cambisols, the heavy metal concentrations in the control soil, and the 2nd levels for soil heavy metals in GB15618-1995, the study area could be divided, based on the distances from the railroad, into four pollution zones: heavy pollution zone (0--10 m), medium pollution zone (10--50 m), slight pollution zone (50--100 m), and warning zone (100--500 m), respectively.

Hu, X., Liu, L. Y., Li, S. J., Xiao, B. L. and Liu, M. X. 2009. Estimation of sand transportation rate for fixed and semi-fixed dunes using meteorological wind data. Pedosphere. 19(1): 129-136.
ABSTRACT: Taibus County, Inner Mongolia, China, lies in a farming-pastoral ecotone, where severe wind erosion and various aeolian sand hazards are prevalent and fixed and semi-fixed sand dunes occur frequently. This study was conducted to investigate the relationships between sand transportation rate and wind speed for the fixed and semi-fixed sand dunes based on field measurements. The annual quantity of soil erosion by wind was estimated using meteorological wind data. The results indicated that the sand transportation rate in Taibus County in 2000 was 57.38 kg cm-1 year-1 for the semi-fixed dunes and 4.56 kg cm-1 year-1 for the fixed dunes. The total duration of erosive winds covered 12.5% of the time of the year, and spring posed the highest potential of sand transportation. Wind with low speed (d"17 m s-1) and high frequency plays a dominant role in sand transportation, while strong wind (e"17 m s-1) with low frequency significantly enhanced the sand transportation. Erosive wind speed, directions, and frequency were three crucial dynamic factors influencing sand hazards in the farming-pastoral ecotone. The dominant factors intensifying sand and dust storms in Taibus County might be related to the favorable wind condition in combination with the durable drought, which led to land desertification and vegetation degradation.

Zhu, J. H., Yu, P. T., Sogn, T. A., Wang, Y. H. and Mulder, J. 2008. Application of the nutrient cycling model NuCM to a forest monitoring site exposed to acidic precipitation in China. Pedosphere. 18(6): 681--690.
ABSTRACT: The nutrient cycling model NuCM is one of the most detailed models for simulating processes that influence nutrient cycling in forest ecosystems. A field study was conducted at Tieshanping, a Masson pine (Pinus massoniana Lamb.) forest site, in Chongqing, China, during 2001--2002, to monitor the impacts of acidic precipitation on nutrient cycling. NuCM simulations were compared with observed data from the study site. The model produced an approximate fit with the observed data. It simulated the mean annual soil solution concentrations in the two simulation years, whereas it sometimes failed to reproduce seasonal variation. Even though some of the parameters required by model running were measured in the field, some others were still highly uncertain and the uncertainties were analyzed. Some of the uncertain parameters necessary for model running should be measured and calibrated to produce a better fit between modeled results and field data.

Pouvelle, S., Feer, F. and Ponge, J. F. 2008. Topsoil as affected by dung deposition under resting places of red howler monkey (Alouatta seniculus). Pedosphere. 18(6): 691--698.
ABSTRACT: The short-term influence of dung deposition and the further redistribution of dung by dung beetles were studied under a resting place of the red howler monkey (Alouatta seniculus) living in tropical rainforests of South America. Monkey dung was experimentally clumped on the field in a place used by troops of howler monkeys for resting in the Nouragues Reserve Station, French Guiana. Dung-treated plots were sampled serially over three weeks and compared with controls located in their immediate vicinity. The composition of the soil matrix (top 10 cm) was studied in successive microlayers using an optical method. Under the influence of dung beetle activity, the topsoil became more homogeneous by losing its litter, its content in earthworm faeces increased in the course of time, and surface mineral deposits were penetrated by roots. The results were interpreted in the light of present knowledge on the effects of soil animal activity on plant growth and survival of seedlings.

Yang, L. L., Zhang, F. S., Mao, R. Z., Ju, X. T., Cai, X. B. and Lu, Y. H. 2008. Conversion of natural ecosystems to cropland increases the soil net nitrogen mineralization and nitrification in Tibet. Pedosphere. 18(6): 699--706.
ABSTRACT: A comparative study was conducted to determine the NH4+ and NO3- concentrations in soil profiles and to examine the net nitrogen (N) mineralization and nitrification in adjacent forest, grassland, and cropland soils on the Tibetan Plateau. Cropland soil showed significantly higher inorganic N concentrations in soil profiles compared with forest and grassland soils. NO3--N accounted for 70%--90% of inorganic N in cropland soil, while NH4+-N was the main form of inorganic N in forest and grassland soils. The average net N mineralization rate at 0--20 cm depth was approximately twice in cropland soil (1.48 mg kg-1 d-1) as high as in forest (0.83 mg kg-1 d-1) or grassland soil (0.72 mg kg-1 d-1). Cropland showed strong net nitrification, with the net rate almost equal to the total net N mineralization. Urea addition stimulated soil respiration, particularly in forest soil. Most urea-N, however, remained as NH4+ in forest and grassland soils, while NO3- was the main form of inorganic N to increase in cropland soil. Higher rates of net nitrification in cropland soils suggest that land use change on the Tibetan Plateau may lead to high N losses through nitrate leaching.

Wang, Z. Y., Gao, D. M., Li, F. M., Zhao, J., Xin, Y. Z., Simkins, S. and Xing, B. S. 2008. Petroleum hydrocarbon degradation potential of soil bacteria native to the Yellow River Delta. Pedosphere. 18(6): 707--716.
ABSTRACT: The bioremediation potential of bacteria indigenous to soils of the Yellow River Delta in China was evaluated as a treatment option for soil remediation. Petroleum hydrocarbon degraders were isolated from contaminated soil samples from the Yellow River Delta. Four microbial communities and eight isolates were obtained. The optimal temperature, salinity, pH, and the ratios of C, N, and P (C:N:P) for the maximum biodegradation of diesel oil, crude oil, n-alkanes, and polyaromatic hydrocarbons by indigenous bacteria were determined, and the kinetics changes in microbial communities were monitored. In general, the mixed microbial consortia demonstrated wider catabolic versatility and faster overall rate of hydrocarbon degradation than individual isolates. Our experimental results demonstrated the feasibility of biodegradation of petroleum hydrocarbon by indigenous bacteria for soil remediation in the Yellow River Delta.

Yu, D. S., Shi, X. Z., Wang, H. J., Zhang, X. Y. and Weindorf, D. C. 2008. Function of soils in regulating rainwater in southern China: Impacts of land uses and soils. Pedosphere. 18(6): 717--730.
ABSTRACT: One of the most important functions of soils is to regulate rainwater and mitigate flooding and associated damages; this function can be estimated by the rainwater regulation ratio (·), i.e., percent of regulated rainwater. Fifteen experimental plots were set up on the hills in Yingtan of Jiangxi Province, southern China. These plots were under three land use patterns, cultivated cropland, noncultivated land, and orchard interplanted with cash crops. With aid of an artificial rainfall simulator and Guelph method, rainfall, runoff, soil infiltration, and so on were measured in situ. Results showed that the orchard interplanted with cash crops was more effective in regulating rainwater than the other two land use patterns. When the maximum infiltration intensity was three times higher than the observed mean, · was higher than 70% for all plots. · was related to land use, slope gradient, and soil properties such as soil infiltration, organic carbon, bulk density, and texture. There is still more room to improve capacity of rainwater drainage (underground percolation) than that of rainwater storage in soils. Therefore, enhancing soil permeability is vital to improve the rainwater regulation efficiency in soils.

Chen, Y. Q., Ren, G. J., An, S. Q., Sun, Q. Y., Liu, C. H. and Shuang, J. L. 2008. Changes of bacterial community structure in copper mine tailings after colonization of reed (Phragmites communis). Pedosphere. 18(6): 731--740.
ABSTRACT: Soil samples were collected from both bare and vegetated mine tailings to study the changes in bacterial communities and soil chemical properties of copper mine tailings due to reed (Phragmites communis) colonization. The structures of bacterial communities were investigated using culture-independent 16S rRNA gene sequencing method. The bacterial diversity in the bare mine tailing was lower than that of the vegetated mine tailing. The former was dominated by sulfur metabolizing bacteria, whereas the latter was by nitrogen fixing bacteria. The bare mine tailing was acidic (pH = 3.78), whereas the vegetated mine tailing was near neutral (pH = 7.28). The contents of organic matter, total nitrogen, and ammonium acetate-extractable potassium in vegetated mine tailings were significantly higher than those in the bare mine tailings (P < 0.01), whereas available phosphorus and electrical conductivity were significantly lower than those in the bare mine tailings (P < 0.01). The results demonstrated that 16S rRNA gene sequencing could be successfully used to study the bacterial diversity in mine tailings. The colonization of the mine tailings by reed significantly changed the bacterial community and the chemical properties of tailings. The complex interactions between bacteria and plants deserve further investigation.

Zhao, Q., Zeng, D. H., Fan, Z. P. and Lee, D. K. 2008. Effect of land cover change on soil phosphorus fractions in southeastern Horqin sandy land, northern China. Pedosphere. 18(6): 741--748.
ABSTRACT: In the past 50 years, large areas of the Horqin sandy land were afforested to prevent desertification. Although the afforestation policy appears successful, many people now doubt whether it is suitable to plant trees with high density on the poor soils in semiarid regions. Little is known about the impacts of afforestation on the sandy soil properties, although the evaluation of these impacts is fundamental to judge the rationality of afforestation policy. Soil phosphorus (P) fractions, acid phosphomonoesterase activities, and other soil chemical properties were compared among five adjoining typical ecosystems on poor sandy soils in southeastern Horqin sandy land. The ecosystems studied are natural elm savanna, degraded grassland, Mongolian pine (Pinus sylvestris var. mongolica) plantation, Chinese pine (Pinus tabulaeformis) plantation, and mixed plantation of Mongolian pine and poplar (Populus simonii). The results showed that organic P dominated soil P (47%--65%) was the principal source of available P. The degradation of elm savanna to grassland significantly reduced soil pH and resulted in an overall reduction in soil fertility, although slightly increased labile inorganic P. Grassland afforestation had no significant influence on soil pH, organic carbon, and total N but significantly reduced total P. Impacts of grassland afforestation on soil P fractions depended on tree species. Natural elm savanna had higher soil P conserving ability than artificial plantations. Therefore, with the aim of developing a sustainable ecosystem, we suggested that vegetations with low nutrient demand (particularly P) and efficient nutrient cycling would be more suitable for ecosystem restoration in the semiarid region.

Ashwini, K. M. and Sridhar, K. R. 2008. Distribution of pill millipedes (Arthrosphaera) and associated soil fauna in the Western Ghats and west coast of India. Pedosphere. 18(6): 749--757.
ABSTRACT: Seven sampling sites in each of three biomes (Western Ghats, foothills of Western Ghats and west coast) of southwestern India were investigated to study the distribution, abundance and ecology of pill millipedes (Arthrosphaera) and associated fauna in relation to edaphic features. Abundance and biomass of Arthrosphaera and other millipedes were the highest in Western Ghats, while earthworms were in foothills. Arthrosphaera magna and Arthrosphaera spp. were common in Western Ghats and foothills respectively, while no Arthrosphaera were found in the west coast. None of the sampling sites consisted of more than one species of Arthrosphaera. Biomass of Arthrosphaera, other millipedes and earthworms significantly differed in Western Ghats (P = 9.48 × 10-7) and foothills (P = 1.35 × 10-8), as did the biomass of species of Arthrosphaera (P = 2.76 × 10-7) between Western Ghats and foothills. Correlation analysis revealed that biomass of Arthrosphaera was significantly (P = 0.01, r = 0.45) correlated with soil organic carbon rather than other edaphic features (pH, phosphate, calcium and magnesium). Distribution pattern, abundance, biomass and ecology of Arthrosphaera of Western Ghats in relation to soil qualities were compared with millipedes of other regions of the world.

Huang, Y., Li, T., Huang, Z. J. and Fei, Y. H. 2008. Ectomycorrhizal fungus-induced changes of Cu and Cd speciation in the rhizosphere of Chinese pine seedlings. Pedosphere. 18(6): 758--765.
ABSTRACT: To understand the role of ectomycorrhizas in improving the tolerance of its host to excessive heavy metals in soil, this study was conducted to exam the patterns of four fractions (the exchangeable, the carbonate-bound, the Fe-Mn oxide-bound and the organically bound) of both Cu and Cd in the rhizosphere of Chinese pine (Pinus tabulaeformis) seedlings grown in excessive Cu and Cd environment. The results showed that the speciation of Cu and Cd in the rhizosphere was significantly influenced by inoculation of ectomycorrhizal fungus Boletus edulis. Compared to the rhizosphere, the content of exchangeable Cu slightly decreased in the mycorrhizosphere of the seedlings grown in 166 and 400 mg kg-1 Cu contaminated soil, whereas the exchangeable Cd in the mycorrhizosphere decreased remarkably to only 33% and to 60% that of the rhizosphere at 0.75 and 1.50 mg kg-1 Cd levels, respectively. These indicate the potential capacity of mycorrhizas to alleviate the damage of heavy metals to the host plants by reducing the bioavailability of heavy metals in soil. Distribution of the 4 tested fractions of Cu and Cd at different contamination levels showed that there was a strong tendency of changing from loosely associated fractions to strongly associated fractions in the mycorrhizosphere. The most stable Cd fraction, organically bound Cd, was significantly larger in the mycorrhizosphere than in the rhizosphere at different Cd contamination levels. This phenomenon was also observed for Cu but the difference was not statistically significant.

Xue, Y, F., Liu, L, Liu, Z. P., Mehta, S. K. and Zhao, G. M. 2008. Protective role of Ca against NaCl toxicity in Jerusalem artichoke by up-regulation of antioxidant enzymes. Pedosphere. 18(6): 766--774.
ABSTRACT: The ameliorative effect of external Ca2+ on Jerusalem artichoke (Helianthus tuberosus L.) under salt stress was studied through biochemical and physiological analyses of Jerusalem artichoke seedlings treated with or without 10 mol L-1 CaCl2, 150 mmol L-1 NaCl, and/or 5 mmol L-1 ethylene-bis(oxyethylenenitrilo)-tetraacetic acid (EGTA) for five days. Exposure to NaCl (150 mmol L-1) decreased growth, leaf chlorophyll content, and photosynthetic rate of Jerusalem artichoke seedlings. NaCl treatment showed 59% and 37% higher lipid peroxidation and electrolyte leakage, respectively, than the control. The activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were decreased by NaCl, indicating an impeded antioxidant defense mechanism of Jerusalem artichoke grown under salt stress. Addition of 10 mmol L-1 CaCl2 to the salt solutions significantly decreased the damaging effect of NaCl on growth and chlorophyll content and simultaneously restored the rate of photosynthesis almost to the level of the control. Ca2+ addition decreased the leaf malondialdehyde (MDA) content and electrolyte leakage from NaCl-treated seedlings by 47% and 24%, respectively, and significantly improved the activities of SOD, POD, and CAT in NaCl-treated plants. Addition of EGTA, a specific chelator of Ca2+, decreased the growth, chlorophyll content, and photosynthesis, and increased level of MDA and electrolyte leakage from NaCl-treated plants and from the control plants. EGTA addition to the growth medium also repressed the activities of SOD, POD, and CAT in NaCl-treated and control seedlings. External Ca2+ might protect Jerusalem artichoke against NaCl stress by up-regulating the activities of antioxidant enzymes and thereby decreasing the oxidative stress.

Yu, Z. Y., Chen, F. S., Zeng, D. H., Zhao, Q. and Chen, G. S. 2008. Soil inorganic nitrogen and microbial biomass carbon and nitrogen under pine plantations in Zhanggutai sandy soil. Pedosphere. 18(6): 775--784.
ABSTRACT: The dynamics of soil inorganic nitrogen (NH4+-N and NO3--N) and microbial biomass carbon (Cmic) and nitrogen (Nmic) under 30-year-old fenced Pinus sylvestris L. var. mongolica Litvin (SF), unfenced P. sylvestris L. var. mongolica Litvin (SUF), and unfenced Pinus densiflora Siebold et Zucc. (DUF) plantations in the Zhanggutai sandy soil of China were studied during Apr. to Oct. 2004 by the in situ closed-top core incubation method. All mentioned C and N indices in each stand type fluctuated over time. The ranges of inorganic N, Cmic, and Nmic contents in the three stand types were 0.7--2.6, 40.0--128.9, and 5.4--15.2 µg g-1, respectively. The average contents of soil NH4+-N and Cmic under the three 30-year-old pine plantations were not different. However, soil NO3--N and total inorganic N contents decreased in the order of SUF e" SF e" DUF, the Nmic content was in the order of SF = SUF > DUF, and the Cmic:Nmic ratio was in the order of SUF = DUF > SF. Seasonal variations were observed in soil inorganic N, microbial biomass, and plant growth. These seasonal variations had certain correlations with microbe and plant N use in the soil, and their competition for NH4+-N was mostly regulated by soil N availability. The influence of tree species on inorganic N and Nmic were mainly because of differences in litter quality. Lack of grazing decreased the Cmic:Nmic ratio owing to decreased carbon output and increased the ability of soil to supply N. The soil N supply under the P. sylvestris var. mongolica plantation was lower than under the P. densiflora plantation.

Li, Y. F., Luo, A. C., Wei, X. H. and Yao, X. G. 2008. Changes in phosphorus fractions, pH, and phosphatase activity in the rhizosphere of two rice genotypes. Pedosphere. 18(6): 785--794.
ABSTRACT: A rhizobox experiment with two phosphorus (P) treatments, zero-P (0 mg P kg-1) and plus-P (100 mg P kg-1) as Ca(H2PO4)2•H2O, was conducted to study the chemical and biochemical properties in the rhizosphere of two rice genotypes (cv. Zhongbu 51 and Pembe) different in P uptake ability and their relationship with the depletion of soil P fractions. Plant P uptake, pH, phosphatase activity, and soil P fractions in the rhizosphere were measured. Both total dry weight and total P uptake of Pembe were significantly (P < 0.05) higher than those of Zhongbu 51 in the zero-P and plus-P treatments. Significant depletions of resin-Pi, NaHCO3-Pi, NaHCO3-Po, and NaOH-Pi, where Pi stands for inorganic P and Po for organic P, were observed in the rhizosphere of both Zhongbu 51 and Pembe under both P treatments. Pembe showed a greater ability than Zhongbu 51 in depleting resin-Pi, NaHCO3-Pi, NaHCO3-Po, NaOH-Pi, and NaOH-Po in the rhizosphere. HCl-Pi and residual-P were not depleted in the rhizosphere of both genotypes, regardless of P treatments despite significant acidification in the rhizosphere of Pembe under zero-P treatment. Higher acid phosphatase (AcPME) activity and alkaline phosphatase (AlPME) activity were observed in the rhizosphere of both Zhongbu 51 and Pembe compared to the corresponding controls without plant. AcPME activity was negatively (P < 0.01) correlated to NaHCO3-Po concentration in the rhizosphere of both Zhongbu 51 and Pembe, suggesting that AcPME was associated with the mineralization of soil organic P.

Wang, X. M., Jie, X. L., Zhu, Y. G., Hou, Y. L. and Zhang, T.Q. 2008. Relationships between agronomic and environmental soil test phosphorus in three typical cultivated soils in China. Pedosphere. 18(6): 795--800.
ABSTRACT: A study was conducted to determine the relationships between agronomic soil test P and environmental soil test P in three soils predominately distributing in three typical agricultural production areas in China. Soil P was analyzed using Bray-1 (BP), Olsen (OP), and Mehlich-3 (MP) methods as agronomic tests, and using Fe-oxide impregnated filter paper (FeP), anion-exchange resin membrane (RP), and water (WP) as environmental tests. There were linear relationships between soil P extractable with all the tests evaluated. The regression coefficients, R2, ranged from 0.8164 to 0.9409 between each two of the ATSP, and ranged from 0.4702 to 0.8990 between each two of the environmental soil test P, when the three soils were considered separately. When soil test P was analyzed across all the three soils, the highest regression R2 was found between OP and MP (0.7940) amongst agronomic soil test P, and between FeP and RP amongst environmental soil test P (0.8842). While all of the three agronomic soil test P was linearly related to each of the environmental soil test P across the three soils, strongest relationships were found between OP and environmental soil test P. Agronomic OP may be adopted as an analytical tool for environmental prediction of soil P.

Kong, W. D., Zhu, Y. G., Fu, B. J., Han, X. Z., Zhang, L. and He, J. Z. 2008. Effect of long-term application of chemical fertilizers on microbial biomass and functional diversity of a black soil. Pedosphere. 18(6): 801--808.
ABSTRACT: An experiment with seven N, P, K-fertilizer treatments, i.e., control (no fertilizer), NP, NK, PK, NPK, NP2K, and NPK2 where P2 and K2 indicate double amounts of P and K fertilizers respectively, was conducted to examine the effect of long-term continuous application of chemical fertilizers on microbial biomass and functional diversity of a black soil (Udoll in the USDA Soil Taxonomy) in Northeast China. The soil microbial biomass C ranged between 94 and 145 mg kg-1, with the NK treatment showing a lower biomass; the functional diversity of soil microbial community ranged from 4.13 to 4.25, with an increasing tendency from control to double-fertilizer treatments, and to triple-fertilizer treatments. The soil microbial biomass, and the microbial functional diversity and evenness did not show any significant differences among the different fertilizer treatments including control, suggesting that the long-term application of chemical fertilization would not result in significant changes in the microbial characteristics of the black soil.

An, S. S., Huang, Y. M., Zheng, F. L. and Yang, J. G. 2008. Aggregate characteristics during natural revegetation on the Loess Plateau. Pedosphere. 18(6): 809--816.
ABSTRACT: Field investigations and laboratory analysis were conducted to study the characteristics of soil water-stable aggregates during vegetation rehabilitation in typical grassland soils of the hilly-gullied loess area. The relationship between water-stable aggregates and other soil properties was analyzed using canonical correlation analysis and principal component analysis. The results show that during the natural revegetation, the aggregates > 5 mm dominated and constituted between 50% and 80% of the total soil water-stable aggregates in most of the soil layers. The 2--5 mm aggregate class was the second main component. The mean value of water-stable aggregates > 5 mm within the 0--2 m soil profile under different plant communities decreased in the following order: Stipa grandis > Stipa bungeana Trin. > Artemisia sacrorum Ledeb. > Thymus mongolicus Ronn. > Hierochloe odorata (L.) Beauv. Clay, organic matter, and total N were the key factors that influenced the water stability of the aggregates. Total N and organic matter were the main factors that affected the water stability of the aggregates > 5 mm and 0.5--1 mm in size. The contents of Fe2O3, Al2O3, and physical clay ( N > Mg > K > S > P. Monthly variations in nutrient concentrations were greater in leaf litter (LL) than other litter components. The highest and lowest concentrations of N, P, K, and S in LL were found in the growing season and the nongrowing season, respectively, but Ca and Mg were the opposite. Nutrient returns via litterfall showed a marked monthly pattern with a major peak in October and one or two small peaks in February and/or May, varying with the element and stand type, but no marked monthly variations in nutrient returns via woody litter, reproductive litter, except in May for the BF, and moss litter. Not only litter production but also nutrient concentration controlled the annual nutrient return and the monthly nutrient return pattern. The monthly patterns of the nutrient concentration and return were of ecological importance for nutrient cycling and plant growth in the subalpine forest ecosystems.

Hu, X., Wang, X. R. and Wang, C. 2006. Bioaccumulation of lanthanum and its effect on growth of maize seedlings in a red loamy soil. Pedosphere. 16(6): 799-805.
ABSTRACT: Through a pot culture lanthanum nitrate was applied to maize seedlings grown in a red loamy soil to investigate the physiological and toxic effects of added La on the growth of crop seedlings and La bioaccumulation to help understand the environmental chemistry behaviors of rare earth element as fertilizers in soils. Compared to the control, La concentrations in shoots and especially in roots of maize seedlings increased with an increase of La in the soil. Also, with added concentrations of La e" 0.75 g La kg-1 soil and e" 0.05 g La kg-1 soil, the dry weight of shoots and roots of maize seedlings was significantly reduced (P d" 0.05), respectively, compared with the control. Additionally, La e" 0.5 g kg-1 in the soil significantly inhibited (P d" 0.05) primary root elongation. Roots were more sensitive to La stress than shoots and thus could be used as a biomarker to La stress. Overall, in the red loamy soil studied, La had no significant beneficial effects on the growth of maize at the added La levels above 0.1 g kg-1 soil.

Cui, Z. L., Chen, X. P. , Li, J. L., Xu, J. F., Shi, L. W. and Zhang, F. S. 2006. Effect of N fertilization on grain yield of winter wheat and apparent N losses. Pedosphere. 16(6): 806-812.
ABSTRACT: Excessive nitrogen (N) fertilizer application to winter wheat is a common problem on the North China Plain. To determine the optimum fertilizer N rate for winter wheat production while minimizing N losses, field experiments were conducted for two growing seasons at eight sites, in Huimin County, Shandong Province, from 2001 to 2003. The optimum N rate for maximum grain yield was inversely related to the initial soil mineral N content (Nmin) in the top 90 cm of the soil profile before sowing. There was no yield response to the applied N at the three sites with high initial soil mineral N levels (average 212 kg N ha-1). The average optimum N rate was 96 kg N ha-1 for the five sites with low initial soil Nmin (average 155 kg N ha-1) before sowing. Residual nitrate N in the top 90 cm of the soil profile after harvest increased with increasing fertilizer N application rate. The apparent N losses during the wheat-growing season also increased with increasing N application rate. The average apparent N losses with the optimum N rates were less than 15 kg N ha-1, whereas the farmers’ conventional N application rate resulted in losses of more than 100 kg N ha-1. Therefore, optimizing N use for winter wheat considerably reduced N losses to the environment without compromising crop yields.

Tan, M. Z., Xu, F.M., Chen, J., Zhang, X. L. and Chen, J. Z. 2006. Spatial prediction of heavy metal pollution for soils in peri-urban Beijing, China based on fuzzy set theory. Pedosphere. 16(5): 545-554.
ABSTRACT: Fuzzy classification combined with spatial prediction was used to assess the state of soil pollution in the peri-urban Beijing area. Total concentrations of As, Cr, Cd, Hg, and Pb were determined in 220 topsoil samples (0--20 cm) collected using a grid design in a study area of 2 600 km2. Heavy metal concentrations were grouped into three classes according to the optimum number of classes and fuzziness exponent using the fuzzy c-mean (FCM) algorithm. Membership values were interpolated using ordinary kriging. The polluted soils of the study area induced by the measured heavy metals were concentrated in the northwest corner and eastern part, especially the southeastern part close to the urban zone, whereas the soils free of pollution were mainly distributed in the southwestern part. The soils with potential risk of heavy metal pollution were located in isolated spots mainly in the northern part and southeastern corner of the study region. The FCM algorithm combined with geostatistical techniques, as compared to conventional single geostatistical kriging methods, could produce a prediction with a quantitative uncertainty evaluation and higher reliability. Successful prediction of soil pollution achieved with FCM algorithm in this study indicated that fuzzy set theory had great potential for use in other areas of soil science.

Zhang, X. X., Cheng, S. P., Zhu, C. J. and Sun, S. L. 2006. Microbial PAH-degradation in soil: Degradation pathways and contributing factors. Pedosphere. 16(5): 555-565.
ABSTRACT: Adverse effects on the environment and high persistence in the microbial degradation and environmental fate of polycyclic aromatic hydrocarbons (PAHs) are motivating interest. Many soil microorganisms can degrade PAHs and use various metabolic pathways to do so. However, both the physio-chemical characteristics of compounds as well as the physical, chemical, and biological properties of soils can drastically influence the degradation capacity of naturally occurring microorganisms for field bioremediation. Modern biological techniques have been widely used to promote the efficiency of microbial PAH-degradation and make the biodegradation metabolic pathways more clear. In this review microbial degradation of PAHs in soil is discussed, with emphasis placed on the main degradation pathways and the environmental factors affecting biodegradation.

Alves, M. E. and Lavorenti, A. 2006. Remaining phosphorus estimate through multiple regression analysis. Pedosphere. 16(5): 566-571.
ABSTRACT: The remaining phosphorus (Prem), P concentration that remains in solution after shaking soil with 0.01 mol L-1 CaCl2 containing 60 ¼g mL-1 P, is a very useful index for studies related to the chemistry of variable charge soils. Although the Prem determination is a simple procedure, the possibility of estimating accurate values of this index from easily and/or routinely determined soil properties can be very useful for practical purposes. The present research evaluated the Prem estimation through multiple regression analysis in which routinely determined soil chemical data, soil clay content and soil pH measured in 1 mol L-1 NaF (pHNaF) figured as Prem predictor variables. The Prem can be estimated with acceptable accuracy using the above-mentioned approach, and pHNaF not only substitutes for clay content as a predictor variable but also confers more accuracy to the Prem estimates.

Lan, Y. Q., Yang, J. X. and Deng, B. 2006. Catalysis of dissolved and adsorbed iron in soil suspension for chromium(VI) reduction by sulfide. Pedosphere. 16(5): 572-578.
ABSTRACT: The kinetics of Cr(VI) reduction by sulfide in soil suspensions with various pHs, soil compositions, and Fe(II) concentrations was examined using batch anaerobic experimental systems at constant temperature. The results showed that the reaction rate of Cr(VI) reduction was in the order of red soil < yellow-brown soil < chernozem and was proportional to the concentration of HCl-extractable iron in the soils. Dissolved and adsorbed iron in soil suspensions played an important role in accelerating Cr(VI) reduction. The reaction involved in the Cr(VI) reduction by Fe(II) to produce Fe(III), which was reduced to Fe(II) again by sulfide, could represent the catalytic pathway until about 70% of the initially present Cr(VI) was reduced. The catalysis occurred because the one-step reduction of Cr(VI) by sulfide was slower than the two-step process consisting of rapid Cr(VI) reduction by Fe(II) followed by Fe(III) reduction by sulfide. In essence, Fe(II) / Fe(III) species shuttle electrons from sulfide to Cr(VI), facilitating the reaction. The effect of iron, however, could be completely blocked by adding a strong Fe(II)-complexing ligand, 1,10-phenanthroline, to the soil suspensions. In all the experiments, initial sulfide concentration was much higher than initial Cr(VI) concentration. The plots of lnc[Cr(VI)] versus reaction time were linear up to approximately 70% of Cr(VI) reduction, suggesting a first-order reaction kinetics with respect to Cr(VI). Elemental sulfur, the product of sulfide oxidation, was found to accelerate Cr(VI) reduction at a later stage of the reaction, resulting in deviation from linearity for the lnc[Cr(VI)] versus time plots.

Liu, Y. S., Wang, J. Y. and Guo, L. Y. 2006. GIS-Based assessment of land suitability for optimal allocation in the Qinling Mountains, China. Pedosphere. 16(5): 579-586.
ABSTRACT: A GIS-based method was used to assess land suitability in the Qinling Mountains, Shaanxi Province of China through simultaneous consideration of physical features and current land use. Through interpretation of Landsat TM images and extensive field visits the area was modeled into 40 land types in five altitudinal zones (valleys and gullies, hillsides and terraces, foothills, mid-mountain, and sub-alpine mountain). Then, a suitability score was assigned to five physical factors (climate, hydrology, topography, soil, and vegetation). Next, their integrated overall suitability value scores were compared with the observed land cover to determine whether it should be reallocated a new use. Results showed that the five suitability classes of agriculture, forest, grassland, farmland-woodland, and scrub-pasture had altitudinal stratification and a total of 1 151 km2 (8.89%) of lands on the northern slopes of the Qinling Mountains had to be reallocated. To achieve this reallocation, 657 km2 of arable land should be reduced, and forest, grassland and scrub-pasture increased by 615 km2, 131 km2 and 405 km2, respectively. Implementation of these recommended land reallocations should help achieve suitable use of land resources and prevent land degradation.

Wang, X. B., Cai, D. X., Hoogmoed, W. B., Oenema, O. and Perdok, U. D. 2006. Potential effect of conservation tillage on sustainable land use---A review of global long-term studies. Pedosphere. 16(5): 587-595.
ABSTRACT: Although understood differently in different parts of the world, conservation tillage usually includes leaving crop residues on the soil surface to reduce tillage. Through a global review of long-term conservation tillage research, this paper discusses the long-term effect of conservation tillage on sustainable land use, nutrient availability and crop yield response. Research has shown several potential benefits associated with conservation tillage, such as potential carbon sequestration, nutrient availability, and yield response. This research would provide a better perspective of the role of soil conservation tillage and hold promise in promoting application of practical technologies for dryland farming systems in China.

Xu, G. L., Mo, J. M., Zhou, G. Y. and Fu, S. L. 2006. Preliminary response of soil fauna to simulated N deposition in three typical subtropical forests. Pedosphere. 16(5): 596-601.
ABSTRACT: A field-scale experiment arranged in a complete randomized block design with three N addition treatments including a control (no addition of N), a low N (5 g m-2 year-1), and a medium N (10 g m-2 year-1) was performed in each of the three typical forests, a pine (Pinus massoniana Lamb.) forest (PF), a pine-broadleaf mixed forest (MF) and a mature monsoon evergreen broadleaf forest (MEBF), of the Dinghushan Biosphere Reserve in subtropical China to study the response of soil fauna community to additions of N. Higher NH4+ and NO3- concentrations and a lower soil pH occurred in the medium N treatment of MEBF, whereas the NO3- concentration was the lowest in PF after the additions of N. The response of the density, group abundance and diversity index of soil fauna to addition of N varied with the forest type, and all these variables decreased with increasing N under MEBF but the trend was opposite under PF. The N treatments had no significant effects on these variables under MF. Compared with the control plots, the medium N treatment had significant negative effect on soil fauna under MEBF. The group abundance of soil fauna increased significantly with additions of higher N rates under PF. These results suggested that the response of soil fauna to N deposition varied with the forest type and N deposition rate, and soil N status is one of the important factors affecting the response of soil fauna to N deposition.

Pang, X. Y., Bao, W. K. and Zhang, Y. M. 2006. Evaluation of soil fertility under different Cupressus chengiana forests using multivariate approach. Pedosphere. 16(5): 602-615.
ABSTRACT: The distribution and growing conditions of Cupressus chengiana forests along with the physical and chemical properties of soils in Northwest Sichuan were studied in 2002 to investigate the conditions and characteristics of soil fertility of C. chengiana and to compare and investigate differences of soil fertility for six C. chengiana populations and their relationships with vegetation, climate and disturbance. The results of the study at 0--20 cm soil depth showed that 1) significant differences (P < 0.05) existed among populations for soil bulk density, soil total porosity, capillary porosity, maximum water-holding capacity, capillary water-holding capacity and topsoil natural water content; 2) chemical characteristics of soil organic matter, total N, total P, alkali-hydrolyzable N, available P, available K and cation exchange capacity were significantly different among the populations; and 3) based on the significant effect of soil fertility factors on forest growth, soil physical and chemical characteristics could be selected as an integrated fertility index (IFI) for evaluation of different C. chengiana populations. Principal component and cluster analyses showed significant differences probably due to the difference of vegetation conditions, management measurements, human-induced disturbances and environmental factors. In order to protect the soil ecological functions in fragile ecological regions, C. chengiana could be used in programs enclosing the hill for natural afforestation, natural forest protection programs, and programs replacing agriculture with afforestation measures.

Li, T. Q., Yang, X. E, Yang, J. Y. and He, Z. L. 2006. Zn accumulation and subcellular distribution in the Zn hyperaccumulator Sedum alfredii Hance. Pedosphere. 16(5): 616-623.
ABSTRACT: Zn accumulation and subcellular distribution in leaves of the hyperaccumulating ecotype (HE) and non-hyperaccumulating ecotype (NHE) of Sedum alfredii Hance were studied using radiotracer and gradient centrifugation techniques. Leaf Zn accumulation in the HE of S. alfredii was 18.5--26.7 times greater than that in the NHE when the plants were grown at 1--500 ¼mol Zn L-1. Leaf section uptake of 65Zn was highly dependent on external Zn levels. Greater 65Zn uptake in HE was noted only at external Zn levels e" 100 ¼mol L-1. Zinc subcellular distribution in the leaves of the two ecotypes of S. alfredii was: cell wall > soluble fraction > cell organelle. However, more Zn was distributed to the leaf cell wall and soluble fractions for HE than for NHE. In the leaf of HE, 91%--94% of the Zn was found in the cell walls and the soluble fraction and only 6%--9% Zn was distributed in the cell organelle fraction. For NHE, about 20%--26% Zn was recovered in the cell organelle fraction. In stems, Zn distribution to the cell wall fraction was approximately two fold greater in the HE than that in the NHE. For the hyperaccumulating ecotype of S. alfredii, the cell wall and the vacuole played a very important role in Zn tolerance and hyperaccumulation.

Ye, X. J., Wang Z. Y., Tu, S. H. and Sulewski, G. 2006. Nutrient limiting factors in acidic vegetable soils. Pedosphere. 16(5): 624-633.
ABSTRACT: Nutrient limiting factors in acidic soils from vegetable fields of the Chongqing suburbs of China were assessed by employing the systematic approach developed by Agro Services International (ASI) including soil testing, nutrient adsorption study, and pot and field experiments to verify the results of soil testing, with a conventional soil test (CST) used for comparison. The ASI method found the moderately acidic soil (W01) to be N and P deficient; the strongly acidic soil (W04) to be N, K and S deficient; and the slightly acidic soil (W09) to be N, K, S, Cu, Mn, and Zn deficient. The CST method showed that W01 had P, B and Cu deficiencies; W04 had N, P and S deficiencies; and W09 had N, P, S, B, Cu, and Zn deficiencies. There were differences between the two methods. Among the two indicator plants selected, the response of sorghum on the three soils was more closely related to the ASI results than that of sweet pepper.

Wu, C. Y., Chen, Y., Wang, J. Y. and Wang, S. J. 2006. Estimation of turnover and equilibrium of soil organic matter using a mathematical approach. Pedosphere. 16(5): 634-645.
ABSTRACT: The methods based on N uptake of aerial-plants, soil organic matter (SOM) dynamics, Jenny’s equation, and actual measurement of long-term field experiments in Jiaxing, Quzhou, Huangyan and Hangzhou of Zhejiang Province, China were used to determine the organic mineralization rate being helpful in estimating the organic requirement for SOM equilibrium. The results showed that the estimated mineralization ratios of SOM for Jiaxing and Quzhou were, respectively, 0.0404 and 0.0508 based on N uptake of aerial-plants in non-fertilized plots; 0.0405 and 0.012 using SOM dynamics in non-fertilized plots; and 0.0413 and 0.0513 using the actual investigated data and Jenny’s equation. With Jenny’s equation, soil organic C balance in manure + N-P-K plots was estimated at nearly 28.8 g kg-1 for Jiaxing and 32.4 g kg-1 for Quzhou with predicted SOM linearly related to the actual investigated values (r2 = 0.9640 for Jiaxing and 0.8541 for Quzhou). To maintain the SOM balance in the non-fertilized plots the recommended rate of organic materials was 3 000--6 600 kg ha-1 and the relevant rates of farm yard manure (FYM) in the manure and N-P-K plots were estimated at 3 375 (dry) and 17 670 kg ha-1 (wet) for Jiaxing, 1 845 (dry) and 6 090 kg ha-1 (wet) for Quzhou.

Zhang, L. H., Shi, W. M. and Wang, X. C. 2006. Difference in selenium accumulation in shoots of two rice cultivars. Pedosphere. 16(5): 646-653.
ABSTRACT: Two japonica rice (Oryza sativa L.) cultivars, Xiushui 48 and S. Andrea, differing in their ability to accumulate Se in the grain (as high as a three-fold difference), were compared for selenium (Se) accumulation in their shoots when their growth media was supplied with different forms of Se. Results indicated that when treated with 0.25 µmol L-1 Na2SeO3, Xiushui 48 accumulation of Se in the shoots was significantly more rapid (P d" 0.05) than S. Andrea, probably because of greater Se uptake and transport in Xiushui 48. Xiushui 48 rice seedlings had a higher shoot-Se accumulation rate and absorbed selenocysteine (Se-Cys) more rapidly than S. Andrea seedlings. However, when treated with Se as 0.25 µmol L-1 selenomethionine (Se-Met), the S. Andrea seedlings accumulation rate was significantly greater (P d" 0.05) than that of Xiushui 48. Possibly, the high Se accumulation rate of Xiushui 48 seedling shoots compared to S. Andrea shoots was the result of a higher capacity of Xiushui 48 to transform selenite to organic Se compounds and a higher selenite uptake rate.

Huang, L. Y., Li, H. X., Zhang, X. M., Lu, W. S. and Liu, Y. J. 2006. Silicate adsorption in paddy soils of Guangdong Province, China. Pedosphere. 16(5): 654-659.
ABSTRACT: Silicate adsorption in eight paddy soils developed from four different parent materials in Guangdong Province, China was examined to obtain fundamental knowledge of silicate adsorption to improve the efficacy of silicate fertilizer use in these areas. A correlation analysis showed that silicate adsorption did not obey the Langmuir equation (r = -0.664--0.301) but did obey the Freundlich and Temkin equations (P d" 0.01, r = 0.885--0.990). When the equilibrium silicate concentration (Ci) was less than 45 mg SiO2 kg-1, the adsorption capacity was in the following decreasing order of paddy soils: basalt-derived > Pearl River Delta sediment-derived > granite-derived > sand-shale-derived. Stepwise regression and path analysis showed that for the investigated paddy soils amorphous MnO and Al2O3 were the two most important materials that affected silicate adsorption. Moreover, as Ci increased, amorphous Al2O3 tended to play a more important role in silicate adsorption, while the effects of amorphous MnO on silicate adsorption tended to decrease.

Huang, X. X., Gao, M., Wei, C. F., Xie, D. T. and Pan, G. X. 2006. Tillage effect on organic carbon in a purple paddy soil. Pedosphere. 16(5): 660-667.
ABSTRACT: The distribution and storage of soil organic carbon (SOC) based on a long-term experiment with various tillage systems were studied in a paddy soil derived from purple soil in Chongqing, China. Organic carbon storage in the 0--20 and 0--40 cm soil layers under different tillage systems were in an order: ridge tillage with rice-rape rotation (RT-rr) > conventional tillage with rice only (CT-r) > ridge tillage with rice only (RT-r) > conventional tillage with rice-rape rotation (CT-rr). The RT-rr system had significantly higher levels of soil organic carbon in the 0--40 cm topsoil, while the proportion of the total remaining organic carbon in the total soil organic carbon in the 0--10 cm layer was greatest in the RT-rr system. This was the reason why the RT-rr system enhanced soil organic carbon storage. These showed that tillage system type was crucial for carbon storage. Carbon levels in soil humus and crop-yield results showed that the RT-rr system enhanced soil fertility and crop productivity. Adoption of this tillage system would be beneficial both for environmental protection and economic development.

Feng, Y. J., Li, F., Wang, X. L., Liu, X. M. and Zhang, L. N. 2006. Principal chemical properties of artificial soil composed of fly ash and furfural residue. Pedosphere. 16(5): 668-672.
ABSTRACT: To solve soil shortage in reclaiming subsided land of coal mines, the principal chemical properties of artificial soil formed by mixing organic furfural residue and inorganic fly ash were examined. The results indicated that the artificial soil was suitable for agriculture use after irrigation and desalination, the available nutrients in the artificial soil could satisfy the growth demand of plants, and the pH tended to the neutrality.

Rao, P. H., He, M., Yang, X., Zhang, Y. C., Sun, S. Q. and Wang, J. S. 2006. Effect of an anionic surfactant on hydraulic conductivities of sodium- and calcium-saturated soils. Pedosphere. 16(5): 673-680.
ABSTRACT: The effect of sodium dodecylbenzenesulfonate (SDBS), an anionic surfactant used widely in household products and industrial processes, on saturated hydraulic conductivities (Ksat) of an Anthrosol saturated with sodium (Na-soil) or calcium (Ca-soil) was analyzed in a laboratory experiment using the constant head method, and adsorption and dispersion experiments were also conducted to infer the possible mechanisms of Ksat fluctuations. The results showed that SDBS was more intensely adsorbed in the Ca-soil than in the Na-soil. With an increase in the SDBS concentration, the stability of the Na-soil suspensions decreased when the SDBS concentration was less than 1.2 mmol L-1 and then above this concentration, increased markedly, while the stability of the Ca-soil suspensions increased gradually at all SDBS concentrations studied. With an increase in the SDBS concentration, the Ksat of the Na-soil increased, which resulted mainly from the increase of water channels in the soil because of the coagulation of the soil particles, while the Ksat of Ca-soil decreased mainly on account of the clogging of partial water channels by precipitated Ca(DBS)2 and the fine soil particles generated.

Lei, H. J., Li, B. G., Bai, Y. L., Huang, Y. F., Lü, Y. Z. and Li, G. T. 2006. Modeling soil organic matter dynamics under intensive cropping systems on the Huang-Huai-Hai Plain of China. Pedosphere. 16(4): 409-419.
ABSTRACT: A modified CQESTR model, a simple yet useful model frequently used for estimating carbon sequestration in agricultural soils, was developed and applied to evaluate the effects of intensive cropping on soil organic matter (SOM) dynamics and mineralization as well as to estimate carbon dioxide emission from agricultural soils at seven sites on the Huang-Huai-Hai Plain of China. The model was modified using site-specific parameters from short- and mid-term buried organic material experiments at four stages of biomass decomposition. The predicted SOM results were validated using independent data from seven long-term (10- to 20-year) soil fertility experiments in this region. Regression analysis on 1 151 pairs of predicted and measured SOM data had an r2 of 0.91 (P d" 0.01). Therefore, the modified model was able to predict the mineralization of crop residues, organic amendments, and native SOM. Linear regression also showed that SOM mineralization rate (MR) in the plow layer increased by 0.22% when annual crop yield increased by 1 t ha-1 (P d" 0.01), suggesting an improvement in SOM quality. Apparently, not only did the annual soil respiration efflux merely reflect the intensity of soil organism and plant metabolism, but also the SOM MR in the plow layer. These results suggested that the modified model was simple yet valuable in predicting SOM trends at a single agricultural field and could be a powerful tool for estimating C-storage potential and reconstructing C storage on the Huang-Huai-Hai Plain of China.

Zheng, F. L. 2006. Effect of vegetation changes on soil erosion on the Loess Plateau. Pedosphere. 16(4): 420-427.
ABSTRACT: Vegetation is one of the key factors affecting soil erosion on the Loess Plateau. The effects of vegetation destruction and vegetation restoration on soil erosion were quantified using data from long-term field runoff plots established on the eastern slope of the Ziwuling secondary forest region, China and a field survey. The results showed that before the secondary vegetation restoration period (before about 1866--1872), soil erosion in the Ziwuling region of the Loess Plateau was similar to the current erosion conditions in neighboring regions, where the soil erosion rate now is 8 000 to 10 000 t km-2 year-1. After the secondary vegetation restoration, soil erosion was very low; influences of rainfall and slope gradient on soil erosion were small; the vegetation effect on soil erosion was predominant; shallow gully and gully erosion ceased; and sediment deposition occurred in shallow gully and gully channels. In modern times when human activities destroyed secondary forests, soil erosion increased markedly, and erosion rates in the deforested lands reached 10 000 to 24 000 t km-2 year-1, which was 797 to 1 682 times greater than those in the forested land prior to deforestation. Rainfall intensity and landform greatly affected the soil erosion process after deforestation. These results showed that accelerated erosion caused by vegetation destruction played a key role in soil degradation and eco-environmental deterioration in deforested regions.

Hua, J. F., Jiang, Y. and Liang, W. J. 2006. Response of nematodes in a Hapli-Udic Argosol to urea amended with urease and nitrification inhibitors. Pedosphere. 16(4): 428-434.
ABSTRACT: Effects of urea amended with urease and nitrification inhibitors on soil nematode communities were studied in a Hapli-Udic Argosol (Cambisol, FAO) in Liaoning Province of Northeast China. A completely random design with four treatments, i.e., conventional urea (CU), slow-release urea amended with a liquid urease inhibitor (SRU1), SRU1 + nitrification inhibitor dicyandiamide (SRU2), and SRU1 + nitrification inhibitor 3,5-dimethylpyrazole (SRU3) and four replicates were applied. Thirty-nine genera of nematodes were identified, with Cephalobus and Aphelenchus being dominant; and in all treatments, the dominant trophic group was bacterivores. In addition, during the growth period of spring wheat (Triticum aestivum L.), soil urease activity was lower in SRUs than in CU. The numbers of total nematodes and bacterivores at wheat heading and ripening stages, and omnivores-predators at ripening stage were higher in SUR3 than in CU, SRU1 and SRU2 (P < 0.05).

Zhou, W. J., Wang, K. R., Zhang, Y. Z., Yin, L. C. and Li, H. S. 2006. Phosphorus transfer and distribution in a soybean-citrus intercropping system. Pedosphere. 16(4): 435-443.
ABSTRACT: A mini-plot field experiment was conducted on a loamy clay Oxisol to compare and evaluate P absorption and transfer in plant organs and P movement in soil profile at three P application depths under the soybean-citrus intercropping versus the monoculture using a 32P tracer technique. Total P absorption (Pt) by soybean and P accumulation (Pa) in soybean organs decreased significantly (P < 0.05) under the intercropping in contrast to the monoculture. With intercropping, when 32P was applied in topsoil (15 cm soil layer), total 32P absorption (32Pt) in soybeans was significantly lower (P < 0.05), but when 32P was applied to deeper soil layers (35 or 55 cm soil layer), 32Pt in soybeans was significantly greater (P < 0.05). The percentage of P in leaves to total P (Pa/Pt) and 32P in leaves to total 32P (32Pa/32Pt) for soybean were e" 25% and those of root e" 12%. When P was applied in topsoil and 55 cm soil layer, no significant differences were found between intercropping and monoculture for Pt of citrus. The P absorbed by citrus was transferred rapidly to the growing organs of aboveground during the experiment, and the speed of transferring to the growing organs slowed when P was applied to the deeper soil layers. In intercropping, P mobility was heightened in the soil profile, and P in deeper soil layers moved up to topsoil more rapidly.

Wang, Q. J., Zhang, J. H. and Fan, J. 2006. An analytical method for relationship between hydraulic diffusivity and soil sorptivity. Pedosphere. 16(4): 444-450.
ABSTRACT: A simple method was developed to relate soil sorptivity to hydraulic diffusivity and water absorption experiments were conducted utilizing one-dimensional horizontal soil columns to validate the relationship. In addition, an estimation method for hydraulic diffusivity with disc infiltrometer was developed. The results indicated a favorable fit of the theoretical relation to the experimental data. Also, the experiment with disc infiltrometer for estimating the diffusivity showed that the new method was feasible.

Mao, J., Jiang, X. Q., Yang, L. Z., Zhang, J., Qiao, Q. Y., He, C. D. and Yin, S. X. 2006. Nitrous oxide production in a sequence batch reactor wastewater treatment system using synthetic wastewater. Pedosphere. 16(4): 451-456.
ABSTRACT: The rate of nitrous oxide emission from a laboratory sequence batch reactor (SBR) wastewater treatment system using synthetic wastewater was measured under controlled conditions. The SBR was operated in the mode of 4 h for aeration, 3.5 h for stirring without aeration, 0.5 h for settling and drainage, and 4 h of idle. The sludge was acclimated by running the system to achieve a stable running state as indicated by rhythmic changes of total N, dissolved oxygen, chemical oxygen demand, NO2-, NO3-, NH4+, pH, and N2O. Under the present experimental conditions measured nitrous oxide emitted from the off-gas in the aerobic and anaerobic phases, respectively, accounted for 8.6%--16.1% and 0--0.05% of N removed, indicating that the aerobic phase was the main source of N2O emission from the system. N2O dissolved in discharged water was considerable in term of concentration. Thus, measures to be developed for the purpose of reducing N2O emission from the system should be effective in the aeration phase.

Jabbar, M. T., Shi, Z. H., Wang, T. W. and Cai, C. F. 2006. Vegetation change prediction with geo-information techniques in the Three Gorges area of China. Pedosphere. 16(4): 457-467.
ABSTRACT: A computerized parametric methodology was applied to monitor, map, and estimate vegetation change in combination with “3S” (RS---remote sensing, GIS---geographic information systems, and GPS---global positioning system) technology and change detection techniques at a 1:50 000 mapping scale in the Letianxi Watershed of western Hubei Province, China. Satellite images (Landsat TM 1997 and Landsat ETM 2002) and thematic maps were used to provide comprehensive views of surface conditions such as vegetation cover and land use change. With ER Mapper and ERDAS software, the normalized difference vegetation index (NDVI) was computed and then classified into six vegetation density classes. ARC/INFO and ArcView software were used along with field observation data by GPS for analysis. Results obtained using spatial analysis methods showed that NDVI was a valuable first cut indicator for vegetation and land use systems. A regression analysis revealed that NDVI explained 94.5% of the variations for vegetation cover in the largest vegetation area, indicating that the relationship between vegetation and NDVI was not a simple linear process. Vegetation cover increased in four of areas. This meant 60.9% of land area had very slight to slight vegetation change, while 39.1% had moderate to severe vegetation change. Thus, the study area, in general, was exposed to a high risk of vegetation cover change.

Tang, X. Y., Yang, H., Du, M. Y., Zhao, Q. G. and Li, R. Y 2006. Identification of 137Cs reference sites in southeastern China. Pedosphere. 16(4): 468-476.
ABSTRACT: The 137Cs vertical distributions in uncultivated and cultivated soils, developed from Quaternary red clay, granite, argillaceous shale, and red sandstone, were studied to develop reliable guidelines for selecting reference sites in southeastern China, which is dominated by strong acidic and/or clay-textured soils, and examine their reliability by comparing them to the reported 137Cs reference inventory data to see whether they agreed with the global distribution pattern. It was observed that a relatively high proportion of 137Cs was concentrated in the surface layers of soils with relatively high clay content. In the paddy soils developed from granite more 137Cs penetrated to depths below the plow layer (about 45.3%), when compared to those from the other three parent materials. The relatively low soil 137Cs inventories on crests excluded using the crest as the 137Cs reference site; instead the paddy field on the hillock plain was selected. Furthermore, within a specific county characterized by great systematic spatial variations of rainfall and topography across the landscape, a significant (P < 0.01) and positive linear relationship (r2 = 0.81) between local 137Cs inventory and corresponding local annual rainfall was observed. Thus, for areas with large variations in rainfall, a single uniform value of local 137Cs reference inventory should be used with caution.

Quan, B., Chen, J. F., Qiu, H. L., RÖmkens, M. J. M., Yang, X. Q., Jiang, S. F., And Li, B. C. 2006. Spatial-temporal pattern and driving forces of land use changes in Xiamen. Pedosphere. 16(4): 477-488.
ABSTRACT: Using Landsat TM data of 1988, 1998 and 2001, the dynamic process of the spatial-temporal characteristics of land use changes during 13 years from 1988 to 2001 in the special economic zone of Xiamen, China were analyzed to improve understanding and to find the driving forces of land use change so that sustainable land utilization could be practiced. During the 13 years cropland decreased remarkably by nearly 11 304.95 ha. The areas of rural-urban construction and water body increased by 10 152.24 ha and 848.94 ha, respectively. From 1988 to 2001, 52.5% of the lost cropland was converted into rural-urban industrial land. Rapid urbanization contributed to a great change in the rate of cropland land use during these years. Land-reclamation also contributed to a decrease in water body area as well as marine ecological and environmental destruction. In the study area 1) urbanization and industrialization, 2) infrastructure and agricultural intensification, 3) increased affluence of the farming community, and 4) policy factors have driven the land use changes. Possible sustainable land use measures included construction of a land management system, land planning, development of potential land resources, new technology applications, and marine ecological and environmental protection.

Ma, Y., Liu, W. P. and Wen, Y. Z. 2006. Enantioselective degradation of rac-metolachlor and S-metolachlor in soil. 16(4): 489-494.
ABSTRACT: Separation of chiral enantiomers and the dissipation of rac-metolachlor and S-metolachlor in soil were evaluated using achiral high-performance liquid chromatography (HPLC) and chiral gas chromatography (GC) methods. Under the experimental conditions the possible metabolite was considered to be N-(2-ethyl-6-methyl-phenyl)-2-hydroxy-acetamide. Because of the presence of two chiral elements (asymmetrically substituted carbon and chiral axis), the baseline separation of metolachlor enantiomers was not achieved. S-metolachlor degraded faster in soil than rac-metolachlor. After a 42-day incubation, 73.4% of rac-metolachlor and 90.0% of S-metolachlor were degraded. However, due to the absence of biological processes the degradation process in sterilized soil showed no enantioselectivity. The results indicated that enantioselective degradations could greatly affect the environmental fate of metolachlor and should be considered when the environmental behavior of these compounds was assessed.

Dang, T. H., Cai, G. X., Guo, S. L., Hao, M. D. and Heng, L. K. 2006. Effect of nitrogen management on yield and water use efficiency of rainfed wheat and maize in Northwest China. Pedosphere. 16(4): 495-504.
ABSTRACT: A field experiment with four treatments and four replicates in a randomized complete block design was conducted at the Changwu Experimental Station in Changwu County, Shaanxi Province, of Northwest China from 1998 to 2002. The local cropping sequence of wheat, wheat-beans, maize, and wheat over the 4-year period was adopted. A micro-plot study using 15N-labelled fertilizer was carried out to determine the fate of applied N fertilizer in the first year. When N fertilizer was applied wheat (years 1, 2 and 4) and maize (year 3) grain yield increased significantly (P < 0.05) (> 30%), with no significant yield differences in normal rainfall years (Years 1, 2 and 3) for N application at the commonly application rate and at 2/3 of this rate. Grain yield of wheat varied greatly between years, mainly due to variation in annual rainfall. Results of 15N studies on wheat showed that plants recovered 36.6%--38.4% of the N applied, the N remained in soil (0--40 cm) ranged from 29.2% to 33.6%, and unaccounted-for N was 29.5%--34.2%. The following crop (wheat) recovered 2.1%--2.8% of the residual N from N applied to the previous wheat crop with recovery generally decreasing in the subsequent three crops (beans, maize and wheat).

Jiang, P. K. and Xu, Q. F. 2006. Abundance and dynamics of soil labile carbon pools under different types of forest vegetation. Pedosphere. 16(4): 505-511.
ABSTRACT: Soil organic matter (SOM) in forest ecosystems is not only important to global carbon (C) storage but also to sustainable management of forestland with vegetation types, being a critical factor in controlling the quantity and dynamics of SOM. In this field experiment soil plots with three replicates were selected from three forest vegetation types: broadleaf, Masson pine (Pinus massoniana Lamb.), and Chinese fir (Cunninghamia lanceolata Hook.). Soil total organic C (TOC), two easily oxidizable C levels (EOC1 and EOC2, which were oxidized by 66.7 mmol L-1 K2Cr2O7 at 130--140 ºC and 333 mmol L-1 KMnO4 at 25 ºC, respectively), microbial biomass C (MBC), and water-soluble organic C (WSOC) were analyzed for soil samples. Soil under the broadleaf forest stored significantly higher TOC (P d" 0.05). Because of its significantly larger total soil C storage, the soil under the broadleaf forest usually had significantly higher levels (P d" 0.05) of the different labile organic carbons, EOC1, EOC2, MBC, and WSOC; but when calculated as a percentage of TOC each labile C fraction of the broadleaf forest was significantly lower (P d" 0.05) than one of the other two forests. Under all the three vegetation types temperature as well as quality and season of litter input generally affected the dynamics of different organic C fractions in soils, with EOC1, EOC2, and MBC increasing closely following increase in temperature, whereas WSOC showed an opposite trend.

Zhang, Y. L. and Wang, Y. S. 2006. Soil enzyme activities with greenhouse subsurface irrigation. Pedosphere. 16(4): 512-518.
ABSTRACT: Various environmental conditions determine soil enzyme activities, which are important indicators for changes of soil microbial activity, soil fertility, and land quality. The effect of subsurface irrigation scheduling on activities of three soil enzymes (phosphatase, urease, and catalase) was studied at five depths (0--10, 10--20, 20--30, 30--40, and 40--60 cm) of a tomato greenhouse soil. Irrigation was scheduled when soil water condition reached the maximum allowable depletion (MAD) designed for different treatments (-10, -16, -25, -40, and -63 kPa). Results showed that soil enzyme activities had significant responses to the irrigation scheduling during the period of subsurface irrigation. The neutral phosphatase activity and the catalase activity were found to generally increase with more frequent irrigation (MAD of -10 and -16 kPa). This suggested that a higher level of water content favored an increase in activity of these two enzymes. In contrast, the urease activity decreased under irrigation, with less effect for MAD of -40 and -63 kPa. This implied that relatively wet soil conditions were conducive to retention of urea N, but relatively dry soil conditions could result in increasing loss of urea N. Further, this study revealed that soil enzyme activities could be alternative natural bio-sensors for the effect of irrigation on soil biochemical reactions and could help optimize irrigation management of greenhouse crop production.

Wang, X. and Cai, Q. S. 2006. Steel slag as an iron fertilizer for corn growth and soil improvement in a pot experiment. Pedosphere. 16(4): 519-524.
ABSTRACT: The feasibility of steel slag used as an iron fertilizer was studied in a pot experiment with corn. Slag alone or acidified slag was added to two Fe-deficient calcareous soils at different rates. Results showed that moderate rates (10 and 20 g kg-1) of slag or acidified slag substantially increased corn dry matter yield and Fe uptake. Application of steel slag increased the residual concentration of ammonium bicarbonate-diethylenetriamine pentaacetic acid (AB-DTPA) extractable Fe in the soils. The increase of extractable Fe was usually proportional to the application rate, and enhanced by the acidification of slag. Steel slag appeared to be a promising and inexpensive source of Fe to alleviate crop Fe chlorosis in Fe-deficient calcareous soils.

Zhou, G. M., Xu, J. M. and Jiang, P. K. 2006. Effect of management practices on seasonal dynamics of organic carbon in soils under bamboo plantations. Pedosphere. 16(4): 525-531.
ABSTRACT: Soil samples for conventional management (CM) and intensive management (IM) practices were taken over a year at 2-month intervals to determine the effect of management practices on soil organic carbon (SOC) and to quantify seasonal dynamics in SOC for bamboo (Phyllostachys pubescens Mazel ex H. de Lehaie) stands. The results with IM compared to CM showed large decreases in total organic carbon (TOC), microbial biomass carbon (MBC), water-soluble organic carbon (WSOC), and the MBC/TOC ratio in the soils. With all IM plots in the 0--20 cm depth across sampling periods, average decreases compared with CM were: TOC, 12.1%; MBC, 26.1%; WSOC, 29.3%; the MBC/TOC ratio, 16.1%; and the WSOC/TOC ratio, 20.0%. Due to seasonal changes of climate, seasonal variations were observed in MBC and WSOC. Soil MBC in the 0--20 cm depth in September compared to May were 122.9% greater for CM and 57.6% greater for IM. However, due primarily to soil temperature, soil MBC was higher during the July to November period, whereas because of soil moisture, WSOC was lower in July and January. This study revealed that intensive management in bamboo plantations depleted the soil C pool; therefore, soil quality with IM should be improved through application of organic manures.

Wang, X. C. and Lu, Q. 2006. Effect of waterlogged and aerobic incubation on enzyme activities in paddy soil. Pedosphere. 16(4): 532-539.
ABSTRACT: An incubation experiment with soil water content treatments of 0.15 (W1), 0.20 (W2), and 0.40 (W3) g g-1 soil was carried out for two months to investigate the activities of important enzymes involved in C, N, P, and S cycling in a paddy soil from the Taihu Lake region, China, under waterlogged and aerobic conditions. Compared with air-dried soil, waterlogging resulted in a significant decrease (P d" 0.05) of fluorescein diacetate (FDA) and ²-D-glucosidase activities, and this effect was enhanced with increasing waterlogging time. Waterlogging also significantly inhibited (P d" 0.05) arylsulfatase as well as alkaline and acid phosphatase activities, but did not decrease the activities with the increase in waterlogging time. Short-term waterlogging did not affect urease activity, but prolonged waterlogging decreased it markedly. In contrast, the aerobic incubation (W1 and W2 treatments) significantly increased (P d" 0.05) FDA, alkaline phosphatase, and ²-D-glucosidase activities. With aerobic treatments the activities of FDA and alkaline phosphatase increased with incubation time, whereas ²-D-glucosidase activity decreased. A significant difference (P d" 0.05) was usually observed between the W1 and W2 treatments for the activities of FDA as well as alkaline and acid phosphatase; however, ²-D-glucosidase and urease were usually not significant (P d" 0.05). No activity differences were observed between waterlogging and aerobic incubation for arylsulfatase and urease.

Jin, L., Wang, X. J., Gu, Z. L., Zhou, D. Z. and Xie, S. Q. 2006. Biodegradation of lubricating oil in wastewater with Zoogloea sp. Pedosphere. 16(4): 540-544.
ABSTRACT: The purpose of this study was to identify microbial strains that have a strong ability to biodegrade lubricating oil. No. 20 lubricating oil was used as the sole carbon source in an isolation medium to screen bacteria from sludge that had been contaminated with crude oil. Through both morphological and biochemical methods, the bacterial strain that had the highest biodegrading capacity was identified as Zoogloea sp. On the basis of these preliminary results, a biological contact oxidation method was employed to further assess the ability of the Zoogloea sp. strain to treat wastewater contaminated by No. 20 lubricating oil using three oxidation cabins and two hydraulic retaining times (HRT). Results showed that the concentration of No. 20 lubricating oil with a 12 h hydraulic retaining time and 16.5 L h-1 inflow rate was reduced by 99.3% in 15 d, and with a 6 h hydraulic retaining time and 33 L h-1 inflow rate it decreased by 98.6% in 12 d. The results from this study indicated that Zooglea sp. had a strong potential to be utilized in biodegradation of lubricating oil.

Zhong, Z. K. and Makeschin, F. 2006. Comparison of soil nitrogen availability indices under two temperate forest types. Pedosphere. 16(3): 273-283.
ABSTRACT: To evaluate the validity of different indices in estimating soil readily mineralizable N, soil microbial biomass (Nmic), soil active N (SAN), soluble organic N (SON), net N mineralization rate (NNR) and gross N mineralization rate (GNR) in mineral soils (0--10 cm) from six forest stands located in central Germany were determined and compared with two sampling times: April and November. Additionally, soil density fractionation was conducted for incubated soils (with addition of 15NH4-N and glucose, 40 days) to observe the sink of added 15N in different soil fractions. The study showed that Nmic and NNR in most stands differed significantly (P d" 0.05) between the two sampling times, but not GNR, SAN and SON. In November, no close relationships were found between GNR and other N indices, or between Nmic, SON, and SAN and forest type. However, in April, GNR was significantly correlated (P d" 0.05) with Nmic, SAN, and NNR along with Nmic under beech being significantly higher (P d" 0.05) than under conifers. Furthermore, density fractionation revealed that the light fraction (LF, 0.063--2 mm, >1.7 g cm-3) was not correlated with the other N indices. In contrast, results from the incubation study proved that more 15N was incorporated into the heavy fraction (HF < 0.063 mm, > 1.7 g cm-3) than into LF, indicaing that more labile N existed in HF than in LF. These findings suggested that attention should be paid to the differences existing in N status between agricultural and forest soils.

Jasinska, E., Wetzel, H., Baumgartl, T. and Horn, R. 2006. Heterogeneity of physico-chemical properties in structured soils and its consequences. Pedosphere. 16(3): 284-296.
ABSTRACT: Structured soils are characterized by the presence of inter- and intra-aggregate pore systems and aggregates, which show varying chemical, physical, and biological properties depending on the aggregate type and land use system. How far these aspects also affect the ion exchange processes and to what extent the interaction between the carbon distribution and kind of organic substances affect the internal soil strength as well as hydraulic properties like wettability are still under discussion. Thus, the objective of this research was to clarify the effect of soil aggregation on physical and chemical properties of structured soils at two scales: homogenized material and single aggregates. Data obtained by sequentially peeling off soil aggregates layers revealed gradients in the chemical composition from the aggregate surface to the aggregate core. In aggregates from long term untreated forest soils we found lower amounts of carbon in the external layer, while in arable soils the differentiation was not pronounced. However, soil aggregates originating from these sites exhibited a higher concentration of microbial activity in the outer aggregate layer and declined towards the interior. Furthermore, soil depth and the vegetation type affected the wettability. Aggregate strength depended on water suction and differences in tillage treatments.

Zhou, Q. X., Zhang, Q. R. and Sun, T. H. 2006. Technical innovation of land treatment systems for municipal wastewater in Northeast China. Pedosphere. 16(3): 297-303.
ABSTRACT: On the basis of ecological principles including holistic optimization, cycling and regeneration, and regional differentiation, land treatment systems (LTSs) for municipal wastewater were continuously explored and updated in the western Shenyang area and the Huolinhe area, China. Intensified pretreatment, addition of a man-made soil filtration layer, and use of an ecologically diversified secondary plant cover were proved to be technically feasible. Hydraulic loading was determined according to the assimilation capacity of soil ecosystems, thus ensuring safe operation of wastewater treatment. This modernized and alternative approach to wastewater treatment had been widely applied in middle-sized and small cities and towns of Northeast China, and these innovative systems in some areas had indicated favorable ecological, social, and economic benefits.

Yu, D. S., Shi, X. Z. and Weindorf, D. C. 2006. Relationships between permeability and erodibility of cultivated Acrisols and Cambisols in subtropical China. Pedosphere. 16(3): 304-311.
ABSTRACT: The relationships between soil erodibility factor (K) and soil saturated permeability (Kfs) for cultivated Acrisols derived from Quaternary red clay and Cambisols derived from red sandstone were studied and quantified using a rainfall simulator and Guelph permeameter in a hilly area of subtropical China. A negative correlation existed between Kfs of the topsoil (0--5 cm) and K. The empirical expression K H" a × Kfs-b + c, where a, b and c are the structural coefficients related to soil properties, such as soil type, soil parent material, organic matter, pH and mechanical composition, best described the relationship between soil saturated permeability and soil erodibility.

Liu, Y. G., Wang, X. H., Zeng, G. M., Li, X., Zhou, C. H., Fan, T., Li,Y. L. and Yuan, X. Z. 2006. Redistribution of Pb, Zn and Cu fractions in tailing soils treated with different extractants. Pedosphere. 16(3): 312-318.
ABSTRACT: The efficiency of EDTA, HNO3 and CaCl2 as extractants to remove Pb, Zn and Cu from tailing soils without varying soil pH was investigated with distributions of Pb, Zn and Cu being determined before and after extraction using the sequential extraction procedure of the optimized European Community Bureau of Reference (BCR). Results indicated that EDTA and HNO3 were both effective extracting agents.The extractability of extractants for Pb and Zn was in the order EDTA > HNO3 > CaCl2, while for Cu it was HNO3 > EDTA > CaCl2. After EDTA extraction, the proportion of Pb, Zn and Cu in the four fractions varied greatly, which was related to the strong extraction and complexation ability. Before and after extraction with HNO3 and CaCl2, the percentages of Pb, Zn and Cu in the reducible, oxidizable and residual fractions changed little compared to the acid-extractable fraction. The lability of metal in the soil and the kinds of extractants were the factors controlling the effects of metal extraction.

Zhang, T. H., Su, Y. Z., Cui, J. Y., Zhang, Z. H. and Chang, X. X. 2006. A leguminous shrub (Caragana microphylla) in semiarid sandy soils of North China. Pedosphere. 16(3): 319-325.
ABSTRACT: Caragana microphylla Lam., a pioneer leguminous shrub species for vegetation re-establishment, is widely distributed in the semi-fixed and fixed sandy lands of the Horqin region. Some soil chemical and physical properties were measured under the canopy of C. microphylla and in the adjacent open areas to determine the effects of individual shrubs on soil properties. The influence of isolated C. microphylla on chemical and physical properties of the topsoil was significantly different between plots under the shrub canopy and in the shrub interspaces. Beneath the shrub canopy greater amounts of fine particle fractions, a higher water-holding capacity, and a lower bulk density, as well as higher aboveground and belowground litter biomass were found. Soil organic C and total N concentrations were 23%--31.6% and 14%--27.2% higher under the shrub canopies than in the shrub interspaces, respectively, giving rise to “islands of fertility”. In a desertified sandy grassland ecosystem, C. microphylla was believed to play a major role in organic C sequestration, N accumulation, and the hydrologic cycle. Additionally, it has been found to be of ecological importance for vegetative restoration and reversal of desertification.

Bai, L. P., Sui, F. G., Ge, T. D., Sun, Z. H., Lu, Y. Y. and Zhou, G. S. 2006. Effect of soil drought stress on leaf water status, membrane permeability and enzymatic antioxidant system of maize. Pedosphere. 16(3): 326-332.
ABSTRACT: A simulation experiment on the responses of maize (Zea mays L.) from the third leaf stage to maturity for different soil water levels (well-watered, moderately stressed, and severely stressed) was conducted by controlling irrigation and using a mobile rain shelter in a neutral loam, meadow soil to determine the effects on leaf water status, membrane permeability and enzymatic antioxidant system for different growth stages. The results indicated that drought stress relied on drought intensity and duration, with more severe drought stress creating more serious effects on maize. Compared with well-watered conditions, during the silking and blister stages moderate stress did not significantly change the relative water content (RWC) and did change significantly the relative conductivity (RC) (P < 0.05) of the leaves; however, severe stress did significantly decrease (P < 0.01) the leaf RWC and increase (P < 0.01) membrane permeability (leaf relative conductivity). Furthermore, under severe drought stress antioxidant enzyme activities declined significantly (P < 0.01) in later stages, namely for superoxide dismutase (SOD) the tasseling and blister stages, for peroxidase (POD) the milk stage, and for catalase (CAT) during the tasseling, blister, and milk stages. Meanwhile, membrane lipid peroxidation (measured as malondialdehyde content) significantly increased (P < 0.01) in all stages.

Zhao, C. J., Wang, J. H., Liu, L. Y., Huang, W. J. and Zhou, Q. F. 2006. Relationship of 2 100--2 300 nm spectral characteristics of wheat canopy to leaf area index and leaf N as affected by leaf water content. Pedosphere. 16(3): 333-338.
ABSTRACT: The effects of leaf water status in a wheat canopy on the accuracy of estimating leaf area index (LAI) and N were determined in this study using extracted spectral characteristics in the 2 000--2 300 nm region of the short wave infrared (SWI) band. A newly defined spectral index, relative adsorptive index in the 2 000--2 300 nm region (RAI2000--2300), which can be calculated by RAI2000--2300 = (R2224
ÿ R2054) (R2224 + R2054)-1, with R being the reflectance at 2 224 or 2 054 nm, was utilized. This spectral index, RAI2000--2300, was significantly correlated (P 90% and 22 great groups between 60%--90%. These soil great groups could serve as cross-reference benchmarks. There were 19 great groups in GSCC with maximum referencibility < 60%, which could be used as cross-reference benchmarks until new and better results were available. For these soils, if the translation was made at a lower soil taxon level or on a regional basis, it would improve their referencibility enabling them to serve as new cross-reference benchmarks.

Shi, Z., Cheng, J. L., Huang, M. X. and Zhou, L. Q. 2006. Assessing reclamation levels of coastal saline lands with integrated stepwise discriminant analysis and laboratory hyperspectral data. Pedosphere. 16(2): 154--160.
ABSTRACT: At different times over the past 30 years in Zhejiang Province, China, the coastal tidelands have been successively enclosed and reclaimed for agricultural land use. The purpose of this work was to evaluate whether laboratory hyperspectral data might be used to estimate the physicochemical characteristics of these reclaimed saline soils. A coastal region of Shangyu City (Zhejiang Province), which was grouped into four subzones according to reclamation history, was used as the study area, and soil samples were collected in each subzone. Physicochemical analyses showed that the soils were characterized by high electrical conductivity and sand content with low organic matter; the longer the saline lands had been reclaimed, the lower were the electrical conductivity and sand content and the higher the organic matter content. These changing trends of soil chemical and physical properties were found in laboratory reflectance spectra of soil samples and their first-order derivative curves. Stepwise discriminant analysis (SDA) identified six salient spectral bands at 488, 530, 670, 880, 1 400, and 1 900 nm. Using derived discriminant functions for saline lands with different historical years of reclamation, classification revealed an overall accuracy from a self-test of 86.6% and from cross-validation of 89.3%. Therefore, as opposed to time-consuming field investigations, this study suggested that remotely sensed hyperspectral data could serve as a promising measure to assess the reclamation levels of coastal saline lands.

Wang, F., Bian, Y. R., Jiang, X., Gao, H. J., Yu, G. F. and Deng, J. C. 2006. Residual characteristics of organochlorine pesticides in Lou soils with different fertilization modes. Pedosphere. 16(2): 161--168.
ABSTRACT: Soil samples with three fertilization treatments (no fertilizer, corn straw and farm manure) collected from a Lou soil (Eum-orthic Anthrosol classfied using Chinese Soil Taxonomy) in northwestern China were analysed for residual levels and their characteristics of organochlorine pesticides (±-HCH, ²-HCH, ³-HCH, ´-HCH, HCB, o,p'-DDT, p,p'-DDT, o,p'-DDE, p,p'-DDE, p,p'-DDD, ±-endosulfan, dieldrin and endrin). Organochlorine pesticides (OCPs) were detected in all soil samples except ´-HCH and their total concentrations ranged from 159.31 ± 9.00 to 179.77 ± 2.58 ng g-1 with an order of HCHs > DDTs > (dieldrin + endrin) > HCB > ±-endosulfan. Among all the compounds, ³-HCH had the highest concentration followed by p, p'-DDE. The residual levels of HCH isomers and DDT as well as their metabolites in soil with different fertilization treatments were in the order of ³-HCH > ²-HCH H" ±-HCH > ´-HCH and p,p'-DDE > p,p'-DDT > o,p'-DDT > p,p'-DDD H" o,p'-DDE, respectively. DDE/DDT ratios ranged from 1.59 ± 0.13 to 3.35 ± 0.16 and endrin/dieldrin ratios from 1.40 ± 0.06 to 9.20 ± 4.05, both indicating no new occurrence of these pesticides in these soils, while ±-HCH/³-HCH ratios of 0.04 indicated a new input of lindane (almost pure ³-HCH) in the past several years. The farm manure treatments showed lower DDT residues than samples without fertilizer. Also addition of corn straw and farm manure increased soil organic matter content and decreased the soil pH which could retard the degradation of DDT in the soil.

Meng, F. X., Ou, W., Li, Q., Jiang, Y., and Wen, D. Z. 2006. Vertical distribution and seasonal fluctuation of nematode trophic groups as affected by land use. Pedosphere. 16(2): 169--176.
ABSTRACT: A field investigation was conducted at the Shenyang Experimental Station of Ecology, Chinese Academy of Sciences, in an aquic brown soil of Northeast China under three land use types (cropland, abandoned cropland, and woodland) in order to evaluate whether the vertical distribution and seasonal fluctuation for the number of total nematodes and trophic groups could reflect soil ecosystem differences and to determine the relationships between soil chemical properties and soil nematodes. The majority of soil nematodes were present in the 0--20 cm soil layers, and for these land use types plant parasites were the most abundant trophic group. In the abandoned cropland the numbers of plant parasites reached a peak on the August sampling date, whereas the cropland and woodland peaked on the October sampling date. Meanwhile, in all land use types the number of total nematodes, bacterivores, plant parasites, and omnivores-predators was negatively (P < 0.05, except for bacterivores in cropland, which was not significant) correlated with bulk density, and positively (P < 0.05, except for fungivores in abandoned cropland, which was not significant) correlated with total organic carbon and total nitrogen.

Yin, Y. F. and Cai, Z. C. 2006. Equilibrium of organic matter in heavy fraction for three long-term experimental field soils in Chin. Pedosphere. 16(2): 177--184.
ABSTRACT: Considerable evidence that the soil organic matter (OM) level in agricultural soils will gradually over time reach an equilibrium state under certain bioclimatic conditions and for certain cropping systems has been accumulating. Although models or long-term experiments have been used, this research used physical fractionation procedure to attain an soil OM equilibrium value. To obtain soil OM equilibrium values in the heavy fraction, typical soils from three long-term field experiments at Fengqiu and Yingtan State Key Agro-Ecological Experimental Stations in China were studied using a simple density fractionation procedure and employing the Langmuir equation. Results for the fluvo-aquic soil with organic fertilizer treatments indicated that the soil OM equilibrium value in the heavy fraction was twofold more than that in the inorganic treatments; however, for the paddy soil developed on red soil the OM equilibrium value in the heavy fraction for both treatments was almost identical. It suggested that for fluvo-aquic soils the increased potential of OM for the heavy fraction in the long run was larger for the organic than the inorganic fertilizer applications, whereas for paddy soils developed on red soils under the same conditions the present OM content in the heavy fraction was at or close to this equilibrium level for all treatments, and increased potential was very limited.

Liao, M. 2006. Effects of organic acids on adsorption of cadmium onto kaolinite, goethite, and bayerite. Pedosphere. 16(2): 185--191.
ABSTRACT: Effects of organic acids (oxalic, acetic, and citric) on adsorption characteristics of Cadmium (Cd) on soil clay minerals (kaolinite, goethite, and bayerite) were studied under different concentrations and different pH values. Although the types of organic acids and minerals were different, the effects of the organic acids on the adsorption of Cd on the minerals were similar, i.e., the amount of adsorbed Cd with an initial solution pH of 5.0 and initial Cd concentration of 35 mg L-1 increased with increasing concentration of the organic acid in solution at lower concentrations, and decreased at higher concentrations. The percentage of Cd adsorbed on the minerals in the presence of the organic acids increased considerably with increasing pH of the solution. Meanwhile, different Cd adsorption in the presence of the organic acids, due to different properties on both organic acids and clay minerals, on kaolinite, goethite, or bayerite for different pHs or organic acid concentrations was found.

Yang, L. F. and Cai, Z. C. 2006. Soil respiration during a soybean-growing season. Pedosphere. 16(2): 192--200.
ABSTRACT: Soil respiration induced by soybean cultivation over its entire growing season and the factors influencing soil respiration were investigated to examine the seasonal pattern of soil respiration induced by soybean cultivation, explore soybean growth and photosynthesis on soil respiration, and determine the temperature dependence on soil respiration. Soil respiration in a pot experiment with and without soybean plants was sampled using the static chamber method and measured using gas chromatograph. Air temperature was a dominant factor controlling soil respiration rate in unplanted soil. Additionally, rhizosphere respiration comprised 62% to 98% of the soil respiration rate in the soybean-planted soil varying with the soybean growth stages. Harvesting aerial parts of soybean plant caused an immediate drop in the soil respiration rate at that stage. After harvesting the aerial parts of the soybean plant, a highly significant correlation between soil respiration rate and air temperature was found at the flowering stage (P < 0.01), the pod stage (P < 0.01), and the seed-filling stage (P < 0.05). Thus, rhizosphere respiration during the soybean-growing period not only made a great contribution to soil respiration, but also determined the seasonal variation pattern of the soil respiration rate.

Fang, H. J., Yang, X. M., Zhang, X. P. and Liang, A. Z. 2006. Using 137Cs tracer technique to evaluate erosion and deposition of black soil in Northeast China. Pedosphere. 16(2): 201--209.
ABSTRACT: Soil and water losses through erosion have been serious in the black soil region of Northeast China. Therefore, a sloping cultivated land in Songnen Plain was selected as a case study to: 1) determine the 137Cs reference inventory in the study area; 2) calculate erosion and deposition rates of black soil on different slope locations; 3) conduct a sensitivity analysis of some model parameters; and 4) compare overall outputs using four different models. Three transects were set in the field with five slope locations for each transect, including summit, shoulder-slope, back-slope, foot-slope, and toe-slope. Field measurements and model simulation were used to estimate a bomb-derived 137Cs reference inventory in the study area. Soil erosion and deposition rates were estimated using four 137Cs models and percentage of 137Cs loss/gain. The 137Cs reference value in the study area was 2 232.8 Bq m-2 with 137Cs showing a clear topographic pattern, decreasing from the summit to shoulder-slope, then increasing again at the foot-slope and reaching a maximum at the toe-slope. Predicted soil redistribution rates for different slope locations varied. Among models, the Yang Model (YANG-M) overestimated erosion loss but underestimated deposition. However, the standard mass balance model (MBM1) gave predictions similar to a mass balance model incorporating soil movement by tillage (MBM2). Sensitivity analysis of the proportion factor ³ and distribution pattern of 137Cs in the surface layer demonstrated the impact of 137Cs enrichment on calculation of the soil erosion rate. Factors influencing the redistribution of fallout 137Cs in landscape should be fully considered as calculating soil redistribution rate using 137Cs technique.

Yu, C. L., Luo, S. G., Peng, X. L. and Liu, Y. Y. 2006. Effects of boron, zinc, and iron on the gentiopicroside content and yield of gentian. Pedosphere. 16(2): 210--214.
ABSTRACT: A field experiment of 2-year-old gentian (Gentiana manshurica Kitag.) with application of boron (B), zinc (Zn), and iron (Fe) in Taikang County, Heilongjiang Province, was conducted to study the effects of the three microelements on gentiopicroside content in the roots of gentian, uptake of these elements, and root dry weight as well as the ratio of root dry weight to fresh weight. Zinc sulfate, ferrous sulfate, and borax were split sprinkled on 2-year-old gentian on June 26, July 18, and August 25, 2002, with sprinkling water taken as a control. Compared with the control, applying B significantly increased (P < 0.05) the gentiopicroside content by 7.9%, and there was a highly significant increase of 22.4% (P < 0.01) in the root dry weight. Meanwhile, B content in the shoots of gentian gradually increased from the vegetative to the harvesting period, while Fe decreased at first and then increased. Fe treatment increased the gentiopicroside content only by 4.0% and the content was slightly decreased by the Zn treatment (3.1%) as compared to the control. The three microelements had different effects on the gentiopicroside content and appropriate microelement application could increase active ingredient content of gentian.

Sun, D. F., Li, H., Dawson, R., Tang, C. J. and Li, X. W. 2006. Characteristics of steep cultivated land and the impact of the Grain-for-Green Policy in China. Pedosphere. 16(2): 215--223.
ABSTRACT: The Grain-for-Green Policy in China could not only improve China’s ecological quality, but also influence grain supplies for a short term. Based on data from the detailed nationwide land use survey in 1996 and the steep cultivated land survey update in 2000, a regression model for the driving forces affecting steep cultivated lands was developed, and cluster analysis was used to identify seven steep cultivated land types in order to analyze the grain availability impact of the project with land usage estimates for 2010 and 2030. The results suggested that consecutive days with minimum daily temperature over 10ºC and the dominant slope in a county constrained the spatial distribution of steep cultivated lands. In terms of socioeconomic factors, steep cultivated land was a complex interaction of population size, gross domestic production level, and the richness and quality of cultivated lands having slopes less than 15º. The trends for steep cultivated land in 2010 and 2030 were forecast using a driving forces model and China’s grain security criteria and showed that the Grain-for-Green Policy at the national level would not cause a grain shortage or threaten food security criteria. However, if steep sloped lands were to be retired from production, some regions would need grain supplements as early as 2010. Also, assuming that only 60% of the cultivated land at the national level was needed, population and economic development pressures in 2030 would require some steep cultivated lands to be used for grain production.

Ju, X. T., Liu, X. J., Zhang, F. S. and Christie, P. 2006. Effect of long-term fertilization on organic nitrogen forms in a calcareous alluvial soil on the North China Plain. Pedosphere. 16(2): 224--229.
ABSTRACT: In order to illustrate the change of nitrogen (N) supply capacity after long-term application of manure and chemical fertilizer, as well as to properly manage soil fertility through fertilizer application under the soil-climatic conditions of the North China Plain, organic N forms were quantified in the topsoil with different manure and chemical fertilizer treatments in a 15-year fertilizer experiment in a Chinese calcareous alluvial soil. Soil total N (TN) and various organic N forms were significantly influenced by long-term application of chemical fertilizer and manure. TN, total hydrolysable N, acid-insoluble N, amino acid N and ammonium N in the soil increased significantly (P < 0.05) with increasing manure and fertilizer N rates, but were not influenced by increasing P rates. Also, application of manure or N fertilizer or P fertilizer did not significantly influence either the quantity of amino sugar N or its proportion of TN. Application of manure significantly increased (P < 0.05) hydrolysable unknown N, but adding N or P did not. In addition, application of manure or N fertilizer or P fertilizer did not significantly influence the proportions of different soil organic N forms.

Agyarko, K., Kwakye, P. K. , Bonsu, M., Osei, B. A., Asare Donkor, N. and Manor, E. 2006. Breakdown of azadirachtin A in a tropical soil amended with neem leaves and animal manures. Pedosphere. 16(2): 230--236.
ABSTRACT: A field investigation was conducted to assess the breakdown of azadirachtin A in a tropical coastal savanna soil amended with neem leaves (NL) combined with poultry manure (PM) or cow dung (CD) using gas chromatography. Samples in polythene bags 15 cm long and 4.8 cm in diameter were randomly placed to a depth of 14 cm in the soil, and azadirachtin A concentration was assessed on days 0, 14, 28, 42, 56, 70, and 84. Azadirachtin A degradation in the soil followed first-order reaction kinetics with different half-lives obtained for varying combinations of the amendments. Higher neem amendment levels of 100 g gave shorter half-lives of azadirachtin A than the lower levels of 50 g. Within the 50 g NL group the additions of the poultry manure and the cow dung gave significantly shorter (P < 0.05) half-lives of azadirachtin A than the sole neem amendment, whereas in the 100 g NL group only additions of 10 g CD and 10 g PM were significantly less (P < 0.05) than the sole neem amendment. Different changes resulting from the kind and quantity of animal manure added were observed in the half-lives of azadirachtin A. The 100 g NL group had significantly higher (P < 0.05) moisture content, which, coupled with the likely differences in microbial biomass, could be the major factor responsible for variations in the half-life of the compound. Therefore, the quantity of the neem leaves applied and the addition of animal manure affected the breakdown of azadirachtin A in the soil amended with neem leaves.

Ndakidemi, P. A. and Semoka, J. M. R. 2006. Soil fertility survey in Western Usambara Mountains, northern Tanzania. Pedosphere. 16(2): 237--244.
ABSTRACT: Soil samples from thirty sites representing four agro-ecological zones in the Western Usambara Mountains (WUM) of the Lushoto District in northern Tanzania were collected and analyzed for different nutrients. The results suggested that the major soil fertility constraint was P deficiency. On the basis of critical levels established in other areas, 90% of the soils were ranked as P deficient. This was followed by N, which was ranked as inadequate in 73% of the sites. Magnesium, K, and Ca also appeared limiting with 67%, 53% and 50% of the soils falling below the established critical values, respectively. A few soils (10%) were also found to contain exchangeable Al. The metallic micronutrients (Cu, Fe, and Zn) were adequate in all soils. Two sites had excessive Mn that could lead to toxicity in crops, and one was Mn deficient.

Zhou, J. B., Xi, J. G., Chen, Z. J. and Li, S. X. 2006. Leaching and transformation of nitrogen fertilizers in soil after application of N with irrigation: A soil column method. Pedosphere. 16(2): 245--252.
ABSTRACT: A soil column method was used to compare the effect of drip fertigation (the application of fertilizer through drip irrigation systems, DFI) on the leaching loss and transformation of urea-N in soil with that of surface fertilization combined with flood irrigation (SFI), and to study the leaching loss and transformation of three kinds of nitrogen fertilizers (nitrate fertilizer, ammonium fertilizer, and urea fertilizer) in two contrasting soils after the fertigation. In comparison to SFI, DFI decreased leaching loss of urea-N from the soil and increased the mineral N (NH4+-N + NO3--N) in the soil. The N leached from a clay loam soil ranged from 5.7% to 9.6% of the total N added as fertilizer, whereas for a sandy loam soil they ranged between 16.2% and 30.4%. Leaching losses of mineral N were higher when nitrate fertilizer was used compared to urea or ammonium fertilizer. Compared to the control (without urea addition), on the first day when soils were fertigated with urea, there were increases in NH4+-N in the soils. This confirmed the rapid hydrolysis of urea in soil during fertigation. NH4+-N in soils reached a peak about 5 days after fertigation, and due to nitrification it began to decrease at day 10. After applying NH4+-N fertilizer and urea and during the incubation period, the mineral nitrogen in the soil decreased. This may be related to the occurrence of NH4+-N fixation or volatilization in the soil during the fertigation process.

Gao, C., Sun, B. and Zhang, T. L. 2006. Sustainable nutrient management in Chinese agriculture: Challenges and perspective. Pedosphere. 16(2): 253--263.
ABSTRACT: China has to raise agricultural productivity in its limited and shrinking farmland to guarantee food security for its huge and ever-growing population. Sustainable soil nutrient management is of paramount importance to the world’s most populous country. Critical challenges the country is facing in sustaining soil fertility and in alleviating the hazardous impact of intensive fertilizer use are discussed in this paper. It is emphatically pointed out that national strategies as well as area-specific action plans with respect to scientific nutrient management are urgently needed to balance productivity and sustainability in the future. Relevant proposals for addressing those challenges are also presented.

Liang, L., Nagumo, T. and Hatano, R. 2006. Nitrogen flow in the rural ecosystem of Mikasa City in Hokkaido, Japan. Pedosphere. 16(2): 264-272.
ABSTRACT: This study of Mikasa City in 2001, which analyzed N flow between N production and N load in seven agricultural and settlement subsystems, i.e., paddy, onion, wheat, vegetable, dairy, chicken, and citizen subsystems, aimed to compare N flow in each subsystem, to determine the main sources of the N load, and to evaluate the influence of agricultural production and food consumption on N cycling in a rural area. The results showed that in Mikasa city, 38.5% of the N load came from point sources and the remainder from non-point sources with intensive vegetable farming imparting a serious N load. Because of the internal N cycling in the dairy subsystem, chemical fertilizer application was reduced by 70.2%, and 23.72 Mg manure N was recycled to the field; therefore, the N utilization efficiency was raised from 18.1% to 35.1%. If all the manure N in the chicken subsystem was recycled, chemical fertilizer application would be reduced by 8.1% from the present level, and the point sources of N pollution would be reduced by20.8%.

 IF  MERGEFIELD q_volumn 16 = 16 "" ""  MERGEFIELD q_author Pen-mouratov, S., Rakhimaev, M. and Steinberger, Y.  MERGEFIELD q_year 2006.  MERGEFIELD q_title Spatio-temporal effect on soil respiration in fine-scale patches in a desert ecosystem.  MERGEFIELD q_journal Pedosphere.  MERGEFIELD q_volumn 16( MERGEFIELD q_issue 1):  MERGEFIELD q_pages 1--9.
ABSTRACT:  MERGEFIELD q_abstract Soil organisms in terrestrial systems are unevenly distributed in time and space, and often aggregated. Spatio-temporal patchiness in the soil environment is thought to be crucial for the maintenance of soil biodiversity, providing diverse microhabitats tightly interweaving with resource partitioning. Determination of a "scale unit" to help understand ecological processes has become one of the important and most debatable problems in recent years. A fieldwork was carried out in the northern Negev Desert highland, Israel to determine the influence of fine-scale landscape patch moisture heterogeneity on biogeochemical variables and microbial activity linkage in a desert ecosystem. The results showed that the spatio-temporal patchiness of soil moisture to which we attribute influential properties, was found to become more heterogenic with the decrease in soil moisture availability (from 8.2 to 0.4 g kg-1) toward the hot, dry seasons, with coefficient of variation (CV) change amounting to 66.9%. Spatio-temporal distribution of organic matter (OM) and total soluble nitrogen (TSN) was found to be relatively uniformly distributed throughout the wet seasons (winter and spring), with increase of relatively high heterogeneity toward the dry seasons (from 0.25% to 2.17% for OM, and from 0 to 10.2 mg kg-1 for TSN) with CV of 47.4% and 99.7% for OM and TSN, respectively. Different spatio-temporal landscape patterns were obtained for Ca (CV = 44.6%), K (CV = 34.4%), and Na (CV = 92%) ions throughout the study period. CO2 evolution (CV = 48.6%) was found to be of lower heterogeneity (varying between 2 and 39 g CO2-C g-1 dry soil h-1) in the moist seasons, e.g., winter and spring, with lower values of respiration coupled with high heterogeneity of Na+ and low levels of TSN and organic matter content, and with more homogeneity in the dry seasons (varying between 1 and 50 g CO2-C g-1 dry soil h-1). Our results elucidate the heterogeneity and complexity of desert system habitats affecting soil biota activity.

 IF  MERGEFIELD q_volumn 16 = 16 "" ""  MERGEFIELD q_author Su, Z. Y., Xiong, Y. M., Zhu, J. Y., Ye, Y. C. and Ye, M.  MERGEFIELD q_year 2006.  MERGEFIELD q_title Soil organic carbon content and distribution in a small landscape of Dongguan, South China.  MERGEFIELD q_journal Pedosphere.  MERGEFIELD q_volumn 16( MERGEFIELD q_issue 1):  MERGEFIELD q_pages 10--17.
ABSTRACT:  MERGEFIELD q_abstract Global warming has become an increasing concern, and using soil as a carbon sink to sequester carbon dioxide has attracted much attention in recent years. In this study, soil organic carbon (SOC) content and organic carbon density were estimated based on a soil survey of a small landscape in Dongguan, South China, with spatial heterogeneity of SOC distribution and the impacts of land-use patterns on soil organic carbon content assessed. Field sampling was carried out based on a 150 m × 150 m grid system overlaid on the topographic map of the study area and samples were collected in three 20-cm layers to a depth of 60 cm. Spatial variability in the distribution of SOC was assessed using the Kruskal-Wallis test. Results showed that SOC in the topsoil layer (0--20 cm) was not much higher or even lower in some sites than the underlying layers, and except for the two sites covered with natural woodland, it did not exhibit a pronounced vertical gradient. The difference in both horizontal and vertical distribution of SOC was not statistically significant. However, in the topsoil layer among land-use/land-cover patterns, significant differences (P d" 0.05) in SOC distribution existed, indicating that management practices had great impact on SOC content. SOC storage in the study area to a depth of 20, 40, and 60 cm was estimated as 2.13 × 106 kg, 3.46 × 106 kg, and 4.61 × 106 kg, respectively.

 IF  MERGEFIELD q_volumn 16 = 16 "" ""  MERGEFIELD q_author Liu, B. R, Jia, G. M., Chen, J. and Wang, G.  MERGEFIELD q_year 2006.  MERGEFIELD q_title A review of methods for studying microbial diversity in soils.  MERGEFIELD q_journal Pedosphere.  MERGEFIELD q_volumn 16( MERGEFIELD q_issue 1):  MERGEFIELD q_pages 18--24.
ABSTRACT:  MERGEFIELD q_abstract Soil microorganisms play a central role in decomposing organic matter, in determining the release of mineral nutrients, and in nutrient cycling. Recently, extensive studies have focused on soil microbial diversity. However, understanding the diversity of this complex microbial community in the soil environment is a challenging task. Thus, it is important to master and comprehend appropriate methods for studying soil microbial diversity. Concepts of soil microbial diversity and major methods of study are briefly introduced in this paper. Then, the application of biochemical-based and molecular-based techniques in this area, and their advantages and disadvantages are evaluated. Based on recent related research, perspectives for studying microbial diversity in soils are presented.

 IF  MERGEFIELD q_volumn 16 = 16 "" ""  MERGEFIELD q_author Jiang, D., Hengsdijk, H., Dai, T. B., de Boer, W., Jing, Q. and Cao, W. X.  MERGEFIELD q_year 2006.  MERGEFIELD q_title Long-term effects of manure and inorganic fertilizers on yield and soil fertility for a winter wheat-maize system in Jiangsu, China.  MERGEFIELD q_journal Pedosphere.  MERGEFIELD q_volumn 16( MERGEFIELD q_issue 1):  MERGEFIELD q_pages 25-32.
ABSTRACT:  MERGEFIELD q_abstract Winter wheat-maize rotations are dominant cropping systems on the North China Plain, where recently the use of organic manure with grain crops has almost disappeared. This could reduce soil fertility and crop productivity in the long run. A 20-year field experiment was conducted to 1) assess the effect of inorganic and organic nutrient sources on yield and yield trends of both winter wheat and maize, 2) monitor the changes in soil organic matter content under continuous wheat-maize cropping with different soil fertility management schemes, and 3) identify reasons for yield trends observed in Xuzhou City, Jiangsu Province, over a 20-year period. There were eight treatments applied to both wheat and maize seasons: a control treatment (C); three inorganic fertilizers, that is, nitrogen (N), nitrogen and phosphorus (NP), and nitrogen, phosphorus and potassium (NPK); and addition of farmyard manure (FYM) to these four treatments, that is, M, MN, MNP, and MNPK. At the end of the experiment the MN, MNP, and MNPK treatments had the highest yields, about 7 t wheat ha-1 and 7.5 t maize ha-1, with each about 1 t ha-1 more than the NPK treatments. Over 20 years with FYM soil organic matter increased by 80% compared to only 10% with NPK, which explained yield increases. However, from an environmental and agronomic perspective, manure application was not a superior strategy to NPK fertilizers. If manure was to be applied, though, it would be best applied to the wheat crop, which showed a better response than maize.

 IF  MERGEFIELD q_volumn 16 = 16 "" ""  MERGEFIELD q_author Xia, J., Feng, H. L., Zhan, C. S. and Niu, C. W.  MERGEFIELD q_year 2006.  MERGEFIELD q_title Determination of a reasonable percentage for ecological water-use in the Haihe River Basin, China.  MERGEFIELD q_journal Pedosphere.  MERGEFIELD q_volumn 16( MERGEFIELD q_issue 1):  MERGEFIELD q_pages 33--42.
ABSTRACT:  MERGEFIELD q_abstract An investigation was conducted to study problems of determining a reasonable percentage for ecological water-use in the Haihe River Basin of China. Three key aspects for the ecological water requirement (EWR) were analyzed, involving i) the EWR for river system, ii) the EWR for wetlands and lakes, and iii) the EWR for discharge into the sea to maintain the estuary ecological balance of the Haihe River. The Montana method and related water level-flow relationships, and the statistic approach based on hydrological records were applied to estimate different components of EWR. The results showed that the total ecological water demand in the region was about 3.47--14.56 billion m3. Considering flow regime change and uncertainty, the ecological water demand could be estimated by the hydrological frequency approach. Preliminary analysis showed that for different annual runoff under the frequencies of 20%, 50%, 75% and 95%, the ecological water demand approached 12%--50%, 18%--74%, 24%--103%, 35%--148% and 16%--66%, respectively. By further analysis to balance ecological water-use and socioeconomic water-use, the rational percentage of ecological water-use was estimated as 35%--74%, that provides useful information to judge whether the allocation of water resources is reasonable, and was proved to be satisfactory by comparing with the practical condition.

 IF  MERGEFIELD q_volumn 16 = 16 "" ""  MERGEFIELD q_author Zhang, M. K., He, Z. L., Calvert, D. V. and Stoffella, P. J.  MERGEFIELD q_year 2006.  MERGEFIELD q_title Extractability and mobility of copper and zinc accumulated in sandy soils.  MERGEFIELD q_journal Pedosphere.  MERGEFIELD q_volumn 16( MERGEFIELD q_issue 1):  MERGEFIELD q_pages 43--49.
ABSTRACT:  MERGEFIELD q_abstract Extractability and mobility of Cu and Zn and their relationships with 1) accumulation of Cu and Zn and 2) soil pH were studied in three sandy soils (Wabasso, Ankona, and Winder) from commercial citrus groves in Florida, USA. The soils, with a broad range of Cu and Zn concentrations, were fractionated by a modified procedure of Amacher, while Cu and Zn mobility were evaluated using column leaching. The extractability of Cu and Zn increased with decreasing soil pH. Also with increasing total soil Cu and Zn for extractable Cu in the Wabasso sand a threshold level, where the metal extraction rate increased, was noted at 100 mg kg-1, whereas for extractable Zn in the Wabasso sand the threshold level was found at 60 mg kg-1 and in the Ankona sand at 120 mg kg-1. These results suggested that the release potential of Cu and Zn was greater in the Wabasso sand than in the Ankona sand. The column leaching experiment showed that at total soil Cu or Zn concentrations < 100 mg kg-1 all leachates had low Cu and Zn concentrations. However at total concentrations > 200 mg kg-1 for Cu and > 150 mg kg-1 for Zn with decreasing soil pH, the concentrations of both Cu and Zn in the leachates increased exponentially. Also in these sandy soils soluble Cu and Zn mainly originated from the exchangeable fractions, and pH was a key factor controlling Cu and Zn extractability and mobility.

 IF  MERGEFIELD q_volumn 16 = 16 "" ""  MERGEFIELD q_author Jiang, H. T., Xu, F. F., Cai, Y. and Yang, D. Y.  MERGEFIELD q_year 2006.  MERGEFIELD q_title Weathering characteristics of sloping fields in the Three Gorges Reservoir area, China.  MERGEFIELD q_journal Pedosphere.  MERGEFIELD q_volumn 16( MERGEFIELD q_issue 1):  MERGEFIELD q_pages 50--55.
ABSTRACT:  MERGEFIELD q_abstract For the purpose of understanding the weathering characteristics of surface layers in purple mudstone sloping fields of the Three Gorges Reservoir area of China, oxide content of major elements, composition of clay minerals, magnetic susceptibility, and difference in weathering characteristics of surface layers under different slope gradients were determined. The results showed that the oxide content of Si, Al, and Fe ranged from 60% to 75% and the weathering coefficient with depth showed no trend along the slope gradient. Also, for gentle (10º and 15º) and intermediate (25º and 40º) slopes the clay relative diffraction peak for kaolinite at the surface between 0--10 cm and 10--20 cm declined with an increase in slope gradient, while the relative diffraction peak for kaolinite in weathered layers on steep slopes (50º and 60º) disappeared altogether. Magnetic susceptibility decreased with increasing depth and, for a given depth layer, decreased with an increase in slope gradient. Analysis of the oxide content, weathering coefficients, clay minerals, and magnetic susceptibility showed that in the Three Gorges Reservoir area, the pedogenesis of the weathering layer in purple mudstone sloping fields was weak with weaker soil formation going from gentle slope to steep slope.

 IF  MERGEFIELD q_volumn 16 = 16 "" ""  MERGEFIELD q_author Guo, J. F., Yang, Y. S., Chen, G. S., Xie, J. S. and Lin, P.  MERGEFIELD q_year 2006.  MERGEFIELD q_title Soil C and N pools in Chinese fir and evergreen broadleaf forests and their changes with slash burning in mid-subtropical China.  MERGEFIELD q_journal Pedosphere.  MERGEFIELD q_volumn 16( MERGEFIELD q_issue 1):  MERGEFIELD q_pages 56--63.
ABSTRACT:  MERGEFIELD q_abstract Soil organic carbon (C) and total nitrogen (N) pools of a Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) (CF) forest, and an evergreen broadleaf (EB) forest located in mid-subtropical, southeastern China, were compared before clearcutting, with the effect of slash burning on organic C and total N in the top 10 cm of soil before and after burning also being evaluated. Prior to clearcutting CF forest had significantly lower (P < 0.05) organic C and total N in the soil (0--100 cm) compared to EB forest with approximately 60% of the C and N at the two forest sites stored at the 0 to 40 cm soil. In post-burn samples of the 0--10 cm depth at 5 days, 1 year, and 5 years for CF and EB forests, significantly lower levels (P < 0.05) of organic C and total N than those in the pre-burn samples were observed. Compared to the pre-burn levels, at post-burn year 5, surface soil organic C storage was only 85% in CF forest and 72% in EB forest, while total N storage was 77% for CF forest and 73% for EB forest. Slash burning caused marked long-term changes in surface soil C and N in the two forest types.

 IF  MERGEFIELD q_volumn 16 = 16 "" ""  MERGEFIELD q_author Zhang, X. H., Zhang, G. S., Zhang, Z. H., Xu, J. H. and Li, S. P.  MERGEFIELD q_year 2006.  MERGEFIELD q_title Isolation and characterization of a dichlorvos-degrading strain DDV-1 of Ochrobactrum sp.  MERGEFIELD q_journal Pedosphere.  MERGEFIELD q_volumn 16( MERGEFIELD q_issue 1):  MERGEFIELD q_pages 64--71.
ABSTRACT:  MERGEFIELD q_abstract The objective of this research was to isolate a dichlorvos(2,2-dichlorovinyl dimethyl phosphate)-degrading strain of Ochrobactrum sp., and determine its effectiveness in remediation of a dichlorvos-contaminated soil. A dichlorvos-degrading bacterium (strain DDV-1) was successfully isolated and identified as an Ochrobactrum sp. Based on its 16S rDNA sequence analysis. Strain DDV-1 was able to utilize dichlorvos as a sole carbon source, and the optimal pH and temperature for its cell growth and degradation were 7.0 and 30 ºC, respectively. Also, the growth and degradation of strain DDV-1 showed the same response to dissolved oxygen. In addition, the soil degradation test indicated that in soil spiked with 100 mg L-1 or 500 mg L-1 dichlorvos and inoculated with 0.5% or 1.0% (v/v) strain DDV-1, complete degradation of dichlorvos could be achieved in 24 h. The present study showed that strain DDV-1 was a fast dichlorvos-degrading bacterium in soil. However, further research will be needed to clarify the degradation pathway and the properties of the key enzymes involved in its biodegradation.

 IF  MERGEFIELD q_volumn 16 = 16 "" ""  MERGEFIELD q_author Tan, W. F., Liu, F., Li, Y. H., Hu, H. Q. and Huang, Q. Y.  MERGEFIELD q_year 2006.  MERGEFIELD q_title Elemental composition and geochemical characteristics of iron-manganese nodules in main soils of China.  MERGEFIELD q_journal Pedosphere.  MERGEFIELD q_volumn 16( MERGEFIELD q_issue 1):  MERGEFIELD q_pages 72--81.
ABSTRACT:  MERGEFIELD q_abstract Elemental composition and geochemical characteristics of iron-manganese nodules from nine main soils in China were studied by chemical and multivariate statistical analyses to better understand the reactions and functions of iron-manganese nodules in soils and sediment. Compared to the corresponding soils, Mn, Ba, Cd, Co and Pb had strong accumulation, Ni had moderate accumulation, while Ca, Cu, Fe, Na, P, Sr and Zn accumulated to a minor degree in the iron-manganese nodules. In contrast, Si, Al, K, Mg and Ti were reduced in the iron-manganese nodules. The contents of Ba, Cd, Co, Cu, Ni, Pb and Zn were positively and significantly correlated with that of MnO2 in the iron-manganese nodules, while the contents of Cr, Cu, Ni, Pb and Zn were positively and significantly correlated with that of Fe2O3 in soils. Based on a principle component analysis, the elements of iron-manganese nodules were divided into four groups: 1) Mn, Ba, Cd, Co, Cu, Li, Ni, Pb and Zn that were associated with Mn oxides, 2) Fe, Cr and P that were associated with Fe oxides, 3) Si, K, and Mg that were included in the elemental composition of phyllosilicate, and 4) Ca, Na, Al and Ti that existed in todorokite, birnessite, lithiophorite and phyllosilicate. It was suggested that accumulation, mineralization and specific adsorption were involved in the formation processes of soil iron-manganese nodules.

 IF  MERGEFIELD q_volumn 16 = 16 "" ""  MERGEFIELD q_author Ding, S. M., Liang, T., Zhang, C. S., Wang, L. J. and Sun, Q.  MERGEFIELD q_year 2006.  MERGEFIELD q_title Accumulation and fractionation of rare earth elements in a soil-wheat system.  MERGEFIELD q_journal Pedosphere.  MERGEFIELD q_volumn 16( MERGEFIELD q_issue 1):  MERGEFIELD q_pages 82--90.
ABSTRACT:  MERGEFIELD q_abstract Time series bioaccumulation of rare earth elements (REEs) in field-grown wheat with and without a dressing of extraneous REE fertilizer at different growth stages and fractionation of REEs during their transport in a soil-wheat system were determined. Time-dependent accumulation of extraneous REEs was found in different parts of wheat. An upward transport of extraneous REEs from roots to shoots under a soil dressing and a downward transport from leaves to roots with a foliar dressing were also observed. Moreover, fractionation of REEs occurred in the soil-wheat system. Compared to the host soil a positive Eu anomaly in the stems and grains as well as heavy REE enrichment in the grains were found. The ability of the different wheat organs to fractionate Eu from the REE series was ranked in the order of stems e" grains > leaves > roots.

 IF  MERGEFIELD q_volumn 16 = 16 "" ""  MERGEFIELD q_author Chen, Y. C., Xiong, Z. T. and Dong, S. Y.  MERGEFIELD q_year 2006.  MERGEFIELD q_title Chemical behavior of cadmium in purple soil as affected by surfactants and EDTA.  MERGEFIELD q_journal Pedosphere.  MERGEFIELD q_volumn 16( MERGEFIELD q_issue 1):  MERGEFIELD q_pages 91--99.
ABSTRACT:  MERGEFIELD q_abstract A soil batch experiment was conducted to investigate both separate and compound effects of three types of surfactants: anionic dodecylbenzene sulfonic acid sodiumsalt (DBSS), cationic cetyltrimethylammonium bromide (CTAB), and non-ionic nonyl phenol polyethyleneoxy ether (TX-100), as well as ethylenediaminetetraacetic acid (EDTA) on cadmium solubility, sorption kinetics, and sorption-desorption behavior in purple soil. The results indicated that both individual application of the three types of surfactants and surfactants combined with EDTA could stimulate Cd extraction from the soil with a general effectiveness ranking of EDTA/TX-100 > EDTA/DBSS > EDTA/CTAB > EDTA > TX-100 > DBSS > CTAB. Further study showed that the compound application of surfactants and EDTA had stronger (P < 0.05) effects on Cd solubility than those added individually. The application of surfactants and EDTA to purple soil (P < 0.05) decreased the proportion of Cd sorbed, while their effectiveness ranking was similar to that of enhanced solubilization. The sorption kinetics of Cd in purple soil was best described by the double-constant equation, while the Freundlich equation gave an excellent fit to the sorption isotherm curves. Therefore, surfactant-enhanced remediation of Cd contaminated soil is feasible and further research should be conducted.
 IF  MERGEFIELD q_volumn 16 = 16 "" ""  MERGEFIELD q_author Liu, G. M., Yang, J. S. and Yao, R. J.  MERGEFIELD q_year 2006.  MERGEFIELD q_title Electrical conductivity in soil extracts: Chemical factors and their intensity.  MERGEFIELD q_journal Pedosphere.  MERGEFIELD q_volumn 16( MERGEFIELD q_issue 1):  MERGEFIELD q_pages 100--107.
ABSTRACT:  MERGEFIELD q_abstract The electrical conductivity (EC) of 1:5 soil-water extract (EC1:5) was studied utilizing path coefficient analysis. The study focused on revealing the main chemical factors contributing to EC of soil extracts and their relative importance. Results showed that the most important factors influencing the EC1:5 of coastal salt-affected soils were the concentration of salt in 1:5 soil-water extract (Sc), Cl-, and the sodium adsorption ratio (SAR), while effects of pH, CO32-, HCO3-, soluble sodium percentage (SSP), and sodium dianion ratio (SDR) were very weak. Though the direct path coefficients between EC1:5 and SO42-, Ca2+, Mg2+, K+, or Na+ were not high, influence of other chemical factors caused the coefficients to increase, making the summation of their direct and indirect path coefficients relatively high. Evidences showed that multiple regression relations between EC1:5 and most of the primary factors (Sc, Cl-, and SAR) had sound reliability and very good accuracy.

 IF  MERGEFIELD q_volumn 16 = 16 "" ""  MERGEFIELD q_author Zhang, J. H., Wang, K., Bailey, J. S. and Wang, R. C.  MERGEFIELD q_year 2006.  MERGEFIELD q_title Predicting nitrogen status of rice using multispectral data at canopy scale.  MERGEFIELD q_journal Pedosphere.  MERGEFIELD q_volumn 16( MERGEFIELD q_issue 1):  MERGEFIELD q_pages 108--117.
ABSTRACT:  MERGEFIELD q_abstract Two field experiments were conducted in Jiashan and Yuhang towns of Zhejiang Province, China, to study the feasibility of predicting N status of rice using canopy spectral reflectance. The canopy spectral reflectance of rice grown with different levels of N inputs was determined at several important growth stages. Statistical analyses showed that as a result of the different levels of N supply, there were significant differences in the N concentrations of canopy leaves at different growth stages. Since spectral reflectance measurements showed that the N status of rice was related to reflectance in the visible and NIR (near-infrared) ranges, observations for rice in 1 nm bandwidths were then converted to bandwidths in the visible and NIR spectral regions with IKONOS (space imaging) bandwidths and vegetation indices being used to predict the N status of rice. The results indicated that canopy reflectance measurements converted to ratio vegetation index (RVI) and normalized difference vegetation index (NDVI) for simulated IKONOS bands provided a better prediction of rice N status than the reflectance measurements in the simulated IKONOS bands themselves. The precision of the developed regression models using RVI and NDVI proved to be very high with R2 ranging from 0.82 to 0.94, and when validated with experimental data from a different site, the results were satisfactory with R2 ranging from 0.55 to 0.70. Thus, the results showed that theoretically it should be possible to monitor N status using remotely sensed data.

 IF  MERGEFIELD q_volumn 16 = 16 "" ""  MERGEFIELD q_author Wang, X. C.and Lu, Q.  MERGEFIELD q_year 2006.  MERGEFIELD q_title Beta-glucosidase activity in paddy soils of the Taihu Lake region, China.  MERGEFIELD q_journal Pedosphere.  MERGEFIELD q_volumn 16( MERGEFIELD q_issue 1):  MERGEFIELD q_pages 118-124.
ABSTRACT:  MERGEFIELD q_abstract The profile distribution of ²-glucosidase activity in twelve typical paddy soil profiles with high productivity in the Taihu Lake egion of China were investigated. Activities of ²-glucosidase in the plow layers were in the range of 52.68--137.02 ¼g PNP g-1 soil h-1 with a mean of 89.22 ¼g PNP g-1 soil h-1. However, most plow layers ranged from 70 to 110 ¼g PNP g-1 soil h-1. The profile distribution of ²-glucosidase activity in the 12 soil profiles decreased rapidly with soil depth, with activity at the 60 cm depth only about 10% of that in the surface layers (0--15 cm or 0--20 cm). In these soil profiles, bð²-glucosidase activity was significantly positively correlated with soil organic carbon and arylsulphatase activity. Meanwhile, a significantly negative correlation was shown between ²-glucosidase activity and soil Ph.

 IF  MERGEFIELD q_volumn 16 = 16 "" ""  MERGEFIELD q_author Yan, D. Z., Wang, D. J., Sun, R. J. and Lin, J. H.  MERGEFIELD q_year 2006.  MERGEFIELD q_title N mineralization as affected by long-term N fertilization and its relationship with crop N uptake.  MERGEFIELD q_journal Pedosphere.  MERGEFIELD q_volumn 16( MERGEFIELD q_issue 1):  MERGEFIELD q_pages 125--130.
ABSTRACT:  MERGEFIELD q_abstract A field experiment established in 1997 was conducted to study the effect of long-term N fertilizer application on N mineralization in a paddy soil determined using a laboratory anaerobic incubation and followed with a field incubation to measure the relationship between in situ N mineralization and crop N uptake. To estimate N mineralization in the laboratory, soil samples were collected from plots with N application at different rates for six years and were incubated. Soils treated with fertilizer N mineralized more N than unfertilized soils and mineralization increased with N application rates. Also, the fraction of total N mineralized increased with increasing N fertilizer application. These findings meant that a substantial portion of previously applied N could be recovered slowly over time in subsequent crops. The field incubation of the plot receiving no fertilizer N showed that the NH4+-N concentration varied greatly during the rice-growing season and seasonal changes of N mineralization were due more to accumulation of NH4+-N than NO3--N. Rice N uptake increased up to a maximum of 82 kg N ha-1 during the season. The close agreement found between in situ N mineralization and rice N uptake suggested that the measurement of in situ N mineralization could provide useful recommendations for adequate fertilizer N application.

 IF  MERGEFIELD q_volumn 16 = 16 "" ""  MERGEFIELD q_author Liu, Y. G., Zhang, H. Z., Zeng, G. M., Huang, B. R. and Li, X.  MERGEFIELD q_year 2006.  MERGEFIELD q_title Heavy metal accumulation in plants on Mn mine tailings.  MERGEFIELD q_journal Pedosphere.  MERGEFIELD q_volumn 16( MERGEFIELD q_issue 1):  MERGEFIELD q_pages 131--136.
ABSTRACT:  MERGEFIELD q_abstract The Xiangtan Manganese (Mn) Mine in the middle of Hunan Province, China, has been mined since 1913 with mine tailings including excavated wastes, wastewater, and smelting wastes. A survey was conducted on the Mn mine tailing soils and eight plants on the Mn mine tailings. The concentrations of soil Mn, Pb, and Cd and the metal-enrichment traits of these eight plants were analyzed simultaneously. Exceptionally high concentrations of these three metals were found in the soils, especially on the tailing dam. Each plant investigated in this study accumulated the three heavy metals, but no hyperaccumulator of these metals was found. However, analysis indicated that Poa pratensis Linn., Gnaphalium affine D. Don, Pteris vittata L., Conyza canadensis (L.) Cronq., and Phytolacca acinosa Roxb. Possessed specially good metal-enrichment and metal-tolerant traits. P. pratensis, G. affine, and P. vittata were Pb-tolerant plants; and C. canadensis, P. pratensis, and G. affine were Cd-tolerant plants. P. acinosa had a great tolerance to Mn, and it was a valuable plant for on-site phytoremediation. Phragmites communis Trin. Was found to have high metal tolerance and economic benefit as a raw material for paper and should be considered for soil remediation. G. affine and C. canadensis had excessive accumulation of Mn and could be useful in phytoremediation. However, although P. pratensis was a good accumulator, it was not a suitable plant for soil remediation because its biomass was too little.

Klose, S. and Makeschin, F. 2005. Soil properties in coniferous forest stands along a fly ash deposition gradient in eastern Germany. Pedosphere. 15(6): 681--694.
ABSTRACT: Physical, chemical, and microbial properties of forest soils subjected to long-term fly ash depositions were analyzed in spruce (Picea abies (L.) Karst.) stands of eastern Germany on three forest sites along an emission gradient of 3 (high input), 6, and 15 km (low input) downwind of a coal-fired power plant. Past emissions resulted in an atypical high mass of mineral fly ash constituents in the organic horizons at the high input site of 128 t ha-1 compared to 58 t ha-1 at the low input site. Magnetic susceptibility measurements proved that the high mineral content of the forest floor was a result of fly ash accumulation in these forest stands. Fly ash deposition in the organic horizons at Site I versus III significantly increased the pH values, effective cation exchange capacity, base saturation and, with exception of the L horizon, concentrations of mobile heavy metals Cd, Cr, and Ni, while stocks of organic C generally decreased. A principal component analysis showed that organic C content and base status mainly controlled soil microbial biomass and microbial respiration rates at these sites, while pH and mobile fractions of Cd, Cr, and Ni governed enzyme activities. Additionally, it was hypothesized that long-term fly ash emissions would eventually destabilize forest ecosystems. Therefore, the results of this study could become a useful tool for risk assessment in forest ecosystems that were subjected to past emissions from coal-fired power plants.

Zepp, H., Tang, J. L. and Zhang, B. 2005. Methodological framework for a multi-scale study on hydrological processes and soil erosion in subtropical southeast China. Pedosphere. 15(6): 695--706.
ABSTRACT: This paper introduces and illustrates the concepts of geoecological process combinations and geographical or landscape dimensions by outlining the methodology of a Sino-German cooperative project in Southeast China and presents the first results of the modelling process for the catchment scale. The project equipped a catchment in subtropical Southeast China from plot scale to catchment scale in order to study the hydrological and soil erosion processes. Distinct spatial differences in principal water and soil material fluxes were quantified. Deep drainage peaks occurred in May, June and July and even in August and November. Measurements in erosion plots as well as sedimentary deposits revealed that there was soil erosion connected with overland flow. Consistent with the results from the regular catenary variations of soil colors, textural stratification and hydrograph analysis, there was also a clear indication of interflow from measured soil moisture data. The experimental set up has the potential to further deepen the understanding of small-scale processes involved in lateral water fluxes and soil erosion. The expected results and interpretations will lead to a further integration of the collected data. In the future, to understand matter transfer in and between landscape ecological units, agricultural influence on nutrient status and flux data will be incorporated.

Zheng, F. L. 2005. Effects of accelerated soil erosion on soil nutrient loss after deforestation on the Loess Plateau. Pedosphere. 15(6): 707--715.
ABSTRACT: Soil erosion and nutrient losses on newly-deforested lands in the Ziwuling Region on the Loess Plateau of China were monitored to quantitatively evaluate the effects of accelerated soil erosion, caused by deforestation, on organic matter, nitrogen and phosphorus losses. Eight natural runoff plots were established on the loessial hill slopes representing different erosion patterns of dominant erosion processes including sheet, rill and shallow gully (similar to ephemeral gully). Sediment samples were collected after each erosive rainfall event. Results showed that soil nutrients losses increased with an increase of erosion intensity. Linear relations between the loss of organic matter, total N, NH4-N, and available P and erosion intensity were found. Nutrient content per unit amount of eroded sediment decreased from the sheet to the shallow gully erosion zones, whereas total nutrient loss increased. Compared with topsoil, nutrients in eroded sediment were enriched, especially available P and NH4-N. The intensity of soil nutrient losses was also closely related to soil erosion intensity and pattern with the most severe soil erosion and nutrient loss occurring in the shallow gully channels on loessial hill slopes. These research findings will help to improve the understanding of the relation between accelerated erosion process after deforestation and soil quality degradation and to design better eco-environmental rehabilitation schemes for the Loess Plateau.

Bölter, M., Soethe, N., Horn, R. and Uhlig, C. 2005. Seasonal development of microbial activity in soils of northern Norway. Pedosphere. 15(6): 716--727.
ABSTRACT: Seasonal development of soil microbial activity and bacterial biomass in sub-polar regions was investigated to determine the impacts of biotic and abiotic factors, such as organic matter content, temperature and moisture. The study was performed during spring thaw from three cultivated meadows and two non-cultivated forest sites near Alta, in northern Norway. Samples from all five sites showed increasing respiration rates directly after the spring thaw with soil respiration activity best related to soil organic matter content. However, distributions of bacterial biomass showed fewer similarities to these two parameters. This could be explained by variations of litter exploitation through the biomass. Microbial activity started immediately after the thaw while root growth had a longer time lag. An influence of root development on soil microbes was proposed for sites where microorganisms and roots had a tight relationship caused by a more intensive root structure. Also a reduction of microbial activity due to soil compaction in the samples from a wheel track could not be observed under laboratory conditions. New methodological approaches of differential staining for live and dead organisms were applied in order to follow changes within the microbial community. Under laboratory conditions freeze and thaw cycles showed a damaging influence on parts of the soil bacteria. Additionally, different patterns for active vs. non-active bacteria were noticeable after freeze-thaw cycles.

Weigel, H. J., Pacholski, A., Burkart, S., Helal, M., Heinemeyer, O., Kleikamp, B., Manderscheid, R., Frühauf, C., Hendrey, G. F., Lewin, K. and Nagy, J. 2005. Carbon turnover in a crop rotation under free air CO2 enrichment (FACE). Pedosphere. 15(6): 728--738.
ABSTRACT: Mostly based on assumptions derived from controlled-environment studies, predicted future atmospheric CO2 concentrations [CO2] are expected to have considerable impacts on carbon ? turn-over in agro-ecosystems. In order to allow the in situ examination of C-transformations in the plant-soil system of arable crop rotations under future [CO2], a free air carbon dioxide enrichment (FACE) experiment (550 ¼mol mol-1 CO2) was started at Braunschweig, Germany in 1999. The crop rotation under investigation comprised winter barley, a cover crop (ryegrass), sugar beets and winter wheat. Assessments of CO2 effects included the determination of above- and belowground biomass produc-tion, measurements of canopy CO2- and H2O- fluxes, soil microbial biomass and in situ soil respira-tion. The results obtained during the 1st crop rotation cycle (3 years) showed that for the selected crops elevated [CO2] entailed significant positive effects (P < 0.05) on aboveground (6%--14% stimulation) and belowground biomass production (up to 90% stimulation), while canopy evapotran-spiration was reduced. This resulted in increased soil water content. Also, depending on crop type and season, high CO2 stimulated in situ soil respiration (up to 30%), while soil microbial biomass did not show significant responses to elevated [CO2] during the first rotation cycle.

Peng, X. H., Zhang, B., Zhao, Q. G. and Horn, R. 2005. Soil strength characteristics along an arable eroded slope. Pedosphere. 15(6): 739--745.
ABSTRACT: Undisturbed soil cores were taken from different slope positions (upslope, backslope and footslope) and soil depths (0--15, 20--35 and 100--115 cm) in a soil catena derived from Quaternary red clay to determine the spatial changes in soil strength along the eroded slope and to evaluate an indicator to determine soil strength during compaction. Precompression stress, as an indicator of soil strength, significantly increased from topsoil layer to subsoil layer (P < 0.05) and was affected by slope position. In the subsoil layer (20--35 cm), the precompression stress at the footslope position was significantly greater than at the backslope and upslope positions (P < 0.05), while there were no significant differences at 0--15 and 100--115 cm. Precompression stress followed the spatial variation of soil clay content with soil depth and had a significant linear relationship with soil porosity (r2 = 0.40, P < 0.01). Also, soil cohesion increased with increasing soil clay content. The precompression stress was significantly related to the applied stress corresponding to the highest change of pore water pressure (r2 = 0.69, P < 0.01). These results suggested that soil strength induced by soil erosion and soil management varied spatially along the slope and the maximum change in pore water pressure during compaction could be an easy indicator to describe soil strength.

Kocher, B., Wessolek, G. and Stoffregen, H. 2005. Water and heavy metal transport in roadside soils. Pedosphere. 15(6): 746--753.
ABSTRACT: Roads with very high traffic loads in regions with soils of low pH and low sorption capacity might be a source of percolation water loaded with heavy metals. Looking at some “worst case” scenarios, this study focused on the input of traffic related pollutants and on Pb, Cd, Cu, Zn, Ni and Cr concentrations in the soil matrix and soil solution respectively. The analysis also included pH and electrical conductivity and at some sites dissolved organic substances (DOC). The investigations were carried out on sandy soils with more or less low pH values at four motorway sites in Germany. The average of daily traffic was about 50 000 up to 90 000 vehicles. Soil pore water was collected in two soil depths and at four distances from the road. The pH in general decreased with increasing distance from the roadside. The elevated pH near the roadside was presumably caused by deposition of dust and weathering residues of the road asphalt, as well as by infiltration of salt that was used during winter time. At these road sites, increased heavy metal concentrations in the soil matrix as well as in the soil solution were found. However, the concentrations seldom exceeded reference values of the German Soil Protection Act. The soil solution concentrations tended to increase from the road edge to 10 m distance, whereas the concentration in the soil matrix decreases. Elevated DOC concentrations corresponded with elevated Cu concentrations but did not substantially change this tendency. High soil water percolation rates were found near the roads. Thus, even low metal concentrations of percolation water could yield high metal loads in a narrow area beside the road.

Kahle, P., Baum, C. and Boelcke, B. 2005. Effect of afforestation on soil properties and mycorrhizal formation. Pedosphere. 15(6): 754--760.
ABSTRACT: A study was conducted on Cambisols in Northern Germany to analyze the effect of fast growing trees (Salix and Populus spp.) used in agroforestry on soil chemical and physical properties and also on endo- and ectomycorrhizal colonization of the fine roots. Representative plots of three trials, Gülzow (GUL), Vipperow (VIP) and Rostock (ROS), were used to measure the topsoil inventories at the very beginning and after six (GUL), seven (VIP) and ten (ROS) years of afforestation with fast growing trees. The effect on soil organic carbon, plant available nutrients, reaction, bulk density, porosity and water conditions was analyzed. Arable soils without tree coppice were used as controls. Additionally, the endo- and ectomycorrhizal colonization of two Salix and two Populus clones were investigated at one site (GUL) in 2002. The amounts of organic carbon in the topsoil increased significantly (P < 0.01) presumably induced by leaf and root litter and also by the lack of tillage. The soil bulk density significantly decreased and the porosity of the soil increased significantly (both P < 0.01). The proportion of medium pores in the soil also rose significantly (P < 0.05 and 0.0l). Generally, afforestation of arable soils improved soil water retention. Ectomycorrhizas dominated the mycorrhizal formation of the Salix and Populus clones, with the accumulation of organic matter in the topsoil suspected of supporting the ectomycorrhizal formation. Thus, agroforestry with Salix and Populus spp. Conspicuously affected chemical and additionally physical properties of the top layer of Cambisols within a period of six years.

Xia, J., Wang, G. S., Ye, A. Z. and Niu, C. W. 2005. A distributed monthly water balance model for analyzing impacts of land cover change on flow regimes. Pedosphere. 15(6): 761--767.
ABSTRACT: The Miyun Reservoir is the most important water source for Beijing Municipality, the capital of China with a population of more than 12 million. In recent decades, the inflow to the reservoir has shown a decreasing trend, which has seriously threatened water use in Beijing. In order to analyze the influents of land use and cover change (LUCC) upon inflow to Miyun Reservoir, terrain and land use information from remote sensing were utilized with a revised evapotranspiration estimation formula; a water loss model under conditions of human impacts was introduced; and a distributed monthly water balance model was established and applied to the Chaobai River Basin controlled by the Miyun Reservoir. The model simulation suggested that not only the impact of land cover change on evapotranspiration, but also the extra water loss caused by human activities, such as the water and soil conservation development projects should be considered. Although these development projects were of great benefit to human and ecological protection, they could reallocate water resources in time and space, and in a sense thereby influence the stream flow.

Gourley, C. and Ridley, A. 2005. Controlling non-point source pollution in Australian agricultural systems. Pedosphere. 15(6): 768--777.
ABSTRACT: The Australian farming sector is continuing to intensify, particularly within 300 km of the east and southern coastlines. In the future there will be fewer and larger farms, which will use more fertilizer, support more stock, grow more monoculture crops, and utilise more marginal soils. This is likely to increase the major environmental impacts of soil degradation, salt, nutrient and sediment contamination of waterways, and greenhouse gas emissions.
Australian national water policy continues to focus on land, stream and groundwater salinity issues, although there is now a greater recognition of the importance of nitrogen and phosphorus losses from agriculture. The general philosophy of policy for dealing with non-point source pollution has been towards a voluntary rather than regulatory approach, with State and National governments supporting a range of programs to encourage sustainable agricultural practices. A catchment (watershed) based approach, through the use of integrated catchment management plans, is the primary way that non-point source pollution is addressed at the farm and local level. At an industry level, cotton, grains, meat, sugarcane and dairy amongst others, as well as the Australian fertilizer industry, have responded to non-point source issues by investing in research and development, and developing codes of practice aimed at abating these environmental impacts. Understanding the economic, social, political and cultural contexts of farming as well as the environmental impacts of agriculture are very important in determining the appropriateness of policy responses for Australian farming systems.

Liu, Y. S., Hu, Y. C. and Peng, L. Y. 2005. Accurate quantification of grassland cover density in an alpine meadow soil based on remote sensing and GPS. Pedosphere. 15(6): 778--783.
ABSTRACT: The principles of remotely estimating grassland cover density in an alpine meadow soil from space lie in the synchronous collection of in situ samples with the satellite pass and statistically linking these cover densities to their image properties according to their geographic coordinates. The principles and procedures for quantifying grassland cover density from satellite image data were presented with an example from Qinghai Lake, China demonstrating how quantification could be made more accurate through the integrated use of remote sensing and global positioning systems (GPS). An empirical model was applied to an entire satellite image to convert pixel values into ground cover density. Satellite data based on 68 field samples was used to produce a map of ten cover densities. After calibration a strong linear regression relationship (r2 = 0.745) between pixel values on the satellite image and in situ measured grassland cover density was established with an 89% accuracy level. However, to minimize positional uncertainty of field samples, integrated use of hyperspatial satellite data and GPS could be utilized. This integration could reduce disparity in ground and space sampling intervals, and improve future quantification accuracy even more.

Zhang, Z. H., Tang, C. and Rengel, Z. 2005. Salt dynamics in rhizosphere of Puccinellia ciliata Bor. In a loamy soil. Pedosphere. 15(6): 784--791.
ABSTRACT: A glasshouse experiment using a rhizobox technique was conducted to examine salt dynamics in the rhizosphere of a salt-tolerant grass, Puccinellia ciliata Bor. 'Irwin Hunter', grown in a loamy soil, and to study the effect of rainfall flush on salt accumulation in the rhizosphere. The rhizobox (10 × 5.5 × 50 cm) had a nylon mesh (1 ¼m) positioned vertically in the middle to create two compartments filled with soil amended with 1 g NaCl kg-1. The plants were grown in one compartment only. Flushed treatments received 275 mL of deionized water two days before harvest. In the plant-growing compartment, soils were sectioned vertically at 5 cm intervals. Significant differences in soil electrical conductivity (EC) (P < 0.05) and pH (P < 0.05) were observed for depths, but not between flushed and non-flushed treatments. In the no-plant compartment (rhizosphere), soil cores were taken horizontally at depths of 5, 20 and 40 cm and sliced at 1, 2, 3, 4, 5, 7, 10, 15 and 20 mm away from the roots. Soil EC and Cl- concentration at the 5 and 20 cm depths, and Na+ concentration at the 5 cm depth significantly decreased (P < 0.05) with the distance away from the root, but no significant differences were observed in soil pH and concentrations of the K+ and Ca2+. The flush treatment only had significant influence on soil EC, pH, and Cl- concentration at the 20 cm depth. Thus, salt accumulation could occur in the rhizosphere of salt-tolerant species on saline soils, and the periodic low rainfall might not have a strong influence on salt distribution in the rhizosphere and/or root zone.

Xia, Y. P., He, Z. L., Stoffella, P. J., Calvert, D. V., Zhang, M. K., Yang, X. E. and Wilson, S. B. 2005. Effect of compost amendment on heavy metals, nitrogen and phosphorus in a peat-based container medium. Pedosphere. 15(6): 792--796.
ABSTRACT: A laboratory study was conducted to evaluate the effect of compost amendment on mobility and leaching potential of heavy metals, nitrogen (N) and phosphorus (P) from a peat-based commercial container medium containing 700 g kg-1 peat, 200 g kg-1 perlite and 100 g kg-1 vermiculite at varying amendment rates of compost (0, 0.25, 0.50, 0.75 and 1.00 L L-1). Increasing compost amendment significantly and linearly increased the pH (P < 0.01), the total concentrations of organic carbon (P < 0.05), copper (Cu) (P < 0.01), cadmium (Cd) (P < 0.01), and lead (Pb) (P < 0.01), and increased the bulk density (P < 0.01) of the medium. The electrical conductivity (EC), and total N and P of the medium increased significantly (P < 0.01) and quadratically with increasing compost amendment. The relationship of the C/N ratio of the medium with the compost amendment rate was decreasing, significant (P < 0.01) and cubic while that of the total Zn was increasing, significant (P < 0.01) and cubic. Extractable P, NO3-N, and NH4-N increased initially with an increasing compost amendment of up to 0.50 L L-1 and then decreased with further increasing compost rate. Increasing compost rates resulted in a highly significant (P < 0.01) and linear increase in total Cd, Cu, and Pb, and a highly significant (P < 0.01) and cubic increase in total Zn in the medium. Increasing compost rates also significantly (P < 0.01) increased extractable Cu (linearly) and Zn (quadratically), but significantly (P < 0.01) decreased extractable Pb (linearly). There was no significant effect of compost amendment on the extractable Cd concentration in the medium. However, with increasing compost rates from 0.25 to 1.00 L L-1, extractability of P, Cd, Cu, Pb and Zn (extractable concentration as a percent of total) was decreased, indicating that compost amendment could lower the leachability of these elements from the medium.

Yang, Y. J., Yang, J. S., Liu, G. M. and Yang, X. Y. 2005. Space-time variability and prognosis of soil salinization in Yucheng City, China. Pedosphere. 15(6): 797--804.
ABSTRACT: This research used both geostatistics and GIS approach to compare temporal change of soil salt between 1980 and in 2003; to analyze the spatial distribution of surface soil salt ; to developed methods for predicting soil salinization potential based on recent improvements to the Dempster-Shafer theory; and to develop probability maps of potential salinization in Yucheng City, China. A semivariogram model of soil salt content was developed from the spherical model, and then employing kriging interpolation the spatial distribution of salt content in 2003 was obtained utilizing data from 100 soil sampling points. Potential salinization distribution was mapped using an approach that integrated soil data of the second general survey in 1980 in Yucheng City, which included groundwater salinity, groundwater depth, soil texture, soil organic matter content, and geomorphic maps. With the support of Dempster-Shafer theory and fuzzy set technique the factors that affected potential soil salinization were characterized and integrated; and then soil salinization was predicted. Finally a prognosis map of potential salinization distribution in the research area was obtained, with higher probability values indicating higher hazards to salinity processes. The distribution of the potential soil salinization probability was a successive surface.

Sun, Y. R., Ma, D. K., Lin, J. H., Schulze Lammers, P. and Damerow, L. 2005. An improved frequency domain technique for determining soil water content. Pedosphere. 15(6): 805--812.
ABSTRACT: For many years a soil water content sensor with low-cost, reliability and sufficient accuracy has been desirable. Thus, an improved measurement method based on the frequency domain (FD) principle for determining soil water content was considered. Unlike other measurement principles, a new measurable index, ·, which was independent of the output impedance and the amplitude of the oscillator while relying on the electrical impedance of a multi-pin probe, was proposed. Moreover, a model for processing the impedance of the multi-pin soil probe was developed, and several important electrical parameters for establishing their operating ranges, applicable to this probe were evaluated. In order to confirm the theoretical analysis, an experiment was conducted with a 4-pin probe. Using the developed model, the relationship between the proposed index · and soil volumetric water content was shown to be linear (R2 = 0.9921). Thus, as the measurable index, · seemed satisfactory.

Alves, M. E. and Lavorenti, A. 2005. Point of zero salt effect: Relationships with clay mineralogy of representative soils of the S?o Paulo State, Brazil. Pedosphere. 15(5): 545--553.
ABSTRACT: The point of zero salt effect (PZSE) is the soil pH value at which the magnitude of the variable surface charges is not changed due to variations in the ionic concentration of the soil solution. This property influences not only electrochemical phenomena occurring at the solid-solution interface but also the flocculation degree of the soil particles. In this study we investigated the relationships between the clay mineralogy and the PZSE values of representative soils of the S?o Paulo State, Brazil. The results confirmed the usefulness of the difference between the soil pH values measured in 1 mol L-1 KCl (pHKCl) and in water (pHH2O) (2 pHKCl – pHH2O) for estimating the PZSE of tropical soils, except for the ones rich in exchangeable Al; furthermore, the DpH index (pHKCl – pHH2O) was highly correlated with the difference between the PZSE and pHH2O values, reiterating the DpH utility for estimating both the signal and the magnitude of the net surface charge of tropical soils. Finally, correlation and multiple regression analyses showed that the PZSE value of weathered non-allophanic tropical soils tends to increase and to equal the soil pH due to the weathering-induced kaolinite destabilization and concomitant Fe- and Al-oxide accumulation.

Li, Z. P., Zhang, T. L., Han, F. X. and Felix-henningsen, P. 2005. Changes in soil C and N contents and mineralization across a cultivation chronosequence of paddy fields in subtropical China. Pedosphere. 15(5): 554--562.
ABSTRACT: Dynamics of soil organic matter in a cultivation chronosequence of paddy fields were studied in subtropical China. Mineralization of soil organic matter was determined by measuring CO2 evolution from soil during 20 days of laboratory incubation. In the first 30 years of cultivation, soil organic C and N contents increased rapidly. After 30 years, 0--10 cm soil contained 19.6 g kg-1 organic C and 1.62 g kg-1 total N, with the corresponding values of 18.1 g kg-1 and 1.50 g kg-1 for 10--20 cm, and then remained stable even after 80 years of rice cultivation. During 20 days incubation the mineralization rates of organic C and N in surface soil (0--10 cm) ranged from 2.2% to 3.3% and from 2.8% to 6.7%, respectively, of organic C and total N contents. Biologically active C size generally increased with increasing soil organic C and N contents. Soil dissolved organic C decreased after cultivation of wasteland to 10 years paddy field and then increased. Soil microbial biomass C increased with number of years under cultivation, while soil microbial biomass N increased during the first 30 years of cultivation and then stabilized. After 30 years of cultivation surface soil (0--10 cm) contained 332.8 mg kg-1 of microbial biomass C and 23.85 mg kg-1 of microbial biomass N, which were 111% and 47% higher than those in soil cultivated for 3 years. It was suggested that surface soil with 30 years of rice cultivation in subtropical China would have attained a steady state of organic C content, being about 19 g kg-1.

Xia, J., Liu, M. Y. and Jia, S. F. 2005. Water security problem in North China: Research and perspective. Pedosphere. 15(5): 563--575.
ABSTRACT: This paper addresses the emergence of water security problems in North China with the aim of highlighting key water resources management and water security issues for the long-term development of North China. Three key problems related to water resources and security issues in North China in the 21st century are addressed, namely 1) the water cycle under environmental change, 2) agricultural water saving, and 3) water security. Development of international research related to these issues is also reviewed. The research plan developed recently by the Chinese Academy of Sciences (CAS) is discussed and suggestions on research and development of water resources science in North China are presented. Thanks to focus on experimental catchments and dedicated research stations, a detailed knowledge of the water cycle on North China farmland has been compiled. A range of techniques that include isotope tracers has been used to acquire hydrologic data. Much research has been devoted to developing distributed hydrological models at different scales. In the well irrigation district, five different water saving irrigation regimes have been investigated, and these regimes have had widespread application, and reduced water use 60--150 mm while they increased WUE by 20%--30%. Furthermore, preventing water pollution is the most essential step to ensure North China’s water security.

Zhang, X. Y., Chen, S. Y., Pei, D., Liu, M. Y. and Sun, H. Y. 2005. Evapotranspiration, yield and crop coefficient of irrigated maize under straw mulch. Pedosphere. 15(5): 576--584.
ABSTRACT: Maize (Zea mays L.), a staple crop grown from June to September during the rainy season on the North China Plain, is usually inter-planted in winter wheat (Triticum aestivum L.) fields about one week before harvest of the winter wheat. In order to improve irrigation efficiency in this region of serious water shortage, field studies in 1999 and 2001, two dry seasons with less than average seasonal rainfall, were conducted with up to five irrigation applications to determine evapotranspiration, calculate the crop coefficient, and optimize the irrigation schedule with maize under mulch, as well as to establish the effects of irrigation timing and the number of applications on grain yield and water use efficiency (WUE) of maize. Results showed that with grain production at about 8 000 kg ha-1 the total evapotranspiration and WUE of irrigated maize under mulch were about 380--400 mm and 2.0--2.2 kg m-3, respectively. Also in 2001 WUE of maize with mulch for the treatment with three irrigations was 11.8% better than that without mulch. In the 1999 and 2001 seasons, maize yield significantly improved (P = 0.05) with four irrigation applications, however, further increases were not significant. At the same time there were no significant differences for WUE with two to four irrigation applications. In the 2001 season mulch lead to a decrease of 50 mm in the total soil evaporation, and the maize crop coefficient under mulch varied between 0.3--1.3 with a seasonal average of 1.0.

Wei, J., Lin, Z. H., Xia, J. and Tao, S. Y. 2005. Interannual and interdecadal variability of atmospheric water vapor transport in the Haihe River Basin. Pedosphere. 15(5): 585--594.
ABSTRACT: The seasonal mean atmospheric precipitable water and water vapor transport over the Haihe River Basin (HRB) in North China with a focus on their interannual to interdecadal variability, and then the relationships of the interannual and interdecadal variability of the water cycle over the HRB to the Pacific Decadal Oscillation (PDO) and El Nino-Southern Oscillation (ENSO) phenomena were investigated using the observational and National Centers for Environmental Prediction (NCEP) reanalysis data. There was a strong interdecadal variability for the water cycle (such as precipitation and water vapor transport) over the region, with an abrupt change occurring mostly in the mid 1970s. The intensity of the East Asian summer monsoon largely affected the atmospheric water vapor transport. Generally, the net meridional convergence of the water vapor flux over the region was relatively large before 1965, and it declined gradually from then on with a further notable decrease since mid 1970s. Zonal water vapor transport was similar to meridional, but with a much smaller magnitude and no noteworthy turning in the mid 1970s. Results also suggested that the wind field played an important role in the water vapor transport over the HRB before the mid 1960s, and the interdecadal variability of the water cycle (precipitation, water vapor transport, etc.) in the summer was related to the PDO; however, interannual variation of the water vapor transport could also be related to the ENSO phenomena.

Yuan, F., Xie, Z. H., Liu, Q. and Xia, J. 2005. Simulating hydrologic changes with climate change scenarios in the Haihe River Basin. Pedosphere. 15(5): 595--600.
ABSTRACT: Climate change scenarios, predicted using the regional climate modeling system of PRECIS (providing regional climates for impacts studies), were used to derive three-layer variable infiltration capacity (VIC-3L) land surface model for the simulation of hydrologic processes at a spatial resolution of 0.25 × 0.25 in the Haihe River Basin. Three climate scenarios were considered in this study: recent climate (1961--1990), future climate A2 (1991--2100) and future climate B2 (1991--2100) with A2 and B2 being two storylines of future emissions developed with the Intergovernmental Panel on Climate Change (IPCC) special report on emissions scenarios. Overall, under future climate scenarios A2 and B2, the Haihe River Basin would experience warmer climate with increased precipitation, evaporation and runoff production as compared with recent climate, but would be still likely prone to water shortages in the period of 2031--2070. In addition, under future climate A2 and B2, an increase in runoff during the wet season was noticed, indicating a future rise in the flood occurrence possibility in the Haihe River Basin.

Li, Y. Y., Shao, M. A., Zheng, J. Y. and Zhang, X. C. 2005. Spatial-temporal changes of soil organic carbon during vegetation recovery at Ziwuling, China. Pedosphere. 15(5): 601--610.
ABSTRACT: To probe the processes and mechanisms of soil organic carbon (SOC) changes during forest recovery, a 150-year chronosequence study on SOC was conducted for various vegetation succession stages at the Ziwuling area, in the central part of the Loess Plateau, China. Results showed that during the 150 years of local vegetation rehabilitation SOC increased significantly (P < 0.05) over time in the initial period of 55--59 years, but slightly decreased afterwards. Average SOC densities for the 0--100 cm layer of farmland, grassland, shrubland and forest were 4.46, 5.05, 9.95, and 7.49 kg C m-3, respectively. The decrease in SOC from 60 to 150 years of abandonment implied that the soil carbon pool was a sink for CO2 before the shrubland stage and became a source in the later period. This change resulted from the spatially varied composition and structure of the vegetation. Vegetation recovery had a maximum effect on the surface (0--20 cm) SOC pool. It was concluded that vegetation recovery on the Loess Plateau could result in significantly increased sequestration of atmospheric CO2 in soil and vegetation, which was ecologically important for mitigating the increase of atmospheric concentration of CO2 and for ameliorating the local eco-environment.

Dolui, A. K. and Roy, S. S. 2005. Phosphate sorption-desorption characteristics in two Inceptisols and an Alfisol of Chattisgarh, India. Pedosphere. 15(5): 611--619.
ABSTRACT: Two Inceptisols and an Alfisol of the Indravati Catchment area in Chattisgarh, India, comprising several gradients in physical and chemical properties were studied to relate phosphate sorption and desorption to soil properties. From the P isotherm curve, the standard P requirement (SPR) of the soils was determined. Phosphate sorption data were also fitted both to the Langmuir and Freundlich Equations. The mean sorption maximum values for three different soil series were: Bastar > Geedam > Mosodi. The fraction of added phosphate sorbed for the 3 series followed this same trend as did SPR; the phosphate sorption maximum and the maximum phosphate buffering capacity, which were estimated by the Langmuir isotherm; and the Freundlich constant 1/n. However, phosphate desorption, as well as the maximum recovery percent did not follow this order. The phosphate affinity constant (K) was also different following the same progression for the 3 soil series as the Freundlich constant K?, which measured sorption strength. Meanwhile, an inverse order existed for K and K? versus the percent desorbed relative to the sorbed as well as the maximum recovery percent. In addition, significant correlation coefficients among sorption parameters of P and soil factors were found.

Wang, K., Shi, X. Z., Yu, D. S., Shi, D. M., Chen, J. M., Xu, B. B., Liang, Y. and Li, D. C. 2005. Environmental factors affecting temporal and spatial dynamics of soil erosion in Xingguo County, South China. Pedosphere. 15(5): 620--627.
ABSTRACT: By using soil erosion maps of four different time periods and a digital elevation model (DEM), in combination with the remote sensing and GIS technologies, soil erosion dynamics in Xingguo County of Jiangxi Province in South China were analyzed on both temporal and spatial scales in soils of different parent materials, altitudes and slopes. The results showed that from 1958 to 2000 severe soil erosion was coming under control with a decreasing percentage of the land under severe erosion. It was also found that the soils developed from Quaternary red clay, granite and purple shale were more susceptible to soil erosion and that areas sitting between 200 to 500 m in altitude with a slope less than 3o or between 7o to 20o where human activities were frequent remained to be zones where soil erosion was most likely to occur. These areas deserve special attention in monitoring and controlling.

Lang, Y. H., Jiang, X., Martens, D. and Zhao, Q. G. 2005. Comparison of extraction techniques with different solvents for DDT analogues in sediments. Pedosphere. 15(5): 628--633.
ABSTRACT: Four techniques, Soxhlet extraction (SOX), ultrasonic extraction (USE), fluidized-bed extraction (FBE) and accelerated solvent extraction (ASE) with different solvents (methanol, hexane/acetone and acetonitrile) were used for the extraction of DDT analogues in sediments. Results revealed that the four extraction techniques had high recoveries (> 86.0%) with low standard deviations for most of DDT analogues (< 12.0%), meaning that they could all successfully extract DDT analogues in sediments. Accelerated solvent extraction using methanol and hexane/acetone (1:1), fluidized-bed extraction using hexane/acetone (1:1) and the ultrasonic extraction using hexane/acetone (1:1) were comparable or better than Soxhlet extraction using hexane/acetone (1:1). Considering solvent- and time-consumption, level of automation, and environmental risk, accelerated solvent extraction with hexane/acetone (1:1) was better than the other extraction techniques.

Xu, L. G., Yang, J. S., Zhang, Q. and Liu, G. M. 2005. Salt-water transport in unsaturated soils under crop planting: Dynamics and numerical simulation. Pedosphere. 15(5): 634--640.
ABSTRACT: A laboratory salt-water dynamics experiment using unsaturated soils in packed silt loam and clay soil columns with different soil texture profiles and groundwater level under crops were conducted to study the changes of salt-water dynamics induced by water uptake of crops and to propose the theoretical basis for the regulation and control of salt-water dynamics as well as to predict salinity levels. The HYDRUS 1D model was applied to simulate the one-dimensional movement of water and salt transport in the soil columns. The results showed that the salts mainly accumulated in the plow layer in the soil columns under crops. Soil water and salt both moved towards the plowing layer due to soil water absorption by the crop root system. The salt contents in the column with lower groundwater were mostly greater than that with high groundwater. The water contents in the soil columns increased from top to the bottom due to plant root water uptake. The changes in groundwater level had little influence on water content of the root zone in the soil columns with crop planting. Comparison between the simulated and the determined values showed that model simulation results were ideal, so it is practicable to do numerical simulation of soil salt and water transport by the HYDRUS 1D model. Furthermore, if the actual movement of salt and water in fields is to be described in detail, much work needs to be done. The most important thing is to refine the parameters and select precise boundary conditions.

Cao, L. K., Chen, G. J. and Lu, Y. T. 2005. Nitrogen leaching in vegetable fields in the suburbs of Shanghai. Pedosphere. 15(5): 641--645.
ABSTRACT: Nitrogen (N) leaching in vegetable fields from December 2002 to May 2003 with equal dressings of total N for a sequential rotation of Chinese flat cabbage (Brassica chinensis L. var. rosularis) and lettuce (Lactuca sativa L.) in a suburban major vegetable production base of Shanghai were examined using the lysimeter method to provide a scientific basis for rational utilization of nitrogen fertilizers so as to prevent nitrogen pollution of water resources. Results showed that leached N consisted mainly of nitrate N, which accounted for up to more than 90% of the total N loss and could contribute to groundwater pollution. Data also showed that by partly substituting chemical N (30%) in a basal dressing with equivalent N of refined organic fertilizer in the Chinese flat cabbage field, 64.5% of the leached nitrate N was reduced, while in the lettuce (Lactuca sativa L.) field, substituting 1/2 of the chemical N in a basal dressing and 1/3 of the chemical N in a top dressing with equivalent N of refined organic fertilizers reduced 46.6% of the leached nitrate N. In the two-year sequential rotation system of Chinese flat cabbage and lettuce, nitrate-N leaching in the treatment with the highest amount of chemical fertilizer, was up to 46.55 kg ha-1, while treatment plots with the highest amount of organic fertilizer had only 17.58 kg ha-1. Thus, partly substituting refined organic fertilizer for chemical nitrogen in the first two seasons has a great advantage of reducing nitrate-N leaching.

Li, X. Y., Zhang, H. W., Zhou, Q. X., Su, Z. C. and Zhang, C. G. 2005. Effects of acetochlor and methamidophos on fungal communities in black soils. Pedosphere. 15(5): 646--652.
ABSTRACT: Using plate counting and ergosterol assay, single and joint effects of acetochlor and methamidophos on the dynamics of soil fungal population and total fungal biomass in the black soil zone of Northeast China were investigated. The results demonstrated that acetochlor at high concentration levels (150 and 250 mg kg-1) had an acute and mostly chronic toxicity on both the soil fungal population and total fungal biomass, but at a low concentration (50 mg kg-1) generally had a stimulating effect that was stronger with total fungal biomass than with the soil fungal population. Methamidophos at high concentration levels (250 mg kg-1) alone and almost all of its combinations with various dosages of acetochlor increased the soil fungal population, whereas at most sampling dates with 250 mg methamidophos kg-1 soil, total fungal biomass increased, but in combination with acetochlor it was decreased in the early period of incubation and then increased 28 days after incubation. Thus, through measuring the number of colony forming unit of the soil fungal population along with the total fungal biomass, a better understanding on effects of agrochemicals on soil fungi could be made.

Yang, W. Q., Wang, K. Y., Kellom?ki, S. and Gong, H. D. 2005. Litter dynamics of three subalpine forests in Western Sichuan. Pedosphere. 15(5): 653--659.
ABSTRACT: Litter production, components and dynamics was investigated and forest floor litter was quantified throughout a whole year in three subalpine forests, dominated by tree species of spruce (SF), fir (FF) and birch (BF), in Western Sichuan, China, in order to understand the key factors that influenced litter production and dynamics. Litterfall in the three forests consisted mainly of leaves, woody litter, reproductive organs and moss. Contribution of leaf litter to the total litterfall was significantly (P < 0.05) greater than that of woody litter, reproductive organs or moss. Regardless of the stands, litterfall exhibited a marked monthly variation with the maximum litterfall peaks occurring in October, with smaller peaks occurring in February for SF and FF, and May for BF. The analysis indicated that tree species, stand density, leaf area index (LAI), stand basal area and stand age were the key factors determining litter production. Meanwhile tree species and phenology controlled the litter dynamics, with wind and snow modifying the proportion of litter component and dynamics.

Yang, H. D., Hu, Y. M., Deng, F. Q., Chen, F. X. and Wang, F. 2005. Application of immune algorithm to evaluation of soil resource quality. Pedosphere. 15(5): 660--668.
ABSTRACT: Based on the geographic information system (GIS) technology, ArcInfo software was adopted to collect, process and analyze spatial data of Guangdong Province for an evaluation of soil resource quality. Using the overlay analysis method and combining evaluation factors from Guangdong soil resource quality, an evaluation unit was determined. Because of its favorable convergent speed and its ability to search solutions, the immune algorithm was applied to the soil resource quality evaluation model. At the same time, the evaluation results of this newly proposed method were compared to two other methods: sum of index and fuzzy synthetic. The results indicated that the immune algorithm reflected the actual condition of soil resource quality more exactly.

Niu, L. A., Hao, J. M., Ding, Z. Y., Li, X. B., Niu, X. S. and Zhang, B. Z. 2005. Long-term fertilization effect on fertility of salt-affected soils. Pedosphere. 15(5): 669--675.
ABSTRACT: The long-term effects of annual fertilizer applications on the fertility of salt-affected soils under the rotation system of wheat (Triticum L.) and maize (Zea mays L.) are not well documented. In 1984, research plots were established to test the effects of annual applications of different rates of nitrogen (N) and phosphorus (P) fertilizers on the fertility of a salt-affected soil (Typic Ustochrept) at the Quzhou Experimental Station, Quzhou County, Hebei Province, China. In October 2001, composite soil samples (0--20 and 20--40 cm) were collected from each plot and analyzed for soil fertility indices. Seventeen years of N and P fertilizer applications increased the soil organic matter (SOM) in the surface layer. With combined N, 270 (N1) and 540 (N2) kg N ha-1 year-1, and P, 67.5 (P1) and 135 (P2) kg P2O5 ha-1 year-1, fertilizer applications, total soil N mostly significantly decreased (P < 0.05). Soil total P in the 0--20 cm layer of the P2 treatment significantly (P < 0.05) increased as compared to those of the other treatments. Rapidly available P (RP) in the 0--20 cm layer of the N1P2 treatment was significantly higher than those in the other treatments except the P2 treatment; and RP in the 0--20 cm layer of the P2 treatment significantly increased as compared to those of the other treatments except the P1 and N1P2 treatments. RP in the subsurface soil layer (20--40 cm) of the P2 treatment (4.2 mg P kg-1) was significantly (P < 0.05) higher than those in the other treatments. Nevertheless, long-term N fertilization did not significantly increase the alkali-hydrolyzable N in the soil. However, in the salt-affected surface soils the application of combined N and P fertilizers over 17 years significantly (P < 0.05) decreased rapidly available potassium (K). The results suggested that while under long-term fertilizer applications some soil fertility parameters could be maintained or enhanced, careful monitoring of soil fertility was necessary as other nutrients such as K could become depleted.

Wang, S. P., Zhou, G. S., Gao, S. H. and Guo, J. P. 2005. Soil organic carbon and labile carbon along a precipitation gradient and their responses to some environmental changes. Pedosphere. 15(5): 676--680.
ABSTRACT: Based on data from a field survey in 2001 along the Northeast China transect (NECT), a precipitation gradient, and a short-term simulation experiment under ambient CO2 of 350 mmol mol-1 and doubled CO2 of 700 mmol mol-1 with different soil moisture contents of 30%--45%, 45%--60%, and 60%--80% soil water holding capacity, the distribution of soil organic carbon and labile carbon along the NECT, their relationships with precipitation and their responses to CO2 enrichment and soil moisture changes were analyzed. The results indicated that the soil labile carbon along the gradient was significantly related to soil organic carbon (r = 0.993, P < 0.001). The soil labile carbon decreased more rapidly with depth than organic carbon. The soil organic and labile carbon along the gradient decreased with decrease in longitude in both the topsoils and subsoils, and the coefficient of variation for the labile carbon was greater than that for the soil organic carbon. Both the soil organic carbon and labile carbon had significant linear relationships with precipitation, with the correlation coefficient of soil organic carbon being lower (0.677 at P < 0.001) than that of soil labile carbon (0.712 at P < 0.001). In the simulation experiment with doubled and ambient CO2 and different moisture contents, the coefficient of variation for soil organic carbon was only 1.3%, while for soil labile carbon it was 29.7%. With doubledCO2 concentration (700 mmol mol-1), soil labile carbon decreased significantly at 45% to 60% of soil moisture content. These indicated that soil labile carbon was relatively more sensitive to environmental changes than soil organic carbon.

Li, Y. T., Becquer, T., Quantin, C., Benedetti, M., Lavelle, P. and Dai, J. 2005. Microbial activity indices: Sensitive soil quality indicators for trace metal stress. Pedosphere. 15(4): 409--416
ABSTRACT: Physicochemical properties, total and DTPA (diethylenetriaminepentaacetic acid)-extractable Cu, Zn, Pb and Cd contents, microbial biomass carbon ? content and the organic C mineralization rate of the soils in a long-term trace metal-contaminated paddy region of Guangdong, China were determined to assess the sensitivity of microbial indices to moderately metal-contaminated paddy soils. The mean contents of total Cu, Zn, Pb and Cd were 251, 250, 171, and 2.4 mg kg-1 respectively. DTPA-extractable metals were correlated positively and significantly with total metals, CEC, and organic C (except for DTPA-extractable Cd), while they were negatively and highly significantly correlated with Ph, total Fe and Mn. Metal stress resulted in relatively low ratios of microbial biomass C to organic C and in remarkable inhibition of the microbial metabolic quotient and C mineralization rate, which eventually led to increases in soil organic C and C/N. Moreover, microbial respiratory activity showed a stronger correlation to DTPA-extractable metals than to total metal content. Likewise, in the acid paddy soils some “linked” microbial activity indices, such as metabolic quotient and ratios of basal respiration to organic C, especially during initial incubation, were found to be more sensitive indicators of soil trace metal contamination than microbial biomass C or basal respiration alone.

Wang, S. Q., Yu, G. R., Zhao, Q. J., Niu, D., Chen, Q. M. and Wu, Z. F. 2005. Spatial characteristics of soil organic carbon storage in China’s croplands. Pedosphere. 15(4): 417--423
ABSTRACT: The soil organic carbon (SOC) pool is the largest component of terrestrial carbon pools. With the construction of a geographically referenced database taken from the second national general soil survey materials and based on 1 546 typical cropland soil profiles, the paddy field and dryland SOC storage among six regions of China were systematically quantified to characterize the spatial pattern of cropland SOC storage in China and to examine the relationship between mean annual temperature, precipitation, soil texture features and SOC content. In all regions, paddy soils had higher SOC storage than dryland soils, and cropland SOC content was the highest in Southwest China. Climate controlled the spatial distribution of SOC in both paddy and dryland soils, with SOC storage increasing with increasing precipitation and decreasing with increasing temperature.

Du, Z. Y., Zhou, J. M., Wang, H. Y., Du, C. W. and Chen, X. Q. 2005. Effect of nitrogen fertilizers on movement and transformation of phosphorus in an acid soil. Pedosphere. 15(4): 424--431
ABSTRACT: The effects of two different nitrogen fertilizers (urea and NH4Cl) with monocalcium phosphate (MCP) on the movement and transformation of fertilizer P in soil microsites along with soil pH changes at different distances from the fertilizer application site were studied in an incubation experiment. A highly acidic red soil (Ultisol, pH 4.57) from south China with MCP fertilizer alone or in combination with NH4Cl or urea was added to the surface of soil cylinders and packed in wax blocks. After 7 and 28 days, the extraction and analysis of each 2 mm layer from the interface of the soil and fertilizer showed that added NH4Cl or urea did not change the movement distance of fertilizer P. However, P transformation was significantly affected (P < 0.05). After 7 days, at 0--8 mm distance from the fertilizer site the addition of urea significantly decreased the water-extractable P concentration; however, after 28 days the effect of N addition had disappeared. Also, at limited distances close to the fertilizer site NH4Cl application with MCP significantly increased acid-extractable P and available P, while with the addition of urea they significantly decreased. Compared with application of MCP alone, addition of urea significantly increased soil pH in fertilizer microsites, whereas the addition of NH4Cl significantly decreased soil pH.

Yang, H., Wu, X., Zhou, L. X. and Yang, Z. M. 2005. Effect of dissolved organic matter on chlorotoluron sorption and desorption in soils. Pedosphere. 15(4): 432--439
ABSTRACT: A batch equilibrium techniques was used to examine the effect of dissolved organic matter (DOM) extracted from both non-treated sludge (NTS) and heat-expanded sludge (HES) on the sorption and desorption of chlorotoluron (3-(3-chloro-p-tolyl)-1,1-dimethylurea) in two types of soils, a yellow fluvo-aquic and a red soil from China. Without DOM, sorption of chlorotoluron was significantly greater (P < 0.05) in the red soil than in the yellow fluvo-aquic soil. However, with DOM the effect was dependent on the soil type and nature of DOM. Chlorotoluron sorption was lower in the yellow fluvo-aquic soil than in the red soil, suggesting that with the same DOM levels the yellow fluvo-aquic soil had a lower sorption capacity for this herbicide. Application of DOM from both NTS and HES led to a general decrease in sorption to the soils and an increase in desorption from the soils. Desorption of chlorotoluron also significantly increased (P < 0.05) with an increase in the DOM concentration. Additionally, for sorption and desorption, at each DOM treatment level the NTS treatments were significantly lower (P < 0.05) than the HES treatments. This implied that non-treated sludge had a greater effect on the sorption and desorption of chlorotoluron than heat-expanded sludge.

Zhang, W. J., Rui, W. Y., Tu, C., Diab, H. G., Louws, F. J., Mueller, J. P., Creamer, N., Bell, M., Wagger, M. G. and Hu, S. 2005. Responses of soil microbial community structure and diversity to agricultural deintensification. Pedosphere. 15(4): 440--447
ABSTRACT: Using a scheme of agricultural fields with progressively less intensive management (deintensification), different management practices in six agroecosystems located near Goldsboro, NC, USA were tested in a large-scale experiment, including two cash-grain cropping systems employing either tillage (CT) or no-tillage (NT), an organic farming system (OR), an integrated cropping system with animals (IN), a successional field (SU), and a plantation woodlot (WO). Microbial phospholipid fatty acid (PLFA) profiles and substrate utilization patterns (BIOLOG ECO plates) were measured to examine the effects of deintensification on the structure and diversity of soil microbial communities. Principle component analyses of PLFA and BIOLOG data showed that the microbial community structure diverged among the soils of the six systems. Lower microbial diversity was found in lowly managed ecosystem than that in intensive and moderately managed agroecosystems, and both fungal contribution to the total identified PLFAs and the ratio of microbial biomass C/N increased along with agricultural deintensification. Significantly higher ratios of C/N (P < 0.05) were found in the WO and SU systems, and for fungal/bacterial PLFAs in the WO system (P < 0.05). There were also significant decreases (P < 0.05) along with agricultural deintensification for contributions of total bacterial and gram positive (G+) bacterial PLFAs. Agricultural deintensification could facilitate the development of microbial communities that favor soil fungi over bacteria.

Liu, Y., Han, S. J., Zhou, Y. M. and Zhang, J. H. 2005. Contribution of root respiration to total soil respiration in a Betula ermanii-dark coniferous forest ecotone of the Changbai Mountains, China. Pedosphere. 15(4): 448--455
ABSTRACT: Total and root-severed soil respiration rates for five plots set up 50 m apart in a Betula ermanii Cham.-dark coniferous forest ecotone on a north-facing slope of the Changbai Mountains, China, were measured to evaluate the seasonal variations of soil respiration, to assess the effect of soil temperature and water content on soil respiration, and to estimate the relative contributions of root respiration to the total soil respiration. PVC cylinders in each of 5 forest types of a B. ermanii-dark coniferous forest ecotone were used to measure soil respirations both inside and outside of the cylinders. The contribution of roots to the total soil respiration rates ranged from 12.5% to 54.6%. The mean contribution of roots for the different plots varied with the season, increasing from 32.5% on June 26 to 36.6% on August 3 and to 41.8% on October 14. In addition, there existed a significant (P < 0.01) logarithmic relationship between total soil respiration rate and soil temperature at 5 cm soil depth. Also, a similar trend was observed for the soil respiration and soil water content at the surface (0--5 cm) during the same period of time.

Zuo, W., Zhou, H. Z., Zhu, X. H., Wang, Q., Wang, W. J. and Wu, X. Q. 2005. Integrated evaluation of ecological security at different scales using remote sensing: A case study of Zhongxian County, the Three Gorges area, China. Pedosphere. 15(4): 456--464
ABSTRACT: Based on related literature and this research, an ecological security evaluation from the pixel scale to the small watershed or county scale was presented using remote sensing data and related models. With the driver-pressure, state and exposure to pollution-response (DPSER) model as a basis, a conceptual framework of regional ecological evaluation and an index system were established. The extraction and standardization of evaluation indices were carried out with GIS techniques, an information extraction model and a data standardization model. The conversion of regional ecological security results from the pixel scale to a small watershed or county scale was obtained with an evaluation model and a scaling model. Two conceptual scale conversion models of regional ecological security from the pixel scale to the county scale were proposed: 1) scale conversion of ecological security regime results from pixel to small watershed; and 2) scale conversion from pixel to county. These research results could provide useful ideas for regional ecological security evaluation as well as ecological and environmental management.

Wang, X. D., Zhong, X. H. and Fan, J. R. 2005. Spatial distribution of soil erosion sensitivity on the Tibet Plateau. Pedosphere. 15(4): 465--472
ABSTRACT: The Tibet Plateau, occupying the main part of Qinghai-Tibet Plateau and having an average altitude of 4 500 m, has geomorphological features that are unique in the world, with soil erosion being one of the main ecological problems. Thus the main objectives of the present research were to set up an efficient and simple way of evaluating spatial distributionof soil erosion sensitivity in the Tibet Plateau as well as the responses of soil erosion to changes of natural environmental conditions, and to indicate key regions where soil erosion should be preferentially controlled. Based on the Universal Soil Loss Equation (USLE), the study applied geographic information system (GIS) technology to develop a methodological reference framework, from which soil erosion sensitivity could be evaluated. The impact of precipitation, soil, topography and vegetation on soil erosion was divided into classes of extreme sensitivity, high sensitivity, medium sensitivity, low sensitivity and no sensitivity. With the aid of GIS, the resultant map from overlaying various factors showed that soil erosion sensitivity had great discrepancy in different parts of the region. In the southeastern part of the Tibet Plateau there were mainly three classes of sensitivity, namely, extreme, high and medium sensitivity. However, the other two classes, low and no sensitivity, were dominant in the northwestern part.

Wang, X. B., Cai, D. X., Hoogmoed, W. B., Oenema, O. and Perdok, U. D. 2005. Scenario analysis of tillage, residue and fertilization management effects on soil organic carbon dynamics. Pedosphere. 15(4): 473--483
ABSTRACT: Based on 10-year field data from experiments on residue/fertilizer management in the dryland farming region of northern China, Century model was used to simulate the site-specific ecosystem dynamics through adjustment of the model’s parameters, and the applicability of the model to propose soil organic carbon (SOC) management, temporally and spatially, in cases such as of tillage/residue/fertilization management options, was identified via scenario analysis. Results between simulations and actual measurements were in close agreement when appropriate applications of stover, manure and inorganic fertilizer were combined. Simulations of extreme C/N ratios with added organic materials tended to underestimate the measured effects. Scenarios of changed tillage methods, residue practices and fertilization options showed potential to maintain and enhance SOC in the long run, while increasing inorganic N slowed down the SOC turnover rate but did not create a net C sink without any organic C input. The Century model simulation showed a good relationship between annual C inputs to the soil and the rate of C sequestration in the top 20 cm layer and provided quantitative estimations of changes in parameters crucial for sustainable land use and management. Conservation tillage practices for sustainable land use should be integrated with residue management and appreciable organic and inorganic fertilizer application, adapted according to the local residue resource, soil fertility and production conditions. At least 50% residue return into the soil was needed annually for maintenance of SOC balance, and manure amendment was important for enhancement of SOC in small crop-livestock systems in which crop residue land application was limited.

Li, J. Y., Xu, R. K. and Ji, G. L. 2005. Dissolution of aluminum in variably charged soils as affected by low-molecular-weight organic acids. Pedosphere. 15(4): 484--490
ABSTRACT: Low-molecular-weight (LMW) organic acids exist widely in soils and play an important role in soil processes such as mineral weathering, nutrient mobilization and Al detoxification. In this research, a batch experiment was conducted to examine the effects of LMW organic acids on dissolution of aluminum in two variably charged soils, an Ultisol and an Oxisol. The results showed that the LMW organic acids enhanced the dissolution of Al in the two investigated soils in the following order: citric > oxalic > malonic > malic > tartaric > salicylic > lactic > maleic. This was generally in agreement with the magnitude of the stability constants for the Al-organic complexes. The effects of LMW organic acids on Al dissolution were greater in the Ultisol than in the Oxisol as compared to their controls. Also, the accelerating effects of citric and oxalic acids on dissolution of Al increased with an increase in pH, while the effects of lactic and salicylic acids decreased. Additionally, when the organic acid concentration was less than 0.2 mmol L-1, the dissolution of Al changed little with increase in acid concentration. However, when the organic acid concentration was greater than 0.2 mmol L-1, the dissolution of Al increased with increase in acid concentration. In addition to the acid first dissociation constant and stability constant of Al-organic complexes, the promoting effects of LMW organic acids on dissolution of Al were also related to their sorption-desorption equilibrium in the soils.

Tian, X. H. and Saigusa, M. 2005. Response of tomato plants to a new application method of polyolefin-coated fertilizer. Pedosphere. 15(4): 491--498
ABSTRACT: The response of tomato (Lycopersicon esculentum) plants basically fertilized with 0.3 g N per plant of compound fertilizer with a N:P2O5:K2O ratio of 20:10:20 to sticks of polyolefin-coated fertilizer (POCF) (Long70 with a N:P2O5:K2O ratio of 14:12:14) applied 23 d after transplanting was investigated using rooting boxes in the greenhouse. The results at 26 and 40 d after stick fertilizer treatment showed that the use of the stick fertilizer greatly increased the production of many new fine roots from the tomato plants. Compared to the unfertilized control, root length and root length density in the stick fertilizer treatment increased 3.6-6.7 fold. In the soil zones near the stick fertilizer, root weight and root mass density were also significantly higher for the stick fertilizer treatment. Additionally, the use of the stick fertilizer increased the N, P and K concentrations in the leaves and stems of the tomato plants. The new fine roots growing near the stick fertilizer not only absorbed more nutrients and translocated them to the shoots, but also contained more nutrients within themselves. The soil ammonium and nitrate data showed that nitrogen released from the stick fertilizer played a major role in inducing the production of new fine roots. These results indicated that stick fertilizer could be used as an alternative to the co-situs application technique to change and control the root distribution of crops as well as to increase the potential capacity of roots for water and nutrient absorption.

Norse, D. 2005. Non-point pollution from crop production: Global, regional and national issues. Pedosphere. 15(4): 499--508
ABSTRACT: China is now the world’s largest producer and user of industrial fertilizers and manures. Consequently China plays a substantial role in global N cycle dynamics and in man’s disruption of the nitrogen cycle though there are still significant uncertainties about the size and significance of emission and leaching rates. A major cause of China’s global role is the overuse of nitrogen fertilizers, which is most serious with intensive vegetable production where application rates can be up to 50% greater than crop needs, but is also a problem with wheat, rice and maize.
China’s overuse of nitrogen fertiliser over the past 10-20 years has resulted in non-point pollution (NPS) from crop production becoming a major cause of water pollution, and the situation is projected to get worse. In contrast, water pollution from point sources such as intensive livestock production and urban or industrial development is being brought more under control. The consequences for air pollution are equally serious. Emissions of nitrous oxide from fertilizers and manures may be so large that China could be responsible for 25-30% of global emissions of this damaging greenhouse gas and of the global warming resulting from it.
The main national and local issues relate particularly to low fertilizer use efficiency and the losses of ammonia and Nox that lead to acid precipitation, and leaching and run-off losses that result in high nitrate levels in groundwater and eutrophication of rivers and lakes. The reasons why farmers overuse nitrogen fertilizer are complex and not fully understood. They involve agro-climate differences between provinces and counties, farming systems and farm income structures. Although there is a wide range of institutional and technological improvements that can greatly reduce this overuse rapid progress in reducing NPS is unlikely.

Huang, Y. L., Chen, L. D., Fu, B. J., Zhang, L. P. and Wang, Y. L. 2005. Evapotranspiration and soil moisture balance for vegetative restoration in a gully catchment on the Loess Plateau, China. Pedosphere. 15(4): 509--517
ABSTRACT: Evapotranspiration, soil moisture balance and the dynamics in a gully catchment of the Loess Plateau in China were determined with 6 land use treatments including natural grassland, shrubs (Caragana microphylla), two woodlands (Prunus armeniaca var. ansu and Pinus tabulaeformis), cultivated fallow, and farmland (Triticum aestivum L.) in order to obtain a better understanding of soil moisture balance principles and to improve vegetation restoration efficiency for ecological rebuilding on the plateau. Average runoff from cultivated fallow was very high, reaching 10.3% of the seasonal rainfall. Evapotranspiration under T. aestivum was not significantly different from natural grasslands. Compared with natural grass, evapotranspiration was significantly greater (P < 0.05) in 2002 and there was an increase in soil moisture depleted in the 1--3 m soil under P. armeniaca, P. tabulaeformis and C. microphylla. During the two year study the average soil moisture (0--100 cm soil profile) of T. aestivum was generally the highest, with P. armeniaca, P. tabulaeformis and C. microphylla usually the lowest. Thus, according to the soil moisture balance principle for this area the planned reforestation project was not ecologically reasonable. Reducing human disturbance and restoration with grass could be more effective.

Li, S. T., Zhou, J. M., Wang, H. Y., Du, C. W. and Chen, X. Q. 2005. Kinetics of phosphate release from three phosphate-treated soils. Pedosphere. 15(4): 518--525
ABSTRACT: Phosphate release from three selected soils after treatments of1.6 and 2.4 mmol L-1 P was investigated using sequential extractions and fitted using six kinetic models, including zero order (Z), first order (F), second order (S), parabolic diffusion (PD), two constant rate (TC), and Elovich type (ET) equations. The results showed that the rate of P release was initially rapid and then gradually declined with time. Also, P release increased with added P. Total P release followed the order: paddy soil with 2.4 mmol L-1 P > red soil with 2.4 mmol L-1 P > paddy soil with 1.6 mmol L-1 P > fluvo-aquic soil with 2.4 mmol L-1 P > fluvo-aquic with 1.6 mmol L-1 P > red soil with 1.6 mmol L-1 P. For the two P treatments P release from the paddy soils in the first extraction was 44.3 and 45.6% of total released P, respectively, which were higher than those from red and fluvo-aquic soils. The ratio of P release at the equilibrium state was 14.0% and 13.1% in the paddy soil treated with 1.6 and 2.4 mmol L-1 P, respectively, but only 5.1% and 9.2% in the red soil and 7.0% and 5.2% in the fluvo-aquic soil, respectively. Comparison of the coefficients of determination (R2) indicated that ET, TC, and PD equations could describe the P release data better than Z, F, and S equations.

Li, J. Y., Hua, Q. X., Tan, J. F., Zhou, J. M. and Hou, Y. L. 2005. Mineral coated fertilizer effect on nitrogen-use efficiency and yield of wheat. Pedosphere. 15(4): 526--531
ABSTRACT: A field experiment with winter wheat (Triticum aestivum L.) was conducted on a silt loam calcaric endorusti-ustic Cambosols derived from the Yellow River alluvial deposits in Henan, China, from 2001 to 2002 to evaluate N recovery and agronomic performance of different mineral coated fertilizers (MiCFs) compared to normal urea used in wheat cropping systems under field conditions. Five treatments, including CK (check, no N fertilizer), urea and three different MiCFs at an equivalent N application rate were established in a randomized complete block design. N release from MiCFs in soil was more synchronous with the N requirement of wheat throughout the growth stages than that from urea, with grain yield of the MiCF treatments significantly higher (P < 0.05) than that of the treatment urea. Correspondingly, the N recovery rate was greater for all MiCFs compared to urea, increasing from 32.8% up to 50.1%. Due to its high recovery and low cost, use of the mineral coated N fertilizers was recommended instead of the polymer coated N fertilizers.

Wang, G. H., Zhou, D. R., Yang, Q., Jin, J. and Liu, X. B. 2005. Solubilization of rock phosphate in liquid culture by fungal isolates from rhizosphere soil. Pedosphere. 15(4): 532--538
ABSTRACT: Rock phosphate (RP) is a low efficiency P fertilizer that is directly applied to the soil and can be solubilized by phosphate-solubilizing microorganisms (PSMs) in fermentation or soil conditions. This study investigated dynamic solubilization of 2 concentrations of rock phosphate in a liquid culture with different dosages of glucose by two fungal isolates, Aspergillus niger P39 and Penicillium oxalicum P66, from soybean and wheat rhizosphere soil. Although during the 20 day culture period A. niger P39 had a stronger ability to acidify the culture media than P. oxalicum P66, soluble P concentrations at glucose dosages of 30 and 50 g L-1 with RP of 15 g L-1 in the culture solution were much higher by P. oxalicum P66. The greater effectiveness of P. oxalicum P66 compared to A. niger P39 in the solubilization of RP was strongly associated with the production of organic acids. This study suggested that for RP solubilization the type rather than the concentration of PSM produced organic acids was more important.

Huang, C. M., Wang, C. S. and Tang, Y. 2005. Stable carbon and oxygen isotopes of pedogenic carbonates in Ustic Vertisols: Implications for paleoenvironmental change. Pedosphere. 15(4): 539--544
ABSTRACT: Pedogenic carbonates, found extensively in arid and semiarid regions, are important in revealing regional climatic and environmental changes as well as the carbon cycle. In addition, stable carbon and oxygen isotopic compositions of pedogenic carbonates have been used to rebuild paleoecology (biomass and vegetation) and to estimate paleotemperature and paleoprecipitation during past geological time. By utilizing the stable carbon and oxygen isotopic compositions (´13C and ´18O) of secondary nodules in Ustic Vertisols, this study looked into the climatic and environmental changes in the dry valleys of the Yuanmou Basin, Yunnan Province, in southwestern China. The results showed that during the early Holocene, a warm-humid or hot-humid climate existed in the Yuanmou Basin, but since then fluctuations in climate have occurred, with a dry climate prevailing. A highly significant correlation (r = 0.92, n = 9) between ´13C and ´18O values of carbonates illustrated that there had been a continual shifting between cold-humid and warm-dry climates in southwestern China including the Yuanmou Basin since the early Holocene.

Cha, Z. Z., Lin, Z. M., Luo, W., Li, S. C. and Luo, X. H. 2005. Sustainable land management practices for rubber plantations in mountainous area of Hainan. Pedosphere. 15(3): 404--408
ABSTRACT: This research was designed to help solve existing sustainable use problems such as soil nutrient loss and soil fertility decline in natural rubber plantations located in the hilly land of the south central mountainous area of Hainan Island, China. Two different land management practices, sustainable and traditional, were adopted in a four-year experiment. Contour terraced fields and deep ditches for green manure were built in a sustainable way with a balanced, need-based application of complex fertilizer. Results of the four-year experiment showed that these sustainable measures compared to traditional measures improved available P and available K; had a 47.8% less soil erosion (an average of 3 663 t km-2 year-1) and a 15.9% lower runoff coefficient of 0.53; increased the dry rubber yield by 42.4%; and improved the economic benefit by 2.4 times. The sustainable land management scheme not only improved land utilisation efficiency, but also helped maintain soil fertility while increasing production in rubber plantations. It thereby offered a reasonable and sustainable use for land resources in the tropical mountainous areas.

Wu, S. M., Hu, D. X. and Ingham, E. R. 2005. Comparison of soil biota between organic and conventional agroecosystems in Oregon, USA. Pedosphere. 15(3): 395--403
ABSTRACT: Soil samples at 0--10 cm in depth were collected periodically at paired fields in Corvallis, Oregon, USA to compare differences in soil microbial and faunal populations between organic and conventional agroecosystems Results showed that the organic soil ecosystem had a significantly higher (P < 0.05) average number or biomass of soil bacteria; densities of flagellates, amoebae of protozoa; some nematodes, such as microbivorous and predaceous nematodes and plant-parasitic nematodes; as well as Collembola. Greater numbers of Rhabditida (such as Rhabditis spp.), were present in the organic soil ecosystem while Panagrolaimus spp. Were predominant in the conventional soil ecosystem. The omnivores and predators of Acarina in the Mesostigmata (such as Digamasellidae and Laelapid), and Prostigmata (such as Alicorhaiidae and Rhagidiidae), were also more abundant in the organic soil ecosystem. However, fungivorous Prostigmata (such as Terpnacaridae and Nanorchestidae) and Astigmata (such as Acarida) were significantly higher (P < 0.05) in the conventional soil ecosystem, which supported the finding that total fungal biomass was greater in the conventional soil ecosystem. Seansonal variations of the population depended mostly on soil moisture condition and food web relationship. The population declined from May to October for both agroecosystems. However, higher diversities and densities of soil biota survived occurred in the organic soil ecosystem in the dry season.

Wang, L. G., Jiang, X., Mao, Y. M., Zhao, Z. H. and Bian, Y. R. 2005. Organophosphorus pesticide extraction and cleanup from soils and measurement using GC-NPD. Pedosphere. 15(3): 386--394
ABSTRACT: The objectives of this study were to optimize instrumental parameters and conditions for analysis of selected organophosphorus pesticides (OPPs) by gas chromatography (GC) with nitrogen-phosphorus detection (NPD) (GC-NPD); to select an appropriate solvent system; to conduct a comparison of sonication and shaking extractions; and to select an appropriate procedure for extracting organophosphorus pesticides from soils. Procedure ? consisted of n-hexane or petroleum ether, together with acetone used as solvents, while Procedure II contained several solvents including acetone, methanol, dichloromethane, and n-hexane or petroleum ether. Experimental results indicated that a mixture of petroleum ether/acetone (2:1, v/v) could be used in place of n-hexane/acetone (2:1, v/v) as it was a less expensive solvent system. In addition, shaking under a water bath at 20 oC was more effective than sonication. Also, Procedure ? was more effective, safer, and more timesaving than Procedure II. Procedure ? was applied to three soil types of different organic matter content, with recoveries of the OPPs from the yellow-brown soils, which had a higher organic matter content, being lower than those from the yellow and red soils.

Yuan, F., Ran, W. and Shen, Q. R. 2005. Nitrification potential of soils under liquid incubation conditions. Pedosphere. 15(3): 379--385
ABSTRACT: A red soil, a fluvo-aquic soil and a permeable paddy soil were used in a long-term investigation to study changes in nitrification with treatments: 1) soil incubation, 2) liquid incubation inoculated with soil samples, and 3) liquid incubation inoculated with ammonia-oxidizing bacteria (AOB) from the soils. There were significant differences (P < 0.001) in nitrification rates among the three soils when measured for 28 days by adding (NH4)2SO4 at the rate of 154 mg N kg-1 dry soil to fresh soil. However, the amounts of nitrifying bacteria in the three soils were not related to soil nitrification capacity. When the soil samples or the isolates of AOB enriched from the corresponding soil were incubated in liquid with pH 5.8, 7.0 and 8.0 buffers and 10 mmol L-1 ammonium nitrogen, there were no significant nitrification differences in the same soil type at each pH. The ability to oxidize ammonia through AOB from different types of soils in a homogeneous culture medium was similar, and the soil nitrification capacity could reflect the inherent properties of a soil. Altering the culture medium pH of individual soil type also showed that acidification of an alkaline fluvo-aquic soil decreased nitrification capacity, whereas alkalinization of the acidic red soil and permeable paddy soil increased their nitrification. For a better insight into factors influencing soil nitrification processes, soil properties including texture and clay composition should be considered.

Yang, C. M., Yang, L. Z. and Yan, T. M. 2005. Chemical and microbiological parameters of paddy soil quality as affected by different nutrient and water regimes. Pedosphere. 15(3): 369--378
ABSTRACT: A field experiment was conducted from 1999 to 2002 to compare and evaluate the effects of nutrient and water regimes on paddy soil quality by investigating soil chemical and microbiological parameters. Four nutrient regimes, a control, chemical fertilizers only (CF), chemical fertilizers with swine manure (SM), and chemical fertilizers with wheat straw (WS), and two soil moisture regimes, continuous waterlogging (CWL) and alternate wetting and drying (AWD), were investigated. With SM and WS total organic carbon and total nitrogen in the paddy soil were significantly higher (P < 0.05) than those with CF. A similar effect for organic amendments was observed in the soil light fraction organic C (LFOC), water-soluble carbohydrates (WSC), and water-soluble organic C (WSOC). CWL, in particular when swine manure was incorporated into the paddy soil, markedly decreased soil redox potential (Eh) and increased total active reducing substances (ARS). Meanwhile, as compared to CF, SM and WS significantly (P < 0.05) increased soil microbial biomass C (MBC) and mineralizable carbon, with differences in AWD being higher than CWL. In addition, SM and WS treatments significantly (P < 0.05) improved rice above-ground biomass and grain yield, with AWD being greater than CWL. Thus, for ecologically sustainable agricultural management of paddy soils, long-term waterlogging should be avoided when organic manure was incorporated into paddy soil.

Zheng, S. J., He, Y. F., Tang, C. X. and Masaoka, Y. 2005. A modified method for measuring root iron reductase activity under normal laboratory conditions. Pedosphere. 15(3): 363--368
ABSTRACT: Based on the strong chelating property of bathophenanthroline disulfonic acid (BPDS) with Fe(II), root Fe(III) chelate reductase activity is usually measured with a spectrophotometer using MES (2-morpholinoethanesulfonic acid) or HEPES (2-(4-(2-Hydroxyethyl)-1-piperazinyl) ethanesulfonic acid) buffer in the dark because of high autoreduction rate of Fe(III) in the presence of light. However, the exclusion of light is inconvenient, especially when analyzing a large number of samples. The objective of this study was to develop a new method for determination of root reductase activity under normal laboratory conditions using a suitable buffer composition and Fe(III) concentration to eliminate the autoreduction of Fe(III). A modified method using a Tris (2-amino-2-hydroxymethyl-1,3-propanediol) buffer at pH 7.5 instead of MES or HEPES buffer and a decreased FeEDTA (Fe ethylene diamine tetraacetic acid) concentration of 50 ¼mol L-1 was developed. The autoreduction of Fe(III) using the Tris buffer was undetectable for temperatures at 4 and 28 C and was also much lower than that using the other buffers even with sunlight during measurement of Fe(III) reduction. Furthermore, the differences in Fe(III) reductase activity among 5 plant species and 14 red clover cultivars(Trifolium pratense L.) could be easily detected with the modified method. The method developed in this study to measure root Fe chelate reductase activity was not only effective and reliable but also easily managed under normal laboratory light conditions.

Pan, J. J., Zhang, T. L. and Zhao, Q. G. 2005. Dynamics of soil erosion in Xingguo County, China, determined using remote sensing and GIS. Pedosphere. 15(3): 356--362
ABSTRACT: The spatial and temporal dynamics of soil erosion in Xingguo County, Jiangxi Province, China were studied using multi-period remote sensing images and GIS. The results indicated that the soil erosion status of the region has been improving, particularly since the 1980s, with the erosion rate showing an evident decline over the past 30 years. The improvement showed not only in the decline of eroded soil area, but also with the reduction in the extent of erosion. The extent of erosion mainly changed by one level, and the change primarily occurred with the severely or moderately eroded soil types. However, in general, soil erosion was still an overriding problem in the region with some areas becoming more serious, especially those with large quantities of granite.

Shen, R. P., Sun, B. and Zhao, Q. G. 2005. Spatial and temporal variability of N, P and K balances for agroecosystems in China. Pedosphere. 15(3): 347--355
ABSTRACT: Nitrogen, phosphorus, and potassium balances for agroecosystems in China from 1993 to 2001 were calculated at national and provincial levels using statistical data and related parameters, and their spatial and temporal variabilities were analyzed with GIS to estimate the potential impacts of nutrient N, P and K surpluses or deficits to soil, water and air. At the national scale, the N and P balances from 1993 to 2001 showed a surplus, with the nitrogen surplus remaining relatively stable from 1997--2001. Although during this period the P surplus pattern was similar to N, it had smaller values and kept increasing as the use of phosphate fertilizer increased year by year. However, K was deficient from 1993 to 2001 even though from 1999 to 2001 the K deficit decreased. The spatial analysis revealed higher N surpluses in the more developed southeastern provinces and lowest in the western and northern provinces where there was less chemical fertilizer input. The serious K deficit occurred in Shanghai and Beijing municipalities, Jiangsu, Zhejiang and Hubei provinces, and Xinjiang autonomous regions. For the years 1992, 1996 and 2001, N surpluses and K deficits had significant positive spatial correlations with per capita gross domestic product (GDP), per capita gross industrial output value, and per capita net income of rural households. This showed that the level of economic development played an important role on nutrient balances in the agroecosystems.

Jiang, Y., Zhang, Y. G., Liang, W. J. and Li, Q. 2005. Pedogenic and anthropogenic influence on calcium and magnesium behaviors in Stagnic Anthrosols. Pedosphere. 15(3): 341--346
ABSTRACT: The formation of Stagnic Anthrosols is closely related to rice planting and parent materials. Six representative pedons, two from each of three Stagnic Anthrosol subgroups, Vertic Haplic-, Vertic Gleyic-, and Sulfic Gleyic-Stagnic Anthrosols, from different parent materials and soil formation processes, from Liaoning Province, China, were selected and used along with additional supporting data to assess the potential impact in each soil subgroup combination of both pedogenic and anthropogenic factors on the migration and geochemical characteristics of calcium (Ca) and magnesium (Mg) and their relations to soil particle-size composition. Results revealed that exchangeable Mg was correlated positively with clay and silt content, but negatively with sand content, suggesting that clay and silt could retain more exchangeable Mg than sand. Also, in the six pedons exchangeable Ca/Mg ratios generally decreased with depth, which was most likely due to the preferential retention of Mg below the Ap1 horizon and the effects of bio-cycling in rice-soil systems. The pedons with high pH had smaller exchangeable Ca/Mg ratios than those with low pH. Thus, it was concluded that exchangeable Ca/Mg ratios could be helpful in classification of Stagnic Anthrosols.

Chen, T. H., Peng, S. C., Xu, H. F., Shi, X. L. and Huang, C. H. 2005. Mechanism for Cu2+ sorption on palygorskite. Pedosphere. 15(3): 334--340
ABSTRACT: A single-factor experiment of copper ion adsorption on pure palygorskite was carried out to understand the Cu2+ sorption of palygorskite---an important clay mineral in soil and sedimentary rock. In addition, pH of the solution and the surface microstructure of palygorskite were investigated before and after adsorption. The experimental results indicated that efficiency of Cu2+ removal was related to the oscillation rate of the specimen shaker, sorption time, initial pH value and the amount of adsorbent added. Palygorskite induced Cu2+ hydrolysis and interaction between copper hydroxide colloids and palygorskite surfaces, as observed with transmission electron microscopy (TEM), were the main contributions to palygorskite removal of Cu2+. This mechanism was different from adsorption at the mineral-water interface. It was proposed that surface hydrolysis of palygorskite raised the alkalinity of the palygorskite-water interface and suspension system. Thus, the induced pH of the solution was then high enough for Cu2+ hydrolysis on the mineral surface and in solution.

Bao, H. J., Wu, Y. Z., Wu, C. F. and Xu, B. G. 2005. Planning and design for eco-sustainable farmland consolidation. Pedosphere. 15(3): 327--333
ABSTRACT: With a view of sustainable development, different kinds of farmland consolidation are reviewed. A planning and design mode for eco-sustainable farmland consolidation, which integrated the ecotypic board, the ecotypic tunnel, the ecotypic island, and the ecotypic boundary, is proposed. Then, an actual case of farmland consolidation, a project located in Yinzhou County, Zhejiang Province, is used to demonstrate the effective application procedures of the planning and design mode.

Han, X. Z., Song, C. Y., Wang, S. Y. and TANG, C. 2005. Impact of long-term fertilization on phosphorus status in black soil. Pedosphere. 15(3): 319--326
ABSTRACT: A twelve-year field trial was carried out to determine the impact of long-term fertilization on phosphorus (P) distribution in the soil profile, P balance, and the transformation and availability of soil P in a black soil (Phaeozem, FAO). Under a wheat-soybean-corn rotation, during twelve years where no fertilizer was applied, crops removed 60 and 81 mg P kg-1 soil in the control and NK treatment, respectively. About one third of the P absorbed by crops was originated from organic P. Ca2-P, Ca8-P, Al-P and Fe-P were the main forms of inorganic P absorbed by crops. The surplus P from fertilization remained in the 0--20 cm soil layer and increased with the application rate of P. The combined application of NP or NPK increased available P to a lesser extent than the combined application of PK. Fertilizer P had mainly transformed to the Al-P, Fe-P, Ca2-P, and Ca8-P forms. By using the P budget (X), changes in total P (Y1) and available P (Y2) in soils under the current cropping system could be predicted by the equations: Y1 = 0.02 + 1.01X and Y2 = 2.08 + 0.15X.

Chen, W., Luo, J. K. and Shen, Q. R. 2005. Effect of NH4+-N/NO3--N ratios on growth and some physiological parameters of Chinese cabbage cultivars. Pedosphere. 15(3): 310--318
ABSTRACT: The responses of three cultivars of Chinese cabbage (Brassica chinensis L.), one of the main vegetable crops in China, to different ratios of NH4+-N/NO3--N was investigated to find the optimal ratio of ammonium to nitrate for maximal growth and to explore ways of decreasing the nitrate content, increasing nitrogen use efficiency of Chinese cabbage, and determining distributions of nitrogen and carbon. Three cultivars of Chinese cabbage were hydroponically grown with three different NH4+-N/NO3--N ratios (0:100, 25:75 and 50:50). The optimal ratio of NH4+-N/NO3--N for maximal growth of Chinese cabbage was 25:75. The increase in the ratio of NH4+-N/NO3--N significantly decreased nitrate content in various tissues of Chinese cabbage in the order of petiole > leaf blade > root. The highest total nitrogen (N) content was found when the ratio of NH4+-N/NO3--N was 25:75, and N contents in plant tissues were significantly different, mostly being in the order of leaf blade > petiole > root. At the NH4+-N/NO3--N ratio of 25:75, the biomasses of Chinese cabbage cultivars 'Shanghaiqing', 'Liangbaiye 1' and 'Kangre 605' increased by 47%, 14% and 27%, respectively. The biomass, SPAD chlorophyll meter readings and carbon content of 'Shanghaiqing' were all higher than those of 'Liangbaiye 1', while nitrate and total nitrogen contents were lower. Thus, partial replacement of nitrate by ammonium could improve vegetable production by both increasing yields and decreasing nitrate content of the plants.

Gao, H. J., Jiang, X., Wang, F., Bian, Y. R., Wang, D. Z., Deng, J. C. and Yan, D. Y. 2005. Residual levels and new inputs of chlorinated POPs in agricultural soils from Taihu Lake region. Pedosphere. 15(3): 301--309
ABSTRACT: Selected persistent organochlorine pesticides (OCPs), including 1 ÿ1 ÿ1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and its principal metabolites 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD), hexachlorocyclohexane (HCH) and its isomers (±-, ²-, ³-, and ´-HCH), hexachlorobenzene (HCB), endosulfan, dieldrin, and endrin were quantified to determine current levels of organochlorine pesticides, to assess the eco-toxicological potential, and to distinguish previous and current inputs in agricultural soils from the Taihu Lake region. Gas chromatography equipped with a 63Ni electron-capture detector (GC-ECD) system was employed. Thirteen OCPs were detectable in all soil samples, with DDTs being the main residues, and HCHs had the second highest level of OCP residues. Although OCP residual levels were lower than those in 1990s, the residual levels for most of the DDTs and some of HCHs were still higher than the national environmental standards for agricultural soils. The ratios of DDT/DDE and ³-/±-HCH in twelve soils indicated that new inputs could be present in the soils. Thus, efforts should be made to completely ban the production of OCPs and their use in agriculture so as to reduce the threat of OCPs to food quality and human health.

Zhao, Y. C., Shi, X. Z., Yu, D. S., Pagella, T. F., Sun, W. X. and Xu, X. H. 2005. Soil organic carbon density in Hebei Province, China: Estimates and uncertainty. Pedosphere. 15(3): 293--300
ABSTRACT: In order to improve the precision of soil organic carbon (SOC) estimates, the sources of uncertainty in soil organic carbon density (SOCD) estimates and SOC stocks were examined using 363 soil profiles in Hebei Province, China, with three methods: the soil profile statistics (SPS), GIS-based soil type (GST), and kriging interpolation (KI). The GST method, utilizing both pedological professional knowledge and GIS technology, was considered the most accurate method of the three estimations, with SOCD estimates for SPS 10% lower and KI 10% higher. The SOCD range for GST was 84% wider than KI as KI smoothing effect narrowed the SOCD range. Nevertheless, the coefficient of variation for SOCD with KI (41.7%) was less than GST and SPS. Comparing SOCD’s lower estimates for SPS versus GST, the major sources of uncertainty were the conflicting area of proportional relations. Meanwhile, the fewer number of soil profiles and the necessity of using the smoothing effect with KI were its sources of uncertainty. Moreover, for local detailed variations of SOCD, GST was more advantageous in reflecting the distribution pattern than KI.

Wu, L. H., Mo, L. Y., Fan, Z. L., Tao, Q. N. and Zhang, F. S. 2005. Absorption of glycine by three agricultural species under sterile sand culture conditions. Pedosphere. 15(3): 286--292
ABSTRACT: Seedlings of wheat (Triticum aestivum L.), Chinese cabbage (Brassica campestris L.) and mung bean (Phaseolus radiatus L.) were grown for 30 days in sterile sand media with 6 N treatments, I.e. NH4+-N, glycine-N, 3 different ratios of glycine-N:NH4+-N (NH4+-N was labeled with 15N) and a control receiving no N, to assess the importance of amino acids in excessive N nutrition along with inorganic N interactions. The contribution of nitrogen derived from glycine-N to total plant N was investigated. The total plant N of the three species treated with N was significantly greater (P < 0.05) than the control treatment. Also, seedlings from all the three species had significantly more total N as NH4+-N (P < 0.05) than at least two of the four treatments with glycine-N. However, for all species, differences in total N among treatments with a mixture of glycine-N and NH4+-N were mostly not significant. The contribution of N derived from glycine-N to plant total N content for all species increased with increasing glycine-N:NH4+-N ratio in the treatment solution. These results indicated that agricultural plants could effectively use organic nitrogen from organic nitrogen sources (e.g. glycine) and from organic and inorganic N mixtures (e.g. a glycine-N and NH4+-N mix). There were also genotypic differences in glycine-N and NH4+-N uptake by agricultural species.

Zhao, Y. W., Hu, Z. Y., Cao, Z. H., Beaton, J. D., Henderson, A. M., Fan, M. X. and Xu, C. K. 2005. Transformation efficiency of sulfur for a mulberry leaf-silkworm cocoon system in the lower-middle reaches of the Yangtze River, China. Pedosphere. 15(3): 281--285
ABSTRACT: Cocoon samples were collected from fifty-two mulberry gardens with high, intermediate, and low silkworm cocoon productivities in the lower-middle reaches of the Yangtze River in the six China’s provinces of Jiangsu, Jiangxi, Anhui, Fujian, Hunan, and Hubei to determine the transformation efficiency of S from mulberry leaves to silkworm cocoons, and to evaluate the sulfur cycle (uptake and output) in the mulberry leaf-silkworm cocoon system with typical mulberry gardens in the lower-middle reaches of the Yangtze River in China. The transformation efficiency of sulfur (TES) from mulberry leaves into silkworm cocoons in the high-productivity mulberry gardens was significantly lower (P < 0.05) than that in the low-productivity gardens. For the high-productivity mulberry gardens the TES from mulberry leaves into the cocoon shell was significantly higher (P < 0.05) than that for low-yield mulberry gardens. Producing 1 kg dry cocoon in mulberry gardens required uptake of about 20 g S, however 1 kg of dry cocoon only removed about 4 g S. Therefore, recycling of these organic wastes with silkworm cultivation was important for sulfur balances.

Zhang, Y. S., Shao, X. H., Lin, X. Y. and Scherer, H. W. 2005. Effect of organic acids and protons on release of non-exchangeable NH4+ in flooded paddy soils. Pedosphere. 15(3): 273--280
ABSTRACT: In a model experiment, which imitated the rhizosphere of rice, the effect of organic acids (oxalic acid, citric acid) and protons on the release of non-exchangeable NH4+ and the resin adsorption of N was studied in a paddy soil, typical for Zhejiang Province, China. Oxalic and citric acids under low pH conditions, in combination with proton secretion, favored the mobilization of NH4+ ions and increased resin adsorption of N. The release of non-exchangeable NH4+ was associated with less formation of iron oxides. These could coat clay minerals and thus hinder the diffusion of NH4+ ions out of the interlayer. Protons enhanced the release of NH4+, and then they could enter the wedge zones of the clay minerals and displace non-exchangeable NH4+ ions.

Chen, R. R., Yin, R., Lin, X. G. and Cao, Z. H. 2005. Effect of arbuscular mycorrhizal inoculation on plant growth and phthalic ester degradation in two contaminated soils. Pedosphere. 15(2): 263--269
ABSTRACT: A 60-day pot experiment was carried out using di-(2-ethylhexyl) phthalate (DEHP) as a typical organic pollutant phthalic ester and cowpea (Vigna sinensis) as the host plant to determine the effect of arbuscular mycorrhizal inoculation on plant growth and degradation of DEHP in two contaminated soils, a yellow-brown soil and a red soil. The air-dried soils were uniformly sprayed with different concentrations of DEHP, inoculated or left uninoculated with an arbuscular mycorrhizal (AM) fungus, and planted with cowpea seeds. After 60 days the positive impact of AM inoculation on the growth of cowpea was more pronounced in the red soil than in the yellow-brown soil, with significantly higher (P < 0.01) mycorrhizal colonization rate, shoot dry weight and total P content in shoot tissues for the red soil. Both in the yellow-brown and red soils, AM inoculation significantly (P < 0.01) reduced shoot DEHP content, implying that AM inoculation could inhibit the uptake and translocation of DEHP from roots to the aboveground parts. However, with AM inoculation no positive contribution to the degradation of DEHP was found.

Williams, A., Xing, B. S. and Veneman, P. 2005. Effect of cultivation on soil organic matter and aggregate stability. Pedosphere. 15(2): 255--262
ABSTRACT: Agricultural sustainability relates directly to maintaining or enhancing soil quality. Soil quality studies in Canada during the 1980’s showed that loss of soil organic matter (SOM) and soil aggregate stability was standard features of non-sustainable land management in agroecosystems. In this study total soil organic carbon (SOC), particulate organic matter (POM), POM-C as a percentage of total SOC, and aggregate stability were determined for three cultivated fields and three adjacent grassland fields to assess the impact of conventional agricultural management on soil quality. POM was investigated using solid-state 13C nuclear magnetic resonance (NMR) to determine any qualitative differences that may be attributed to cultivation. Results show a highly significant loss in total SOC, POM and aggregate stability in the cultivated fields as compared to the grassland fields and a significant loss of POM-C as a percentage of total SOC. Integrated results of the NMR spectra of the POM show a loss in carbohydrate-C and an increase in aromatic-C in the cultivated fields, which translates to a loss of biological lability in the organic matter. Conventional cultivation decreased the quantity and quality of SOM and caused a loss in aggregate stability resulting in an overall decline in soil quality.

Liu, X. J., Ju, X. T., Chen, X. P., Zhang, F. S. and Romheld, V. 2005. Nitrogen recommendations for summer maize in northern China using the Nmin test and rapid plant tests. Pedosphere. 15(2): 246--254
ABSTRACT: A field experiment with a split-plot design was carried out at Dongbeiwang Farm in Beijing Municipality to establish reliable N fertilizer recommendation indices for summer maize (Zea mays L.) in northern China using the soil Nmin (mineral N) test as well as the plant nitrate and SPAD (portable chlorophyll meter readings) tests. The results showed that Nmin sollwert (NS), which consisted of Nmin (60 kg N ha-1 at the third leaf stage) + fertilizer N (120 kg N ha-1 at the tenth leaf stage) could meet the N requirement of summer maize with a target yield of 6 t ha-1. Sap nitrate concentrations and SPAD chlorophyll meter readings in the latest expanded maize leaves at the tenth leaf stage were positively correlated with NS levels, indicating that plant nitrate and SPAD tests reflected the N nutritional status of maize well. Considering that winter wheat subsequently utilized N after the summer maize harvest, the 0--90 cm soil Nmin (74 kg N ha-1) and apparent N loss (12 kg N ha-1) in the NS60+40 treatment were controlled at environmentally acceptable levels. Therefore NS60+40, giving a total N supply of 100 kg N ha-1, was considered the optimal N fertilizer input for summer maize under these experimental conditions.

Assareh, M. H., Sardabi, H. and Sabbaghzadeh, F. 2005. Plant regeneration of Ziziphus spina-christi by in vivo and in vitro methods. Pedosphere. 15(2): 238--245
ABSTRACT: Christ’s thorn (Ziziphus spina-christi L. Desf.) is ecologically and economically important in Iran. Since it is a cross-pollinated plant with a wide range of genetic variability, an investigation was carried out to determine the best method for mass and clonal propagation. Three vegetative methods were examined, including 1) cutting, where shoots with a 22--25 cm length and three shoot diameters were treated with two culture media; 2) layering, where air layering and trench layering treatments consisted of three growth regulators at three levels of concentration; and 3) tissue culture with nodal segments bearing axillary buds that were removed from shoots of mature trees at different seasons. Several experiments were carried out to determine the best disinfectant chemical, the best culture method, the best season, the appropriate explant characteristics and media type. Rooting was successful only on the sandy beds for cuttings with more than 8.0 mm diameter. For the trench layering method, only one specimen in one replicate rooted a very small root, while for the air layering method, only seedlings with growth regulator treatments rooted successfully. The best season for explant harvesting was determined as mid summer, and among the disinfecting treatments, Ca(Ocl)2 at a concentration of 0.5 g kg-1 for 20 minutes was the best. There were no significant differences for shoot weight and length with a Murashige and Skoog (MS) media with and without a hormone.

Wang, H., Dai, L. M., Yang, B. S., Lang, Q. L. and Gu, H. Y. 2005. Occurrence and culture of mycorrhizal fungi associated with oaks in Dandong Region, Liaoning Province. Pedosphere. 15(2): 232--237
ABSTRACT: With both field investigation and pure culture experiments, the occurrence and optimal essential growth of mycorrhizal fungi with oaks in Dandong Region of Liaoning Province, China were investigated from 1997--2002. A total of 36 species of mycorrhizal fungi associated with oaks were observed. The results showed that the occurrence of mycorrhizal fungi was related to tree species, tree ages, and months of the year, with at least 20 fungi species being associated with more than two oak species. The highest Simpson index (SI) and Shannon index (Hàÿ) values, 0.95 and 4.44 respectively, were found in the 15--25 year-old age group. The optimum month for fungal occurrence was August, when the SI and Hàÿ values were 0.97 and 5.16, respectively. Additionally, the cultivated mycorrhizal fungus grew best at temperature of 25--30 oC and at pH of 5--6. The results also indicated that the association between mycorrhizal fungi and oaks was common.

Chen, Y. and Lian, B. 2005. Ability of Bacillus mucilaginosus GY03 strain to adsorb chromium ions. Pedosphere. 15(2): 225--231
ABSTRACT: A research with Bacillus mucilaginosus cultured in nitrogen-free medium for forming a flocculant material to adsorb Cr+6 was conducted to determine the effects of different pH, volume, treatment time, and chromium (VI) concentrations on chromium (VI) adsorption by microbial flocculant (MBF), which was produced from the B. mucilaginosus GY03 strain. The results showed that MBF had outstanding flocculation on chromium (VI). Based on the results of a one-way experiment and actual wastewater treatment conditions, the optimum conditions, obtained by using orthogonal experiments, for chromium (VI) adsorption by MBF were: Cr6+ solution pH--9, flocculant material volume--15 mL, treatment time--12 h and chromium ion concentration--30 mg L-1. The results demonstrated that the MBF produced from GY03 could be used in the chromium-containing wastewater treatment. Meanwhile, after extraction and analysis of the MBF polysaccharides, it was found that MBF was mainly composed of glycoprotein. Analysis on constituents of monosaccharide showed that polysaccharides of B. mucilaginosus were composed of rhamnose, glucose etc. Thus, because it was applied over a wide range of pH, in small amounts and had a rapid flocculation speed the flocculant used in this experiment had a vast field of application potential.

Jia, L. Q., Ou, Z. Q. and Ouyang, Z. Y. 2005. Ecological behavior of linear alkylbenzene sulfonate (LAS) in soil-plant systems. Pedosphere. 15(2): 216--224
ABSTRACT: More and more linear alkylbenzene sulfonate (LAS) has contaminated the water and soil via pollution discharge, making it important to identify the ecological behavior and toxicity of LAS so as to carry out measures that will reduce its negative effects on the ecosystem. The ecological behavior of LAS, including degradation, migration, and plant uptake in both soil-paddy rice and soil-soybean systems, was studied. Reduction of LAS in pot and field plots followed the first order reaction kinetics with degradation half-lives of 35--50 days with LAS decreasing to very low concentrations after a season of crop growth. Strong migration ability for LAS was found and the breakthrough time in a 1.5 m soil monolith was significantly shortened to 23 days by preferential flow. Leachate volumes of soil-paddy and soil-soybean systems at preferential breakthrough were much different, while the leachate volumes at equilibrium governed by soil adsorption/desorption processes were very similar. Significant uptake of LAS in both paddy rice and soybeans was observed in pot and field experiments (P S3 > S4 > S5. The pattern of nitrogen uptake with ecological succession was less conspicuous, being complicated by the immediate effect of fire and possibly the ability of the woodland species to extract nitrogen from the deeper ground. In the absence of fire for 3 to 6 years, the build-up of SOM and TKN was accompanied by active mineralization, thus paving the way for the invasion of shrub and tree species. A close relationship existed between nitrogen mineralization and ecological succession with this vegetation gradient. Inherent mechanisms to preserve nitrogen in a fire-prone environment including immobilization and uptake and the practical relevance of nitrogen mineralization to reforestation are discussed.

Wang, X. X., Sun, B., Zhang, T. L. and He, Y. Q. 2005. Fate of urea applied to peanut (Arachis hypogaea L.) on a sloping Udic Ferrosol in subtropical China. Pedosphere. 15(2): 173--180
ABSTRACT: A field experiment was conducted to study the outcome of N using isotope-labeled urea with a peanut cropping system in a Udic Ferrosol on a 7% slope at the Ecological Experimental Station of Red Soil, Chinese Academy of Sciences. The micro-plots were designed in two sets with three replicates and four N treatments. An iron frame with its edge 10 cm above the ground was used to control soil erosion and runoff in set A, but in set B the upper edge of the frame was level with the ground. Randomly positioned 15N fertilized micro-plots were established along the contour. At harvest on August 13, 2002, which was four months after urea application, the peanuts had absorbed 30.6%--38.0% of the urea, transpired 13.1%--22.4% to the atmosphere, lost 6.4%--8.4% through soil erosion and surface runoff, and maintained 40.7%--48.9% in the 0--60 cm soil layer with 0.5%--5.0% below 60 cm.

Minami, K. 2005. N cycle, N flow trends in Japan, and strategies for reducing N2O emission and NO3- pollution. Pedosphere. 15(2): 164--172
ABSTRACT: To feed an increasing population, large amounts of chemical nitrogen fertilizer have been used to produce much of our food, feed and fiber thereby increasing nitrogen levels in soils, natural waters, crop residues, livestock wastes, and municipal and agricultural wastes, with national and international concern about its potential adverse effects on environmental quality and public health. To understand these phenomena and problems, first the nitrogen cycle and the environment are described. Then recent trends for nitrogen cycling through the food and feed system, N2O emissions from fertilized upland and paddy soils, and NO3- pollution in ground water in Japan are reported. Finally, mitigation strategies in Japan for reducing N2O emission and NO3- pollution are proposed, including nitrification inhibitors, controlled release fertilizers, utilization of plant species that could suppress nitrification, utilizing the toposequence, government policy, and appropriate agricultural practices. Of all the technologies presented, use of nitrification inhibitors and controlled release fertilizers are deemed the most important with further development of these aspects of technologies being expected. These practices, if employed worldwide, could help reduce the load, or environmental deterioration, on the Earth’s biosphere.

Wei, Y. P., Chen, D. L., Davidson, B. and White, R. E. 2005. Bio-economic strategy to combat non-point pollution in China. Pedosphere. 15(2): 156--163
ABSTRACT: While non-point pollution from agriculture has become an increasingly serious problem in China, some progress has been made in studying the causal biophysical processes. However, few studies have assessed the economic consequences of non-point pollution in China or the policy options that could be employed to combat it. In this work a sustainable strategy to control non-point pollution from crop production, which involved taxing excessive inputs of irrigation water and fertilizer, was proposed. The approach taken to assess these measures combined biophysical and economic models, having a trade-off between economic returns and an improved environment. A proven and practical spatially referenced water and nutrient management model was used to determine the quantities of excessive irrigation water and fertilizer for specific soil and land use. Also, a set of indicators were proposed for evaluating the effects of agricultural economic output and agricultural practices on the environment.

Bouwman, A. F., Van Drecht, G. and Van der Hoek, K. W. 2005. Global and regional surface nitrogen balances in intensive agricultural production systems for the period 1970--2030. Pedosphere. 15(2): 137--155
ABSTRACT: Global nitrogen (N) budgets for intensive agricultural systems were compiled for a 0.5 by 0.5 degree resolution. These budgets include N inputs (N fertilizer, animal manure, biological N fixation and atmospheric N deposition) and outputs (N removal from the field in harvested crops and grass and grass consumption by grazing animals, ammonia volatilization, denitrification and leaching). Data for the historical years 1970 and 1995 and a projection for 2030 were used to study changes in the recovery of N and the different loss terms for intensive agricultural systems. The results indicated that the overall system N recovery and fertilizer use efficiency slowly increased in the industrialized countries between 1970 and 1995, the values for developing countries have decreased in the same period. For the coming three decades our results indicated a rapid increase in both the industrialized and developing countries. High values of > 80% for fertilizer use efficiency may be related to surface N balance deficits, implying a depletion of soil N and loss of soil fertility. The projected intensification in most developing countries would cause a gradual shift from deficits to surpluses in the coming decades. The projected fast growth of crop and livestock production, and intensification and associated increase in fertilizer inputs would cause a major increase in the surface N balance surplus in the coming three decades. This implied increasing losses of N compounds to air (ammonia, nitrous oxide and nitric oxide), and groundwater and surface water (nitrate).

Li, Z. X., Cai, C. F., Shi, Z. H. and Wang, T. W. 2005. Aggregate stability and its relationship with some chemical properties of red soils in subtropical China. Pedosphere. 15(1): 129--136
ABSTRACT: The stability of aggregates in the surface soil is crucial to soil erosion and runoff generation. Thus, to understand the stability and the breakdown mechanisms of soil aggregates as well as the relationship between aggregate stability and selected soil properties, such as different forms of Fe and Al oxides, organic matter, CEC and clay content, the aggregates of slightly and severely eroded red soils derived from Quaternary red clay in Subtropical China were analyzed using the routine wet sieving and the Le Bissonnais methods. The results indicated that the aggregates of severely eroded soils were more stable than those of slightly eroded soils. Different aggregate breakdown mechanisms resulted in different particle size distribution. The slaking from entrapped air in aggregates severely destroyed the soil aggregates, especially in the slightly eroded soils. Meanwhile, mechanical breakdown and microcracking had little effect on the aggregates compared to slaking. The fragments resulting from slaking were mainly microaggregates that increased in size with increasing clay content. The main fragment size of the slightly eroded soils was 1.0--0.2 mm, while for the severely eroded soils it was 5.0--2.0 mm and 1.0--0.5 mm. Overall, more than 20% of the fragments were smaller than 0.2 mm. In addition, aggregate stability was positively and often significantly correlated with Fed, Ald, Feo and clay content, but significantly and negatively correlated to SOC.

Wang, T. J., Yang, H. M., Gao, L. J., Zhang, Y., Hu, Z. Y. and Xu, C. K. 2005. Atmospheric sulfur deposition on farmland in East China. Pedosphere. 15(1): 120--128
ABSTRACT: Atmospheric sulfur deposition onto typical farmland in East China was investigated using both field measurements and numerical modeling. The field measurements were conducted at the Experiment Station of Red Soil Ecology, Chinese Academy of Sciences, 10 km from Yingtan, Jiangxi Province, East China, between November 1998 and October 1999, and at the Changshu Ecological Experiment Station, Chinese Academy of Sciences, in a rapidly developing region of Jiangsu Province, East China, between April 2001 and March 2002. The regional acid deposition model system (RegADMS), in which the dry deposition velocities of SO2 and sulfate aerosols (SO42-) were estimated using a big-leaf resistance analogy model, was applied to simulate air sulfur deposition over East China and sulfur deposition onto different land use types in East China. The wet scavenging coefficients were parameterized in terms of precipitation rate, and the effect of sub-grid processes due to inhomogeneous land use on dry deposition velocity was also included. Results of the field measurements showed that over 83% of the total sulfur deposition at the Yingtan site was dry deposition, while at the Changshu site 42% was dry deposition. The total sulfur deposition was much larger at the Yingtan site than at the Changshu site, which suggested contrasting air pollution and meteorological situations. The modeling results revealed that the total annual sulfur deposition over East China was 1.88 Mt, of which 72.8% was deposited onto farmland, and dry deposition accounted for 43% of the total sulfur deposited. The modeling results were generally in agreement with those of the observation. Overall, this study suggested that atmospheric sulfur deposition played an important role in the soil sulfur balance, which could have a significant effect on agricultural ecosystems in the study region.

Li, Z. P., Zhang, T. L., Li, D. C., Velde, B. and Han, F. X. 2005. Changes in soil properties of paddy fields across a cultivation chronosequence in subtropical China. Pedosphere. 15(1): 110--119
ABSTRACT: Rice production plays a crucial role in the food supply of China and a better understanding of the changes in paddy soil fertility and the management effects is of practical importance for increasing rice productivity. In this study, field sampling in a typical red soil region of subtropical China, Jiangxi Province, was used to observe changes in the soil physical, chemical, and biological properties in a cultivation chronosequence of paddy fields. After cultivation, clay (< 0.002 mm) content in the soil, which was 39% in the original uncultivated wasteland, decreased, to 17% in the 80-year paddy field, while silt (0.02--0.002 mm) content increased. Additionally, macroporosity increased and pore shapes became more homogeneous. Soil Ph generally increased. Soil organic C and total N content of the 0-10 cm layer increased from 4.58 and 0.39 g kg-1 to 19.6 and 1.62 g kg-1, respectively in the paddy fields after 30-year cultivation and then remained stable. Soil total P content increased from 0.5 to 1.3 g kg-1 after 3 years of rice cultivation, indicating that application of phosphate fertilizer could accelerate phosphorous accumulation in the soil. Total K content in the 0--10 cm soil layer for the 80-year paddy fields decreased by 28% compared to that of the uncultivated wasteland land. Total Fe and free Fe contents declined with years of cultivation. The bacterial population increased and urease activity noticeably intensified after years of cultivation. In this chronosequence it appeared that it took 30 years to increase soil fertility to a relatively constant value that was seen after 80 years of cultivation.

Zhou, B., Zhang, X. G., Wang, F. and Wang, R. C. 2005. Soil organic matter mapping by decision tree modeling. Pedosphere. 15(1): 103--109
ABSTRACT: Based on a case study of Longyou County, Zhejiang Province, the decision tree, a data mining method, was used to analyze the relationships between soil organic matter (SOM) and other environmental and satellite sensing spatial data. The decision tree associated SOM content with some extensive easily observable landscape attributes, such as landform, geology, land use, and remote sensing images, thus transforming the SOM-related information into a clear, quantitative, landscape factor-associated regular system. This system could be used to predict continuous SOM spatial distribution. By analyzing factors such as elevation, geological unit, soil type, land use, remotely sensed data, upslope contributing area, slope, aspect, planform curvature, and profile curvature, the decision tree could predict distribution of soil organic matter levels. Among these factors, elevation, land use, aspect, soil type, the first principle component of bitemporal Landsat TM, and upslope contributing area were considered the most important variables for predicting SOM. Results of the prediction between SOM content and landscape types sorted by the decision tree showed a close relationship with an accuracy of 81.1%.

Li, Q. M., Wang, X. X. and Bi, S. P. 2005. Impacts of Choerospondias axillaris growth on acidity of Udic Ferrosols in subtropical China. Pedosphere. 15(1): 95--102
ABSTRACT: Changes in acidity of Udic Ferrosols, caused by growth of Choerospondias axillaris (Roxb.) Burtt et Hill, in comparison to wild grass, were investigated for Ph distribution in the soil profile, exchangeable acidity, and cation status in the soil leachate of a simulated leaching experiment. Soils were sampled in profiles at 5 cm intervals to a depth of 100 cm. In the 15--60 cm layer the soils with 10-year old C. axillaris had significantly lower Ph (P < 0.05), with the largest difference being 0.41; and in the 25--75 cm soil depths, especially in the 30--55 cm layer, the soils had a significantly higher exchangeable acidity, ranging 1.93 to 3.02 cmolc kg-1. There was also higher aluminum, potassium, and sodium contents in the soil leachate under C. axillaris than with wild grasses. This suggested that the growth of C. axillaris accelerated acidification of Udic Ferrosols and promoted soil clay mineral weathering.

Yan, X. K., Chang, K. W. and Xu, H. L. 2005. Effects of paper mill sludge on potassium, sodium, calcium, and magnesium concentrations in different soybean cultivars. Pedosphere. 15(1): 84--94
ABSTRACT: A field experiment was conducted on a sandy loam soil at an Experimental Farm in Taejon, South Korea, to determine the effects of paper mill sludge compost application rates on K, Na, Ca and Mg concentrations of soybean (Glycine max (L.) Merr.) aboveground tissues and the genotypic effects on the concentrations of these elements. Sludge compost treatments of 0, 75, and 150 t ha-1 were applied to 30 diverse soybean cultivars. Concentrations of K, Na, Ca, and Mg in aboveground tissues harvested 69 days after planting (DAP) varied with the genotype and the application rate of paper-mill sludge compost, with the sludge compost application rate exerting stronger influence on these concentrations than the genotype. The magnitude of variation caused by both genotype and sludge compost application was in the order of Mg > K > Ca > Na. Significantly positive correlations were observed between K and Na (P < 0.01), Na and Ca (P < 0.05), and Ca and Mg (P < 0.01). Also, the lower the sludge compost application rate, the larger the variation in the concentrations of K, Na, and Ca. From this several cultivars were identified for use as an accumulator for one or more of these elements.

LÜ, J. J., Yang, H., Gao, L. and Yu, T. Y. 2005. Spatial variation of P and N in water and sediments of Dianchi Lake, China. Pedosphere. 15(1): 78--83
ABSTRACT: Dianchi Lake is one of the most eutrophic lakes in China. In order to understand this eutrophication and to help control the pollution, this research investigated the spatial distribution of Kjeldahl nitrogen (K-N) and total phosphorus (TP) through analysis of bottom water and sediment (3 depths) samples collected at 118 sites around Dianchi Lake. The concentrations of K-N and TP for the lake bottom water in the Caohai part of the lake, were much higher than those in the Waihai part, generally decreasing from north to south. In the sediments, the K-N concentration was higher in the Caohai part and the middle of the Waihai part. On the other hand, TP in the sediments was greater in the southern and western parts. Both K-N and TP had similar spatial distributions for the sediment samples of three different depths. Vertically, the K-N and TP concentration in the sediments decreased with an increase in depth. This was evidence that eutrophication and pollution of Dianchi Lake was becoming gradually more severe. Exterior factors including uncontrolled input of domestic and industrial effluents as well as non-point pollution around the lake were the main reasons for serious eutrophication; therefore, controlling these was the first step in reducing eutrophication of Dianchi Lake.
Zhang, G. L., Burghardt, W. and Yang, J. L. 2005. Chemical criteria to assess risk of phosphorus leaching from urban soils. Pedosphere. 15(1): 72--77
ABSTRACT: Soils from urban and suburban areas are normally enriched with phosphorus (P). Sixteen urban soils with a wide range of total P concentrations under typical urban land uses were sampled and analyzed for extractable P concentrations using water, sodium bicarbonate and citric acid. Meanwhile the soils were artificially leached in columns and P concentrations in the leachates were determined. With linear regression a two-stage linear relationship was found to exist between concentrations of P in the leachates and soil P contents obtained by various chemical measurements, I.e., there was a “change-point” denoting the critical threshold value for extractable P between the regression lines, above which concentrations of P in leachates increased substantially. These threshold “change-point” values were 1.5 mg kg-1 for water-soluble P and CaCl2-P, 25 mg kg-1 for Olsen-P, and 250-350 mg kg-1 for citric acid-P with the sharpest change and the best predictor [r2 (upper) = 0.928, r2 (lower) = 0.807] appearing for Olsen-P. These “change-points” were considered important criteria in assessing the risk of P leaching from urban soils and could be used as standards to delineate and target hazardous areas in urban and suburban areas.

Cai, Z. C., Kang, G. D., Tsuruta, H. and Mosier, A. 2005. Estimate of CH4 emissions from year-round flooded rice fields during rice growing season in China. Pedosphere. 15(1): 66--71
ABSTRACT: A special kind of rice field exists in China that is flooded year-round. These rice fields have substantially large CH4 emissions during the rice-growing season and emit CH4 continuously in the non-rice growing season. CH4 emission factors were used to estimate the CH4 emissions from year-round flooded rice fields during the rice-growing season in China. The CH4 emissions for the year-round flooded rice fields in China for the rice growing season over a total area of 2.66 Mha were estimated to be 2.44 Tg CH4 year-1. The uncertainties of these estimations are discussed as well. However, the emissions during the non-rice growing season could not be estimated because of limited available data. Nevertheless, methane emissions from rice fields that were flooded year-round could be several times higher than those from the rice fields drained in the non-rice-growing season. Thus, the classification of “continuously flooded rice fields” in the IPCC ( International Panel on Climate Change) Guidelines for National Greenhouse Gas Inventories is suggested to be revised and divided into “continuously flooded rice fields during the rice growing season” and “year-round flooded rice fields”.

Fan, X. H., Song, Y. S., Lin, D. X., Yang, L. Z. and Zhou, J. M. 2005. Ammonia volatilization losses from urea applied to wheat on a paddy soil in Taihu Region, China. Pedosphere. 15(1): 59--65
ABSTRACT: Ammonia volatilization losses from urea applied as a basal fertilizer and a top dressing at tillering stage in a wheat field of Taihu Region, China, were measured with a micrometeorological technique. Urea as fertilizer was surface broadcast at 81 (low N) and 135 (high N) kg N ha-1 as basal at the 3-leaf stage of the wheat seedling on December 2002, and 54 (low N) and 90 (high N) kg N ha-1 as top dressing on February 2003. Ammonia volatilization losses occurred mainly in the first week after applying N fertilizer and mainly during the period after basal fertilizer application, which accounted for more than 80% of the total ammonia volatilization over the entire wheat growth period. Regression analysis showed that Ammonia volatilization was affected mainly by pH and NH4+-N concentration of the surface soil and air temperature. Ammonia volatilization flux was significantly correlated with pH (r = 0.5956 and 0.7049, P = 0.05) and NH4+-N concentration (r = 0.7563 and 0.7755, P = 0.05 or 0.01) of the surface soil and with daily air average temperature and highest temperature (r = 0.6042--0.8353, P = 0.05 or 0.01 ). Thus, application of urea N fertilizer to wheat should consider the characteristics of ammonia volatilization in different periods of N application so as to reduce ammonia losses.

Sun, G., Wu, N. and Luo, P. 2005. Soil N pools and transformation rates under different land uses in a subalpine forest-grassland ecotone. Pedosphere. 15(1): 52--58
ABSTRACT: Soil nitrogen pools (NP), denitrification (DN), gross nitrification (GN), N2O and CO2 flux rates with their responses to temperature increases were determined under five different land uses and managements in a subalpine forest-grassland ecotone of the eastern Tibetan Plateau. Land uses consisted of 1) sparse woodland, 2) shrub-land, 3) natural pasture, 4) fenced pasture, and 5) tilled pasture mimicking a gradient degenerating ecosystem under grazing impacts. The NO3--N content was higher than the NH4+-N content. Comparing tilled pasture with fenced pasture showed that higher intensive management (tillage) led to a significant decrease of soil organic matter (SOM) (P < 0.05) in the soils, which was in contrast to the significant increases (P < 0.05) of DN, GN, N2O and CO2 flux rates. GN (excluding tilled pasture) and CO2 flux rates increased with a temperature rise, but DN and N2O flux rates normally reached their maximum values at 12--14 oC with tilled pasture (the highest management intensity) being very sensitive to temperature increases. There was a difference between net nitrification and GN, with GN being a better indicator of soil nitrification.

Bhatti, A. U., Khan, Q., Gurmani, A. H. and Khan, M. J. 2005. Effect of organic manure and chemical amendments on soil properties and crop yield on a salt affected Entisol. Pedosphere. 15(1): 46--51
ABSTRACT: A field experiment was conducted for two consecutive years in a farmer’s field at Haji Mora Village, Dera Ismail Khan (D.I. Khan) in the Northwest Frontier Province (NWFP) of Pakistan to compare various management practices, such as the effect of various organic manures and gypsum in a rice-wheat cropping system on a saline-sodic Entisol (Zindani soil series). The treatments consisted of 1) a control (rice-wheat), 2) gypsum, 3) farmyard manure (FYM), 4) berseem (Trifolium alexandrinum L.) as green manure (GM), and 5) dhancha (Sesbania sp.) as GM. All treatments increased yields of both rice and wheat significantly (P < 0.01) over the control, with the green manure treatments proving more economical than the others; while they decreased pH, electrical conductivity (EC), and sodium adsorption ratio (SAR) of the soil. Saturation percentage and available water of the soil were raised for all treatments due to an increase in organic matter content of the soil.

Qi, X. Z. and Lin, Z. S. 2005. Grassland evolution under soil degradation: Numerical simulation and test. Pedosphere. 15(1): 41--45
ABSTRACT: Both theoretical and field observations were examined to study the close relationship between soil degeneration and the evolution of grassland vegetation. A general n-species model of equal competition under different degrees of soil degradation was applied to field data in order to probe the dynamic processes and mechanisms of vegetation evolution due to the effects of the soil’s ecological deterioration on grassland vegetation. Comparisons were made between the theoretical results and the practical surveys with satisfactory results.

Xu, Q. F. and Jiang, P. K. 2005. Microbial development in soils under intensively managed bamboo (Phyllostachys praecox) stands. Pedosphere. 15(1): 33--40
ABSTRACT: Phyllostachys praecox C. D. Chu et C. S. Chao, a favored bamboo shoot species, has been widely planted in recent years. Four stands with different historical management practices were selected for this study to understand the evolution of soil microbial ecology by determining the effects of a new mulching and heavy fertilization practice on soil quality using microbiological parameters. Compared with the traditional practice (index 1), microbial biomass carbon (MBC) and soil microbial respiration carbon (MRC) with the new management practice significantly decreased (P < 0.01 and P < 0.05, respectively) with 1--2 years of mulching (index 2) and then for continued mulching significantly increased (P < 0.05). The ratios of MBC/TOC (total organic carbon) and MRC/TOC also significantly diminished (P < 0.05) with mulching. The average well color development (AWCD) and Shannon index decreased with mulching time, and the significant decrease (P < 0.05) in Shannon index occurred from index 2 to index 3. The results from a principal components analysis (PCA) showed that the scores of the first principal component for indexes 1 and 2 were significantly larger (P < 0.05) than soils mulched 3--4 years or 5--6 years. Also, the second principal component scores for index 1 were larger than those for index 2, suggesting that the ability of soil microorganisms to utilize soil carbon was decreasing with longer use of the new management practice and causing a deterioration of soil biological properties.

Yang, J. C., Huang, J. H., Pan, Q. M., Tang, J. W. and Han, X. G. 2005. Soil phosphorus dynamics as influenced by land use changes in humid tropical, southwest China. Pedosphere. 15(1): 24--32
ABSTRACT: Land use changes can greatly influence soil phosphorus (P) dynamics, especially when converting native forests to agricultural land. Soils in Xishuangbanna, which is one of southwest China’s tropical areas that maintain fragments of primary forests, were studied to a) evaluate the effect of two common land use changes, conversion of forests to agricultural land or rubber tree plantation, on the dynamics of available P and total P in bulk soils as well as total P in particle size fractions; b) assess the relationship between soil P dynamics and soil organic carbon (SOC); and c) elucidate the relationship between soil P content and soil properties such as pH and texture. Clearing secondary forests with subsequent shifting cultivation and establishment of rubber tree plantation caused significant decreases (P < 0.05) in available P in 0--20 cm soil depths, whereas for total P there was a significant decrease (P < 0.05) when converting to shifting cultivation, rubber tree plantation, or fallow fields at both 0--20 and 20--40 cm depths. Abandonment of fields used for shifting cultivation led to significant increases (P < 0.05) in available P at 20--40 cm depth. In addition, there was a significant positive relationship between soil organic carbon and soil P content. Compared to secondary forests, the ratio of organic carbon to total P in surface soils (0--20 cm) of shifting cultivation and rubber tree plantation was significantly lower (P < 0.05).

Cai, P., Huang, Q. Y., Zhang, X. W. and Chen, H. 2005. Binding and transformation of extracellular DNA in soil. Pedosphere. 15(1): 16--23
ABSTRACT: DNA is the genetic material of various organisms. Extracellular DNA adsorbed or bound on surface-active particles in soils has been shown to persist for long periods against nucleases degradation and still retain the ability to transform competent cells. This paper reviews some recent advances on the binding and transformation of extracellular DNA in soils, which is fundamental to understanding the nature of the soil, regulating biodiversity, and assessing the risk of releasing genetically engineered microorganisms (GEMs) as well as being helpful for development of the genetic evolutional theory of bacteria. Several influencing factors, such as soil pH, ionic strength, soil surface properties, and characteristics of the DNA polymer, are discussed. To date, the understanding of the type of molecular binding sites and the conformation of adsorbed and bound DNA to soil particles is still in its infancy.

Zhou, D. M., Xue, Y., Liu, X. H., Hao, X. Z., Chen, H. M., Shen, Z. G. and Si, Y. B. 2005. Responses of different pakchoi (Brassica chinensis L.) cultivars to Cu toxicity. Pedosphere. 15(1): 9--15
ABSTRACT: Two pot experiments with a completely random design and 4 replications were performed in a greenhouse to examine the response difference of 17 cultivars of pakchoi (Brassica chinensis L.) grown in a Cu-spiked and a clean soil to Cu. The response of pakchoi to Cu toxicity varied with the cultivars. The biomass in cultivars of ‘Gaogengbai’, ‘Siyueman’ and ‘Suzhouqing’ were sensitive to soil Cu pollution, but the cultivars of ‘Heixinwu’, ‘Huoqingcai’ and ‘Hkcaixin’ were relatively tolerant. When the 17 cultivars of pakchoi grew in clean garden soil, the Cu concentrations in the aboveground part were positively correlated (r = 0.6693) with their root Cu concentrations. However, when they grew in the Cu-spiked soil a highly negative correlation coefficient (r = -0.5376) was obtained in the Cu concentration between the aboveground part and the root. This meant that the Cu tolerant cultivars had a weak ability to transfer Cu from their root to their aboveground part, and therefore stored much more Cu in their root than the Cu sensitive cultivars.

Xing, B. S., Liu, J. D., Liu, X. B. and Han, X. Z. 2005. Extraction and characterization of humic acids and humin fractions from a black soil of China. Pedosphere. 15(1): 1--8
ABSTRACT: Twenty-three progressive extractions were performed to study individual humic acids (Has) from a typical black soil (Mollisol) in Heilongjiang Province, China using elemental analysis and spectroscopic techniques. After 23 HA extractions the residue was separated into high and low organic carbon humin fractions. HA yield was the highest for the first extraction and then gradually decreased with further extractions. Organic carbon (OC) of the humin fractions accounted for 58% of total OC even after 23 successive HA extractions. In addition, the atomic C/H ratio decreased during the course of extraction while C/O increased; the E4/E6 ratio from the UV analysis decreased with further extraction while E2/E3 increased; the band assigned to aliphatic carbon (2 930 cm-1) in the diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) spectra gradually increased with progressive extraction; the calculated ratio of the sum of aromatic carbon peak heights to that of aliphatic carbon peak heights from DRIFTS spectra declined with extractions; and nuclear magnetic resonance (NMR) data suggested that HA aliphatic carbons increased with extractions while aromatic carbons decreased. Thus, hydrophobicity and aliphaticity of Has increased with extractions while polarity and aromaticity decreased. These data showed substantial chemical, structural, and molecular differences among the 23 Has and two humin fractions. Therefore, these results may help explain why soil and sediment humin fractions have high sorption capacity for organic contaminants.

Zhang, Y. M., Chen, D. L., Zhang, J. B., Edis, R., Hu, C. S. and Zhu, A. N. 2004. Ammonia volatilization and denitrification losses from an irrigated maize-wheat rotation field in the North China Plain. Pedosphere. 14(4): 533--540
ABSTRACT: Ammonia (NH3) volatilization, denitrification loss, and nitrous oxide (N2O) emission were investigated from an irrigated wheat-maize rotation field on the North China Plain, and the magnitude of gaseous N loss from denitrification and NH3 volatilization was assessed. The micrometeorological gradient diffusion method in conjunction with a Bowen Ratio system was utilized to measure actual NH3 fluxes over a large area, while the acetylene inhibition technique (intact soil cores) was employed for measurement of denitrification losses and N2O emissions. Ammonia volatilization loss was 26.62% of the applied fertilizer nitrogen (N) under maize, while 0.90% and 15.55% were lost from the wheat field at sowing and topdressing, respectively. The differences in NH3 volatilization between different measurement events may be due to differences between the fertilization methods, and to differences in climatic conditions such as soil temperature. Denitrification losses in the fertilized plots were 0.67%--2.87% and 0.31%--0.49% of the applied fertilizer N under maize and wheat after subtracting those of the controls, respectively. Nitrous oxide emissions in the fertilized plots were approximately 0.08%--0.41% and 0.26%-0.34% of the applied fertilizer N over the maize and wheat seasons after subtracting those of the controls, correspondingly. The fertilizer N losses due to NH3 volatilization were markedly higher than those through denitrification and nitrous oxide emissions. These results indicated that NH3 volatilization was an important N transformation in the crop-soil system and was likely to be the major cause of low efficiencies with N fertilizer in the study area. Denitrification was not a very important pathway of N fertilizer loss, but did result in important evolution of the greenhouse gas N2O and the effect of N2O emitted from agricultural fields on environment should not be overlooked.

Zhang, H. Y., Li, Z. G., Pan, Y. H. and Li, L. M. 2004. Denitrifying bacteria in paddy soils of the Taihu Lake Basin, China. Pedosphere. 14(4): 527--532
ABSTRACT: This study attempted to determine the characteristics of the communities, the ecological factors, and the denitrifying enzyme activity for denitrifying bacteria found in the paddy soils of the Taihu Lake Basin, China. Samples of the six main soil types of the basin were taken from paddy fields with different fertilities. The total numbers of bacteria and denitrifying bacteria in the high fertility soils were much more than those in low fertility soils, and the number of denitrifying bacteria accounted for 49% to 80% of the total number of bacteria. The O2 content was an important ecological factor that affected denitrification. Of test the strains isolated from the paddy soils in the Taihu Lake Basin, some (e.g., Pseudomonas spp.) grew well under low oxygen partial pressure, while others (e.g., Bacillus spp.) had no strict predilection with O2 content. Another critical ecological factor was the nitrogen concentration. Three selected denitrifying bacteria grew better in a culture medium with 135 instead of 276 mg L-1 nitrogen. At the same time 67% of the test strains were able to reduce NO3- to NO2- and 56% had N2O reductase.

Abou-ismail, O., Huang, J. F. and Wang, R. C. 2004. Rice yield estimation by integrating remote sensing with rice growth simulation model. Pedosphere. 14(4): 519--526
ABSTRACT: Since remote sensing can provide information on the actual status of an agricultural crop, the integration between remote sensing data and crop growth simulation models has become an important trend for yield estimation and prediction. The main objective of this research was to combine a rice growth simulation model with remote sensing data to estimate rice grain yield for different growing seasons leading to an assessment of rice yield at regional levels. Integration between NOAA (National Oceanic and Atmospheric Administration) AVHRR (Advanced Very High Resolution Radiometer) data and the rice growth simulation model ORYZA1, named as Rice-SRS Model, resulted in accurate estimates for rice yield in Shaoxing, China, with an estimation error reduced to 1.03%and 0.79% over-estimation and 0.79% under-estimation for early, single and late season rice, respectively. Selecting suitable dates for remote sensing images was an important factor which could influence estimation accuracy. Thus, given the different growing periods for each rice season, four images were needed for early and late rice, while five images were preferable for single season rice. Estimating rice yield using two or three images was possible, however, if images were obtained during the panicle initiation and heading stages.

Hu, J. C., Cao, W. X., Zhang, J. B., Jiang, D. and Feng, J. 2004. Quantifying responses of winter wheat physiological processes to soil water stress for use in growth simulation modeling. Pedosphere. 14(4): 509--518
ABSTRACT: A deep understanding of crop-water eco-physiological relations is the basis for quantifying plant physiological responses to soil water stress. Pot experiments were conducted to investigate the winter wheat crop-water relations under both drought and waterlogging conditions in two sequential growing seasons from 2000 to 2002, and then the data were used to develop and validate models simulating the responses of winter wheat growth to drought and waterlogging stress. The experiment consisted of four treatments, waterlogging (keep 1 to 2 cm water layer depth above soil surface), control (70%--80% field capacity), light drought (40%--50% field capacity) and severe drought (30%--40% field capacity) with six replicates at five growth stages in the 2000--2001 season. Three soil water content treatments (waterlogging, control and drought) with two replicates were designed in the 2001--2002 season. Waterlogging and control treatments are the same as in 2000--2001 season. For the drought treatment, no water was supplied and the soil moisture decreased from field capacity to wilting point. Leaf net photosynthetic rate (PR), transpiration rate (TR), predawn leaf water potential (PLWP), soil water potential, soil water content and dry matter weight of individual organs were measured. Based on crop-water eco-physiological relations, drought and waterlogging stress factors for winter wheat growth simulation model were put forward. Drought stress factors integrated soil water availability, the sensitivity of different development stages and the difference between physiological processes (such as photosynthesis, transpiration and partitioning). The quantification of waterlogging stress factor considered different crop species, soil water status, waterlogging days and sensitivity at different growth stages. Data sets from the pot experiments revealed favorable performance reliability for the simulation sub-models with the drought and waterlogging stress factors.

Zhang, S. R., Sun, B., Zhao, Q. G., Xiao, P. F. and Shu, J. Y. 2004. Temporal-spatial variability of soil organic carbon stocks in a rehabilitating ecosystem. Pedosphere. 14(4): 501--508
ABSTRACT: In global change research, changes of soil organic carbon (SOC) reservoirs in tropical and subtropical regions are still unknown. The temporal-spatial variability of SOC stocks was determined in a basin of over 579 km2 in subtropical China from 1981 to 2002. ArcGIS8.1 software was utilized for spatial analysis of semivariance, ordinary kriging (OK), and probability kriging (PK). Grid and hierarchical approaches were employed for the sampling scenario in 2002 with 106 Global Position System (GPS) established spots sampled. Bulk topsoil samples (0--30 cm) were collected at three random sites on each spot. The SOC content for 1981 came from the SOC map of the Second National Soil Survey. Geostatistical results of the nugget to sill ratio (0.215--0.640) in the rehabilitating ecosystem indicated a moderate spatial dependence for SOC on this large scale. The range of SOC changed from 2.074 km in 1981 to 7.15 km in 2002. The mean topsoil SOC increased by 4.6% from 1981 (10.63 g kg-1) to 2002 (11.12 g kg-1). However, during this 21-year period 25.2% of the total basin area experienced a decrease in SOC. Also, the probability kriging results showed that the geometric mean probabilities of SOCd"6.0 g kg-1, d"11.0 g kg-1 and >15.0 g kg-1 were 0.188, 0.534 and 0.378, respectively in 2002, comparing to 0.234, 0.416 and 0.234 in that order in 1981, respectively. The SOC storage in the topsoil increased by 17.0% during this time with the main increase occurring in forests and cultivated land, which amounted to 82.5% and 17.0% of the total increase, respectively.

Xie, X. L., Sun, B., Zhou, H. Z. and Li, A. B. 2004. Soil organic carbon storage in China. Pedosphere. 14(4): 491--500
ABSTRACT: Soil organic carbon (SOC) storage under different types of vegetations in China were estimated using measured data of 2 440 soil profiles to compare SOC density distribution between different estimates; to map the soil organic carbon stocks under different types of vegetation in China; and to analyze the relationships between soil organic carbon stocks and environmental variables using stepwise regression analyses. Soil organic carbon storage under different types of vegetation in China was estimated at 69.38 Gt (1015 g). There was a big difference in SOC densities for various vegetation types, with SOC distribution closely related to climatic patterns in general. Stepwise regression analyses of SOC against environmental variables showed that SOC generally increased with increasing precipitation and elevation, while it decreased with increasing temperature. Furthermore, the important factor controlling SOC accumulation for forests was elevation, while for temperate steppes mean annual temperature dominated. The more specific the vegetation type used in the regression analysis, the greater was the effect of environmental variables on SOC. However, compared to native vegetation, cultivation activities in the croplands reduced the influence of environmental variables on SOC.

Gao, L., Yang, H., Zhou, J. M. and LÜ, J. J. 2004. Lake sediments from Dianchi Lake: A phosphorus sink or source?. Pedosphere. 14(4): 483--490
ABSTRACT: Dianchi Lake is a highly eutrophic lake in southwestern China where phosphorus (P) is the limiting element for eutrophication and where lake sediments play an important role in the P cycle. One hundred and eighteen sites were sampled throughout Dianchi Lake in 2002 to investigate the P loading of the lake sediments, while fresh surface sediments were studied in the laboratory to clarify its role for phosphorus. The results showed that concentrations of total phosphorus (TP) in sediments were very high, with a maximum value of 6.66 g kg-1, and decreased with sediment depth. P adsorption on surface sediments was rapid with adsorption amounts higher in acidic than in alkaline conditions. The release experiments showed that P release increased as pH rose from 7.0 to 10.5. Additionally, compared with aerobic conditions, P release was much higher under anaerobic conditions, especially with low P content in the lake water. At present, the sediments in Dianchi Lake still function as a sink for phosphorus at high P levels in lake water. However, if the external P load was reduced and P content in lake water became low, the sediment would have a large potential for P release under anaerobic conditions.

Ni, C. Y., Shi, J. Y., Luo, Y. M. and Chen, Y. X. 2004. “Co-culture engineering” for enhanced phytoremediation of metal contaminated soils. Pedosphere. 14(4): 475--482
ABSTRACT: A co-culture of two plant materials, Astragalus sinicus L., a leguminous plant with concomitant nodules, and Elsholtzia splendens Naki---a Cu accumulator, along with treatments of a chelating agent (EDTA), root excretions (citric acid), and a control with E. splendens only were used to compare the mobility of heavy metals in chelating agents with a co-culture and to determine the potential for co-culture phytoremediation in heavy metal contaminated soils. The root uptake for Cu, Zn, and Pb in all treatments was significantly greater (P < 0.05) than that of the control treatment. However with translocation in the shoots, only Cu, Zn, and Pb in plants grown with the EDTA treatment and Zn in plants co-cropped with the A. sinicus treatment increased significantly (P < 0.05). In addition, when a co-culture in soils with heavy and moderate contamination was compared, for roots in moderately contaminated soils only Zn concentration was significantly less (P < 0.05) than that of heavily contaminated soils, however, Cu, Zn, and Pb concentrations of shoots were all significantly lower (P < 0.05). Overall, this “co-culture engineering” could be as effective as or even more effective than chelating agents, thereby preventing plant metal toxicity and metal leaching in soils as was usually observed in chelate-enhanced phytoremediation.

Tang, Y. L., Wang, R. C. and Huang, J. F. 2004. Relations between red edge characteristics and agronomic parameters of crops. Pedosphere. 14(4): 467--474
ABSTRACT: The hyperspectral reflectance of the canopy and the leaves on the main stem for six varieties, two each of rice, corn, and cotton crops, were measured at different growth stages with an ASD FieldSpec Pro FR? to analyze red edge characteristics for leaf area indices (LAI), aboveground biomass, as well as the chlorophyll, carotenoid, and nitrogen content, emphasizing comparative differences on the red edge parameters. The results showed a  double peak phenomenon for the red edge of the canopy spectra but not for the leaves. There were  increase and  decrease change rules for the red edge position, »r, the red edge slope, D»r, and the red edge area, Sr, of the canopy spectra for all 3 crops with a  blue shift for »r of the leaf spectra for all 3 crops as the development stages progressed. For rice, corn, and cotton the LAI and fresh leaf mass had highly significant correlations (P Na+, and for the anions in the descending order H2AsO4- > H2PO4- g" SO42- > Cl- > NO3-.

Shen, R. P. and Kheoruenromne, I. 2003. Monitoring land use dynamics in Chanthaburi Province of Thailand using digital remotely sensed images. Pedosphere. 13(2): 157--164
ABSTRACT: A comprehensive method of image classification was developed for monitoring land use dynamics in Chanthaburi Province of Thailand. Remote sensing, geographical information system, global positioning system and ancillary data were combined by the method which adopts the main idea of classifying images by steps from decision tree method and the hybridized supervised and unsupervised classification. An integration of automatic image interpretation, ancillary materials and expert knowledge was realized. Two subscenes of landsat 5 thematic mapper images of bands 3, 4 and 5 obtained on 15 December 1992, and 17 January 1999, were used for image processing and spatial data analysis in the study. The overall accuracy of the results of classification reached 90%, which was verified by field check. Results showed that shrimp farm land, urban and traffic land, barren land, bush and agricultural developing area increased in area, mangrove, paddy field, swamp and marsh land, orchard and plantation, and tropical grassland decreased, and the forest land kept almost stable. Ecological analysis on the land use changes showed that more attentions should be paid on the effect of land development on ecological environment in the future land planning and management.

Mantel, S., Zhang, X. L. and Zhang, G. L. 2003. Identification of potential for banana in Hainan Island, China. Pedosphere. 13(2): 147--155
ABSTRACT: Land use alternatives are sought to boost agricultural income and productivity in Hainan Island, China. Regional differences exist in crop limitations, such as typhoon risk, low temperatures, poor soil fertility, and drought. In this study, a crop zonation was made for a range of crops, among which is banana, as a way to: (1) establish areas for potential expansion for banana; and (2) identify limitations and options for crop and land management. A spatial soil and terrain database of Hainan Island (1:250000) was linked to the automated land evaluation system. The qualitative models were verified by comparing suitability maps with actual land use. The results may support policy formulation on issues such as alternatives to current land use, assessment of best management practices, and the need for fertilizer programmes.

Zhao, Y. G., Zhang, G. L. and Gong, Z. T. 2003. SOTER-based soil water erosion simulation in Hainan Island. Pedosphere. 13(2): 139--146
ABSTRACT: The actual and potential water erosion rates of soils with different land covers in Hainan Island, China, were estimated based on the Universal Soil Loss Equation and a 1:200000 Soils and Terrain Digital Database, from which soil water erosion factors could be extracted. 92.8% of the whole island had a current erosion rate of lower than 500 t km-2 a-1. Soil erosion risk was considered to be high because of its abundant rainfall. Without vegetation cover, the potential soil erosion rate would be extremely high and 90.8% of the island would have a soil erosion rate higher than 2500 t km-2 a-1. Relative erosion vulnerability of different soil zones, landform types, and lithological regions of the island was compared by introducing a relative erosion hazard parameter alpha. Cambosols developed from siltstone and mudstone in low hill regions were pinpointed as soils with the highest erosion risk in the island.

Liao, M., Xie, X. M. and Subhani, A. 2003. Combined effect of nutrient and pest management on soil ecological quality in hybrid rice double-cropping system. Pedosphere. 13(2): 129--138
ABSTRACT: The mineral fertilizers (NPK) and pesticide, including herbicides, insecticides and fungicides, were applied alone or in combination and the soil sampling was done at different growth stages of the crop to study the changes in soil organic matter, microbial biomass and their activity parameters in a paddy soil with different nutrient and pest management practices in a hybrid rice double-cropping system in Zhejiang Province, China. A consistent increase in the electron transport system (ETS) activity was measured during the different crop growth stages of rice. The use of fertilizers (NPK) alone or with pesticides increased ETS activity, while a decline of ETS activity was noticed with pesticides alone as compared with the control. Nearly an increasing trend in soil phenol content was observed with the progression of crop growth stages, while the usage of pesticides alone caused maximum increments in the soil phenol content. The soil protein content was found nearly stable with fertilizers and/or pesticides application at various growth stages in both crops taken. But notable changes were noticed at different growth stages probably because of fluctuations in moisture and temperature at particular stages, which might have their effects on N mineralization. Marked depletions in the phospholipid content were found with the advancement of crop growth stages, while the incorporation of fertilizers and/or pesticides also produced slight changes, in which a higher decline was noticed with pesticide application alone compared with the control.

Tian, G. M., Wang, F. E., Chen, Y. X., He, Y. F., Fu, Q. L., Kumar, S. and Lin, Q. 2003. Effect of different vegetation systems on soil erosion and soil nutrients in red soil region of southeastern China. Pedosphere. 13(2): 121--128
ABSTRACT: The effect of different vegetation systems including bamboo plantation (BP),forest ecosystem(CF),citrus orchard(Ctr) and farmland(FL) on erosion and nutrients of red soil were investigated in hilly region of southeastern China to find effective control measures for soil erosion.The results showed that all the vegetation systems sould significantly reduce soil erosion and nutrient losses compared to bare land (Br).The ability of different vegetation systems to conserve soil and water was in the order of Ctr>BP>CF>FL>Br.Vegetation could also improve soil fertility.The soil organic matter,total N and totalP contents were much higher in all the vegetation systems than in bare land,especially for the top soils.Vegetation systems improved soil physical properties remarkably.Compared to the bare land,soil organic matter,TP,TK and available K,especially soil microbial biomass C,N and P,increased under all the vegetation covers.However,they were still much lower than expected,thus these biologicalmeasurements are still needed to be carried out continuously.

Zhang, H. T., Zhou, Y., Birnie, R. V., Sibbald, A. and Ren, Y. 2003. Analysis and design of soils and terrain digital database (SOTER) management system based on object-oriented method. Pedosphere. 13(2): 111--119
ABSTRACT: A SOTER management system was developed by analysing, designing, programming, testing, repeated proceeding and progressing based on the object-oriented method. The function of the attribute database management is inherited and expanded in the new system. The integrity and security of the SOTER database are enhanced. The attribute database management, the spatial database management and the model base are integrated into SOTER based on the component object model, and the graphical user interface for Windows is used to interact with clients, thus being easy to create and maintain the SOTER, and convenient to promote the quantification and automation of soil information application.

Dong, R. B., Zhang, W. G., Lu, S. G., Yu, L.Z. and Yu, J. Y. 2003. Effect of reduction associated with organic matter decomposition on magnetic properties of red soils. Pedosphere. 13(2): 103--110
ABSTRACT: Five soils derived from different parent materials were sampled from red soil region of southern China and studied by magnetic methodology to understand to what extent iron reduction would affect soil magnetic properties and how iron reduction would affect the magnetic minerals in soils. Reduction associated with organic matter decomposition strongly affected soil magnetic parameters at low pH. The losses of original soil magnetic signals in terms of magnetic susceptibility, 'Soft' isothermal remanent magnetization, anhysteretic remanent magnetization and saturation isothermal remanent magnetization at pH 4-6 during the two-month saturation treatment, were 66-94, 54-90, 64-95 and 33%-83%, respectively. These changes were interpreted as a consequence of substantial dissolution of maghaemite and haematite in the soils. At pH 10, however, there was no significant magnetic change observed. Moreover, stable single domain soil maghaemite grains were also sensitive to reduction, which suggested that both pedogenic and detrital maghaemite were not stable in acid and reducing environments. Goethite, instead, was the most stable iron form under reducing conditions.

Liang, W. J., Li, Q., Jiang, Y., Chen, W. B. and Wen, D. Z. 2003. Effect of cultivation on spatial distribution of nematode trophic groups in black soil. Pedosphere. 13(2): 97--102
ABSTRACT: Geostatistics combined with geographical information system was applied to assess the spatial distribution of nematode trophic groups following two contrasting soil uses in the black soil region of Northeast China. Two plots, one with fallow for 12 years and the other cultivated, were marked on regular square grids with 2-m spacing. Soil samples were collected from each sampling point, nematodes were extracted from these samples and classified into four trophic groups: bacterivores, fungivores, plant parasites, and omnivores/predators. The numbers of total nematodes and trophic groups analysed had normal distributions on both fallow and cultivated plots. The absolute abundances of total nematodes and trophic groups were observed to be much more homogeneous on cultivated plot than on fallow one. Geostatistical analysis showed that the densities of total nematodes and trophic groups on both fallow and cultivated plots exhibited spatial dependence at the sampled scale and their experimental semivariograms were adjusted to a spherical or exponential model, except those of bacterivores and fungivores on cultivated plot. The spatial distribution of nematode trophic groups was found to be different for the two land uses, indicating that cultivation changed the native condition for soil nematode activities.

Yang, Y. S., Guo, J. F., Chen, G. S., He, Z. M. and Xie, J. S. 2003. Effect of slash burning on nutrient removal and soil fertility in Chinese fir and evergreen broadleaved forests of mid-subtropical China. Pedosphere. 13(1): 87--96
ABSTRACT: A Chinese fir (Cunninghamia lanceolata) forest (CF) and an evergreen broadleaved forest (EB, dominated by Castanopsis fargesii, Lithocarpus glaber and Castanopsis eyrei) located in Fujian Province, southeastern China, were examined following slash burning to compare nutrient capital and topsoil properties with pre-burn levels. After fire, nutrient (N, P and K) removal from burning residues was estimated at 302.5 kg ha-1 in the CF and 644.8 kg ha-1 in the EB. Fire reduced the topsoil capitals of total N and P by ?0 and 10%, respectively, in both forests, while K capital was increased in the topsoils of both forests following fire. Total site nutrient loss through surface erosion was 28.4, 8.4 and 328.7 kg ha-1 for N, P and K, respectively, in the CF. In the EB, the losses of total N, P and K were 58.5, 10.5 and 396.3 kg ha-1, respectively. Improvement of soil structure and increase in mineralization of nutrients associated with increased microbe number and enzyme activities and elevated soil respiration occurred 5 days after fire. However, organic matter and available nutrient contents and most of the other soil parameters declined one year after fire on the burned CF and EB topsoils. These results suggest that short-term site productivity can be stimulated immediately, but reduced subsequently by soil and water losses, especially in South China, where high-intensity precipitation, steep slopes and fragile soil can be expected. Therefore, the silvicultural measurements should be developed in plantation management.

Feng, K., Wang, X. L., Wang, X. Z. and Tang, Y. 2003. Relationship between 2:1 mineral structure and the fixation and release of cations. Pedosphere. 13(1): 81--86
ABSTRACT: The effects of different structures of 2:1 layer minerals, layer charge location, and changes of structure and charge during the weathering process on the fixation and release of interlayer cations are reviewed. It could be concluded that the fixation capacity is determined by the total amount of interlayer charge originating from both octahedral and tetrahedral sheets. The relationship between interlayer cation fixation and octahedral structure of the secondary minerals may be different from that of the primary minerals. The oxidation and reduction of cations with variable valence can greatly influence the cation-fixation capacity.

Lin, C. and Lin, J. 2003. Heavy metals in a sulfidic minespoil: Fractions and column leaching. Pedosphere. 13(1): 75--80
ABSTRACT: Fractions of various heavy metals in a sulfidic mine spoil, collected from an inactive mine site in New South Wales, Australia, were investigated. A column leaching experiment was also conducted to simulate acid mine drainage (AMD) from the mine spoil. Results show that leaching of heavy metals from the mine spoil was extremely significant during the initial water flushing. The amounts of heavy metals leached out dramatically reduced after leaching twice. It is worthwhile to note that in this study, Zn, Mn, Fe, As and Ni in the first leachate exceeded the total amount of each corresponding water-extractable (1:5, soil:water) metal contained in the mine spoil sample. This appears to suggest that 1:5 water extraction did not allow accurate estimation of water-leachable concentrations of the above heavy metals. This work has implications for the management of sulfidic mine spoils. Acid drainage of great environmental concerns is likely to occur only during heavy rainfall events after substantial soluble and readily exchangeable acid and metals are accumulated in the mine spoils. The slow-reacting fractions other than water-soluble and readily exchangeable fractions may pose little environmental hazards. This is particularly true for Pb, As and Ni.

Yang, J. L. and Zhang, G. L. 2003. Quantitative relationship between land use and phosphorus discharge in subtropical hilly regions of China. Pedosphere. 13(1): 67--74
ABSTRACT: The increase of phosphorus concentration is a crucial factor causing the eutrophication of water body, while land use has an important impact on agricultural non-point sources phosphorus discharge. Seven sites controlling the water in four sub-watersheds and the main exit of the Meicun Watershed of Xuancheng County, Anhui Province, were investigated by dynamic monitoring of stream water and nutrient discharge, integrating interpretation of aerial image and GIS analysis to find out how land use affects phosphorus loss with stream water in a typical agriculture-forest watershed in subtropical China. These monitored sites were different in the structure of land use. Phosphorus concentration of the stream water was analysed every week and at the next day of rainfall. The velocity of flow was measured by kinemometer to calculate the runoff flux and phosphorus discharge. Results showed that the runoff flux and the discharges of dissolved phosphorus (DP), particle-associated phosphorus (PAP) and total phosphorus (TP) had significant exponential relationships with the area percentages of forest, pond and paddy field. A significant linear relationship was observed between the TP and PAP concentrations in stream water and the area percentages of forest, pond and paddy field, and the discharge of PAP was also significantly linearly correlated with the discharge of suspended soil particles. There was a logarithmic linear relationship between DP and PAP discharges. The study indicated that the adjustment of land use patterns and construction of ecologically sound landscape could be an important measure to reduce the runoff discharge of phosphorus. The results would be very useful in building the best management practices of agricultural watershed in subtropics.

Li, C. B., Friedman, S. P. and Zhao. A. Z. 2003. Interactions of cations with electrodialyzed clay fraction of soils as inferred from Wien Effect in soil suspensions. Pedosphere. 13(1): 59--66
ABSTRACT: The electrical conductivities (Ecs) of suspensions containing 25 and 30 g kg-1 solids prepared from the electrodialysed clay fraction ( Zn2+ > Mg2+ = Ca2+ > Na+ for latosol; Ca2+ > Zn2+ > Mg2+ = K+ > Na+ for yellow-brown soil; and Zn2+ g" Ca2+ g" Mg2+ > K+ > Na+ for black soil.

Kyuma, K. 2003. Soil resources and land use in tropical Asia. Pedosphere. 13(1): 49--57
ABSTRACT: Tropical Asia is a region comprising South and Southeast Asia and under strong influence of the Asian monsoon climate. It is characterized by an extremely high population density and by high land use intensity. Paddy rice cultivation is the most important form of agriculture in the greater part of the region. Soil resources of tropical Asia have a specific feature in comparison with tropical Africa and America. Ultisols dominate in uplands, and lowland soils like Inceptisols and Histosols are relatively abundant. The latter point is made clearer if we take the landforms of the region with a vast extent of lowlands into consideration. Geologically, tropical Asia with the Himalayan orogeny and active volcanism exhibits a conspicuous contrast to tropical Africa and America with the dominance of the shield structure. This along with the monsoon climate should have determined the basic features of landforms and soil, and accordingly all the agricultural and social characteristics of tropical Asia today. Although paddy rice cultivation in the lowland is highly sustainable, upland cultivation in extensive Ultisol areas tends to be handicapped by low fertility and high erodibility of the soil, resulting in low sustainability. Land shortage is compelling people to exploit slopelands in hills and mountains, on the one hand, and thus far unutilized coastal lowlands, on the other. Both of these new reclamations are facing to serious land degradation problems today. Tropical Asia will continue to be the most densely populated region of the world with ever-increasing population. In order to meet the increasing food demand, lowland rice cultivation should be intensified by the infrastructure development to ease the stresses on slopelands and vulnerable coastal lowlands. At the same time, upland crop production in Ultisol areas should be stabilized and enhanced, providing integrated nutrient management and measures for soil conservation.

Stephens, P. R., Hewitt, A. E., Sparling, G. P., Gibb, R. G. and Shepherd, T. G. 2003. Assessing sustainability of land management using a risk identification model. Pedosphere. 13(1): 41--48
ABSTRACT: New Zealand is highly dependent on its soil resource for continued agricultural production. To avoid depleting this resource, there is a need to identify soils and associated land management practices where there is a risk of soil degradation. Environmental integrity and ecosystem services also need to be maintained. Accordingly, to ensure sustainable production, the on- and off-site environmental impacts of land management need to be identified and managed. We developed a structural vulnerability index for New Zealand soils. This index ranks soils according to their inherent susceptibility to physical degradation when used for agricultural (pasture, forestry and cropping) purposes. We also developed a rule-based model to assess soil compaction vulnerability by characterizing the combined effects of resistance and resilience. Other soil attributes have been appraised using seven chemical, physical and biological indicators of soil quality (total C, total N, mineralizable N, pH, Olsen P, macroporosity and bulk density). These indicators have been applied in a nation-wide project involving data collection from over 500 sites for a range of land uses. These soil quality data can be interpreted through the World Wide Web -- through the interactive decision-support tool SINDI. The land use impact model is a framework to assess agricultural land management and environmental sustainability, and may be applied to land units at any scale. Using land resource data and information, the model explicitly identifies hazards to land productivity and environmental integrity. It utilizes qualitative expert and local knowledge and quantitative model-based evaluations to assess the potential environmental impacts of land management practices. The model is linked to a geographic information system, allowing model outputs, such as the environmental impacts of site-specific best management practices, to be identified in a spatially explicit manner. The model has been tested in New Zealand in an area of pastoral land use. Advantages of this risk identification model include: utilizing current knowledge of the causes and effects of land management practices on soil degradation; linking land management practice to both on- and off-site environmental consequences; identifying important gaps in local knowledge; and providing spatially explicit information on the environmental impact of land management practices.

Noble, A. D., Moody, P., Liu, G. D., Ruaysoongnern, S., Qi, Z. P. and Berthelsen, S. 2003. Quantification and remediation of soil chemical degradation in tropical Australia, China and Thailand. Pedosphere. 13(1): 31--39
ABSTRACT: Soil and land degradation in the tropics can be identified and described in terms of physical, chemical, and biological changes from its pristine state brought about by natural and anthropogenic influences. A characteristic of these ecosystems is their capacity to recycle nutrients through soil organic matter (SOM). Following disturbance through changed land management, SOM is rapidly mineralized and there is a corresponding decline in fertility and the variable charge component of the cation exchange capacity. As these ecosystems are strongly dependent on SOM for their functionality, changed land use can have irreversible impacts on the productivity of these systems. The paper focuses on quantifying chemical degradation through benchmarking using data from paired sites in tropical China (Hainan Island) and Thailand using surface charge fingerprinting. Using values taken from the fingerprint of an undisturbed soil, an index of chemical degradation from ideality was calculated. Various management strategies that attempt to reverse degradative trends or improve poor quality soils in their natural condition are discussed, such as the addition of natural clays and silicated materials. Results are presented to show the effect of each of the aforementioned strategies on surface charge characteristics and associated increases in plant productivity.

Zhang, G. L., Yang, J. L. and Zhao, Y. G. 2003. Nutrient discharges from a typical watershed in the hilly area of subtropical China. Pedosphere. 13(1): 23--30
ABSTRACT: Agriculture is still the biggest contributor of non-point source pollution to water bodies and runoff discharges of nutrients and other chemicals are one of the most important pathways. This study was conducted during 1998-99 in a typical watershed with complex agriculture and forestry systems as well as dotted farmer villages, in a transitional region between the mid- and northern subtropical zones of China. Continuous sampling of stream water was performed regularly at a weekly frequency, with additional sampling after all major rainfall events. The discharges of N and P nutrients and suspended materials were measured and the total and area-averaged annual discharges of all components were calculated. The results showed an uneven seasonal distribution of nutrient discharges with summer storms contributing most to the total fluxes. This study demonstrated a high dependence of runoff volume on rainfall but the overall runoff coefficients were dependent on land use type and watershed size. The area-averaged annual discharges varied greatly among the sub-watersheds with different sizes and land use structures. This is the first study estimating the area-averaged annual discharges of N and P in the hilly areas of subtropical China, which were 1.5 and 0.1 g m-2 year-1, respectively, providing important reference values for the assessment of regional agricultural non-point source pollution.

Gong, Z. T., Zhang, G. L., Zhao, W. J., Zhao, Y. G. and Chen, Z. C. 2003. Land use-related changes in soils of Hainan Island during the past half century. Pedosphere. 13(1): 11--22
ABSTRACT: During the past half century, the land utilization of Hainan Island (China) has undergone a rapid development, but in the meanwhile, soil degradation occurs. An analysis on some basic data of the soil series collected from more than 100 soil profiles at the end of the 1990s and beginning of this century, in combination with data available, showed that soils there suffered a significant decline in organic matter, experienced P and K deficiency with soil K going on losing and undergone acidification with continuing trend. The current situation calls for strategies to build up Hainan into an important province of sound ecology by restoring forests, to improve food quality by implementing K supplement projects, to combat soil acidification by ameliorating the soils and growing leguminous crops and to ensure health of the people by developing dairy production and increasing the daily Ca uptake by the people.

Eswaran, H. and Kimble, J. 2003. Land quality assessment and monitoring: The next challenge for soil science. Pedosphere. 13(1): 1--10
ABSTRACT: Sustainable land management (SLM) is the key to harmonizing environmental and ecological concerns of society with the economic realities of producing adequate food and fibre of high quality and ensuring a basic minimal quality of life. The aim of SLM is to maintain the integrity of the biophysical land resource base, but it can only be realized if land users understand the impacts of land management options on their lands but also on other off-site areas and can optimize the socioeconomic and environmental benefits of their choice. To facilitate this, the contribution of soil survey organizations would be through the assessment and monitoring of land quality. Land quality is a measure of the ability of land to perform specific functions and is derived by an integration of soil survey information with other environmental, and if necessary, socioeconomic information. The desired reliability influences the operational scale of the assessment. Such an assessment would assist in: (1) locating homologous areas for research sites or for transferring technologies; (2) providing the geographic basis for systems analysis (e.g. by modelling); (3) serving as a basis for local, national and global resource assessment and monitoring; (4) providing an ecosystem context for land use, assessments of temporal and spatial variability, and impact of human interventions; (5) serving as a framework for more detailed assessment for all levels of interest; and (6) evaluating global issues such as food security, impacts of climate change, biodiversity monitoring, and addressing desertification. Based on an evaluation of the progress made in soil resource inventories and considering the demands of the environment-focused world, this paper considers the need for countries to mount such a programme. The authors believe that this is the next demand of soil science and that we can fulfill our social contract by periodically providing such information on the state of a nation's land resource.

Wang, S. Q., Zhou, Y., Dong, Y. H. and Yang, L. Z. 2002. Design and applications of land resources and ecological environment information system: A case study of Zigui County in the Three Gorges Area of China. Pedosphere. 12(4): 373--381
ABSTRACT: The design and applications of a land information system built upon ARC/INFO and ArcView are presented. The proposed system not only maintains all the advantages of the more conventional implementations but also enhances them in the following ways: (1) the application program interfaces (API) are used to transmit data and messages among different parts of the system; (2) the integrated system can support studies on land evaluations and ecological analyses by efficient management of attribute and spatial data and (3) correspondingly, spatial records and attributive records are linked by the same identifiers (ID). A case study application in Zigui County of the Three Gorges Area in China demonstrates that the system could employ land use maps and land property data to predicate and analyse the land utilization changes in the past, present and future. The ecological environment analysis can be carried out with the data of land, economics and terrain map used, showing that the system can be widely applied, especially to survey land and environment resources in the countryside area.

Yang, W. Q., Wang, K. Y., Song, G. Y. and He, Y. R. 2002. Preliminary study on biological characteristics of degraded soil ecosystems in dry hot valley of the Jinsha River. Pedosphere. 12(4): 365--372
ABSTRACT: Distribution characteristics of soil animals, microorganisms and enzymatic activity were studied in the dry red soil and Vertisol ecosystems with different degradation degrees in the Yuanmou dry hot valley of the Jinsha River, China. Results showed that Hymenoptera, Araneae and Collembola were the dominant groups of soil animals in the plots studied. The numbers of groups and individuals and density of soil animals in the dry red soil series were higher than those in the Vertisol series, and the numbers of individuals and density of soil animals decreased with the degree of soil degradation. Bacteria dominated microbiocoenosis not only in the dry red soils but also in the Vertisols. Microbial numbers of the dry red soil series were higher than those of Vertisol series, and decreased with the degree of soil degradation. The activities of catalase, invertase [beta-fructofuranosidase], urease and alkaline phosphatase declined with the degradation degree and showed a significant decline with depth in the profiles of both the dry red soils and the Vertisols, but activities of polyphenol oxidase [catechol oxidase] and acid and neutral phosphatase [phosphoric monoester hydrolases] showed the same tendencies only in the Vertisols. It was concluded that the characteristics of soil animals, microorganisms and enzymatic activity could be used as the bioindicators to show the degradation degree of the dry red soils and Vertisols. Correlation among these soil bioindicators was highly significant.

Chilima, J., Huang, C. Y. and Wu, C. F. 2002. Maize (Zea mays L.) and cotton (Gossypium hirsutum L.) straw decomposition in soil: Effect of straw placement, mineral nitrogen and tillage. Pedosphere. 12(4): 353--364
ABSTRACT: With the present understanding that decomposing straw may not only affect soil properties, but possibly greenhouse gas emissions as well, focus among environmental researchers has gradually expanded to include understanding of decomposition rate and stability of straw of different plants in different soils under different management conditions. Against such a background, a short-term (60 days) greenhouse simulation experiment was carried out to study the effects of straw placement, external mineral N source and tillage on straw decomposition of maize and cotton in two contrasting soils, a red soil (Ferrasol) and a black soil (Acrisol). The treatments included: straw addition only (T1); straw addition+mineral N (T2); and straw addition+tillage (T3). Straw was either buried in the soil or placed on the surface. Sampling was done every 15 days. Placement, addition of external mineral N sources (urea, 46% N), straw type, soil type and exposure duration (15, 30, 45 and 60 days) affected straw decomposition. Decomposition was more in buried straw than in surface-placed straw at all sampling dates in red soil. The addition of an external N source significantly increased decomposition. The study could not, however, fully account for the effect of tillage on straw decomposition because of the limited effect of our tillage method due to the artificial barrier to mechanical interference supplied by the mesh bags.

Gorzka, Z., Kazmierczak, M., Paryjczak, T. and Zarczynski, A. 2002. Thermocatalytic oxidation of chloro-derivatives of propane occurring in industrial wastes. pedosphere. 12(4): 349--352
ABSTRACT: The processes of treatment and utilization of organic chlorine compounds: 1,2-dichloropropane andpropylene chlorohydrin, were investigated with application of contact catalysts to obtain the lowest possibletemperature of the process by selection of proper catalysts and determination of optimum reaction parameters.Experiments were carried out with application of oxide, copper-zinc (TMC-2, TMC 3/1) and platinum (PA-2)catalysts. Results of investigations proved the possibility of total oxidation of above-mentioned compoundsand components of industrial wastewater in the temperature range from 350 to 450 !.

Huang, Q. Y., Chen, W. L., Gianfreda, L. and Violante, A. 2002. Adsorption of acid phosphatase on minerals and soil colloids in presence of citrate and phosphate. Pedosphere. 12(4): 339--348
ABSTRACT: The aim of this work was to study the influence of phosphate and citrate, which are common inorganic and organic anions in soils, on the adsorption of acid phosphatase by kaolin, goethite and the colloids separated from yellow-brown soil (YBS) and latosol (LS) in central-south China. The YBS colloid has the major clay mineral composition of 1.4 nm mineral, illite and kaolinite while the LS colloid mainly contains kaolinite and oxides. The adsorption isotherm of acid phosphatase on the examined soil colloids and minerals fitted to the Langmuir model. The amount of enzyme adsorbed in the absence of ligands was in the order of YBS colloid > LS colloid > kaolinH"goethite. In the presence of phosphate or citrate, the amounts of the enzyme adsorbed followed the sequence YBS colloid > kaolin > LS colloid > goethite. The presence of ligands also decreased the binding energy between the enzyme and soil colloids or minerals. With the increase of ligand concentration from 10 to 400 mmol litre-1, different behaviorus for the adsorption of enzyme were found in the colloid and mineral systems studied. A sharp decrease in enzyme adsorption was observed on goethite while gradual decreases of enzyme adsorption were recorded in the two soil colloid systems. However, no any decrease was found for the amount of enzyme adsorbed on kaolin at higher ligand concentrations. When phosphate or citrate was introduced to the system before the addition of enzyme, the ligands usually enhanced the adsorption of enzyme. The results obtained in this study suggested the important role of kaolinite mineral in the adsorption of enzyme molecules in acidic soils in the presence of various ligands.

Zhu, Y. G., Howes, N. K. and Smith, S. E. 2002. Phosphorus uptake and utilisation efficiencies of different wheat cultivars based on a sand-culture screening system. Pedosphere. 12(4): 329--337
ABSTRACT: A sand-based culture system using rock phosphate (P) was developed to simulate the situation in alkalinesoils, with respect to the dominant P form, and five wheat cultivars (Excalibur, Brookton, Krichauff, Westoniaand Sunco) were tested in this screening system to compare their P uptake and utilisation efficiencies. Resultsshowed that these cultivars differed significantly in their ability to acquire P from the sparingly available form(rock phosphate in this case). The accumulation of P by Brookton was three times that by Krichauff. Pconcentrations in plant tissues did not differ significantly, indicating that all cultivars were similar in Putilisation efficiency. A further experiment showed that the greater ability of a cultivar to take up P fromsparingly available form was related to the ability of a cultivar to acidify the rhizosphere. Seed P content wasa confounding factor in this system, and the use of relatively uniform seed with similar P content, preferablylow, was conducive to a successful outcome of the screening process.

Li, X. Y., Ling, W. T. and He, J. Z. 2002. Interaction between charge characteristics and Cu2+ adsorption-desorption of soils with variable or permanent charge. Pedosphere. 12(4): 321--328
ABSTRACT: Charge characteristics and CU2+ adsorption-desorption of soils with variable charge (latosol) and permanent charge (brown soil) and the relationship between them were studied by means of back-titration and adsorption equilibrium respectively. The amount of variable negative charge was much less in variable-charge soil than in permanent-charge soil and increased with the pH in the system, but the opposite trend occurred in the points of zero charge (PZCs). The amount of Cu2+ ions sorbed by permanent-charge soil was more than that by variable-charge soil and increased with the increase of CU2+ concentration within a certain range in the equilibrium solution. The amount of CU2+ ions desorbed with KCl from permanent-charge soil was more than that from variable-charge soil, but the amount of CU2+ ions desorbed with de-ionized water from permanent-charge soil was extremely low whereas there was still a certain amount of desorption from variable-charge soil. The increase of PZC of soils with variable or permanent charge varied with the increment of CU2+ ions added. When the same amount of CU2+ ions was added, the increments of PZC and variable negative surface charge of permanent-charge soil were different from those of variable-charge soil.

Zhou, D. M., Chen, H. M., Hao, X. Z. and Wang, Y. J. 2002. Fractionation of heavy metals in soils as affected by soil types and metal load quantity. Pedosphere. 12(4): 309--319
ABSTRACT: Two series of soil subsamples, by spiking copper (Cu), lead (Pb), zinc (Zn) and cadmium (Cd) in an orthogonal design, were prepared using red soil and brown soil, respectively. The results indicated that heavy metal fractions in these soil subsamples depended not only on soil types, but also on metal loading quantity as well as on interactions among metals in soil. Lead and Cu in red soil appeared mostly in weakly specifically adsorbed (WSA), Fe and Mn oxides bound (OX), and residual (RES) fractions. Zinc existed in all fractions except organic bound one, and Cd was major in water soluble plus exchangeable (SE) one. Different from the results of red soil, Pb and Cu was present in brown soil in all fractions except organic one, but over 75% of Zn and 90% of Cd existed only in SE fraction. Meanwhile, SE fraction for any metal in red soil was lower than that in brown soil and WSA and OX fractions were higher. It is in agreement with low cation exchange capacity and large amounts of metal oxides included in red soil. Metal fractions in soil, especially for water soluble plus exchangeable one, were obviously influenced by other coexisting metals. The SE fraction of heavy metals increased with increasing loading amounts of metals in red soil but not obviously in brown soil, which suggest that metal availability be easily affected by their total amounts spiked in red soil. In addition, more metals in red soil were extracted with 0.20 mol litre-1 NH4Cl (pH 5.40) than that with 1.0 mol litre-1 Mg(NO3)2 (pH 7.0), but the reverse happened in brown soil, implicating significantly different mechanisms of metal desorption from red soil and brown soil.

Liu, J. L. and Xu, S. H. 2002. Applicability of fractal models in estimating soil water retention characteristics from particle-size distribution data. Pedosphere. 12(4): 301--308
ABSTRACT: Soil water retention characteristics are the key information required in hydrological modelling. Fractal models provide a practical alternative for indirectly estimating soil water retention characteristics from particle-size distribution data. Predictive capabilities of three fractal models, i.e., Tyler-Wheatcraft model, Rieu-Sposito model, and Brooks-Corey model, were fully evaluated in this work using experimental data from an international database and literature. Particle-size distribution data were firstly interpolated into 20 classes using a van Genuchten-type equation. Fractal dimensions of the tortuous pore wall and the pore surface were then calculated from the detailed particle-size distribution and incorporated as a parameter in fractal water retention models. Comparisons between measured and model-estimated water retention characteristics indicated that these three models were applicable to relatively different soil textures and pressure head ranges. Tyler-Wheatcraft and Brooks-Corey models led to reasonable agreements for both coarse- and medium-textured soils, while the latter showed applicability to a broader texture range. In contrast, Rieu-Sposito model was more suitable for fine-textured soils. Fractal models produced a better estimation of water contents at low pressure heads than at high pressure heads.

Youwen, Y. and Vance, G. F. 2002. Sodium-zinc exchange selectivity on Wyoming montmorillonite in different background anion solutions. Pedosphere. 12(4): 289--299
ABSTRACT: The effect of background anion on cation exchange reactions, such as Na-Ca and Na-Cu exchange reactions, on montmorillonites has been studied, but the results are not always clear and discrepancies exist in the literature. In this study, the exchange of zinc (Zn2+) for sodium (Na+) on Wyoming montmorillonite was investigated at 298! using Cl-, ClO4-, NO3-, Oac-, and SO42- solution media at a constant total metal charge concentration of 0.0200 molc litre-1. Results indicated that the clay CEC values were essential similar for Cl-, ClO4-, NO3- and SO42- solution media with an average CEC of 0.856 ± 0.008 molc kg-1; in an Oac- solution the clay CEC was much higher than that in other anion media. The specific adsorption of Zn (SAZn), as defined by the extraction of Zn using 0.05 mol litre-1 Na2-EDTA, was different in the various background solutions. The highest value for SAZn was 0.359 ± 0.0350 molc kg-1, which occurred in Oac- solution. There was essentially no difference in the total apparent adsorbed metals (the sum of adsorbed equivalents of Na and Zn per kilogram of clay, Q) among the various background solutions. The average Q for all anion media was 0.807 ± 0.011 molc kg-1 and was independent of exchanger composition. Experimental results indicated that there were no significant monovalent cation complexes such as ZnCl+ or ZnNO3+ that were adsorbed by montmorillonite. The Na-Zn exchange isotherms indicated that there was an adsorption preference for Zn over Na on Wyoming montmorillonite.

Sun, K. G. and Wang, L. G. 2002. Effect of different fertilization practices on yield of a wheat-maize rotation and soil fertility. Pedosphere. 12(3): 283--288
ABSTRACT: A 15-year field experiment was carried out in Henan Province, China, to study the effects of different fertilization practices on yield of a wheat-maize rotation. Fertilizers tested contained N alone (N), N plus P (NP) or plus P and K (NPK), all with or without manure (M). Different long-term fertilization practices affected the yields under the rotation system of wheat and maize differently and the effects on yields was in a general trend of MNPK > MNP > MN > NPK > NP > M > N > the control. The average contribution rate of soil fertility to the highest yield was 37.9%, and the rest 62.1% came from fertilizer applications. The yield effects of the chemical fertilizers were in the order of N > P > K and were increased by application of manure. Balanced fertilization with multielement chemical fertilizers and manure can be effective in maintaining growth in agricultural production. Combined application of chemical fertilizer and organic manure also increased the content of soil organic matter.

Xu, W. H., Wang, Z. Y., Jia, Z. Y., Huang, Y., Yuan, L. J. and Wang, J. M. 2002. Use of several plant materials and chemicals to inhibit soil urease activity and increase nitrogen recovery rate of urea by plant. Pedosphere. 12(3): 275--282
ABSTRACT: Effects of residues of 9 plants, lemon eucalyptus (Eucalyptus citriodora, P1), robust eucalyptus (E. robusta, P2), Nepal camphortree (Cinnamomum glanduliferum, P3), tea (Camellia sinensis f., P4), oleander (Nerium indicum, P5), rape (Brassica campestris, P6), Chinese tallow tree (Sapium sebiferum, P7), tung (Vernicia fordii, P8), and croton (Croton tiglium, P9), 7 chemicals, boric acid (C1), borax (C2), oxalic acid (C3), sodium oxalite (C4), sodium dihydrogen phosphate (C6), sodium silicate (C7) and sodium citrate (C8), and a natural organic substance, humic acid (C5), on urease activity of a neutral purple soil and recovery of urea nitrogen by maize were studied through incubation and pot experiments. Hydroquinone (HQ) was applied as the reference inhibitor. After incubation at 37! for 24 h, 7 inhibitors with higher ability to inhibit urease activity were selected and then incubated for 14 days at 25!. Results of the incubation experiments showed that soil urease activity was greatly inhibited by them, and the inhibition effect followed an order of P2 > P4 > C3 > C2 > P3 > C1 > HQ > P1. The 7 selected materials reduced the accumulative amounts of N released from urea and the maximum urease activity by 11.7%-28.4% and 26.7%-39.7%, respectively, and postponed the N release peak by 2-4 days in the incubation period of 14 days under constant temperature, as compared to the control (no inhibitor). In the pot experiment with the 7 materials at two levels of addition, low (L) and high (H), the C1 (H), C3 (H), C1 (L), P4 (L) and C2 (L) treatments could significantly increase the dry weights of the aboveground parts and the total biomass of the maize plants and the apparent recovery rate of urea-N was increased by 6.3%-32.4% as compared to the control (no hibitor).

He, T. X., Wu, D. Y., He, C. H., Tu, S. H., Wu, G. Q., Wu, W. C., Kong, S. and Wang, J. P. 2002. Fertilization for high yields in corn-sweet potato-wheat rotation: A systematic approach to nutrient limiting factors of soils in Chongqing, China. Pedosphere. 12(3): 265--274
ABSTRACT: A systematic approach was adopted to investigate the nutrient limiting factors in gray-brown purple soils and yellow soils derived from limestone in Chongqing, China, to study balanced fertilization for corn, sweet potato and wheat in rotation. The results showed that N, P and K were deficient in both soils, Cu, Mn, S and Zn in the gray-brown purple soils and Ca, Mg, Mo and Zn for the yellow soils. Balanced fertilizer application increased yields of corn, sweet potato and wheat by 28.4%, 28.7% and 4.4%, respectively, as compared to the local farmers' practice. The systematic approach can be considered as one of the most efficient and reliable methods in fertility study.

Gao, M., Zhou, B. T., Wei, C. F. and Che, F. C. 2002. Characteristics of phosphorous adsorption and desorption by organo-mineral colloidal complexes of purple paddy soils. Pedosphere. 12(3): 257--264
ABSTRACT: The kinetic characteristics of P adsorption and desorption by organomineral colloidal complexes (OMC) were studied using acid, calcareous and neutral purple paddy soils taken from Chongqing and Sichuan, China. The results showed that the P adsorption capacity of the organo-mineral colloidal complexes differed with the soil types, being higher for the acid and calcareous purple soils than for the neutral purple soils. Partial removal of the organic matter increased the adsorption capacity of the colloidal complexes. A very significant positive correlation was found between the amounts of P desorbed from OMC and the P saturation degrees. The P adsorption reaction was quick at the early stage and slowed later. The raise of temperature increased P adsorption capacity and P adsorption rate of the colloidal complexes. The adsorption processes could be described by the Elovich equation.

Zhou, J. B., Li, S. X. and Chen, Z. J. 2002. Soil microbial biomass nitrogen and its relationship to uptake of nitrogen by plants. Pedosphere. 12(3): 251--256
ABSTRACT: The contents of the soil microbial biomass nitrogen (SMBN) in the soils sampled from the Loess Plateau of China were determined using chloroform fumigation aerobic incubation method (CFAIM), chloroform fumigation anaerobic incubation method (CFANIM) and chloroform fumigation-extraction method (CFEM). The N taken up by ryegrass on the soils was determined after a glasshouse pot experiment. The flushes of nitrogen (FN) of the soils obtained by the CFAIM and CFANIM were higher than that by the CFEM, and there were significantly positive correlations between the FN obtained by the 3 methods. The N extracted from the fumigated soils by the CFAIM, CFANIM and CFEM were significantly positively correlated with the N uptake by ryegrass. The FN obtained by the 3 methods was also closely positively correlated with the plant N uptake. The contributions of the SMBN and mineral N and mineralized N during the incubation period to plant N uptake were evaluated with the multiple regression method. The results showed that the N contained in the soil microbial biomass might play a noticeable role in the N supply of the soils to the plant.

Chen, X. T., Wang, G. and Liang, Z. C. 2002. Effect of amendments on growth and element uptake of pakchoi in a cadmium, zinc and lead contaminated soil. Pedosphere. 12(3): 243--250
ABSTRACT: A pot experiment was carried out to study the effects of two amendments, lime and calcium magnesium phosphate, on the growth and Cd, Pb, Zn, Cu, Mn, Fe, N, P and K uptake of pakchoi (Brassica chinensis) in a Cd, Pb and Zn polluted acid soil in the southern part of China. The growth of pakchoi was apparently improved by lime and calcium magnesium phosphate application, the uptake of Cd, Pb, Cu and Zn by pakchoi was significantly depressed and the symptom caused by heavy metals pollution was eliminated. Meanwhile, the absorption of N, K and Mn was also inhibited by these amendments. Soil pH was the main factor controlling the uptake of the heavy metals by pakchoi. This suggests that lime and calcium magnesium phosphate could be used as effective amendments for eliminating the toxicity of heavy metals to the vegetable and inhibiting their absorption by the crop.

Li, C. B., Friedman, S. P. and Zhao, A. Z. 2002. Wien effect in suspensions of electrodialyzed soil particles and its influencing factors. Pedosphere. 12(3): 235--242
ABSTRACT: The electrical conductivity of suspensions and their supernatants from the electrodialyzed clay fractions of latosol, yellow-brown soil and black soil equilibrated with nitrate solutions were determined at different field strengths using a short high-voltage pulse apparatus to demonstrate the Wien effect in soil suspensions and to investigate factors affecting it. It was found that Wien effect was much stronger in suspensions with a clay content of 30 g kg-1 from the soils equilibrated with a 1 x 10-4 KNO3 solution than in their supernatants. The threshold field strength (TFS), at which the relative conductivity is equal to 1.05, i.e., the Wien effect begins to be obvious, of the yellow-brown soil suspensions (clay content of 30 g kg-1) equilibrated with different nitrate solutions of a concentration of 1 x 10-4/z mol L-1, where z is the valence, varied with the type of nitrates, being lowest for NaNO3 (47 kV cm-1) and highest for Ca(NO3)2 (98 kV cm-1). At high field strengths (larger than 130 kV cm-1), the relative conductivities of yellow-brown soil suspensions containing different nitrates diminished in the order: NaNO3 > KNO3 > Mg(NO3)2 > Zn(NO3)2 > Ca(NO3)2. The rates and intensities of the Wien effect in the suspensions of the three soils equilibrated with 5 x 10-5 mol L-1 Ca(NO3)2 solution were in the order of the yellow-brown soil > the latosol > the black soil. The results for the yellow-brown soil suspensions (clay concentration of 30 g kg-1) equilibrated with KNO3 solutions of various concentrations clearly demonstrated that the more dilute the solution, the lower the TFS, and the larger the relative conductivity of the suspensions at high field strengths. The results for yellow-brown soil suspensions with different clay concentrations indicated that as the clay concentration increased, the low field electrical conductivity, EC0, also increased, but the TFS decreased, and the Wien effect increased.

Lin, C. 2002. Characteristics of phosphorus in some Eastern Australian acid sulfate soils. Pedosphere. 12(3): 229--234
ABSTRACT: Forty-five acid sulfate topsoil samples (depth < 0.5 m) from 15 soil cores were collected from 11 locations along the New South Wales coast, Australia. There was an overall trend for the concentration of the HCl-extractable P to increase along with increasing amounts of organic C and the HCl-extractable trivalent metals in the topsoils of some less-disturbed acid sulfate soils (pH < 4.5). This suggests that inorganic P in these soils probably accumulated via biological cycling and was retained by complexation with trivalent metals or their oxides and hydroxides. While there was no clear correlation between pH and the water-extractable P, the concentration of the water-extractable P tended to increase with increasing amounts of the HCl-extractable P. This disagrees with some established models which suggest that the concentration of solution P in acid soils is independent of total P and decreases with increasing acidity. The high concentration of sulfate present in acid sulfate soils appeared to affect the chemical behaviour of P in these soil systems. Comparison was made between a less disturbed wetland acid sulfate soil and a more intensively disturbed sugarcane acid sulfate soil. The results show that reclamation of wetland acid sulfate soils for sugarcane production caused a significant decrease in the HCl-extractable P in the topsoil layer as a result of the reduced biocycling of phosphorus following sugarcane farming. Simulation experiment shows that addition of hydrated lime had no effects on the immobilization of retained P in an acid sulfate soil sample within a pH range 3.5-4.6. When the pH was raised to above 4.6, soluble P in the soil extracts had a tendency to increase with increasing pH until the 15th extraction (pH 5.13). This, in combination with the poor pH-soluble P relationship observed from the less-disturbed acid sulfate soils, suggests that soluble P was not clearly pH-dependent in acid sulfate soils with pH < 4.5.

Liao, M., Xie, X. M., Subhani, A. and Klose, S, 2002. Combined effect of nutrient and pest managements on substrate utilization pattern of soil microbial population in hybrid rice cropping system. Pedosphere. 12(3): 219--228
ABSTRACT: A field experiment was conducted to study the combined effect of nutrient and pest managements on soil biomass phospholipid contents, functional biodiversity and substrate utilization patterns of soil microbial populations in hybrid rice cropping system. The mineral N, P and K fertilizers (as urea, calcium superphosphate and KCl respectively) were incorporated at 100, 25, and 100 kg ha-1, respectively, and the various pesticides were applied at the recommended rates. The results of the experiment demonstrated a decline in the microbial abundance and soil microbial biomass phospholipid contents with the advancement of crop growth, and significant changes in substrate utilization pattern of soil microbial population studied were observed with different management practices and at different growth stages. The principal component analysis (PCA) using all 95-carbon sources (BIOLOG plates) gave good differentiation among the treatments, indicating that they have different patterns of carbon utilization under different habitats. The data showed that diversity in microbial community continuously changed with the progression in crop stage, particularly at physiological maturity (PM) stage that was evident from the utilization of different carbon sources at various crop stages.

Li, F. S. and Kang, S. Z. 2002. Effects of atmospheric CO2 enrichment, applied nitrogen and soil moisture on dry matter accumulation and nitrogen uptake in spring wheat. Pedosphere. 12(3): 207--218
ABSTRACT: Spring wheat (Triticum aestivum cv. Dingxi No. 8654) was treated with two concentrations of atmospheric CO2 (350 and 700 umol mol-1), two levels of soil moisture (well-watered and drought) and five rates of nitrogen fertilizer (0, 50, 100, 150, and 200 mg kg-1 soil) to study the atmospheric CO2 concentration effect on dry matter accumulation and N uptake of spring wheat. The effects of CO2 enrichment on the shoot and total mass depended largely on soil nitrogen level, and the shoot and total mass increased significantly in the moderate to high N treatments but did not increase significantly in the low N treatment. Enriched CO2 concentration did not increase more shoot and total mass in the drought treatment than in the well-watered treatment. Thus, elevated CO2 did not ameliorate the depressive effects of drought and nitrogen stress. In addition, root mass decreased slightly and root/shoot ratio decreased significantly due to CO2 enrichment in no N treatment under well-watered condition. Enriched CO2 decreased shoot N content and shoot and total N uptake; but it reduced root N content and uptake slightly. Shoot critical N concentration was lower for spring wheat grown at 700 umol mol-1 CO2 than at 350 umol mol-1 CO2 in both well-watered and drought treatments. The critical N concentrations were 16 and 19 g kg-1 for the well-watered treatment and drought treatment at elevated CO2 and 21 and 26 g kg-1 at ambient CO2, respectively. The reductions in the movement of nutrients to the plant roots through mass flow due to the enhancement in WUE (water use efficiency) and the increase in N use efficiency at elevated CO2 could elucidate the reduction of shoot and root N concentrations.

Cheng, Z. H., Zhang, J. B. and Zhu, A. N. 2002. Introducing fractal dimension to estimation of soil sensitivity to preferential flow. Pedosphere. 12(3): 201--206
ABSTRACT: Food dye Brilliant Blue was introduced as the tracer in a dye-tracing experiment to obtain dye profile patterns of sandy loam soil, aeolian sandy soil, percolating paddy soil and permeable paddy soil. The dyed soil profiles were then photographed and the photos were scanned into a computer. Edited with certain software, only the dyed areas were left on the profile photos, which indicated the preferential flow paths for water and solute transport. Fractal dimensions of the dye patterns were calculated according to Arnold's function. Soil particle size distribution was analysed by pipette method. The regression analysis showed that there was significant relationship between soil clay content and fractal dimension D of the dye pattern of soil profile. Based on the experiment results, the possibility of introducing fractal dimension to estimation of soil sensitivity to preferential flow is discussed.

Liang, W. J., Chen, L. J., Li, Q., Wang, P. and Duan, Y. X. 2002. Responses of nematode communities to inorganic fertilizer disturbance in a farmland ecosystem. Pedosphere. 12(3): 193--200
ABSTRACT: Nematode communities were monitored in a field study at depths of 0-10 cm and 10-20 cm throughout a maize (Zea mays) growing season in the black soil region of Northeast China. Plots were cropped maize with (IF) and without (NF) nitrogen fertilization. Fifteen families and 16 genera were observed in the nematode suspensions. Cephalobidae, Rhabditidae, Aphelenchus, Filenchus, and Helicotylenchus were found to be dominant genera/families in both plots at both depths. Significant differences were found between treatments and maize growing stages in the total numbers of nematodes during the study period. The total numbers of nematodes at the 0-10 cm depth were higher in the inorganic fertilizer plot than in the control plot (no fertilizer applications) across jointing, filling, and mature stages. Bacterivores were the most abundant trophic groups under two treatments and at both depths, and the relative abundance averaged 42.8%. Omnivores-predators at both depths were lower in the inorganic fertilizer plot than in the control plot during the study period, excluding maize jointing stage. Maturity index (MI) and plant parasite index (PPI) were used to detect the differences between the two treatments, MI and PPI were effective in distinguishing differences in nematode communities during maize growing season. The role of nematode communities as bioindicators of ecosystem disturbance due to fertilization is noted.

Zhang, G. Y., Luo, Y. M. and Deng, X. H. 2002. Determination of surface area of red mud and beringite using methylene blue method. Pedosphere. 12(2): 189--192
ABSTRACT: The adsorption of methylene blue (MB) on three soil amendments, red mud from Hungary, red mud from UK and beringite from Belgium, was studied to determine the surface areas of the amendments using a 0.005 mol L-1 NaCl solution and deionised water as background solutions. The surface areas determined by the methylene blue method in the 0.005 mol L-1 NaCl solution were 3.357, 2.340 and 5.576 m2 g-1 for red mud (Hungary), red mud (UK) and beringite, respectively, slightly lower than those in the deionised water system. The largest surface area of beringite suggested that the MB could adsorb effectively on the interlayer surface of illite. The effect of NaCl on the surface areas was relatively small and may therefore be ignored. Both the 0.005 mol L-1 NaCl solution and deionised water could be used as a background solution for measurement of surface area of oxide-rich materials.

Luo, Y. M. and Christie, P. 2002. Alleviation of soil acidity and aluminium phytotoxicity in acid soils by using alkaline-stabilised biosolids. Pedosphere. 12(2): 185--188
ABSTRACT: A pot experiment was carried out to study alleviation of soil acidity and Al toxicity by applying an alkaline-stabilised sewage sludge product (biosolids) to an acid clay sandy loam (pH 5.7) and a strongly acid sandy loam (pH 4.5). Barley (Hordeum vulgare L. cv. Forrester) was used as a test crop and was grown in the sewage sludge-amended (33.5 t sludge DM ha-1) and unamended soils. The results showed that the alkaline biosolids increased soil pH from 5.7 to 6.9 for the clay sandy loam and from 4.5 to 6.0 for the sandy loam. The sludge product decreased KCl-extractable Al from 0.1 to 0.0 cmol kg-1 for the former soil and from 4.0 to 0.1 cmol kg-1 for the latter soil. As a result, barley plants grew much better and grain yield increased greatly in the amended treatments compared with the unamended controls. These observations indicate that alkaline-stabilised biosolids can be used as a liming material for remedying Al phytotoxicity in strongly acid soils by increasing soil pH and lowering Al bioavailability.

Su, D. C., Yang, F. H. and Zhang, F. S. 2002. Profile characteristics and potential environmental effect of accumulated phosphorus in soils of vegetable fields in Beijing. Pedosphere. 12(2): 179--184
ABSTRACT: Profile characteristics of accumulated P in 10 representative soils of vegetable fields in suburban districts of Beijing were investigated. Bioavailability of the accumulated P and its potential effect on the environment were studied in a greenhouse pot experiment and a soil column experiment. The results showed that the concentration of Olsen-P in the 0-20 cm soil samples of the vegetable fields ranged from 22.1 to 358.0 mg kg-1, which was 2 to 10 times higher than that of the crop fields in the suburbs of Beijing. Most of the excessive phosphorus was accumulated in the topsoils. The longer the soils cultivated with vegetables, the higher the soil total P, Olsen-P and organic matter concentration. Accumulated P in the soils from vegetable fields had higher bioavailability. Application of phosphorus fertilizer could not increase the dry weights of cucumbers, Chinese cabbage, and rape seedlings continuously planted. The soil column study showed high P concentration ( > 0.6 mg L-1) in the leachates from the columns of the vegetable field soils with high accumulated P, which has a potential effect on the groundwater and natural water quality.

Chen, Q., Zhang, H. Y., Tang, L. L., Li, X. L. and Liebig, H. P. 2002. Effects of water and nitrogen supply on spinach (Spinacia oleracea L.) growth and soil mineral N residues. Pedosphere. 12(2): 171--178
ABSTRACT: Effects of conventional and optimized water and nitrogen managements on spinach (Spinacia oleracea L.) growth and soil mineral N (Nmin) residues were compared in an open field experiment in which water balance method and N recommendation with the KNS-system were included. It was shown that the conventional water treatment (seasonal irrigated amount: 175 mm) reduced spinach growth compared to the water balance treatments (seasonal irrigated amount: 80 and 85 mm) at the same N supply level due to N loss through leaching caused by excessive water supply. Although 309 kg N ha-1 was applied in the conventional N treatment, compared to 82 and 66 kg N ha-1 in the optimum N treatments, no significant difference in crop yield was investigated between the N treatments with the same irrigation practice. N uptake in spinach and soil residual Nmin contents were also significantly affected by the irrigation practices. The conventional water supply not only decreased water use efficiency, but also resulted in excessive NO3--N being leached below the root zone. In order to meet the same target value of N requirement for the next crop, cauliflower, based on the KNS-system, at least extra 50 kg N ha-1 was needed in the conventional water treatments in comparison to the water balance treatment.

Luo, Y. M. 2002. Cu and Zn speciation in an acid soil amended with alkaline biosolids. Pedosphere. 12(2): 165--170
ABSTRACT: Fractionation of metals in a granite-derived acid sandy loam soil amended with alkaline-stabilised sewage sludge biosolids was conducted in order to assess metal bioavailability and environmental mobility. Soil solution was extracted by a centrifugation and filtration technique. Metal speciation in the soil solution was determined by a cation exchange resin method. Acetic acid and EDTA extracting solutions were used for extraction of metals in soil solid surfaces. Metal distribution in different fractions of soil solid phase was determined using a three-step sequential extraction scheme. The results show that the metals in the soil solution existed in different fractions with variable lability and metals in the soil solid phase were also present in various chemical forms with potentially different bioavailability and environmental mobility. Alkaline-stabilised biosolids could elevate solubility of Cu and proportion of Cu in organically complexed fractions both in soil liquid and solid phases, and may therefore increase Cu mobility. In contrast, the biosolids lowered the concentrations of water-soluble Zn (labile fraction) and exchangeable Zn and may hence decrease bioavailability and mobility of Zn. However, Fe and Mn oxides bound and organic matter bound fractions are likely to be Zn pools in the sludge-amended soil. These consequences possibly result from the liming effect and metal speciation of the sludge product and the difference in the chemistry between the metals in soil.

Hu, X. F., Gao, X. J., Chen, Z. L., Xu, S. Y., Shen, M. N., Wang, S. P. and He, B. G. 2002. Preliminary study on nitrogen and phosphorus releases from creek sediments in Shanghai suburbs. Pedosphere. 12(2): 157--164
ABSTRACT: A laboratory study was conducted to observe the release of nitrogen and phosphorus from the sediments under both anaerobic and aerobic conditions. The samples used were five creek sediments and a fish-pond sediment (as a comparison) obtained from suburban Shanghai. High loads of nitrogen and phosphorus were found in the creek sediments. Total nitrogen of the sediments ranged from 1.17 to 5.95 g kg-1; total phosphorus from 608.63 to 2033.95 mg kg-1. Making up more than 90% of the total nitrogen, organic nitrogen was the dominant nitrogen fraction in the sediments; whereas inorganic phosphorus was the dominant phosphorus fraction, which made up more than 85 percent of the total phosphorus. Ca-bound phosphorus fraction dominated inorganic phosphorus, which occupied more than 50% of the total. A large amount of ammonium was released from the sediments under both aerobic and anaerobic conditions, and the anaerobic releases were slightly greater than the aerobic. In addition, ammonium contents in the aerobic waters decreased sharply after reaching the peaks because of strong nitrification, compared with the relatively maintained ammonium peaks in the anaerobic waters. Anaerobic phosphate releases were much greater than the aerobic and the released ortho-phosphate was mainly from Fe-bound phosphorus. Ammonium and ortho-phosphate releases from the sample of the dredged creek were the lowest, showing that creek dredging could effectively remove contaminants from the surface of sediments and weaken the release potentials of nitrogen and phosphorus. Ammonium and ortho-phosphate releases from the fish-pond sediment were greater than those from the creek sediments though its total nitrogen and phosphorus were not the highest, which was probably due to the larger amount of biologically degraded organic matter in the fish-pond sediment.

Gao, X. J., Hu, X. F., Wang, S. P., He, B. G. and Xu, S. Y. 2002. Nitrogen losses from flooded rice field. Pedosphere. 12(2): 151--156
ABSTRACT: A field microplot experiment was conducted during the tillering stage of paddy rice to investigate nitrogen (N) losses from flooded rice fields following fertilizer application. After application of ammonium bicarbonate, most of nitrogen in the floodwater was present as NH4-N and its concentration varied widely with time. Concentrations of both NO3-N and NO2-N in the floodwater were low due to the weakened nitrification. Under flooded anaerobic reducing conditions, soil solution concentrations of NO3-N and NH4-N were not high, ranging from 0.6 mg L-1 to 4.8 mg L-1, and decreased with soil depth. However, the groundwater was still contaminated with NO3-N and NH4-N. Rainfall simulation tests showed that the N losses via runoff in rice fields were closely related to the time intervals between fertilizer applications and rainfall events. When a large rain fell for a short period after fertilizer application, the N losses via runoff could be large, which could have a considerable effect on surface water quality. Both irrigation and N fertilizer application must be controlled and managed with great care to minimize N losses via runoff from agricultural land.

Ding, K. Q., Luo, Y. M., Sun, T. H. and Li, P. J. 2002. Bioremediation of soil contaminated with petroleum using forced-aeration composting. Pedosphere. 12(2): 145--150
ABSTRACT: Laboratory simulation studies and a composting pilot study were conducted to evaluate the capacity of three strains of fungi, indigenous fungus Fusarium sp. and Phanerochaete chrysosporium and Coriolus versicolor, to remediate petroleum-contaminated soils. In laboratory, the fungi were inoculated into a liquid culture medium and the petroleum-contaminated soil samples for incubation of 40 and 50 days, respectively. In the 200-day pilot study, nutrient contents and moisture were adjusted and maintained under aerobic condition in composting units using concrete container (118.5 cm x 65.5 cm x 12.5 cm) designed specially for this study. The laboratory simulation results showed that all the three fungi were effective in degrading petroleum in the liquid culture medium and in the soil. At the end of both the laboratory incubations, the degradation rates by Phanerochaete chrysosporium were the highest, reaching 66% after incubation in liquid culture for 50 days. This was further demonstrated in the composting pilot study where the degradation rate by P. chrysosporium reached 79% within 200 days, higher than those of the other two fungi (53.1% and 46.1%), indicating that P. chrysosporium was the best fungus for bioremediation of soil contaminated with petroleum. Further research is required to increase degradation rate.

Luo, Y. M. and Christie, P. 2002. Extractability of Cu in alkaline biosolids-amended soils as influenced by ³-irradiation. Pedosphere. 12(2): 139--144
ABSTRACT: An incubation experiment was conducted to investigate the microbial biomass associated Cu in four contrasting soils to which an alkaline stabilised sewage sludge cake was applied. The organisms of sludge-amended and control soils were killed using gamma-irradiation technique, and the aqueous and acid-extractable Cu concentrations were determined. Addition of the sludge product increased significantly the concentration of both the aqueous and dilute HOAc-extractable Cu in all the irradiated soils compared to the non-sterilised sludge/soil mixtures, but the increase was more pronounced in the dilute acid-extractable Cu, indicating that the Cu rendered extractable in water and dilute acetic acid by gamma-irradiation existed in the both soil liquid and solid phases. The additional increase in extractable Cu following the biocidal treatment is likely to be due to release of Cu from the same fraction of soil microbial biomass.

Yao, Q., Qing, F. L., Li, X. L. and Christie, P. 2002. Utilization of sparingly soluble phosphate by red clover in association with Glomus mosseae and Bacillus megaterium. Pedosphere. 12(2): 131--138
ABSTRACT: A pot experiment was conducted to investigate the mobilization of sparingly soluble inorganic and organic sources of phosphorus (P) by red clover (Trifolium pratense L.) whose roots were colonized by the arbuscular mycorrhizal (AM) fungus Glomus mosseae and in association with the phosphate-solubilizing (PS) bacterium Bacillus megaterium ACCC10010. Phosphate-solubilizing bacteria and rock phosphate had a synergistic effect on the colonization of plant roots by the AM fungus. There was a positive interaction between the PS bacterium and the AM fungus in mobilization of rock phosphate, leading to improved plant P nutrition. In dual inoculation with the AM fungus and the PS bacterium, the main contribution to plant P nutrition was made by the AM fungus. Application of P to the low P soil increased phosphatase activity in the rhizosphere. Alkaline phosphatase activity was significantly promoted by inoculation with either the PS bacterium or the AM fungus.

Chen, B. D., Li, X. L. and Christie, P. 2002. Two arbuscular mycorrhizal fungi colonizing maize under different phosphorus regimes in a compartment cultivation system. Pedosphere. 12(2): 121--130
ABSTRACT: A modified glass bead compartment cultivation system was used to compare some chemical and biological properties of the two arbuscular mycorrhizal (AM) fungi Glomus mosseae and Glomus versiforme using maize (Zea mays) as the host plant with four added levels of available phosphorus (P). The proportion of host plant root length infected was determined at harvest. Shoot and root yields and nutrient concentrations were determined, together with the nutrient concentrations in the AM fungal external mycelium. The morphology of various mycorrhizal structures of the two AM fungi was also compared by microscopic observation. Inoculation with G. mosseae gave higher plant yields than that with G. versiforme, and the two fungi responded differently in infection rate to available phosphorus level. Root infection rate of mycorrhizal maize colonized by G. mosseae decreased markedly with increasing P level, and there was very poor development of the extraradical mycelium at the highest rate of P addition. In contrast, G. versiforme showed greater tolerance to increasing P level. Elemental analysis showed that phosphorus, copper and zinc concentrations in the external mycelium differed between the two fungi and were much higher than those in the host plant. Differences in the morphology of the two fungi were also observed.

Chen, Z. L., Xu, S. Y., Xu, Q. X., Hu, X. F. and Yu, L. Z. 2002. Surface water pollution in the Yangtze River Delta: Patterns and countermeasures. Pedosphere. 12(2): 111--120
ABSTRACT: On the basis of field investigations, observations and experimental data combined with environmental monitoring information, the status and the spatial and temporal patterns of surface water pollution over the past ten years in the Yangtze River Delta have been assessed. The water quality of large rivers is still very good but most of the medium-sized and small rivers have been very seriously polluted. The appearance of black and odorous conditions in rivers in the urban areas has increased due to serious pollution by organic matter with consequent high oxygen demand. Annual increases in N and P concentrations in lakes have accelerated eutrophication. The water quality of rivers in small towns is rapidly deteriorating. The main sources of surface water pollution include industrial and domestic sewage, animal manures, chemical fertilizers in farmland, and polluted sediments in rivers and lakes. Countermeasures against these sources of pollution are presented. Regional laws and regulations for protection of surface waters and their enforcement are urgently required. A regional water environmental management agency should be established. The construction of sewage treatment plants of varying capacity must be accelerated to increase the proportion of sewage treated and to improve the quality of treated effluent. Animal wastes must be recycled effectively and efficiently, and the application rates of fertilizers and manures must be balanced with crop nutrient requirements to prevent diffuse pollution from agriculture. The comprehensive rehabilitation of medium-sized and small rivers should be intensified, and the delimitation and protection of the areas used as sources of drinking water should be strengthened.

Song, Y. C., Li, X. L. and Christie, P. 2002. Uptake of organic phosphorus by arbuscular mycorrhizal red clover. Pedosphere. 12(2): 103--110
ABSTRACT: The capacities of two arbuscular mycorrhizal (AM) fungi, Glomus mosseae and Glomus versiforme, to mineralize added organic P were studied in a sterilized calcareous soil. Mycorrhizal (inoculated with either of the AM fungi) and non-mycorrhizal red clover (Trifolium pratense L.) plants were grown for eight weeks in pots with upper root, central hyphal and lower soil compartments. The hyphal and soil compartments received either organic P (as Na-phytate) or inorganic P (as KH2PO4) at the rate of 50 mg P kg-1. No P was added to the root compartments. Control pots received no added P. Yields were higher in mycorrhizal than in non-mycorrhizal clover. Mycorrhizal inoculation doubled shoot P concentration and more than doubled total P uptake of plants in P-amended soil, irrespective of the form of applied P. The mycorrhizal contribution to inorganic P uptake was 80% or 76% in plants inoculated with G. mosseae or G. versiforme, respectively. Corresponding values were 74% and 82% when Na-phytate was applied. In the root compartments of the mycorrhizal treatments, the proportion of root length infected, hyphal length density and phosphatase activity were all higher when organic P was applied than when inorganic P was added.

Luo, Y. M. and Christie, P. 2002. Effect of alkaline-stabilised sewage sludge on extractable organic carbon and copper in soils. Pedosphere. 12(2): 97--102
ABSTRACT: An incubation experiment was conducted to evaluate the potential for water contamination with sludge-derived organic substances and copper following land application of alkaline-stabilised sewage sludge. Two contrasting sludge-amended soils were studied. Both soils were previously treated with urban and rural alkaline biosolids separately at sludge application rates of 0, 30 and 120 t ha-1 fresh product. The air-dried soil/sludge mixtures were wetted with distilled water, maintained at 40% water-holding capacity and equilibrated for three weeks at 4! before extraction. Subsamples were extracted with either distilled water or 0.5 mol L-1 K2SO4 solution. The concentrations of organic C in the aqueous and chemical extracts were determined directly with a total organic carbon (TOC) analyser. The concentrations of Cu in the two extracts were also determined by atomic absorption spectrophotometry. The relationship between the two extractable organic C fractions was examined, together with that between extractable organic C concentration and extractable Cu concentration. Application of alkaline biosolids increased the concentrations of soil mobile organic substances and Cu. The results are discussed in terms of a possible increase in the potential for leaching of sludge-derived organics and Cu in the sludge-amended soils.

Ma, Y. H., Schnug, E., Si, Y. B., Zhang, L. G., Ding, R. X. and Zhang, J. Z. 2002. Adsorption of SeO32- by soils at different S levels. Pedosphere. 12(1): 89--92
ABSTRACT: A study was conducted using red soil derived from Quaternary red clay, a yellow cinnamon soil from Xiashu loess, and a kaolinite collected from Anhui, China, to illustrate the characteristics of SeO32- adsorption by soils and kaolinite and Se and S interaction in soils so as to provide some scientific information in regulating soil Se status. Results showed that the amounts of SeO32- adsorbed by kaolinite increased with the increase of SeO32- concentration at different rates, but SO42- lowered the amounts of SeO32- adsorbed, and the decrease of the amounts of SeO32- adsorbed tended to be more obvious with the increases of SO42- and SeO32- concentrations. The SeO32- adsorption by the red soil increased with the increase of SeO32- concentration. However, the effect of SO42- concentration on the amounts of SeO32- adsorbed by the red soil appeared not obvious when SeO32- concentration was below 300 umol/g, while the amounts of SeO32- adsorbed by the red soil decreased obviously with the increase of SO42- concentration when SeO32- concentration in the equilibrium was over 300 umol/g. At different S rates, the amount of SeO32- adsorbed by the yellow cinnamon soil gradually increased with the increase of Seo32- concentration, but SO42- showed no obvious effect on SeO32- adsorption amounts by the yellow cinnamon soil at various rates of SeO32-.

Zhou, S. W., Zhang, G. Y. and Zhang, X. N. 2002. Influence of neutral salts and pH on exchangeable acidity of red soil and latosol colloids. Pedosphere. 12(1): 81--88
ABSTRACT: In the present work, the exchangeable acidity of a red soil colloid and a latosol colloid at different pH during reacting with four neutral salts was measured. Soil samples were taken from Jinxian (red soil) of Jiangxi province and Xuwen (latosol) of Guangdong province, China. The results show that the exchangeable acidity increased with increasing amounts of the neutral salts added, and the relation between them was almost linear. When the amount of the neutral salt added was lower than a certain value, the slope of the line was high, and the slope turned low when the amount exceeded that value, so there was a turning point in each line. The addition amounts of the neutral salts for the turning points were affected by the cation species of the neutral salts, but pH had less effect on them. After the turning points occurred, the exchangeable acidity of the red soil colloid still gradually increased with the addition amounts of the neutral salts, but that of the latosol colloid did not increase any more. The exchangeable acidity in NaClO4, KClO4 and NaCl solutions increased at first, and then decreased with increasing pH, that is to say, peak values appeared. The peak positions of the exchangeable acidity in relation to pH changed with neutral salt solutions and were affected by the surface characteristics of the soil colloids, but not affected by the amounts of the neutral salts added. The exchangeable acidity in the Ba(NO3)2 solution increased continuously with increasing pH. The exchangeable acidity of the red soil colloid was obviously larger than that of the latosol colloid.

Dong, L. A., Zhu, Y. M. and Ogura, N. 2002. A modified DRASTIC approach to shallow groundwater vulnerability in the West Lake watershed in Hangzhou, China. Pedosphere. 12(1): 73--80
ABSTRACT: The quality of shallow groundwater in the West Lake watershed, in Hangzhou, Zhejiang, China, was investigated from March to July 2000. Integrating with Blackland GRASS geographical information system, the DRASTIC model was used to compile the groundwater vulnerability map. A land use factor was added to the DRASTIC model and the modified model (LDRASTIC) increased the accuracy of prediction from 26.9 to 51.3%. The vulnerability map showed that the lowly, moderately and highly susceptible area predicted occupied approximately 11.6, 70.9 and 17.5% of the whole watershed, respectively. Compared with the observed values of nitrate and electric conductivity, the LDRASTIC index improved the Pearson correlation coefficients from -0.010 to 0.237 and 0.380 to 0.503; both the improved coefficients were significant at the 0.01 level. The modified DRASTIC analysis showed a great potential as a screening tool for policy decision-making in groundwater management.

Chilima, J., Huang, C. Y. and Wu, C. F. 2002. Microbial biomass carbon trends in black and red soils under single straw application: Effect of straw placement, mineral N addition and tillage. Pedosphere. 12(1): 59--72
ABSTRACT: Quantifying trends in soil microbial biomass carbon (SMBC) under contrasting management conditions is important in understanding the dynamics of soil organic matter (SOM) in soils and in ensuring their sustainable use. Against such a background, a 60-day greenhouse simulation experiment was carried out to study the effects of straw placement, mineral N source, and tillage on SMBC dynamics in two contrasting soils, red soil (Ferralsol) and black soil (Acrisol). The treatments included straw addition + buried (T1); straw addition + mineral N (T2); and straw addition + tillage (T3). Straw was either buried in the soil or placed on the surface. Sampling was done every 15 days. Straw placement, addition of external mineral N sources (Urea, 46% N) and soil type affected SMBC. SMBC levels decreased with exposure durations (15, 30, 45, and 60 days). Rate of SMBC fixation was more in buried straw than in surface placed straw at all sampling dates in both soils. Addition of an external N source significantly increased SMBC level. Soil pH increased in both soil types, with a greater increase in black soil than in red soil. The study could not, however, statistically account for the effect of tillage on SMBC levels because of the limited effect of our tillage method due to the artificial barrier to mechanical interference supplied by the mesh bags, although differences in absolute values were quite evident between treatments T1 and T3.

Zeng, Z. Y. and Meijerink, A. M. J. 2002. Water yield and sediment yield simulations for Teba Catchment in Spain using SWRRB model: II. Simulation results. Pedosphere. 12(1): 49--58
ABSTRACT: Simulated results of water yield, sediment yield, surface runoff, subsurface runoff, peak flow, evapotranspiration, etc. in the Teba catchment, Spain, using SWRRB (Simulator for Water Resources in Rural Basins) model are presented and the related problems are discussed. The results showed that water yield and sediment yield could be satisfactorily simulated using SWRRB model. The accuracy of the annual water yield simulation in the Teba catchment was up to 83.68%, which implied that this method could be effectively used to predict the annual or inter-annual water yield and to realize the quantification of geographic elements and processes of a river basin.

Zeng, Z. Y. and Meijerink, A. M. J. 2002. Water yield and sediment yield simulations for Teba Catchment in Spain using SWRRB model: I. Model input and simulation experiment. Pedosphere. 12(1): 41--48
ABSTRACT: Water yield and sediment yield in the Teba catchment, Spain, were simulated using SWRRB (Simulator for Water Resources in Rural Basins) model. The model is composed of 198 mathematical equations. Approximately 120 items (variables) were input for the simulation, including meteorological and climatic factors, hydrologic factors, topographic factors, parent materials, soils, vegetation, human activities, etc. The simulated results involved surface runoff, subsurface runoff, sediment, peak flow, evapotranspiration, soil water, total biomass, etc. Careful and thorough input data preparation and repeated simulation experiments are the key to get the accurate results. In this work, the simulation accuracy for annual water yield prediction reached to 83.68%.

Chen, G. C. and He, Z. L. 2002. Calibration of KEC value in acidic red soils with fumigation-extraction method. Pedosphere. 12(1): 33--40
ABSTRACT: The commonly used KEC value (0.45) of the fumigation-extraction (FE) method was obtained on the basis of temperate neutral soils. To ascertain its applicability to acidic red soils widespread in Zhejiang, southern China and other subtropical regions, the KEC value was investigated based on 8 acidic red soils by in situ labelling of native soil microorganisms using 14C-labelled glucose. A realistic KEC value for red soils could be obtained by in situ 14C-labelling as long as an incubation period of 72 h is adopted after addition of 14C glucose to soil. The single KEC values for the eight red soils ranged from 0.27 to 0.35 and averaged 0.31. The lower KEC value obtained in red soils probably resulted from different soil quality, compared with other types of soil, which causes possible changes in microbial community structure and extractability of cellular component. Microbial biomass C contents of the eight red soils measured using a unique and constant KEC value of 0.45 decreased by 22.2-40% in comparison to those using variable KEC values. The results suggest that microbial biomass C would be significantly underestimated using the present KEC value and a calibration of the KEC value is necessary for red soils.

Sun, H., Tang, Y. and Zhao, Q. G. 2002. Nitrogen mineralization of prunings of six N2-fixing hedgerow species in a dry valley of the Jinsha River. Pedosphere. 12(1): 25--31
ABSTRACT: A litterbag experiment of 12 weeks was conducted to study nitrogen mineralization process of prunings of six nitrogen-fixing hedgerow species in a dry valley of the Jinsha River in Sichuan, China. Prunings were incorporated into soil or used as mulch. The results indicated that pruning N of the six hedgerow species was mineralized fast in the first week and then decreased slowly in the rest of the study period. When prunings were incorporated into soil, the amount of nitrogen mineralized by the end of the first week accounted for 69.9, 58.2, 54.5, 43.0, 29.6 and 20.6% of the total N in prunings of Desmodium rensonii, Tephrosia candida, Leucaena leucocephala, Albizia yunnanensis, Acacia dealbata, and A. mearnsii, respectively. When prunings of L. leucocephala were used as mulch materials, the amount of nitrogen mineralized in the first week was 16.2% less than that of prunings incorporated into soil. The mineralization pattern of pruning N could be simulated by an exponent model Nt%=N01% (1 - exp(-k1t))+N02% (1 - exp(-k2t)) where Nt% is cumulative mineralized N in time t, N01% and N02% are readily and less readily mineralizable N in prunings, respectively, and k1 and k2 are rate constants. A half-life period of pruning nitrogen mineralization could also be determined by this model. The nitrogen content in the pruning residues decreased quickly in the first week but fluctuated thereafter. The initial C : N ratio was negatively related to the mineralization rate of prunings.

Tu, C., Zheng, C. R. and Chen, H. M. 2002. Effect of heavy metals on phosphorus retention by typic udic ferrisols: Equilibrium and kinetics. Pedosphere. 12(1): 15--24
ABSTRACT: A study was conducted to examine the effect of heavy metals (Cu, Pb, Zn and Cd in combination or alone) on the equilibrium and kinetics of phosphorus (P) retention in Typic Udic Ferrisols by using both equilibrium and flow techniques. Fourteen soil samples, collected from the Ecological Experimental Station of Red Soil in Yintan, Jiangxi, China, with varying artificial contamination of Cu, Pb, Zn and Cd were prepared. Heavy metal pollution led to increases in retention capacity and maximum buffering capacity (MBC) of soil P. The rate of P retention was also increased and the time to reach equilibrium was advanced by heavy metals addition. The Elovich equation provided a satisfactory description of the P kinetic data. The influence of heavy metals on P retention was in the order of Pb > Cu > Zn, with greater effect in multiple metal pollution. These findings suggested that heavy metal pollution caused an increase in P fixation and thus a decline in P availability. Therefore, indirect influences of heavy metal contamination on soil nutrients may need more consideration when determining overall impact of heavy metals on soil environment.

Li, S. T., Zhou, J. M., Wang, H. Y. and Chen, X. Q. 2002. Phenolic acids in plant-soil-microbe system: A review. Pedosphere. 12(1): 1--14
ABSTRACT: Phenolic acids are very common compounds in pedosphere. The objective of this review was to summarize the current knowledge of the behaviours of phenolic acids in plant-soil-microbe system. When phenolic acids originated from leaching, decomposition and exudation of living and dead plant tissues enter soils, they can react physicochemically with soil particle surfaces and/or incorporate into humic matter. Phenolic acids desorbed from soil particle surfaces and remained in solution phase can be utilized by microbe as carbon sources and absorbed by plants. The degradation products of phenolic acids by microbe include some organic and/or inorganic compounds such as new phenolic acids. In addition, phenolic acids in soils can stimulate population and activity of microbe. Phenolic acids can inhibit plants growth by affecting ion leakage, phytohormone activity, membrane permeability, hydraulic conductivity, net nutrient uptake, and enzyme activity. Behaviours of phenolic acids in soils are influenced by other organic compounds (phenolic acids, methionine, glucose, etc. and/or inorganic ions). The role of phenolic acids as allelopathic agents should not be neglected only based on their low specific concentrations in natural soils, because numbers and interactions of phenolic acids will increase their allelopathic activities.

Wang, Y. and Zhang, Y. P. 2001. Quantitative effect of soil texture composition on retardation factor of K+ transport. Pedosphere. 11(4): 377--382
ABSTRACT: With six packed columns composed of < 1 um and 5 um-0.25 mm fractions from an Eum-Orthic Anthrosol (Columns 1-6) and one column of the Eum-Orthic Anthrosol (Column 7), K+ transport experiments under the condition of saturated steady water flow were conducted to qualify the effects of soil texture composition on the retardation factor ? of K+ transport. The results showed that the retardation factor of K+ transport in the tested soil columns greatly increased with increasing clay contents. In an attempt to use pedotransfer function (PTF) approach in the solute transport study, a preliminary PTF was established through the six packed columns (Columns 1-6) with soil basic data including soil bulk density, volumetric water content and clay content to predict the retardation factor, and proved valid by the satisfactory prediction of R in Column 7.

Feng, K., Wang, X. Z., Tang, Y. and Wang, X. L. 2001. Effect of potassium on ammonium fixation and adsorption of vermiculite in binary and ternary systems. Pedosphere. 11(4): 369--375
ABSTRACT: Ammonium fixation and adsorption experiments were conducted to study the effect of potassium on ammonium fixation into interlayer of vermiculite and ammonium adsorption at the surface of vermiculite both in the binary (NH4+-Ca2+) and ternary (NH4+-K+-Ca2+) systems. In the ammonium fixation experiment, 5 mmol NH4+ kg-1 was added alone, or after, before or simultaneously with 5 mmol K+ kg-1 to the vermiculite (vermiculite:solution = 1:1), and the incubation was conducted for 3 days under constant 20!. In the adsorption experiment, after addition of 10 mmol Ca2+ litre-1 as matrix ions, either NH4+ alone with a concentration series from 0.1 to 5.0 mmol NH4+ litre-1 (binary exchange system of NH4+ and Ca2+) or NH4+ together with 5 mmol K+ litre-1 (ternary exchange system of NH4+, K+ and Ca2+) was added to vermiculite at a vermiculite to solution ratio of 1:10 for 24-h equilibrium. The results of the fixation experiment showed that the presence of K+ increased NH4+ fixation for all the treatments, regardless of the addition orders. For ammonium adsorption, a linear relationship between activity ratios of NH4+ to Ca2+ and Mg2+ in the equilibrium solutions (ARNH44) and increases of exchangeable NH4+ at the surface of vermiculite after 24-h equilibrium (DELTAEx-NH4+) was shown for almost the whole concentration ranges tested. Compared with the binary system, the slope of the curve of the ternary system was steeper, indicating a more intensive adsorption of NH4+ in the presence of K+. It was demonstrated that K+ did not reduce the ammonium fixation into the interlayer and ammonium adsorption at the surface of vermiculite, which indicated that, under the experimental conditions of this study, K+ did neither occupy the sites for NH4+-fixation in the interlayer nor the sites for NH4+-adsorption at the surface of vermiculite.

Li, W. Q., Zhang, M. and Van der Zee, S. 2001. Salt contents in soils under plastic greenhouse gardening in China. Pedosphere. 11(4): 359--367
ABSTRACT: Field experiments were conducted on three main soils (brown soil, meadow soil and cinnamon soil) of Shandong Province, China, to study the effect of plastic greenhouse gardening on soil salt contents. As compared to the open fields, the soil nutrient contents in the fields under plastic greenhouse gardening all increased significantly. The organic matter, quickly available N and P increases were extremely significant and the quickly available K increase was also significant. Along with the nutrient increases, the soil salt contents increased clearly in all the soils investigated not only in the top layer but also in the deeper layers, being extremely significant in the 0-10 cm layer and significant in the 10-40 cm layers. The salt contents in the plastic greenhouses had significant correlations with the soil available nitrogen and phosphorous. Soils with longer plastic greenhouse gardening time tended to have more salt. The plastic greenhouse soils contained less CO32- and much more NO3- than the open soils, which indicated a higher influence of human intervention in plastic greenhouses. Among the constituent ions, Cl-, NO3-, Ca2+ and Mg2+ had positive while HCO3- had negative significant or extremely significant correlations with total salt, with correlation coefficients being 0.66, 0.80, 0.92, 0.80 and -0.64, respectively. Nitrate decreased from the top to deeper layers both in the plastic greenhouses and in the open fields. The plastic greenhouse soils contained much more nitrate than the open fields in every layer and even the nitrate contents of the 80-100 cm layer were still several times those of the top layer in the open fields. The main reason for the salt increases was considered to be the inappropriate fertilizer application and selective absorption of nutrients by plants in the plastic greenhouses. The methods recommended to avoid soil salt increase in the plastic greenhouses were to apply fertilizers rationally according to the soils, vegetables and fertilizer properties and to adopt a good intercropping or rotation system.

Gao, Y. J., Huang, D. M., Zhu, P. L., Wang, Z. M. and Li, S. X. 2001. Long-term impact of soil management on microbial biomass C, N and P in rice-based cropping system. Pedosphere. 11(4): 349--357
ABSTRACT: A 12-year (from June 1983 to October 1995) field experiment was conducted in Jiangsu, China, to investigate the effect of different tillage methods and fertilizer application systems on microbial biomass C, N and P of a grey fluvo-aguic soil in rice-based cropping system. Five fertilizer application treatments were designed under conventional tillage (CT) or no tillage (NT) system: no fertilizer; chemical fertilizer only; combining chemical fertilizer with pig manure; combining chemical fertilizer with crop straw and fallow. The results showed that biomass C, N and P were enriched in the surface layer of no-tilled soil, whereas they distributed relatively evenly in the tilled soil, which might result from enrichment of crop residue, organic manure and mineral fertilizer, and surficial development of root systems under NT. Under the cultivation system, NT had slightly greater biomass C, N and P at 0-5 cm depth, significantly less biomass C, N and P at 5-15 cm depth, less microbial biomass C, N and equivalent biomass P at 15-30 cm depth as compared to CT, indicating that tillage was beneficial for the multiplication of organisms in the ploughed layer of soil. Under the fallow system, biomass C, N and P in the surface layer were significantly greater for NT than CT while their differences between the two tillage methods were negligible in the deeper layers. In the surface layer, biomass C, N and P in the soils amended with organic manure combined with mineral fertilizers were significantly greater than those of the treatments only with mineral fertilizers and the control. Soils without fertilizer had the least biomass nutrient contents among the five fertilizer application treatments. Obviously, the long term application of organic manure could maintain the higher activity of microorganisms in soils. The amounts of biomass C, N and P in the fallowed soils varied with the tillage methods; they were much greater under NT than under CT, especially in the surface layer, suggesting that the frequent ploughing could decrease the content of organic matter in the surface layer of the fallowed soil.

Yang, Y. S., Chen, G. S. and Yu, X. T. 2001. Soil fertility in agroforestry system of Chinese fir and villous amomum in subtropical China. Pedosphere. 11(4): 341--348
ABSTRACT: A trial of interplanting and non-interplanting villous amomum (Amomum villosum) under the canopy of Chinese fir (Cunninghamia lanceolata) at age 22 was established in Sanming, Fujian, China, and a survey on soil fertility was carried out 10 years after its establishment. Compared with the control (non-interplanting), the properties of soil humus in agroforestry system were ameliorated, with a higher level of humification and resynthesis of organic detritus. The soil microbial population and enzymatic activities were both higher under the influence of villous amomum. Both the nutrient supplying and nutrient conserving capacities of the soil were improved. This agroforestry system exhibited an advantage of improved soil fertility, as well as an accelerated growth of Chinese fir, it was, therefore, a sustainable management system suited for Chinese fir in South China.

Fu, J. R., Zhu, Y. H. and Jiang, L. N. 2001. Use of controlled release fertilizer for increasing N efficiency of direct seeding rice. Pedosphere. 11(4): 333--339
ABSTRACT: Field trials on a silt-loamy paddy soil derived from shallow-sea deposit in direct sowing rice fields were conducted in Zhejiang, China, in 1996 to compare N efficiency of controlled release fertilizers (LP fertilizers) with the conventional urea. Six treatments including no N fertilizer, conventional urea and different types of LP fertilizers at different rates were designed for two succeeding crops of early and late rice. A blend of different types of LP fertilizers as a single preplant co-situs application released N in a rate and amount synchronizing with uptake pattern of direct sowing rice. A single preplant application of the LP fertilizers could meet the N requirement of rice for the whole growth period without the need of topdressing. Using LP fertilizer blends, equivalent grain yields could be maintained even if the N fertilizer application rates were reduced by 25-50% compared with the conventional urea. Agronomic efficiency of the LP fertilizers was 13.6-86.4% higher than that of the conventional urea in early rice and 100-164.1% in late rice, depending on the amounts of the LP fertilizers applied. N fertilizer recovery rate increased from 27.4% for the conventional application of urea to 41.7-54.1% for the single preplant co-situs application of the LP fertilizers. Use of the LP fertilizers was promising if the increase in production costs due to the high LP fertilizer prices could be compensated by increase in yield and N efficiency, reduction in labour costs and improvement in environment.

Tomar, A., Kumar, N., Pareek, R. P. and Chaube, A. K. 2001. Synergism among VA mycorrhiza, phosphate solubilizing bacteria and Rhizobium for symbiosis with blackgram (Vigna mungo L.) under field conditions. Pedosphere. 11(4): 327--332
ABSTRACT: A field experiment was conducted at the G.B. Pant University Research Station, Ujhani, Uttar Pradesh, India, during kharif 1994-95 to study the effect of Rhizobium, vesicular arbuscular mycorrhiza (VAM, Glomus caledonium) and phosphate solubilizing bacteria (PSB, Pseudomonas striata strain P-27) inoculation, with and without P, on black gram (Vigna mungo) seed yield. Phosphorus application in soil with medium P content (5.4 mg kg1) increased nodulation, grain yield, N and P in plant and grain over no phosphorus control. Forty kilograms of P2O5 each hactare recorded an increase of 20.6% in nodule dry weight, significant increases of 0.35 g kg-1 in N concentration and 1.28 g kg-1 in P concentration of plant over 20 kg P2O5 ha-1. Similar significant increases of 0.59 g kg-1 in grain yield and 0.54 and 0.23 g kg-1 in N and P concentrations of the grain, respectively, over 20 kg P2O5 ha-1 were also obtained with higher dose. Inoculation of Rhizobium + VAM + PSB at all the stages of plant growth recorded maximum increases in all the parameters studied. Dual inoculation of Rhizobium with either VAM or PSB was generally significant in the effect and better than that of VAM + PSB, however, P accumulation in plant and grain was more with VAM+PSB. Among single inoculations, Rhizobium gave the highest and 21.0% more nodule number, 34.7% more nodule dry mass, 0.73 g kg-1 more N in grain and 4.2% higher grain yield over PSB. PSB, however, registered significant increases in P concentration in plant and grain over VAM and Rhizobium.

Wen, Q. X., Cheng, L. L. and Chen, B. Y. 2001. An XPS study of nitrogen structures in soil humic substances. Pedosphere. 11(4): 321--326
ABSTRACT: X ray photoelectron spectroscopy (XPS) was used to examine the N structures of 17 soil humic substances and some of their analogues. Of the 17 soil soil humic substances, 5 were 15N-labelled, newly formed ones, 6 were extracted from native soils under natural vegetation (including subalpine meadow soil, black soil, brown soil, yellow brown soil, red soil, and terra rossa), and 6 were extracted from cultivated soils (including both upland soils and paddy soils). It was found that for soil humic substances XPS method gave similar results as those obtained by 15N CPMAS NMR method. Seventy to eighty-six percent of total N in soil humic substances was in the form of amide, and 6-13% was presented as amines, with the remaining part as heterocyclic N. There was no difference in the distribution of the forms of N between the humic substances from soils formed over hundreds or thousands of years and the newly formed ones. For fulvic acid from weathered coal and benzoquinone-(NH4)2SO4 polymer, the XPS results deviated significantly from the 15N CPMAS NMR data.

Zhang, H. C., Cao, Z. H., Hu, Z. Y., Xu, H. Q., Yu, Y.C., Xu, B. Z. and Xiao, X. F. 2001. Growth responses of trees to micronutrients and their feedback effect in various soil-forest ecosystems of Taihu Lake region. Pedosphere. 11(4): 311--320
ABSTRACT: Vector analysis technique and ecological sequential comparison methods were adopted to study tree growth response to the micronutrients, B, Mo, Cu, Zn, Fe, and Mn, in soils (red soil and yellow brown soil) derived from various parent materials in the two forest areas of the Taihu Lake region in southeast China. The results showed that the dry weight of individual current-year needle of Chinese fir (Cunninghamia lanceolata) grown on the soil derived from granite parent rock was increased by 8 and 13% in comparison with that grown on the soils derived from sandstone and ash-tuff parent rock, respectively. And such dry weight of loblolly pine (Pinus taeda) grown on the soil derived from sandstone parent rock was increased by 21% in comparison with that on the soil derived from ash-tuff parent rock. One of the reasons for those results was that micronutrients content in the soil derived from ash-tuff parent rock were not sufficient to meet the requirement of the growth of Chinese fir and loblolly pine, i.e., micronutrients in soil were deficient and/or induced deficient. The amounts of Cu, Zn, Fe, and Mn uptake by Chinese fir and loblolly pine were in agreement with the contents of available micronutrients in soil respectively, except for B and Mo. Meanwhile, there might exist an antagonism between the uptake of B versus Mo by trees, although more studies are needed to confirm it. Regression analysis indicated that amount of a soil available micronutrient was correlated to the type of parent material and its total amount in the forest floor, except for B. The F test identified that the correlation of each equation reached the significant level to different extents, respectively. The t test confirmed that amount of available forms was mainly depended on the type of parent material for Mo, Cu, Zn and Mn but on the forest floor for Fe. There was a feedback effect of forest stand on the amount of soil available micronutrients. The ability of accumulating available micronutrients in soil was better by the sawtooth oak (Quercus acutissima) stand than by the Chinese fir stand (except for B). The ability of accumulating available Zn, Fe, Mn and Mo in soil was better in the Chinese fir stand than in the loblolly pine stand, while as for available B and Cu, in the latter was better than in the former. When discussing the effect of forest stand on the amount of soil available micronutrients, not only the amount of micronutrient in the forest floor and the parent materials but also the amount of micronutrient taken up by current-year needles have to be considered.

Lin, C. 2001. Analytical methods for environmental risk assessment of acid sulfate soils: a review. Pedosphere. 11(4): 301--310
ABSTRACT: Assessment of acid sulfate soil risk is an important step for acid sulfate soil management and its reliability depends very much on the suitability and accuracy of various analytical methods for estimating sulfide-derived potential acidity, actual acidity and acid-neutralizing capacity in acid sulfate soils. This paper critically reviews various analytical methods that are currently used for determination of the above parameters, as well as their implications for environmental risk assessment of acid sulfate soils.

Zhao, Q. G. 2001. Resource and environmental quality changes and adjustment principles for sustainable development in rapidly developing coastal region of Southeastern China. Pedosphere. 11(4): 289--299
ABSTRACT: Problems in water-land resources and environmental quality increase with the fast economic development in the coastal region of southeastern China. This region has the highest density in population, industry and towns in China, and the large export-oriented economy makes itself a strategic importance while China enters into international markets. The problems facing this region include arable land reduction, land degradation aggravation, high percentage of built-up land with high rate of expansion, expanded non-point pollution, deteriorating water quality, decreasing biodiversity, destroyed ecosystems, severe air pollution, frequently occurring acid rain, and multi-pollutants. The important research fields in the near future should include: (a) influence of high-intensity exploitation of resources on changes of environment quality and its feedback; (b) interface processes, key mechanisms and adjustment principles for degradation of water-, land-, and air-resources and environmental quality; (c) evolvement processes and nurturing theory of biodiversity and ecological resources; and (d) spatio-temporal variation and human-induced effects on regional resources and environment quality. Strategies for sustainable development in the region are as follows: (a) controlling to ensure basic cultivated land area; (b) enforcing remediation of polluted water environment, and controlling non-point pollution; (c) strengthening ecological construction and ecological security; and (d) controlling multi-pollution and preventing trace toxic pollutants.

Wei, Y. Z. 2001. Critical range of soil boron for prognosis of boron deficiency in oilseed rape. Pedosphere. 11(3): 283--288
ABSTRACT: Relationships between seed yields of oilseed rape (Brassica napus) and extractable boron concentrations in three soil layers (A, P and W) were investigated in ten experiments on three types of soils (Alluvic Entisols, Udic Ferrisols and Stagnic Anthrosols) in northern, western, and middle Zhejiang Province, China. A mathematical model was used to describe the relationship between the seed yield of oilseed rape and the extractable boron concentration in P soil layer. The critical range of the concentrations corresponding to 90% of the maximum oilseed rape yield was 0.40-0.52 mg kg-1. The extractable boron concentration of the P layers of the soils was the most stable. The critical range determined was verified through the production practices of oilseed rape in Zhejiang and Anhui provinces.

Zhang, S. H., Kang, S. Z., Cai, H. J. and Nie, G. Y. 2001. A dynamic model for simulating atmospheric, surface and soil water interactions in hillslopes of loess area under natural conditions and its application. Pedosphere. 11(3): 271--282
ABSTRACT: The mechanism of atmospheric, surface and soil water interactions (water transformation) in hillslopes under natural conditions was analysed. A dynamic model was developed to simulate infiltration, overland flow and soil water movement during natural rainfall on hillslopes. Factors including slope angle, slope orientation and raindrop inclination, which affect the rainfall amount on slope, were taken into account in developing the dynamic model. The effect of surface seal on infiltration and water balance under a boundary condition of the second kind was also considered. Application of the model showed that infiltration overland flow and soil water movement in hillslope under natural rainfall conditions was precisely simulated.

Xia, J. and Chen, X. M. 2001. Numerical analysis on soil and rock formation of ancient gravel strata around Nanjing. Pedosphere. 11(3): 263--269
ABSTRACT: Samples were taken from an ancient gravel stratum, a representative soil layer along the middle-lower reaches of the Yangtze River in East China and one of the primary Neozoic strata in Nanjing district. Located mostly on the second and third terraces, the ancient gravel strata formed the geomorphic landscapes of terrace and step. They were complex in constitution, varied widely in stability, multiple source, locally derived and associated with braided streams in the deposition environment. A modified Cross, Iddings, Pirsson and Washington (CIPW) was used to analyse the soil-rock-forming materials of finer grains (less than 2 mm) of the ancient gravel stratum. Results showed that the sandy grains were composed of apatite, ilmenite, potassium felspar, plagioclase, enstatite and free quartz, the clay mainly of kaolinite, and the cement, a combination of silicon, aluminium and iron at 46:44:10. It was found that the ancient gravel stratum had been protected by the overlying Xiashu loess or basalt and the overloading resulted in overconsolidated strata. The modified CIPW method was applicable and effective for semi-quantitative analysis.

Wu, H. T., Yu, G. F., Qing, C. L. and Chen, T. B. 2001. Relationship between soil properties and different fractions of soil Hg. Pedosphere. 11(3): 257--262
ABSTRACT: Correlation and path analysis were used to study the relationship between soil properties and the distribution of different soil Hg fractions with nine representative soils from Chongqing, China. Results showed that clay ( < 2 mm) could increase water-soluble Hg (r=0.007) and soil organic matter (OM) could enhance the increase of elemental Hg (r=0674). The higher the base saturation percentage (BSP), the more the residual Hg (r=0.684). Organic Hg, the sum of acid-soluble organic Hg and alkali-soluble Hg, was positively affected by silt (2-20 um) but negatively affected by pH, with the direct path coefficients, 1.0487 and 0.5121, respectively. The positive effect of OM (0.7614) and negative effect of BSP (-0.8527) on organic Hg were the most significant. The indirect effect of clay via BSP (path coefficient=0.4186) was the highest, showing that the real influencing factor on acid-soluble organic Hg was the BSP. Since the available Hg fraction, water-soluble Hg, was positively affected by soil clay content and the quite immobile and not bioavailable residual Hg by soil BSP, suitable reduction of clay content and increase of BSP would be of much help to reduce the Hg availability and Hg activity Hg-contaminated soil.

Ni, W. Z., Liang, J. S. and Hardter, R. 2001. Yield and quality responses of selected solanaceous vegetable crops to potassium fertilization. Pedosphere. 11(3): 251--255
ABSTRACT: A series of field experiments were conducted for two years on two silty loam soils grown with solanaceous vegetable crops of aubergines (var. serpentinum), tomato (var. commune), sweet pepper (var. grossum) and chilli (lengum) to investigate the effect of K fertilizer application on the fruit yield and quality of the planted crops, and to observe the differences between effects of sulfate of potash (SOP) and muriate of potash (MOP) on aubergines at high levels of K supply. Fruit yields of the tested crops increased significantly with the increasing rate of K application. A more stable yield was observed in crops applied with K fertilizers as the coefficient of variation of their yields decreased with the rate of K application. The dry matter and vitamin C content in fruits of tomatoes, sweet pepper and chilli, and the sugar content and the titratable acidity level of tomato fruits were increased. The S/A ratio (ratio of sugar content to titratable acidity) of tomato fruits were decreased by K fertilizer application, indicating that K fertilizer application could improve the fruit quality of the solanaceous vegetable crops. However, the high rate of K fertilizer might lower the dry matter and vitamin C contents of tomato and sweet pepper fruits. SOP was more effective than MOP in increasing yield and quality of aubergine fruits at the high fertilizer application rate, therefore SOP may be used for high level of K fertilizer application.

Huang, G. F., Wu, Q. T., Li, F. B. and Wong, J. W. C. 2001. Chemical and biological evaluation of maturity of pig manure compost at different C/N ratios. Pedosphere. 11(3): 243--250
ABSTRACT: Aerobic static pile composting (mechanical turning every 3 days) of pig manure was prepared at 8 m3 windrow heaps. Sawdust was used as the bulking agent to provide additional carbon and to increase the porosity of the substrate. Two treatments with initial C:N ratios of 30 and 15, respectively, were used in the study. Dissolved organic carbon, soluble NH2+-N, C:N ratios in solid and aqueous phases, E4/E2 ratios, and seed germination index (GI) were determined to evaluate the maturity of the co-composts. Seed germination index, a biological parameter, was suggested as one of the most reliable maturity indicators for organic compost. Results showed that the treatment with an initial C:N ratio of 30 reached maturity after 49 days of composting; however, the treatment with an initial C:N ratio of 15 should require composting time more than 63 days to obtain maturation. Chemical multi-indicator evaluation was necessary, and the GI measurement was the recommended approach for maturity evaluation in the study.

Liu, J. X., Yang, X. E., Ni, W. Z. and Yang, Y. 2001. Sodium and potassium absorption and distribution in relation to growth and internal potassium use efficiency of K-efficient and -inefficient rice genotypes. Pedosphere. 11(3): 235--242
ABSTRACT: A pot experiment was conducted using two rice (Oryza sativa) genotypes with different internal potassium use efficiency (IKUE) under different sodium (Na) and potassium (K) levels. Adding NaCl at a proper level, enhanced rice vegetative growth and increased grain yield and IKUE under low potassium. Addition of higher rate of NaCl had a negative effect on the growth of the K-efficient rice genotype. Under low-K stress, higher NaCl decreased IKUE of the K-efficient rice genotype but increased IKUE for the K-inefficient genotype. At tillering stage and under low-K stress, adding NaCl increased K and Na contents and decreased the ratio of K:Na for both genotypes. At harvesting stage under low-K stress, adding NaCl increased K and Na contents and K:Na ratio for the K-efficient genotype but decreased the K:Na ratio for the K-inefficient genotype. The accumulated Na was deposited mostly in the roots and sheaths. At tillering stage, the K and Na contents and the K:Na ratios in different parts for both genotypes decreased in the following sequence: K+ in sheaths > K+ in blades > K+ in roots; Na+ in roots > Na+ in sheaths > Na+ in blades; and K:Na in sheaths ?K:Na in roots. The K-efficient genotype had a lower K:Na ratio in roots and sheaths than the K-inefficient genotype under low-K stress. At harvesting stage, K and Na contents in grains were not affected, whereas K:Na ratio in the rice straws was increased for the K-efficient genotype but decreased for the K-inefficient genotype by Na addition. However, this was not observed under K sufficient condition.

Lu, J., Liu, Y. L. and Hirasawa, T. 2001. Study on intermittent irrigation for paddy rice: II. Crop responses. Pedosphere. 11(3): 227--234
ABSTRACT: Effect of intermittent irrigation on the production of paddy rice (Oryza sativa cv. Nipponbare) was studied in a well-puddled paddy field subjected to four treatments (continuous flooding irrigation, and intermittent irrigation II-0, II-1 and II-2), with 2 replicates in which plants were re-irrigated when the soil water potential fell below 0, -10, and -20 kPa, respectively, at soil depth of about 5 cm. Results showed that the reduction in soil water potential to about -10 or -20 kPa did not significantly affect the number of grains and the percentage of ripened grains. While, a lower crop growth rate resulted from a decrease in the net assimilation rate (NAR) during intermittent irrigation II-1 and II-2, and there was also a reduction in the leaf area index during intermittent irrigation II-2. Senescence of lower leaves on stems was promoted in treatments II-1 and II-2 at the ripening stage. Early senescence at ripening stage and water stress around midday decreased the rate of photosynthesis in leaves, causing the lower NAR. These physiological responses of the plants were responsible for the reduction in the dry matter production and grain yield in the intermittent irrigation treatments.

Liu, W. P., Wang, Q. Q., Yang, W. C. and Wang, X. R. 2001. Adsorption of acetanilide herbicides on soil and its components: IV. Sorption of acetanilide herbicides on soils and its correlation with soil properties. Pedosphere. 11(3): 217--226
ABSTRACT: Sorption of acetanilide herbicides, metolachlor, acetochlor, pretilachlor and butachlor on eight soils with various physical and chemical properties was studied. The adsorption isotherms could fit Freundlich equation (r2?.91), and the adsorption extents increased in the order: metolachlor < acetochlor < pretilachlor < butachlor. A good correlation was observed between the product of Freundlich adsorption constants, Kf(1/n), and organic matter content (OM) of soils for each of these herbicides, suggesting that OM is the primary factor dominating the adsorption process of these acetanilide herbicides. Multivariant correlation regression between Kf(1/n) and two factors, water solubility (Sw) of herbicides and OM, was also performed. Kf(1/n) correlated with 1/Sw and OM/Sw, which showed that high Sw corresponds to a weak tendency to adsorb on soils. Infrared spectra and electron spin resonance parameters confirmed that multi-functional H-bonds and charge-transfer bonds were the main adsorption mechanisms of these acetanilide herbicides. The abilities of herbicides to form these adsorption bonds with humic acid increased in the same order as the extent of adsorption.

Lin, C., Bush, R. T. and Mcconchie, D. 2001. Impeded acidification of acid sulfate soils in an intensively drained sugarcane land. Pedosphere. 11(3): 209--216
ABSTRACT: Recent research results suggest that acidification of acid sulfate soils may be inhibited in well-drained estuarine floodplains in eastern Australia by the absence of natural creek levees. The lack of natural levees has allowed the inundation of the land by regular tidal flooding prior to the construction of flood mitigation work. Such physiographical conditions prevent the development of pre-drainage pyrite-derived soil acidification that possibly occurred at many levee-protected sites in eastern Australian estuarine floodplains during extremely dry spells. Pre-drainage acidification is considered as an important condition for accumulation of soluble Fe and consequently, the creation of favourable environments for catalysed pyrite oxidation. Under current intensively drained conditions, the acid materials produced by ongoing pyrite oxidation can be rapidly removed from soil pore water by lateral leaching and acid buffering, resulting in low concentrations of soluble Fe in the pyritic layer, which could reduce the rate of pyrite oxidation.

Wang, X. Z., Curtis, P. S. and Vogel, C. S. 2001. Effects of soil fertility and atmospheric CO2 enrichment on leaf, stem and root dark respiration of Populus tremuloides. Pedosphere. 11(3): 199--208
ABSTRACT: An open-top chamber experiment was conducted at the University of Michigan Biological Station near Pellston, Michigan, USA, to study the effects of soil fertility and CO2 on leaf, stem and root dark respiration (Rd) of Populus tremuloides. Overall, area-based daytime leaf Rd (Rda) was significantly greater at elevated than at ambient CO2 in high-fertility soil, but not in low-fertility soil. Mass-based leaf Rd (Rdm) was overall greater for high- than for low-fertility soil grown trees at elevated, but not at ambient CO2. Nighttime leaf Rda and Rdm were unaffected by soil fertility or CO2, nor was stem Rda, which ranged from 1.0 to 1.4 umol m-2 s-1 in the spring and 3.5 to 4.5 umol m-2 s-1 in the summer. Root Rda was significantly higher in high- than in low-fertility soil, but was unaffected by CO2. Since biomass production of P. tremuloides will be significantly greater at elevated CO2 while specific Rd will either increase or remain unchanged, it was predicted that carbon loss to the atmosphere through respiration from this ecologically important species would increase at higher CO2. Soil fertility would also interact with elevated CO2 in affecting the carbon flow in the plant-soil-air system.

Pu, L. J., Yang, G. S. and Xu, M. J. 2001. Characteristics and process of land use changes in the Yangtze River Delta, China. Pedosphere. 11(3): 193--198
ABSTRACT: As one of the Developing Countries, China has an arable land per capita far below the world's average level. With the high-density population, fast economic development and urbanization, the Yangtze River Delta shows the typical characteristics of land use in developed regions of China, which are: high land reclamation rate and low arable land per capita, intensive land use and high output value, and rapid increasing of construction land area and fast diminishing of arable lands. The analysis indicates that the process of the arable land changes in the Yangtze river Delta could be divided into four different change stages over the past 50 years.

LÜ, J. L., Zhang, Y. P. and Ma, Z. G. 2001. Kinetic equations for describing phosphorus transport. Pedosphere. 11(2): 189--192
ABSTRACT:

Lu, S. G. 2001. Role of organic matter in formation and stability of aggregates in mulberry plantation soils. Pedosphere. 11(2): 185--188
ABSTRACT: The role of organic matter in the formation and stability of soil aggregates in mulberry (Morus alba) plantation soils in the Hang-Jia-Hu Plain, northern Zhejiang Province, China, classified as Thermic Typic Udarents, was evaluated in this study. A positive correlation was found between water-stable aggregate contents and organic matter contents in the mulberry plantation soils, which supported the hypothesis that organic matter was the main cementing agent in formation of aggregates. A close correlation was also found between aggregate stability and organic matter content. Regression analysis showed that total nitrogen content was also an indicator of water-stable aggregate content and stability. The aggregate size distribution indicated that the water-stable aggregates 1-0.25 mm in diameter were the major component of the aggregates in the mulberry plantation soils. The organic matter contents of aggregates ranging from 5 to 0.25 mm in diameter increased with the decrease of aggregate sizes, and the aggregates 1-0.25 mm in diameter had the maximum organic matter content.

Xu, H. W. and Wang, K. 2001. Regionalization for rice yield estimation by remote sensing in Zhejiang Province. pedosphere. 11(2): 175--184
ABSTRACT: In order to provide a scientific basis for rice yield estimation and improve the accuracy of yield estimation in Zhejiang Province, regionalization indices for rice yield estimation by remote sensing (RS) in the province were determined by considering the special features of yield estimation by RS,and based on analysis of the natural conditions of Zhejiang Province.The indices determined included rice cropping system,agroclimate,landform,surface feature structure and rice yield level,where rice planting system was considered as the main one.Then regionalization for rice yield estimation by RS was completed by spatial neighboring analysis with the Geographical Information System (GIS) technology combined with using of tree algorithm.The province was divided into two regions,i.e.,the single-cropping rice region which was subdivided into 3 regions including those in mountains of northwest Zhejiang,water network area of north Zhejiang and mountains of south Zhejiang,and double-cropping rice region which was subdivided into 5 regions including those on plain of north Zhejiang,coastal plains and hills of southeast Zhejiang,Jin-Qu Basin of middle Zhejiang,hills of east Zhejiang,and hills and mountains of northwest Zhejiang.This regionalization took the county borders as the region boundaries,kept the regions connective and made the administrative regions integrity and,then,could meet the requirements of rice yield estimation by RS,showing that the results were quite satisfying.

al-Abed, M., Shi, Z., Yaghi, A. and Wang, R. C. 2001. An integrated GIS/RS approach for soil erosion assessment and modeling in Syrian coastal soils. Pedosphere. 11(2): 167--174
ABSTRACT: An integrated remote sensing (RS) and geographical information system (GIS) technique was employed to characterize the spatial distribution of the risk of soil erosion by water on Latakia district, Syria. The Universal Soil Loss Equation (USLE) was used to calculate the annual soil loss rates for Latakia soils. Mainly, remote sensing data, soil survey, land use inventory, elevation data and climatic atlases were used as resource data sets to generate USLE factor values. The results revealed that integration of GIS/RS with USLE was a practical and effective approach for monitoring soil erosion over large areas.

Wu, P. X., Guo, J. G., Zhang, H. F. and Liao, Z. W. 2001. Adsorption of environmental pollutants on pillared montmorillonite. Pedosphere. 11(2): 159--166
ABSTRACT: Both inorganic and organic pillared montmorillonites were used to adsorb phenol. Batch kinetics and isotherm studies were carried out to evaluate the effect of equilibrium time and pH on adsorption of phenol by montmorillonites and re-adsorbing characteristics of pillared montmorillonites. The adsorption of phenol increased with increasing solution pH values. The elimination ratio of phenol from the solution by the absorption of organic modified pillared montmorillonite (OrPMt) reached equilibrium quickly after vibrating for 5 minutes. Meanwhile for organic montmorillonite (OrMt), pillared montmorillonite (PMt) and montmorillonite (Mt), the time to reach phenol-absorption equilibrium were 20, 30 and 90 minutes, respectively. The adsorbing capacity of the pillared montmorillonite modified with surfactant improved greatly. The phenol-adsorbing capacity of pillared montmorillonites mainly depended on microporous structure and surface component of the modified clays. After calcination at 500!, the pillar structure and the basal spacing (1.83 nm) were still stable. So the pillared montmorillonite could be recycled, and it was a potential material for adsorbing environmental pollutants.

Cheng, L. L., Wen, Q. X. and Chen, B. Y. 2001. Characterization of humic fractions in a 15N-labelled soil by solid-state 13C and 15N NMR. Pedosphere. 11(2): 151--157
ABSTRACT: Five humic fractions were obtained from a uniformly 15N-labelled soil by extraction with 0.1 mol L-1 Na4P2O7, 0.1 mol L-1 NaOH, and HF/HCl-0.1 mol L-1 NaOH, consecutively, and analysed by 13C and 15N CPMAS NMR (cross polarization and magic angle spinning nuclear magnetic resonance). Compared with those of native soils humic fractions studied as a whole contained more alkyls, methoxyls and O-alkyls, being 27-36%, 17-21% and 36-40%, respectively, but fewer aromatics and carboxyls (being 14-20% and 13-90%, respectively). Among those humic fractions, the humic acid (HA) and fulvic acid (FA) extracted by 0.1 mol L-1 Na4P2O7 contained slightly more carboxyls than corresponding humic fractions extracted by 0.1 mol L-1 NaOH, and the HA extracted by 0.1 mol L-1 NaOH after treatment with HF/HCl contained the least aromatics and carboxyls. The distribution of nitrogen functional groups of soil humic fractions studied was similar to each other and also similar to that of humic fraction from native soils. More than 75% of total N in each fraction was in amide form, with 9-13% present as aromatic and/or aliphatic amines and the remainder as heterocyclic N.

Subhani, A., Huang, C. Y., Xie, Z. M., Liao, M. and EL-Ghamry, A. M. 2001. Impact of some agronomic practices on paddy field soil health under varied ecological conditions: II. Influence of soil temperature. Pedosphere. 11(2): 143--150
ABSTRACT: A 21-day incubation experiment was conducted under controlled laboratory conditions to study the effects of elevated temperatures (10, 25, and 40!) on some microbiological and biochemical properties in flooded paddy soil amended or unamended with urea at 100 ug N g-1 soil and/or insecticide (triazophos) at field rate (FR). Enhancements in temperature led to increase the electron transport system (ETS)/dehydrogenase activity and phospholipid contents of the soil, while soil organic matter phenol and protein contents decreased with increasing temperature with or without the addition of inputs. An increase of temperature from 10 ! to 25 or 40 ! enhanced the ETS activity 2 folds (on average for all soils), while the inclusion of N and insecticide increased and decreased it, respectively, compared to the control. The soil phenol and protein contents were highly correlated with temperatures (for all soils, r=-0.936 and -0.971, respectively) and the additions of N and insecticide produced slight reductions and enhancements in them, respectively. At a particular temperature, the soil protein contents remained unaffected among all the soil treatments. An overall slight increase in phospholipid contents with N and a small decline with insecticide addition were noticed against the untreated soil. The toxicity of fertilizer and insecticide decreased as the incubation temperature increased, suggesting faster degradation of agrochemicals with rising temperature.

Zhao, X. L., Qing, C. L. and Wei, S. Q. 2001. Heavy metal runoff in relation to soil characteristics. Pedosphere. 11(2): 137--142
ABSTRACT: Cu, Zn, Pb and Hg runoff from yellow limestone soil [Calcortholl] and purple soils [Typic Udorthents] from Sichuan and Chongqing, China, and the relationships between the mobility of the heavy metals and the soil characteristics were studied in laboratory using a rainfall simulator. The results showed that the concentrations of soluble Zn in surface runoff were significantly negatively correlated with the contents of < 0.002 mm particles and CEC of the soils, indicating that Zn was mostly adsorbed by clays in the soils. The contents of Cu and Hg in surface runoff were positively related to their contents in the soils. The amounts of Cu, Zn, Pb and Hg removed by surface runoff were influenced by the amounts of soil and water losses and their contents in the soils, and were closely related to the contents of soil particles 1-0.02 mm in size.

Xu, S. H., Du, E. H. and Zhang, J. B. 2001. Numerical simulation of preferential flow of contaminants in soil. Pedosphere. 11(2): 131--136
ABSTRACT: A simple modelling approach was suggested to simulate preferential transport of water and contaminants in soil. After saturated hydraulic conductivity was interpolated by means of Krige interpolation method or scaling method, and then zoned, the locations where saturated hydraulic conductivity was larger represented regions where preferential flow occurred, because heterogeneity of soil, one of the mechanisms resulting in preferential flow, could be reflected through the difference in saturated hydraulic conductivity. The modelling approach was validated through numerical simulation of contaminant transport in a two-dimensional hypothetical soil profile. The results of the numerical simulation showed that the approach suggested in this study was feasible.

Han, X. F., Lu, J., Liu, Y. L. and Yu, L. Z. 2001. Coupled transfer of water and heat in red soil: experiment and numerical modelling. Pedosphere. 11(2): 123--130
ABSTRACT: Coupled transfer of soil water and heat in closed columns of homogeneous red soil was studied under laboratory conditions. A coupled model was constructed using soil physical theory, empirical equations and experimental data to predict the coupled transfer. Results showed that transport of soil water was affected by temperature gradient, and the largest net water transport was found in the soil column with initial water content of 0.148 m3 m-3. At the same time, temperature changes with the transport of soil water was in a non-linear shape as heat parameters were function of water content, and the changes of temperature were positively correlated with the net amount of water transported. Numerical modelling results showed that the predicted values of temperature distribution were close to the observed values, while the predicted values of water content exhibited limited deviation at both ends of the soil column due to the slight temperature changes at both ends. It was indicated that the model proposed here was applicable.

Chen, Y. X., Yang, Y., Wang, K. X., Lin, Q. and Tian, G.M. 2001. Effects of heavy metals on ammonification, nitrification and denitrification in maize rhizosphere. Pedosphere. 11(2): 115--122
ABSTRACT: Ammonification, nitrification and denitrification in maize rhizosphere of alluvial soils, collected from the Zhejiang Province in China, were compared with those in the bulk soil after exposure to different kinds of heavy metals. The addition of cadmium at low levels (2 and 5 mg kg-1) could stimulate the ammonification and nitrification in the soils, while inhibition influences were found at high levels of Cd addition (10 and 20 mg kg-1). The relationship between microbial activity and Cd concentration varied with the kind of microorganisms. The nitrifying bacteria were more sensitive to Cd pollution than the ammonifying bacteria. When Cd(II), Cu(II) and Cr(VI) were compared at the same addition concentration of 20 mg kg-1 soil, Cd(II) was the most effective inhibitor of ammonification and denitrification among the three investigated heavy metals, and Cr(VI) had the strongest inhibitory influence on the nitrifying bacteria. The microbial activities in rhizosphere were higher than those in the bulk soil for most of the treatments. Cr(VI) proved to be the most effective in enhancing the microbial activities in the rhizosphere, and this could be caused by the positive reduction of Cr(VI) to Cr(III) in rhizosphere, and the relatively sufficient existence of organic matter which intensified the adsorption of the metal. It seemed that the rhizosphere had some mitigation effect on heavy metal toxicity.

Lin, X. G., Wan, S. G. and Shi, Y. Q. 2001. Tolerance of VA mycorrhizal fungi to soil acidity. Pedosphere. 11(2): 105--113
ABSTRACT: A 45-day greenhouse experiment was carried out to determine effect of vesicular arbuscular (VA) mycorrhizal fungi on colonization rate, plant height, plant growth, hyphae length, total Al in the plants, exchangeable Al in the soil and soil pH by comparison at soil pH 3.5, 4.5 and 6.0. Mung bean (Phaseolus radiatus) [Vigna radiata] and crotalaria (Crotalaria mucronata) [Crotalaria pallida] were grown with and without VA mycorrhizal fungi in pots with red soil. Ten VA myrorrhizal fungi strains were tested, including Glomus epigaeum (No. 90001), G. caledonium (No. 90036), G. mosseae (No. 90107), Acaulospora spp. (No. 34), Scutellospora heterogama (No. 36), S. calospora (No. 37), G. manihotis (No. 38), Gigaspora spp. (No. 47), Glomus manihotis (No. 49), and Acaulospora spp. (No. 53). Being the most tolerant to acidity, strain 34 and strain 38 showed quicker and higher-rated colonization without lagging, three to four times more number of nodules, two to four times more plant dry weight, 30 to 60% more hyphae length, lower soil exchangeable Al, and higher soil pH than without VA mycorrhizal fungi (strain CK). Other strains could also improve plant growth and enhance plant tolerance to acidity, but their effects were not marked. This indicated that VA mycorrhizal fungi differed in the tolerance to soil acidity and so did their inoculation effects. In the experiment, acidic soil could be remedied by inoculation of promising VA mycorrhizal fungi tolerant of acidity.

Yao, H. Y., He, Z. L. and Huang, C. Y. 2001. Phospholipid fatty acid profiles of Chinese red soils with varying fertility levels and land use histories. Pedosphere. 11(2): 97--103
ABSTRACT: Analysis of phospholipid fatty acids (PLFAs) was used to estimate the microbial community structures of eight Chinese red soils (Ultisols) with different fertility levels and land use histories. The total amounts of PLFAs in the soils were significantly correlated with soil organic carbon, total nitrogen, microbial biomass C and basal respiration, indicating that total PLFA was closely related to fertility and sustainability in these highly weathered soils. Soils for the eroded wasteland were rich in Gram-positive species. When the eroded soils were planted with citrus trees, the soil microbial population had changed little in 4 years but took up to 8-12 years before it reached a significantly different population. Multivariate analysis of PLFAs demonstrated that land use history and plant cover type had a significant impact on microbial community structure. However, the difference of soil microbial community structure in the paddy field compared to other land uses was not larger than expected in this experiment.

He, T. X., Wu, D. Y., He, C. H., He, F. J., Marchand, M. and Hardter, R. 2001. Nutrient balance in relation to high yield and good quality of potato on an acid purple soil in Chongqing, China. Pedosphere. 11(1): 83--92
ABSTRACT: A field experiment was carried out from January-June 1996 to study nutrient balance among N, P, K and Mg in potato cultivation on an acid purple soil [Typic Udorthent] in South Western China, China. The experiment included 8 treatments with equal P rate of 120 kg P2O5 hm-2: N0K2, N1K2, N2K2, N3K2, N2K0, N2K1, N2K1Mg and N2K3, where N0, N1, N2 and N3 stand for the N rates of 0, 75, 150 and 225 kg N hm-2, and K0, K1, K2 and K3 for the K rates of 0, 165, 330 and 495 kg K2O hm-2, respectively. Among the treatments designed, Treatment N2K2 with a nutrient supply ratio of N:P2O5:K2O:MgO=1.25:1:2.75:0.28 gave the highest tuber yield and dry matter, highest starch and Zn and lowest NO-3 contents in tuber, and high N, P and K use efficiency with an uptake ratio of N:P:K:Mg=11.38:1:13.32:0.33 by tuber. Yield and starch and protein contents of tuber were the lowest in Treatment N0K2. Dry matter was the lowest but protein and NO-3 contents were the highest in Treatment N2K0. Treatment N2K1Mg had the highest N, P and K utilization rates. Statistical analysis showed that yields of tuber and starch were in a positive linear correlation with the uptake amount of various nutrients and protein of the potato tuber was in a significantly positive linear correlation with tuber N content and in a significantly negative linear correlation with tuber K and Mg contents. Balanced application of N, P, K and Mg fertilizers (Treatment N2K2) was recommended for realization of high yield and good quality in potato cultivation.

Ni, W. Z. and Hardter, R. 2001. Influence of potassium fertilization on yield and quality of foliar vegetable crops. Pedosphere. 11(1): 77--82
ABSTRACT: Over a period of two years, field experiments were conducted on four silty loam soils in China, grown with foliar vegetable crops including Chinese cabbage (Brassica pekinensis cv. Lu-Bai 3), autumn greens (B. chinensis cv. Piao-Geng-Bai), winter greens (B. var. rosularis cv. You-Dong-Er), and summer greens (B. chinensis cv. Zao-Shu 5), respectively [date not given]. Each experiment included one CK (no fertilizer) treatment without K, N and P fertilizers applied, and four treatments with low to high doses, 0-300 kg hm-2 for Chinese cabbage, 0-150 kg hm-2 for autumn and winter greens and 0
ÿ80 kg hm-2 for summer greens, of K fertilizers in the form of sulfate of potash (SOP) applied together with N and P fertilizers. One treatment of K fertilizer in the form of muriate of potash (MOP) applied at high levels (150 or 180 kg hm-2) together with N and P fertilizers was included in the experiments of autumn, winter and summer greens, respectively, in order to compare the effects of SOP and MOP. The market yields of the tested crops increased significantly with the increasing rate of K application. The crops supplied with K fertilizers yielded more stably as the CV% of their yields decreased with the rate of K application. Application of K fertilizers increased not only K contents but also the amounts of N, P and K absorbed in shoots of autumn, winter and summer greens, which were statistically significantly correlated to their yields. Potassium improved the quality of the foliar vegetable crops as their dry matter contents were generally increased, Vc (vitamin C) contents increased, and nitrate contents markedly decreased. Compared to MOP, SOP was more effective on the yields and quality of autumn, winter and summer greens at high levels of fertilization.

Chu, H. Y., Wang, J. H., Xie, Z. B., Zhu, J. G., Li, Z. G. and Cao, Z. H. 2001. Effect of lanthanum on major microbial populations in red soil. Pedosphere. 11(1): 73--76
ABSTRACT: Pure culture and pot culture experiments were carried out to study the effect of lanthanum (La) on bacteria, actinomyces and fungi, and the microbial physiological groups, nitrifier, azotobacter and phosphobacteria, in a red soil taken from an experimental site in Jiangxi Province, China. LaCl3 was added into media at levels of 0, 25, 50, 100, 150, 200, 250 and 500 mg litre-1 in the pure culture experiment, and into soil samples in porcelain pots before rice growing at levels of 0, 6, 30, 150, 300, 600 and 900 mg kg-1 dry soil in the pot culture experiment. The populations of the three groups of soil microbes in the pure culture experiment decreased with the addition level of La, indicating that La was toxic to the soil microbes in pure culture, and the sensitivity of the 3 major microbial types to La was in a decreasing order of actinomyces > bacteria > fungi. In the pot experiment, La had slightly stimulative effect on soil bacteria and actinomyces when applied at low concentrations, while had inhibitory effect on soil bacteria, actinomyces and fungus at high concentrations. When the concentration of La was low, soil azotobacter was stimulated slightly while soil nitrifier was stimulated strongly and the maximum increase was up to 50%. When the concentration of La was high, both soil azotobacter and nitrifier were inhibited, and the inhibition of La to the nitrifier increased with La concentration. La added at all the levels had stimulative effect on soil inorganic and organic phosphobacteria. Among the 4 physiological groups, the soil nitrifier was most sensitive to La, so, it might be reasonable to assume that the soil nitrifier was a sensitive indicator for evaluating the biological and environmental effects of rare earths.

Zhuang, S. Y., Yin, B. and Zhu, Z. L. 2001. A simulation study on effect of surface film-forming material on water evaporation. Pedosphere. 11(1): 67--72
ABSTRACT: A greenhouse experiment was conducted to investigate the effect ofsurface film-forming material (SFFM), a mixture of1618-octadecanols by emulsification, on water evaporation.Air-dried soil with distilled water was incubated firstly for 7 days toreestablish soil biological activity and then for another 7 days aftertreated with SFFM at rates of 0, 1, 2, 4, 6 and 8 g m-2,respectively. Everyday during the 7-day incubation after addition of SFFM, water losses due to evaporation were measured by an electronicbalance. The rate of water evaporation with the addition of SFFM wasreduced significantly compared with the control treatment and theeffectiveness of SFFM on water evaporation reduced with time. Accordingto the equation expressions of the effect of SFFM on water evaporation,the half-life of effectiveness of SFFM on water evaporation wasintroduced and calculated to analyze quantitative relationship betweenthe effectiveness of SFFM on water evaporation and the addition rate ofSFFM. The calculated half-life increased with the addition rate of SFFMand the confidence of the calculated values of the half-life was high,suggesting that the half-life of effectiveness of SFFM on waterevaporation could be described quantitatively and may be helpful forameliorating application method of SFFM and screening surface-filmforming materials in order to improve nitrogen fertilizer useefficiency in flooded rice fields.

Zhao, Y. W., Beaton, J. D., Cao, Z. H., Henderson, A. M., Hu, Z. Y. and Xu, C. K. 2001. Relationships between sulfur concentration in mulberry leaves and the quality of silkworm cocoon. Pedosphere. 11(1): 63--66
ABSTRACT: S concentrations in samples of mulberry leaves and silkworm({ Bombyx mori L.} cocoon shells and quality of cocoon takenfrom typical mulberry gardens of six provinces located in the lower tomiddle reaches of the Yangtze River were analyzed by the method ofapplied biostatistics on sericulture to study the relationships betweencocoon quality and S concentrations in mulberry leaves and cocoonshells. The results showed that two-power function relationshipsbetween concentration of sulfur in mulberry leaves and characters ofcocoon quality were significant (R2=0.139*0.329**,n=24 29, a CFI > II-2 > II-1.

Subhani, A., Liao, M., Huang, C. Y. and Xie, Z. M. 2001. Impact of some agronomic practices on paddy field soil health under varied ecological conditions: I. Influence of soil moisture. Pedosphere. 11(1): 39--48
ABSTRACT: The effects of individual and combined additions of urea (100 ug N g-1 soil) and insecticide (triazophos at field rate, FR) under different moisture levels of air-dried soil, 50% of water-holding capacity (WHC), 100% WHC and flooded soil (FS) on some selected soil properties in a paddy field soil were examined in a laboratory incubation study. The results indicated that after 21-day incubation at 25!, the different moisture levels led to significant changes in the parameters studied. Flooding of soil with distilled water significantly increased the electron transport system (ETS)/dehydrogenase activity and phenol contents of the soil compared to the other moisture levels, while protein and phospholipids behaved differently at varied moisture levels with or without the addition of urea and/or triazophos. Increased ETS activity was observed with N addition at higher moisture levels while insecticide incorporation decreased it at all moisture levels as compared to the control (moisture only). The phenol contents slightly decreased and increased with N and insecticide applications, respectively. The soil protein contents were found to be unaffected among all the soil treatments at all moisture levels. However, among different moisture levels, reduced quantities of proteins were estimated at 50% WHC, suggesting more N-mineralization. Lower quantities of soil biomass phospholipids, among all treatments, were recorded at higher moisture levels (100% WHC and FS) than at the lower levels. An overall slight enhancement in phospholipid contents with N and small reduction with insecticide addition, respectively, was noticed against the untreated soil. The toxicity of fertilizer and insecticide decreased as the soil moisture contents increased, suggesting rapid degradation of agrochemicals.

Lin, C., McConchie, D., Bush, R. T., Sullivan, L. A. and Rosicky, M. 2001. Characteristics of some heavy metals in acid sulfate topsoils, eastern Australia. Pedosphere. 11(1): 31--37
ABSTRACT: Forty-five acid sulfate topsoil samples (depth < 0.5 m) from 15 soil cores at 11 locations along the New South Wales coast, Australia, were selected to investigate the chemical behaviour of Zn, Mn, Cr, Co and Pb in these soils. The amount of HCl-extractable Mn was much smaller than the mean value of the total Mn documented for other soils. This may be attributed to enhanced mobilization of Mn from the soils under the extremely acidic and seasonally flooded conditions encountered in the investigated soils. The pH-dependency of soluble Zn and Mn was strongly affected by the availability of acid reactive Zn and Mn compounds. There were fairly good relationships between soluble Zn and acid reactive Zn compounds, and between soluble Mn and acid reactive Mn compounds. Soluble Zn and soluble Mn concentrations were important controls on exchangeable Zn and Mn concentrations, respectively. In contrast to the suggestion by other authors that adsorption of Co was closely associated with Mn oxides present in soils, the exchangeable Co in the investigated acid sulfate soils was not clearly related to the abundance of Mn minerals. In addition to the fact that there are few Mn minerals present in the soils, this might also be because the availability of cation exchange sites on the crystal surfaces of Mn oxides was reduced under extremely acidic conditions.

Lu, W. J., Reichardt, W. and Huang, C. Y. 2001. Dynamics of phenol degrading-iron reducing bacteria in intensive rice cropping system. Pedosphere. 11(1): 21--30
ABSTRACT: Field and greenhouse experiments were conducted in 1999 to investigate the effects of cropping season, nitrogen fertilizer input and aerated fallow on the dynamics of phenol degrading-iron reducing bacteria (PD-IRB) in tropical irrigated rice (Oryza sativa) systems. In a greenhouse mesocosms the soil used was Maahas clay soil from the IRRI research farm, the Philippines. The PD-IRB population density was monitored at different stages of rice growth in two cropping seasons (dry and early wet) in a continuous annual triple rice cropping system under irrigated condition. In this system, the high nitrogen input (195 and 135 kg N ha-1 in dry and wet seasons, respectively) plots and control plots receiving no N fertilizer were compared to investigate the effect of nitrogen rate on population size. The phenol degrading-iron reducing bacteria (PD-IRB) were abundant in soils under cropping systems of tropical irrigated rice. However, density of the bacterial populations varied with rice growth stages. Cropping seasons, rhizosphere and aerated fallow could affect the dynamics of PD-IRB. In the field trial, viable counts of PD-IRB in the topsoil layer (15 cm) ranged between 102 and 108 cells per gram of dry soil. A steep increase in viable counts during the second half of the cropping season suggested that the population density of PD-IRB increased at advanced crop-growth stages. Population growth of PD-IRB was accelerated during the dry season compared to the wet season. In the greenhouse experiment, the adjacent aerated fallow revealed 1-2 orders of magnitude higher in most probable number (MPN) of PD-IRB than the wet fallow treated plots. As a prominent group of Fe reducing bacteria, PD-IRB predominated in the rhizosphere of rice, since maximum MPN of PD-IRB (2.62 x 108 g-1 soil) was found in rhizosphere soil. Mineral N fertilizer rates showed no significant effect on PD-IRB population density.

Fujita, M. and Fujiyama, S. 2001. Comparison of soil fauna (oribatids and enchytraeids) between conventional and organic (tillage and no-tillage practices) farming crop fields in Japan. Pedosphere. 11(1): 11--20
ABSTRACT: The major soil animal groups, enchytraeid worms and oribatid mites, from soil samples of 0? cm layer obtained from 17 crop fields in central Japan carried out in the springs (April and May) of 1987-1995, were compared in the abundance and diversity between conventional fields (CT) and organically farmed fields with tillage (OT) or no-tillage (ON) practices. The values of abundance, species richness, diversity and evenness were significantly (P < 0.05) greater in OT and ON than in CT, indicating that the abundance and diversity in organic farming fields were greater than those in conventional farming. Out of eight genera collected from all the fields, each of the three genera, Enchytraeus, Fridericia, Henlea, was obtained from at least 56% of total fields. The community structure of enchytraeid genera was different between OT and ON. Enchytraeus was the most abundant in OT, while Fridericia in ON and Henlea comprising 4.4 and 16.7% for OT and ON, respectively. The abundance of oribatids in OT was similar to that in ON, while the species richness and diversity in the former were smaller. Each of the three orbatid species, Tectocepheus velatus, Ramusella tokyoensis and Scheloribates laevigatus was obtained from at least 56% of total fields. These results suggested that no-tillage practice under organic management might contribute to the improvement in quality of soil mesofauna.

Wen, Q. X., Zhuo, S. N. and Cheng, L. L. 2001. 15N NMR spectroscopic study on nitrogen forms in humic substances of soils. Pedosphere. 11(1): 1--9
ABSTRACT: Nitrogen forms of humic substances from a subalpine meadow soil (Cryi-Calcaric Cambisol), a lateritic red soil (Acrisol) and a weathered coal and the effect of acid hydrolysis on N structures of soil humic substances were studied by using 15N cross-polarization magic angle spinning nuclear magnetic resonance spectroscopy. The soil samples were collected from the A horizon (5-25 cm) in Menyuan County, Qinghai Province, from the A horizon (0-18 cm) in Zhangpu County, Fujian Province and in Gong County, Henan Province, China, respectively. Of the detectable 15N-signal intensity in the spectra of soil humic substances 71-79% may be attributed to amide groups, 10-18% to aromatic/aliphatic amines and 6-11% to indole- and pyrrole-like N. In the spectrum of the fulvic acid from weathered coal 46%, at least, of the total 15N-signal intensity might be assigned to pyrrole-like N, 14% to aromatic/aliphatic amines, and the remaining intensities could not be assigned with certainty. Data on nonhydrolysable residue of protein-sugar mixture and a 15N-labelled soil fulvic acid confirm the formation of nonhydrolysable heterocyclic N during acid hydrolysis.

Ma, M. T. and Xie, J. C. 2000. Some fertility characteristics and fertilizer requirements of a newly reclaimed upland red soil derived from Quaternary red clay. Pedosphere. 10(4): 373--382
ABSTRACT: A series of field experiments from 1990 to 1994 in Yingtan, Jiangxi Province, China, were conducted on an upland red soil derived from Quaternary red clay which had been reclaimed three years before the experiments, in order to study the fertility characteristics and fertilizer requirements of the newly reclaimed soil. The field experiments included the nutrient characteristics and fertilizer effect, the K-supplying potential and K-Mg relationship, and the fertilization rates of K and N. The newly reclaimed upland soil was low in both N and P, and its responses to nitrogen and phosphate application were very significant. The K-supplying potential was also low, so the soil was highly responsive to K fertilizer. The effect of Ca and Mg fertilizers was not so great for the reason that certain amounts of Ca and Mg were incorporated into the soil through application of calcium magnesium phosphate during land levelling before the experiments. Among the four micronutrients, B, Mo, Zn and Cu, B had the greatest effect on the soil. The fertilizer requirements of the soil were in the order: P and N > K > lime and B > Mg > Mo, Zn and Cu. Eight crops tested had different fertilizer-requiring characteristics. Rapeseed was very sensitive to P and B fertilizers. Barley was especially sensitive to P and lime and it also responded to B, Mo, Zn and Cu. Sweet potato was especially sensitive to K.

Tu, S. X., Sun, J. H., Guo, Z. F., Huang, M. and Zhang, P. 2000. Genotypic variations in potassium absorption and utilization by Amaranthus spp. Pedosphere. 10(4): 363--372
ABSTRACT: The kinetics of K+ absorption and the utilization of both applied K and K in a calcareous alluvisol with low available K by different genotypes of grain amaranth (Amaranthus spp.), an ancient pseudo-cereal that produces a large biomass and a rich source of healthy nutrients and mineral elements, were studied by means of ion depletion technique and pot experiments. Grain amaranth had a high affinity for K+ uptake in comparison with maize and cotton. However, there were differences among Amaranthus spp. in K absorption and utilization. Some cultivars such as R104, CX-4, Du001, Hy015 and Hr029 which had a higher rate of K absorption and stronger affinity for K+ were typical varieties with high K-use efficiency (KUE). The results showed that high KUE cultivars grew quickly, possessed stronger ability to take up soil slowly available K and mineral K, and did not respond to K fertilization in the soil with low available K. Correspondingly, grain amaranth cultivars CX-77, Cr024, Vd001, Re003 and Sn003 were relatively low in KUE. Compared with high KUE cultivars, they took up more soil available K, and both their dry matter accumulation and K uptake responded significantly to applied K.

Li, X. Y., Dong, Y. Y. And Luo, H. T. 2000. Effects of phosphate adsorption on adsorption-desorption and availability of Cu and Zn ions in Ultisols and Alfisols. Pedosphere. 10(4): 355--362
ABSTRACT: Surface charge, secondary adsorption-desorption and form distribution of Cu2+ and Zn2+ in Ultisols and Alfisols having adsorbed phosphate were studied by potentiometric titration, adsorption equilibrium and sequential extraction method, respectively. The soil surface negative charges increased whereas the amount of positive charges decreased with increase of P adsorbed. The soil secondary adsorption capacity for Cu2+ and Zn2+ was positively significantly correlated with the amount of P adsorbed by the soils, which could be described by the Langmuir equation. The amounts of Cu2+ and Zn2+ desorption from soils were decreased after P adsorption by the soils and the relationship between them was linear. After the soils adsorbed P, form distribution of Cu2+ and Zn2+ in soils changed markedly.

Yuan, L., Wang, Z. H., Fang, D. H., Shun, H. and Huang, J. G. 2000. Bio-mobilization of potassium from clay minerals: II. By ectomycorrhizal fungi. Pedosphere. 10(4): 347--354
ABSTRACT: Ectomycorrhizal fungi, including Cenococcum geophilum SIV (Cg SIV), and Pisolithus tinctorius 2144 (Pt 2144), 441 (Pt 441) and XC1 (Pt XC1), were cultured in Pachlewski liquid medium with H2KPO4, KCl-saturated vermiculite and mica as K sources, respectively, to investigate the mechanism of K absorption and mobilization by the fungi. Fungal growth rate, K absorption and mobilization varied significantly among the fungal species. Faster growth and greater K accumulation in Pt XC1 than Pt 2144, Pt 441 and Cg siv were observed. Ectomycorrhizal fungi depressed HCl-soluble K in minerals after successive extractions by water and NH4OAc. Ratio of the total amount of K, including water-, NH4OAc- and HCl-soluble K, lost from substrates to the K accumulated in fungal colonies was less than 60%. These reveal that the ectomycorrhizal fungi could utilize K in interlayer and structural pools, which are usually unavailable for plants in short period. Large differences in the depletion of K in interlayer and structural pools by fungi were observed at fungal harvest. Taking into account the nutrient absorption by ectomycorrhizal fungi in symbionts and the direct contact between hyphae and soils, the fungi species colonized on the root surfaces seemed to be related to the effectiveness of mycorrhizas to utilize K in soils. Ectomycorrhizal fungi differed in the efflux of protons and oxalate. Pt XC1 was observed to have greatest ability to effuse protons and oxalate among the fungi adopted in the experiment. Furthermore, the higher the concentrations of protons and oxalate in the liquid culture solutions, the larger the depletion of K in interlayer and structural pools in minerals by fungi. Protons could replace interlayer K and chelation of oxalate with Fe and Al in crystal lattice could cause weathering of clay minerals. So, protons and oxalate produced by ectomycorrhizal fungi might play an important role in K mobilization in these two pools.

Yuan, L., Fang, D. H., Wang, Z. H., Shun, H. and Huang, J. G. 2000. Bio-mobilization of potassium from clay minerals: I. By ectomycorrhizas. Pedosphere. 10(4): 339--346
ABSTRACT: A pot experiment was carried out to investigate the effect of ectomycorrhizal fungi on eucalyptus growth and K bio-mobilization from soils and clay minerals. In the experiment, sands mixed with soil, KCl-saturated vermiculite and mica, respectively, were used to nurse eucalyptus seedlings which were non-ectomycorrhized or ectomycorrhized by an ectomycorrhizal fungus Pisolithus tinctorius strain XC1 (Pt XC1) isolated from a forest soil from Xichang, Sichuan Province, China, and an ectomycorrhizal fungus P. tinctorius strain 2144 (Pt 2144) obtained in Australia. More depletion of HCl-soluble K by mycorrhizas from the soil and minerals than non-mycorrhizas suggested that mycorrhizas had a great ability to mobilize K present in the interlayer and feldspar. Mycorrhizal seedlings depressed greatly K digested with HF-HClO4 from substrates after consecutive extractions of soils and minerals by water, ammonium acetate and boiling HCl, while non-mycorrhizal seedlings reduced it little if any, showing that the mycorrhizal seedlings could mobilize and then utilize the structural K in mineral lattice. Ectomycorrhizal fungi played a very important role not only in promoting the growth of eucalyptus seedlings but also in mobilizing K in soils and minerals. The infection of Pt XC1 led to a better growth of eucalyptus seedlings and more K accumulation in the seedlings than that of Pt 2144. The large differences in K accumulation by the seedlings might be due to different abilities of the two ectomycorrhizal fungi to mobilize K in interlayer and lattice pools in the clay minerals.

Zheng, Y. and Zhang, F. S. 2000. Effect of soil moisture on release of low-molecular-weight organic acids in root exudates and the accumulation of iron in root apoplasm of peanut. Pedosphere. 10(4): 333--338
ABSTRACT: A three-compartments rhizobox was designed and used to study the low-molecular-weight organic acids in root exudates and the root apoplastic iron of 'lime-induced chlorosis' groundnut grown on a calcareous soil in relation to different soil moisture conditions. Results showed that groundnut chlorosis developed under condition of high soil moisture level (250 g kg-1), while groundnuts grew well and chlorosis did not develop when soil moisture was kept at a normal level (150 g kg-1). The malic acid, maleic acid and succinic acid contents of chlorotic groundnut increased by 108.723, 0.029 and 22.446 ug cm-2, respectively, compared with healthy groundnuts. The content of citric acid and fumaric acid also increased in root exudates of chlorotic groundnuts. On Days 28 and 42 of groundnut growth, the accumulation of root apoplastic iron in chlorotic groundnuts was higher than that of healthy groundnuts. From Day 28 to Day 42, the mobilization percentages of chlorotic groundnuts and healthy groundnuts to root apoplastic iron were almost the same, being 52.4% and 52.8%, respectively, indicating that the chlorosis might be caused by the inactivation of iron within the groundnut plant grown on a calcareous soil under high soil moisture conditions.

Chen, X. M., Vanclooster, M. and Pan, G. X. 2000. Impact of soil water flux on vadose zone solute transport parameters. Pedosphere. 10(4): 323--332
ABSTRACT: The transport processes of solutes in two soil columns filled with undisturbed soil material collected from an unsaturated sandy aquifer formation in Belgium subjected to a variable upper boundary condition were identified from breakthrough curves measured by means of time domain reflectometry (TDR). Solute breakthrough was measured with 3 TDR probes inserted into each soil column at three different depths at a 10 minutes time interval. In addition, soil water content and pressure head were measured at 3 different depths. Analytical solute transport models were used to estimate the solute dispersion coefficient and average pore-water velocity from the observed breakthrough curves. The results showed that the analytical solutions were suitable in fitting the observed solute transport. The dispersion coefficient was found to be a function of the soil depth and average pore-water velocity, imposed by the soil water flux. The mobile moisture content on the other hand was not correlated with the average pore-water velocity and the dispersion coefficient.

Li, H. X., Zhang, X. M. and Liu, Y. J. 2000. Soil components affecting phosphate sorption parameters of acid paddy soils in Guangdong Province. Pedosphere. 10(4): 317--321
ABSTRACT: Soil components affecting phosphate sorption parameters were studied using acid paddy soils derived from basalt, granite, sand-shale and the Pearl River Delta sediments, respectively, in Guangdong Province, China. For each soil, seven 2.50 g subsamples were equilibrated with 50 mL 0.02 mol L-1 (pH=7.0) of KCl containing 0, 5, 10, 15, 25, 50 and 100 mg P kg-1, respectively, in order to derive P sorption parameters (P sorption maximum, P sorption intensity factor and maximum buffer capacity) by Langmuir isotherm equation. It was shown that the main soil components influencing phosphate sorption maximum (Xm) included soil clay, pH, amorphous iron oxide (Feo) and amorphous aluminium oxide (Alo), with their effects in the order of Alo > Feo > pH > clay. Among these components, pH had a negative effect, and the others had a positive effect. Organic matter (OM) was the only soil component influencing P sorption intensity factor (K). The main components influencing maximum phosphate buffer capacity (MBC) consisted of soil clay. OM, pH, Feo and Alo, with their effects in the order of Alo > OM > pH > Feo > clay. Path analysis indicated that among the components with positive effects on MBC, the effect was in the order of Alo > Feo > clay, while among the components with negative effects, OM > pH. OM played an important role in mobilizing phosphate in acid paddy soils mainly through decreasing the sorption intensity of phosphate by soil particles.

Shi, Z., Wang, K. and Bailey, J. S. 2000. Sampling strategies for soil available K and P at field scale. Pedosphere. 10(4): 309--315
ABSTRACT: Field nutrient distribution maps obtained from the study on soil variations within fields are the basis of precision agriculture. The quality of these maps for management depends on the accuracy of the predicted values, which depends on the initial sampling. To produce reliable predictions efficiently the minimal sampling size and combination should be decided firstly, which could avoid the misspent funds for field sampling work. A 7.9 hectare silage field close to the Agricultural Research Institute at Hillsborough, Northern Ireland, was selected for the study. Soil samples were collected from the field at 25 m intervals in a rectangular grid to provide a database of selected soil properties. Different data combinations were subsequently abstracted from this database for comparison purposes, and ordinary kriging used to produce interpolated soil maps. These predicted data groups were compared using least significant difference test method. The results showed that the 62 sampling sizes of triangle arrangement for soil available K were sufficient to reach the required accuracy. The triangular sample combination proved to be superior to a rectangular one of similar sample size.

Huang, Q. Y., Wu, J. M., Chen, W. L. and Li, X. Y. 2000. Adsorption of cadmium by soil colloids and minerals in presence of rhizobia. Pedosphere. 10(4): 299--307
ABSTRACT: Experiments were conducted to study the adsorption of Cd on two soil colloids (red soil and yellow-brown soil) and three variable-charge minerals (goethite, non-crystalline Fe oxide and kaolin) in the absence and presence of rhizobia. The tested strain Rhizobium fredii C6, tolerant to 0.8 mmol Cd L-1, was selected from 30 rhizobial strains. Results showed that the isotherms for the adsorption of Cd by examined soil colloids and minerals in the presence of rhizobia could be described by Langmuir equation. Within the range of the numbers of rhizobial cells studied, the amount of Cd adsorbed by each system increased with increasing rhizobial cells. Greater increases for the adsorption of Cd were found in red soil and kaolin systems. Rhizobia influence on the adsorption of Cd by examined soil colloids and minerals was different from that on the adsorption of Cu. The presence of rhizobia increased the adsorption affinity of soil colloids and minerals for Cd, particularly for the goethite and kaolin systems. The discrepancies in the influence of rhizobia on the adsorbability and affinity of selected soil colloids and minerals for Cd suggested the different interactions of rhizobia with various soil components. It is assumed that bacterial biomass plays an important role in controlling the mobility and bioavailability of Cd in soils with kaolinite and goethite as the major colloidal components, such as in variable-charge soil.

Xu, J. M., Koskinen, W. C. and Cheng, H. H. 2000. Movement and degradation of metolachlor and metribuzin in North Central Sand Region of Minnesota under irrigated potato production. Pedosphere. 10(4): 289--298
ABSTRACT: Field studies were conducted to determine the dissipation and movement of metribuzin and metolachlor applied at conventional rates to a Verndale sandy loam (Udic Argiboroll) in north-central Minnesota, USA, under irrigated potato production for two years. The rapid dissipation of both metribuzin and metolachlor was found during the initial 10 to 15 days in both years, and more than 70% of the applied herbicide dissipated during this period. From 10 to 15 days after application up to the end of growing season in both years, the levels of both herbicides decreased slowly with time. Metolachlor dissipated at a slower rate than metribuzin in surface soil and could carry over to the next cropping season. Metribuzin and metolachlor were detected in only 6 and 1 of 154 soil samples in the first year and in 3 and 4 of 225 soil samples in the second year, taken from 15 to 75 cm, respectively. Fifty to 67% of water samples from suction samplers at 135-cm depth contained detectable levels ( > 0.4 ug L-1) of herbicides in both years. Under laboratory conditions degradation of both herbicides was much slower than their dissipation in field. Therefore, it appeared that leaching might be an important dissipation pathway for metribuzin and metolachlor under irrigated potato production.

Wang, H. and Chu, T. D. 2000. Characteristics of magnesium release from fluvo-aquic soil and relative availability of magnesium to plants. pedosphere. 10(3): 281--288
ABSTRACT: Experiments including two in laboratory and one in greenhouse were carried out to study non-exchange able magnesium release from fluvo-aquic soils sampled from Daxing and Changping counties located in the suburbs of Beijing and Mg relative availability of the two soils to plants. In a batch experiment in laboratory the soils were incubated under wet conditions and alternation of dry and wet conditions and determined for amount of Mg released at the 4th, 8th and 12th week, respectively, after extraction of exchangeable Mg with 1 mol L-1 NH4Ac. The amount of Mg released from the soil of Daxing was higher than from the soil of Changping, which was in accordance with the fact that the soil of Daxing had higher contents of all forms of Mg than that of Changping. There was little difference in Mg release from soils between wet conditions and alternation of dry and wet conditions. About 1%^ÿ2% of the total non-exchangeable Mg might be released within 12 weeks of incubation, restoring about 30%^ÿ35% of the original soil exchangeable Mg. Results of the experiment on kinetics of Mg release from the soils through continuous extractions with 0.5 mol L-1 NH4Ac (pH 7.0) on a continuous flow apparatus in laboratory showed that Mg released rapidly in the beginning, decreased sharply with time and kept stable at 60 and 240 rain for the soils of Changping and Daxing, respectively. Among the five mathematical models used to describe the kinetics of Mg release, the parabolic diffusion equation best fitted the cumulative Mg release, indicating that diffusion of Mg out of the soils might be the controlling process. The experiment of exhaustive cropping with 1 crop of tomato (Lycopersicon esculentum Mill.) followed by six crops of corn (Zea mays L.) in greenhouse showed that soil exchangeable Mg decreased remarkably with cropping. After three crops, the percentage of the total plant Mg uptake that came from soil non-exchangeable Mg was 29.5% for the soil from Changping and 35% for the soil from Daxing. About 50% of the total Mg uptake by plants in the six crops was believed to come from the soil non-exchangeable Mg form.

Feng ,Y. J., Yang, J. S. and Zheng, J. H. 2000. Correlation between soil water retention capability and soil salt content. pedosphere. 10(3): 275--280
ABSTRACT: The soil moisture retention capability of Chao soil and coastal saline Chao soil in Shandong and Zhejiang provinces were measured by pressure membrane method. The main factors influencing soil moisture retention capability were studied by the methods of correlation and path analyses. The results indicated that ÿ 0.02mm physical clay and soil salt content were the main factors influencing soil moisture retention capability. At soil suction of 30^ÿ50 kPa, the soil salt content would be the dominant factor.

Tan, W. F., Liu, F., Li, Y. H., He, J. Z. and Li, X. Y. 2000. Mineralogy of manganese oxide minerals in iron-manganese nodules of several main soils in China. pedosphere. 10(3): 265--274
ABSTRACT: X-ray diffraction and selective chemical dissolution methods were used to investigate the composition of Mn oxide minerals in Fe-Mn nodules of several main types of soils in China. The changes of relative intensity of X-ray diffraction patterns were studied both before and after chemically selective dissolution. It was found that lithiophorite was a common Mn oxide in all examined Fe-Mn nodules. Todorokite, however, was a predominant Mn oxide in Fe-Mn nodules in cal-aquic Vertisols of Linyi, Shandong Province. The Fe-Mn nodules of arp-udic Luvisols in Wuhan and Zaoyang, Hubei Province, contained birnessite and vernadite. Hollandite was found in Fe-Mn nodules of alt-udic Ferrisols of Yizhang, Hunan Province; arp-udic Luvisols of Zaoyang, Hubei Province; and cal-aquic Vertisols of Linyi, Shandong Province. The Fe-Mn nodules in alt-udic Ferrisols of Guiyang, Hunan Province, had a few coronadites. Mineralogy of Mn oxide minerals in soil Fe-Mn nodules was related to soil environment, soil types and quantities of relevant cations.

Subhani, A., Liao, M., Huang, C. Y. and Xie, Z. M. 2000. Effects of some management practices on electron transport system (Ets) activity in paddy soil. pedosphere. 10(3): 257--264
ABSTRACT: Electron transport system (ETS)/dehydrogenase activity in a paddy field soil was measured under a variety of incubation conditions using the reduction of 2-(p-iodophenyl-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (INT) to iodonitrotetrazolium formazan (INTF). The results exhibited a high positive correlation between the ETS activity and the incubation temperature and soil moisture. Dehydrogenase/ETS activity displayed a negative correlation with insecticide concentrations, and the activity affected adversely as the concentration of the insecticide increased. The higher doses, 5 and 10 field rates (1 field rate = 1500 mL ha-1), of insecticide significantly inhibited ETS activity, while lower rates failed to produce any significant reducing effect. Inorganic N (as urea) of concentrations from 0 to 100 ¼g N g-1 soil showed a positive response to ETS activity. However, at concentrations of 200 and 400¼g N g-1, the activity was reduced significantly.

Zhang, M., Gong, Z. T. and Karathanasia, A. D. 2000. Effect of perched water tables on aluminosilicate stability and soil genesis. pedosphere. 10(3): 247--256
ABSTRACT: The mineral stability and solute activities of soil solution extracted from selected horizons of seven studied pedons of Alfisols in Kentucky, USA, and the relationship between distribution of iron-manganese concretions and the restrictive layers were investigated. The results showed that the genesis and development of these soils and mineral weathering trends were strongly influenced by the depth of bedrock and the presence of perched water tables at lithic (limestone) interfaces due to the dissolution and buffering effect of limestone bedrock. The extractable Mg/Ca ratio as depth function and soil depth above bedrock could be used as indices of weathering and degree of soil development. Maximum iron-manganese concretion accumulation was found to occur in the horizon overlying clay horizon (ÿ40% clay) with a sharp increase in clay content (ÿ 10%), which suggested that zones of Fe-Mn concretion accumulation in soils of the Inner Bluegrass Region appeared to be a sensitive genetic indicator of argillic horizons with restrictive permeability.

Bush, R. T., Sullivan, L. A. and Lin, C. 2000. Iron monosulfide distribution in three coastal floodplain acid sulfate soils, eastern Australia. pedosphere. 10(3): 237--245
ABSTRACT: The distribution of iron monosulfide (quantified as acid volatile sulfur: SAV) was compared with geo chemical properties that are known to affect its formation and accumulation in three coastal Holocene acid sulfate soils (ASS) at Tuckean Swamp, McLeods Creek and Bungawalbyn Swamp respectively. These proper ties included pH, reactive iron (FeR), pore-water sulfate (SO42-) and organic carbon (OC). Iron monosulfide was concentrated at the oxic/anoxic boundary. The Tuckean Swamp and McLeods Creek sites are Holocene sediments, whereas the Bungawalbyn Swamp is a Holocene peat. The concentration of SAV averaged 0.2 g kg-1 in a 0.5 m thick soil layer at the Tuckean Swamp, but was an order of magnitude lower in the oxic/anoxic transition layers at McLeods Creek and Bungawalbyn Swamp. The SAV mineral greigite (FesS4) was identified in the Tuckean Swamp by X-ray diffraction and scanning electron microscopy with quantitative energy dispersive X-ray analysis (SEM-EDX). Very small concentrations of greigite were also observed in the McLeods Creek, based on crystal morphology and elemental composition. The concentration of SAV was a small fraction of the total reduced sulfur, representing at most 3% of the pyrite sulfur. However, the presence of this highly reactive sulfide mineral, distributed within pores where oxygen diffusion is most rapid, has important implications to the potential rate of acid production from these sediments.

Wang, X. J., Xu, H. L., Wang, J. H. and Umemura, H. 2000. Effects of organic and chemical fertilizations and microbe inoculation on physiology and growth of sweet corn plants. pedosphere. 10(3): 229--236
ABSTRACT: A pot culture experiment was carried out in a glasshouse to compare the physiology and growth of sweet corn plants (Zea mays L. cv. Honey Bantam) grown under organic and chemical fertilizations with or without microbial inoculation (MI). The organic fertilizer used was fermented mainly using rice bran and oil mill sludge, and the MI was a liquid product containing many beneficial microbes such as lactic acid bacteria, yeast, photosynthetic bacteria and actinomycetes. The application amounts of the organic fertilizer and chemical fertilizers were based on the same rate of nitrogen, phosphorus and potassium. Sweet corn plants fertilized with organic materials inoculated with beneficial microbes grew better than those without inoculation. There were no significant differences in physiology and growth of the sweet corn plants between treatments of chemical fertilizers with and without MI. Among the organic fertilization treatments, only the sweet corn plants with organic fertilizer and MI applied 4 weeks before sowing had similar photosynthetic capacity, total dry matter yield and ear yield to those with chemical fertilizers. Sweet corn plants in other organic fertilization treatments were weaker in physiology and growth than those in chemical fertilization treatments. There was no significant variance among chemical fertilization treatments at different time. It is concluded from this research that this organic fertilizer would be more effective if it was inoculated with the beneficial microbes. Early application of the organic fertilizer with beneficial microbes before sowing was recommended to make the nutrients available before the rapid growth at the early stage and obtain a yield similar to or higher than that with chemical fertilizations.

Lin, C., Islam, M. M., Bush, R. T., Sullivan, L. A. and Melville, M. D. 2000. Acid release from an acid sulfate soil sample under successive extractions with different extractants. Pedosphere. 10(3): 221--228
ABSTRACT: An acid sulfate soil sample was successively extracted with deionized water, 1 mol L-1 KCI and 0.000 5 mol L-1 Ca(OH)2 solutions. The results showed that only very small amounts of acidity were extracted by deionized water, possibly through slow jarosite hydrolysis. Acid release through jarosite hydrolysis was greatly enhanced by Ca(OH)2 extraction at the expense of the added OH- being neutralized by the acid released. Successive extraction of the sample with KCI removed the largest amounts of acidity from the sample. However, it is likely that the major form of acidity released by KC1 extraction was exchangeable acidity. The results also show the occurrence of low or non charged A1 and Fe species in water and Ca(OH)2 extracts after first a few extractions. It appears that such a phenomenon was related to a decreasing EC value with increasing number of extractions.

Fang, Z., Zhang, Y. G., Zhang, F. S. and Lu, S. H. 2000. Mechanisms of difference in Mn efficiency between wheat and oilseed rape. pedosphere. 10(3): 213--220
ABSTRACT: By solution culture experiment, three wheat genotypes (Triticum aestivum L.) and two oilseed rape genotypes (Brassica napus L.) differing in Mn efficiency under Mn-deficient conditions were uaed to study mechanisms of the difference in Mn efficiency between wheat and oilseed rape. The results showed that there were significant differences in the abilities of MnIV reduction and acidification in root rhizosphere between the two species. Compared with wheat, oilseed rape had much higher reducing capacity and intensity of rhizosphere acidification under Mn-deficient conditions. Moreover, the higher ratio of functional leaves Mn/old leaves Mn in oilseed rape than in wheat was also an important factor for the different Mn efficiencies between the two species.

Chen, L. J., Zhou, L. K., Li, R. H. and Van Cleemput, O. 2000. Comparison of urea-derived N2O emission from soil and soil-plant system. pedosphere. 10(3): 207--212
ABSTRACT: A pot experiment with a sandy loam soil and spring wheat as test crop was conducted to compare the N2O emission from soil system with plant cut off and from soil-plant system with plant kept. The results showed that after urea fertilizer applied, the N2O emission from soil and soil-wheat system decreased exponentially with time, and its total amount was 0.34%^ÿ0.63% and 0.33%^ÿ0.58% of applied urea-N respectively, no significant difference being found between these two systems. The N2O emission had a very significant negative relationship (P = 0.01) with the biomass of wheat plant. A combined application of urease inhibitor hydroquinone and nitrification inhibitor dicyandiamide could reduce the N2O emission by 50%^ÿ83% and 46%^ÿ74%, respectively, from soil and soil-wheat system. The N2O was mainly produced and emitted from soil, and the soil biochemical regulation, i.e., applying related inhibitors into soil could effectively diminish the urea derived N2O emission.

Li, Y., Chen, D. L., White, R. E. and Zhang, J. B. 2000. Coupling GIS with nitrogen leaching models. pedosphere. 10(3): 193--206
ABSTRACT: Geographical information systems (GIS) are increasingly being applied to surface and subsurface flow and transport modeling issues. In this paper, more attentions are focused on the methodology and strategies of coupling GIS with non-point pollution models. Suggestions are made on how to best integrate current available or selected nitrogen leaching models, especially in the aspect of programming development so as to effectively and flexibly address the specific tasks. The new possibilities for dealing with non-point pollution problems at a regional scale are provided in the resulting integrated approach, including embedding grid-based GIS components in models.

El-Ghamry, A. M., Huang, C. Y. and Xu, J. M. 2000. Influence of chlorsulfuron contamination on ratios of biomass carbon and nitrogen to total organic carbon and nitrogen in soil. Pedosphere. 10(2): 189--192
ABSTRACT: This paper reports on the ratios of microbial carbon:organic carbon and microbial biomass-nitrogen:total N, in soils as affected by chlorsulfuron in China.

Wu, W. D., Zheng, S. Z., Lu, Z. H. and Zhang, T. L. 2000. Effect of plant roots on penetrability and anti-scouribility of red soil derived from granite. Pedosphere. 10(2): 183--188
ABSTRACT: Distribution of plant roots in a red soil (China) derived from granite was investigated to study the effect of plant roots on intensifying soil penetrability and anti-scouribility by the double-cutting-ring and the undisturbed soil-flume methods, respectively. Plants were centipede grass (Eremochloa ophiuroides), bermuda grass (Cynodon dactylon), and strite kummerowia (Lespedeza striata). The plant roots system consisting mostly of fibrils, 0.35 root cm-2, the intensifying effect of roots on both the penetrability and the anti-scouribility could be described by exponent equations, DELTA Ks=0.0021RD1.4826 (R2=0.9313) and DELTA As=0.0003RD1.8478 (R2=0.9619), where DELTA Ks is the value of intensified soil penetrability, DELTA As the value of intensified soil anti-scouribility and RD the root density, especially in the top soils within 30 cm in depth where plant roots were concentrated.

Liu, C. Q., Cao, S. Q. and Xu, J. X. 2000. Effect of sulphur in rainfall, irrigation water and percolating water on soil sulphur in Jiangxi Province. Pedosphere. 10(2): 177--182
ABSTRACT: Ten rainfall and irrigation water-collecting posts were set up in different ecotype districts of Jiangxi Province, China, to measure S content in rainfall and irrigation water. A rainwater chemical composition-collecting device was used to collect the sulfur in rainfall, and the amount of sulfur adsorbed on the resin column in the device was determined. The soil percolating water was gathered using 6 lysimeters, built up according to the profile sequence of the red soil derived from red sandstone and the red soil derived from Quaternary red clay, separately. On the lysimeters, peanuts, soyabean and radish were grown in rotation. Two treatments were designed: without S addition and with S addition at a rate of 14 kg S/ha. The SO42- contents in rainfall, irrigation water and soil percolating water were determined by the turbidimetry. The results in 1997 showed that the average annual S content in rainwater was 28.13 kg S/ha, the average S content in irrigation water was 1.7 mg S/litre, and the average content of SO42- in soil percolation water was 2.30 kg S/ha per year and 4.70 kg S/ha per year in treatments without and with sulfur application, respectively. In Jiangxi Province, apart from the losses by runoff and leaching, the sulfur in rainfall available to crops is 7.3 kg S/ha per year and additional S application is required. When rice is grown, however, irrigation water can supply 6.9 kg S/ha, which combined with the sulfur in rain, can almost meet the S requirement of one cropping of rice.

Xie, Z. B., Zhu, J. G., Chu, H. Y., Cao, Z. H. and Deng, X. H. 2000. Effect of lanthanum accumulation on cation exchange capacity and solution composition of red soil. Pedosphere. 10(2): 171--176
ABSTRACT: Pot and adsorption-exchange experiments were carried out by collecting the soil samples from the surface layer (0-15 cm) of red soil at the Ecological Experiment Station of Red Soil, the Chinese Academy of Sciences, in Jiangxi Province of China. When concentrations of the exogenous La3+ exceeded 400 mg/kg, there was less non-exchangeable La3+ than exchangeable La3+ in the soil. Cation exchange capacity of the soil changed slightly with increasing concentration of the exogenous La3+ in both experiments. However, in the adsorption-exchange experiment, when the concentration of the exogenous La3+ was higher than 300 mg/kg, exchangeable basic cations decreased significantly, while exchangeable hydrogen and exchangeable aluminium increased significantly compared with the control treatments. The amounts of base cations (Ca2+, Mg2+, K+ and Na+) exchanged by La3+ in the supernatant solution increased with the concentration of the exogenous La3+, especially when concentration of the exogenous La3+ was higher than 50 mg/kg.

Lu, R. K., Shi, Z. Y. and Sun, B. 2000. Degradation of soil nutrients in Southeast China. Pedosphere. 10(2): 165--170
ABSTRACT: A total of 2190 soil nutrient data in the Second National Soil Survey of China were collected to assess the degradation of soil nutrients in the hilly region of Southeast China. The definition of soil nutrient degradation is suggested, the evaluation criteria are set up and the current status of degradation of red soils and latosols is assessed. The percentages of areas in four grades of soil nutrient degradation, slightly deficient, medium deficient, severely deficient and extremely deficient: were 21.3, 43.3, 16.2 and 3.0% for soil total N; 0.7, 6.4, 16.7 and 76.2% for soil available P; and 25.4, 26.3, 8.6 and 5.0% for soil available K, respectively. The severity of soil nutrient degradation was in the order of P>N>K. The major factors leading to the degradation of soil nutrients in quantity include soil erosion, leaching and the consumption by crops. The principal factor affecting the degradation of soil nutrients in availability is the fixation of N, P and K, especially the fixation of phosphorus. The average amount of P fixed by soils is 408 mg/kg, and upland soils can fix more P than paddy soils.

Shi, S. L., Du, L. J., Cao, Y. C. and Sun, G. Q. 2000. Evaluation of N2-fixation capacity of leguminous shrub plants. Pedosphere. 10(2): 159--163
ABSTRACT: N2-fixation percentages in the aerial parts of the first and second cuttings of five species of leguminous shrub plants, Lespedeza formosa from Jiangxi, Lespedeza pilosa, Lespedeza formosa from Zhejiang, Cajanus cajan and Indigofera pseudotinctoria were investigated in pot culture experiments using natural 15N abundance method with Bischofia javanica, Camptotheca acuminata and Gardenia jasminoides as reference plants. Results showed that the N2-fixation percentages were different for the three genera of leguminous shrubs but similar for three species in the same genus. I. pseudotinctoria had the highest N2-fixation percentage in its aerial part, followed by Lespedeza and C. cajan. The N2-fixation percentages in the aerial parts of the plants that had grown for three years were lower than those of the one-year-old plants except L. formosa from Zhejiang and L. formosa from Jiangxi.

Li, Z. P., Cheng, L. L. and Lin, X. X. 2000. Accumulation of organic matter in infertile red soils and its ecological importance. Pedosphere. 10(2): 149--158
ABSTRACT: Field experiments on the decomposition of organic materials and the accumulation of organic carbon in infertile red soils were conducted at the Ecological Experimental Station of Red Soil, the Chinese Academy of Sciences, and the potential of CO2 sequestration by reclamation and improving the fertility of these soils was estimated. Results showed that in infertile red soils, the humification coefficients of organic materials were high, ranging from 0.28 to 0.63 with an average of 0.43, 41% higher than those in corresponding red soils with medium fertility. This was attributed to the high clay content, high acidity and low native organic matter content of infertile red soils. Compared to those in corresponding normal red soils, the decomposition rates of organic materials were significantly lower in infertile red soils in the first 2 years, thereafter no significant difference was observed between those in the two kinds of soils. Depending on the type and amount of organic manure applied, soil properties and the rotation systems, annual application of organic manure with a rate of 4500 to 9000 kg/ha increased the organic carbon content in surface 20 cm of infertile red soils by 2.1-7.5 g/kg with an average of 4.7 g/kg within the first 5 years. The organic carbon content in infertile red soils which received organic manure annually increased linearly during the first 10 years, thereafter it slowed down, implying that the fertility of the infertile red soils could reach middle or high levels in 10 years if the soil was managed properly. It was estimated that through exploitation of wastelands, re-establishment of fuel forests and improvement of soil fertility, soils in the red soil region of China could sequester 1.50X1015 g of atmospheric CO2.

Hu, F., Li, H. X. and He, Y. Q. 2000. Organic matter decomposition in red soil as affected by earthworms. Pedosphere. 10(2): 143--148
ABSTRACT: The earthworms Pheretima carnosa, Drawida gisti and Eisenia fetida were studied to compare their contributions to the decomposition of various organic materials applied to red soils in a 165-day greenhouse experiment. The native species P. carnosa and D. gisti were equally effective in accelerating the decomposition of maize residue, according to fresh body weight, while commercial species E. fetida had no significant influence on dry mass loss of maize residue. Liming with CaCO3 or CaO showed little effect on maize residue breakdown involved by P. carnosa, but inhibited the process with D. gisti. The capability of P. carnosa to the decomposition of five kinds of organic materials was thoroughly examined. The dry mass losses in worm treatments were in the order of soyabean residue>maize residue>pig manure>semi-decayed maize>ryegrass. However, the relative contributions of the earthworm to dry mass loss were in the order of pig manure (89.8%)>semi-decayed maize residue (49.1%)>maize residue (29.4%)>soyabean residue (20.9%)>ryegrass residue (16.5%). P. carnosa consumed 20-120 mg dry weight of organic material per gram fresh weight of biomass per day.

Sun, B., Zhang, T. L. and Zhao, Q. G. 2000. Leaching and redistribution of nutrients in surface layer of red soils in Southeast China. Pedosphere. 10(2): 135--142
ABSTRACT: The leaching and redistribution of nutrients in the surface layer of 4 types of red soils in Southeast China were studied with a lysimeter experiment under field conditions. Results showed that the leaching was concentrated in the rainy season (from April to June). Generally, the leaching of soil nutrients from the surface layer of red soils was in the order of Ca>Mg>K>NO3-N. In fertilization treatment, the total amount of soil nutrients leached out of the surface layer in a red soil derived from granite was the highest in all soils. Nutrient uptake by grass decreased the leaching of fertilizer ions in surface layer, particularly for NO3-N. Soil total N and exchangeable K, Ca and Mg in the surface layer decreased with leaching and nutrient uptake by grass during the 2 years without new fertilization of urea, Ca(H2PO4)2, KCl, CaCO3 and MgCO3. Ca moved from the application layer (0-5 cm) of fertilizer and accumulated in the 10-30 cm depth in the studied soils, except the Quaternary red clay.

Gong, Z. T., Chen, Z. C., Zhao, W. J. and Shi, H. 2000. Classification of ferrallitic soils in Chinese soil taxonomy. Pedosphere. 10(2): 125--133
ABSTRACT: The development of the classification of ferrallitic soils in China is reviewed and the classification of Ferralsols and Ferrisols in Chinese Soil Taxonomy is introduced in order to discuss the correlation between the ferrallitic soil classification in the Chinese soil taxonomy and those of the other soil classification systems. In the former soil classification systems of China, the ferrallitic soils were classified into the soil groups of Latosols, Latosolic red soils, red soils, yellow soils and dry red soils, according to the combination of soil-forming conditions, soil-forming processes, soil features and soil properties. In the Chinese soil taxonomy, most of ferrallitic soils are classified into the soil orders of Ferralsols and Ferrisols based on the diagnostic horizons and/or diagnostic characteristics with quantitatively defined properties. Ferralsols are the soils that have ferralic horizon, and they are merely subdivided into one suborder and two soil groups. Ferrisols are the soils that have LAC-ferric horizon but do not have ferralic horizon, and they are subdivided into three suborders and eleven soil groups. Ferralsols may correspond to part of Latosols and Latosolic red soils. Ferrisols may either correspond to part of red soils, yellow soils and dry red soils, or correspond to part of Latosols and Latosolic red soils.

Chen, H. M., Zheng, C. R., Wang, S. Q. and Tu, C. 2000. Combined pollution and pollution index of heavy metals in red soil. Pedosphere. 10(2): 117--124
ABSTRACT: A field experiment was conducted to study the effects of Pb, Cd, Cu, Zn and As coexisting in red soil on growth of rice (Oryza sativa), mung bean (Vigna radiata), lucerne (Medicago sativa), slash pine (Pinus elliottii) and aspen (Populus). Results showed that rice, mung bean and lucerne were significantly influenced by combined pollution of the heavy metals. The contents of Pb, Cd and As in rice grains greatly exceeded the National Standards for Food Hygiene of China. Heavy metals at a high concentration seriously retarded growth of mung bean and lucerne, but not so obviously with slash pine and aspen. The composite index is suggested for evaluating the relativity of combined pollution with heavy metals in soils.

He, Y. Q. and Li, Z. M. 2000. Nutrient cycling and balance in red soil agroecosystem and their management. Pedosphere. 10(2): 107--116
ABSTRACT: An experiment was conducted in a red soil derived from Quaternary red clay in the Ecological Experiment Station of Red Soil, the Chinese Academy of Sciences, located in Yingtan, Jiangxi Province, China. The results show that the major ways of nutrient loss are leaching and nitrogen volatilization. Rationalizing crop distribution, stimulating nutrient recycling, and improving internal nutrient flow are effective measures to decrease nutrient loss and to promote nutrient utilization efficiency. The important ways of regulating nutrient cycling and balance in the agroecosystem of the red soil are to establish optimal eco-agricultural models, practice balanced fertilization and combine the cropping system with the livestock system.

Zhao, Q. G. and Cao, H. 2000. Pedosphere and its effect on global changes. Pedosphere. 10(2): 97--106
ABSTRACT: This paper addresses the conception of the pedosphere and its role in global changes. Also addressed are series of environmental issues in China and their relations to the global changes. Research orientation and priorities are indicated, including exploitation and protection of the soil resources, soil fertility and sustainable agricultural development, construction of the ecological environment, and the material cycling in pedosphere and its relation to global changes.

Wang, Y. and Zhang, Y. P. 2000. Column holdup formula of soil solute transport. Pedosphere. 10(1): 89--92
ABSTRACT: The shortcomings of the present two formulae for describing column holdup are analysed and deductions are made to find a new formula. The column holdup, Hw, described by the new formula is dimensional, and related to soil solute transport kinesis and column physical properties. Compared with the other two column holdups, Hw is feasible to describe dimensional column holdup during solute transport process. The relationships between Hw and retardation factor, R, in different solute transport boundary conditions are established.

Lu, S. G. 2000. Influence of particle size on magnetic properties of soils in Zhejiang Province, China. Pedosphere. 10(1): 81--88
ABSTRACT: The relationship between magnetic properties and particle size of soils derived from metamorphic rock, basalt, granite, Quaternary red clay, limestone and mudstone from Zhejiang Province, East China was studied. Based on the variations of the mass magnetic susceptibility (chi), anhysteretic remanent magnetization (ARM), and saturation isothermal remanent magnetization (SIRM) with soil particle size, the relationship could be classified into three groups. For the soils derived from metamorphic rock and basalt, magnetic values were the highest in the gravel and coarse sand fractions and decreased with decreasing soil particle size. The soils derived from sedimentary rock had a bimodal distribution of magnetic values, with peaks in 1-0.5 and 0.005-0.000 5 mm fractions. The soil developed on granite was characterized by a peak of magnetic value in 0.001-0.000 5 mm fractions. Frequency-dependent susceptibility (chifd) and ratios of magnetic parameters (ARM/chi, SIRM/chi and SIRM/ARM) of soil particle fractions showed that variations in ferrimagnetic grain size paralleled those in particle size. chifd peaked in clay fraction and decreased with increasing particle size, irrespective of soil parent materials. The acquisition curves of IRM and demagnetization parameter of different soil particles indicated that there were different magnetic mineral assemblages in different particle fractions.

Liu, X. Z., Kang, S. Z., Shao, M. G. 2000. Effect of shading on gas exchange of cotton leaves under conditions of different soil water contents. Pedosphere. 10(1): 77--80
ABSTRACT: The effect of different shading levels (no-shading, 80% shading, and 40% shading) on photosynthetic and stomatal responses in cotton leaves was investigated under different soil water contents at midday in summer. All cotton leaves exhibited similar basic responses to shading, including decreased net photosynthetic rates, a tendency to decrease in transpiration rates, and increased stomatal conductance and intercellular CO2 concentration. The leaf conductance of 80% shaded and 40% shaded plants increased by 28% and 16.7% compared with no-shaded plants at high water, respectively, but the net photosynthetic rates of 80% shaded and 40% shaded plants declined by 50% and 14.73%, respectively. Results showed that the combined effect of soil moisture and shading on photosynthetic and stomatal responses in cotton leaves was very marked.

Li, S. T., Lin, B., Zhou, W., Liu, Q. C. and Xu, Y. L. 2000. Oxidation of elemental sulfur in selected soils of China. Pedosphere. 10(1): 69--76
ABSTRACT: An incubation experiment was carried out in the laboratory to study the effect of temperature, moisture, phosphorus, organic matter, cropping and previous elemental sulfur application on elemental sulfur oxidation in a fluvo-aquic soil, a black soil, a yellow-brown soil and a red soil. In all the soils tested, sulfur oxidation rate was influenced by temperature and the temperature coefficient (Q10) values at the range from 10 to 30! were 4.41, 4.05, 6.19 and 3.71 for the four soils, respectively. The rate of sulfur oxidation was parabolically related to soil water content. The optimum moisture content for the maximum oxidation rate was different among soils. Phosphorus increased the oxidation rate of elemental sulfur by 57.7, 33.1, 21.7 and 26.4% for the above four soils, respectively, compared with the control (no phosphorus applied). Organic material of maize straw which was ground and passed through a 0.5-mm sieve increased the oxidation rate of elemental sulfur in the four soils by 59.8, 7.8, 39.2 and 540.4%, respectively. Elemental sulfur which was applied previously to soils significantly enhanced the oxidation of elemental sulfur subsequently added and increased sulfur-oxidizing populations such as autotrophic elemental sulfur oxidizers with pH optimum 6.8, autotrophic thiosulfate oxidizers with pH optimum 6.8, heterotrophic thiosulfate oxidizers and heterotrophic sulfate producers. Cropping had little effect on elemental sulfur-oxidizing potentiality of soils.

Zhu, D. W., Chen, X. H., Cheng, D. S., Geng, M. J. and Liu, W. D. 2000. Electrical characteristics and desorption kinetics of soil boron. Pedosphere. 10(1): 61--68
ABSTRACT: The status and activities of boron in soils were studied using electroultrafiltration (EUF). Soil samples, including brown-red soil and calcareous alluvial soil, were collected from Hubei Province, China. The soil samples were incubated in saturated water and then their nutrients were ultrafiltrated with EUF equipment. Filtration and extraction were conducted in accordance with routine process, but fractions in anode and cathode were all collected. Analyses of B, K+, Mg2+, Ca2+, Cl- and pH in fractions supposed that boron existed not only in a simple form of borate but also in ion-pair with cations partly in acidic soil, and borate was the primary form existing in the calcareous soil. In studying desorption kinetics with EUF, the boron content of fractions 2-6 was accumulated, and the accumulative quantities were fit to time factors in three kinetic equations: the zero-order, first-order, and parabolic diffusion equations. The parabolic diffusion equation had the best degree of fit, followed by the zero-order equation, and the first-order equation was the worst.

Yao, A. J., Qin, C. L. and Mou, S. S. 2000. Effect of humus on activity of mineral-bound Hg: III. Effect on leachability and transfer of mineral-bound Hg under acid leaching condition. Pedosphere. 10(1): 53--60
ABSTRACT: Effects of humus fractions (fulvic acid, brown humic acid and grey humic acid) on the leachability and transferring activity of five types of mineral-bound Hg were investigated. Under the acid leaching condition; fulvic acid could promote leachability and vertical transference of all the mineral-bound Hg. Brown humic acid could retard the leaching and transferring processes of CaCO3-Hg, Fe2O3-Hg, MnO2-Hg and kaolinite-Hg but not bentonite-Hg. Grey humic acid could greatly enhance residing ability of the mineral-bound Hg in the soil column and restrain them from vertical transferring. The effect of humus on leachability and transferring activity on the mineral-bound Hg was closely related to its ability to convert the mineral-bound Hg into organic-bound form and the transferability of the latter in the soil column. The characteristics of the mineral-bound Hg in speciation were the internal factors that determined the extent and rate of the influence of the humus.

Yuan, L., Wang, S. S., Wang, Z. H. and Huang, J. G. 2000. Tea-grown soils and tea quality in Sichuan and Chongqing, China. Pedosphere. 10(1): 45--52
ABSTRACT: Made teas and typical tea-grown soils in Sichuan and Chongqing were collected to investigate soil nutrients, related soil properties and tea quality. The tea-grown soils in Sichuan and Chongqing are distributed mainly in mountainous areas. The high annual precipitation (over 1100 mm), precipitous soil slopes, low cohesion among soil particles and high soil porosity suggested that intensive erosion and leaching might occur in these soils. Moreover, they were very acidic and poor in mineral nutrients such as N, P, K, Ca and Mg except S. The average content of total S was 20.40 g kg-1, much higher than that of organic matter in these soils, revealing that S in the tea-grown soils existed mainly in inorganic forms and very little in organic forms. Water-extractable S accounted for only a small amount of total S, which showed that most parts of sulfur in these soils were insoluble in water. K and S varied greatly in made teas. The concentrations of N and P, however, varied little in these teas even though they differentiated significantly in the tea-grown soils. The high concentration of nitrogen in made teas could result in the high free amino acids and low polyphenol of teas. Significantly positive correlation was established between potassium and polyphenol in made teas. Teas with high ratio of phenol to free amino acids were usually good in taste and appearance.

Yao, H. Y., He, Z. L., Campbell, C. D. and Wilson, M. J. 2000. Some limitations of BIOLOG system for determining soil microbial community. Pedosphere. 10(1): 37--44
ABSTRACT: A laboratory experiment was conducted to evaluate the effect of triphenyltetrazolium chloride (TTC) on soil microorganisms and the availability of pH characterization medium in BIOLOG plates. Application of TTC decreased the colour development sharply and resulted in a great biocidal effect on the growth and reproduction of soil microorganisms. The microtitration plates with 21 carbon sources and two different pH levels (4.7 and 7.0) were used to determine microbial community structure of eight red soils. The average utilization (average well colour development) of the carbon sources in the plates with different pH levels generally followed the same sigmoidal pattern as that in the traditional BIOLOG plates, but the pH 4.7 plates increased the discrimination of this technique, compared with the pH 7.0 plates. Since most tested soils are acid, a suitable pH characterization medium would be preferable for a specific soil in the sole carbon source test.

Chen, N. C., Kanazawa, S. and Horiguchi, T. 2000. Chromium(VI) reduction in wheat rhizosphere. Pedosphere. 10(1): 31--36
ABSTRACT: Reduction of Cr(VI) to Cr(III) was studied in a fresh wheat rhizosphere soil (kuroboku, high humic Andosol) pretreated with a basal fertilizer consisting of (NH4)2SO4, P2O5 and KH2PO4 and with K2Cr2O7 by using a rhizobox system. The rhizosphere exerted a positive effect on Cr(VI) reduction. Part of the reason was the decrease of pH in the rhizosphere due to application of (NH4)2SO4, implying that application of physiologically acid fertilizers would reduce Cr(VI) toxicity to plants.

Tu, C., Zheng, C. R. and Chen, H. M. 2000. Effect of heavy metal pollution on potassium behavior in Typic Udic Ferrisol. Pedosphere. 10(1): 21--30
ABSTRACT: The indirect influence of heavy metal contamination of soil on nutrient availability may need to be taken into consideration when determining overall effects of heavy metals. A laboratory experiment was performed to study the effects of combined pollution of Cu, Pb, Zn and Cd on soil K status as indicated by chemical fractions, adsorption-desorption and quantity/intensity (Q/I) relationship of K in a Typic Udic Ferrisol (red soil), by employing uniform design and single factor design. Compared to the control, content of exchangeable K was decreased, but that of soluble K increased in the samples contaminated with heavy metals. Due to heavy metal pollution, potassium adsorption was reduced by 5 to 22%, whereas the desorption percentage of adsorbed K increased by 2 to 32%. The Q/I curves shifted downward, potassium buffering capacity (PBCK) decreased, and equilibrium activity ratio values (ARoK) increased with increasing heavy metal pollution. These influences followed the sequences of Pb>Cu>Zn and combined pollution>individual metals. Displacement of K from cation exchange sites and decrease in soil cation exchange capacity due to heavy metals led to changes of soil K behaviour. The findings suggest that heavy metal pollution of soil might aggravate the degradation of soil K fertility by decreasing K adsorption and buffering capacity and increasing desorption.

Zhuang, J., Yu, G. R. and Liu, X. Y. 2000. Characteristics of lead sorption on clay minerals in relation to metal oxides. Pedosphere. 10(1): 11--20
ABSTRACT: Difference of montmorillonite (Mt), illite (It) and kaolinite (Kt) in lead sorption characteristics and the effects of amorphous Fe and Al oxide coatings on the characteristics were experimentally studied with a logistic model. The sorption curves had a sigmoid pattern due to the use of acetate-type buffer solution. With the model the sorption process could be divided into four stages and the sorption characteristics at these stages are discussed. The results showed that, after Mt, It and Kt were coated by amorphous Fe oxide, their maximum sorption capacity (MSC) and percentage of high-SSC concentration scope (HCS) of Pb2+ increased markedly, but the specific sorption capacity (SSC) decreased. With regard to effects of amorphous Al oxide coating, except for It+Al, the SSC of other samples showed a downtrend, despite that their MSC remained unchanged. Eventually, the grey correlation degrees to Pb2+ sorption for different physicochemical characteristics of the clay minerals were higher for hydronium, zero point of surface charge and hydroxy, but lower for specific surface area, density of surface charge and amount of surface charges.

Wei, S. Q. and Jarvis, N. 2000. Modelling of cadmium transport in soil-crop system. Pedosphere. 10(1): 1--9
ABSTRACT: A model for simulating cadmium transport in a soil-plant system was built using a commercial simulating program named Powersim on the basis of input-output processes happening in the soil-plant system. Convective and dispersive transport processes of cadmium in soil profile are embedded. Simulations on a daily base have been done up to a total simulating time of 250 years. Results show that applications of sewage sludge and fertilizer at the simulated rates would only cause slight cadmium accumulations in each layer of the soil, and cadmium accumulation would be levelling off, reaching an equilibrium concentrations layer by layer downward after certain time. The time scale to reach an equilibrium concentration varies from 10 years for the top three layers to over 250 years for the bottom layers. Plant cadmium uptake would increase from 52 ug m-2 under initial soil cadmium concentrations to 65 ug m-2 under equilibrium soil cadmium concentrations, which would not exceed the maximum allowable cadmium concentration in wheat grains. Main parameters which influence cadmium accumulation and transport in soil are total cadmium input, rainfall, evaporation, plant uptake and soil properties.

Tong, Y. P. and Li, J. Y. 1999. Mobilization of phosphorus in calcareous soils by organic acids. Pedosphere. 9(4): 379--382
ABSTRACT:

Wang, Q. R., Li, J. Y. and Li, Z. S. 1999. Effect of phosphate fertilizers on growth and development of wheat genotypes in a calcareous soil. Pedosphere. 9(4): 375--378
ABSTRACT:

Zhang, X., Zhao, Q. B., Yu, H. M. and Cao, Z. H. 1999. Grey disorder in field flue-cured tobacco. Pedosphere. 9(4): 369--374
ABSTRACT: A field study in Jiangsu, China, was carried out on the grey disorder in flue-cured tobacco leaves. The results showed that low Eh and high available Fe content in the soils were responsible for the grey tobacco and dead roots. Grey disorder leaves produced low quality lamina, which was low in N, nicotine, reduced sugar and K contents. In this study, soil available Mn and leaf Mn contents were in a relatively low level and should not be an important factor in the occurrence of grey disorder in flue-cured tobacco.

Yang, X. L. and Bao, S. D. 1999. Effect of boron fertilizer on flower and fruit drop of prunes. Pedosphere. 9(4): 363--368
ABSTRACT: The effect of boron on falling of apricots (Prunus mume) was studied in an experiment in Jiangsu Province, China, by applying 50 g borate per tree into soil on 15 December 1993 (soil-B) and spraying leaves evenly twice with 1.5 g borate solutionthinkg-1 on 1 and 8 March 1994 (spray-B) on the soil with 0.28 mg rapidly-available Bthinkg-1. Compared with no borate treatment (CK), B concentrations of leaves, short branches and flowers were higher and the percentage of flower and fruit drop was lower in the treatments of soil-B and spray-B. Boron fertilizer increased B concentrations in flowers, leaves and short branches, promoted pollen germination, reduced the percentage of fall of flowers and fruits of apricots, increased the percentage of fertile fruits, and thus increased yields of apricots by 46 and 34.3% in the treatments of soil-B and spray-B, respectively. It was inferred that if B concentration of leaves was lower than 35 mgthinkg-1, the apricots should be fertilized with B. The measured leaves should be picked from branches (3-10 cm in length) germinating from the central section of a tree crown during the last ten days of May or early June.

Zhang, G. Y., Wang, T. Z. Dong, Y. Y. and Li, X. Y. 1999. Study on mechanisms of Cd2+ sorption on goethite by microcalorimetry. Pedosphere. 9(4): 357--362
ABSTRACT: A study on energy changes and mechanisms of Cd sorbed on goethite was performed using the technique of microcalorimetry. The data of the amount of Cd sorption (Aq) and concentration of Cd in equilibrium solution (Ce), and the data of Aq and the heat effect (AH) caused by Cd2+ sorption on goethite all fitted Langmuir isotherm. The amount of heat released from Cd sorption on goethite increased with the amount of Ce or Aq. The reaction process of Cd sorption on goethite may be divided into five stages and three plateaux, depending on the variation of enthalpy change (DELTAaHm) of Cd sorption with Aq, which implied three mechanisms of interaction between Cd and goethite. The experimental results showed that the microcalorimetry may be useful for determination of microcalorie variation in soil.

Yan, S. H., Guo, J. Y. and Zhang, Z. H. 1999. Comparison of mathematical models for describing crop responses to N fertilizer. Pedosphere. 9(4): 351--356
ABSTRACT: Four mathematical models were systematically evaluated in describing responses of barley, Lupinus, rape and a ryegrass-clover mixture at 7 rates of nitrogen application. Residual sum of squares and a total point ranking method were used to assess the model fitting for crop responses to nitrogen application. Sparrow's inverse quadratic polynomial model performed the best.

Zhang, J. B. and Roth, K. 1999. Field-scale contaminant transport through soils: current understanding and open questions. Pedosphere. 9(4): 339--350
ABSTRACT: Agro-chemical transport processes at different scales are discussed and questions are identified by literature review to make suggestions concerning the improvement of research methods for field scale solute transport by evaluation of existing models, and by examination of transport behaviours of solutes in vadose zones on different scales. The results indicate that present research progress and understanding on field scale solute transport has not yet been enough to guarantee the use of these models for the management of field solute movement. More research is required, particularly in aspects of high resolution of spatial structures relevant to the hydraulic and transport properties, explicit numerical simulation of actual structure on field scale and field measurements corroborated with model development.

Jiang, J. J., Ni, S. X., Gong, A. Q., Wang, W. J., Zha, Y., Wang, J. C. and Voss, F. 1999. Grassland degradation and its control in region around Qinghai lake. Pedosphere. 9(4): 331--338
ABSTRACT: Severe degradation was found in all seven types of grasslands in the study area involving 12 counties of the NW Qinghai Province, China. Slightly, moderately and severely degraded grasslands occupied 49.7, 32.0 and 18.3% of the area respectively. The major factors resulting in the degradation were overgrazing, damage from mice, grasshoppers and blown sands, and improper use of grasslands. The measures to deal with these problems should be: (1) livestock management in accordance with grassland carrying capacity for animals; (2) to build more artificial grasslands with a stable and higher grass yield; (3) to put the rotation grazing system into wider use; (4) to clear up poisonous grass species; and (5) to adopt more effective measures to deal with the damage to grasslands by mice and grasshoppers.

Lin, C., Melville, M. D. and Valentine, N. 1999. Characteristics of soluble and exchangeable acidity in an extremely acidified acid sulfate soil. Pedosphere. 9(4): 323--330
ABSTRACT: An extremely acidified acid sulfate soil was investigated to characterize its soluble and exchangeable acidity. The results showed that soluble acidity of a sample determined by titration with a KOH solution was much significantly greater than that indicated by pH measured using a pH meter, particularly for the extremely acidic soil samples. This is because the total soluble acidity of the extremely acidic soil samples was mainly composed of various soluble Al and Fe species, possibly in forms of Al sulfate complexes (e.g. AlSO4+) and ferrous Fe (Fe2+). It is therefore suggested not to use pH alone as an indicator of soluble acidity in acid sulfate soil, particularly for extremely acidic acid sulfate soil. It is also likely that AlSO4+ actively participated in cation exchange reactions. It appears that the possible involvement of this Al sulfate cation in the cation adsorption has significant effect on increasing the amount of acidity being adsorbed by the soils.

Zhang, Z. Q., Meng, Z. F. and Zhang, Y. P. 1999. Calculation of thermodynamic parameters for Freundlich and Temkin isotherm models. Pedosphere. 9(4): 319--322
ABSTRACT: Derivation of the Freundlich and Temkin isotherm models from the kinetic adsorption/desorption equations was carried out to calculate their thermodynamic equilibrium constants. The calculation formulae of three thermodynamic parameters, the standard molar Gibbs free energy change, the standard molar enthalpy change and the standard molar entropy change, of isothermal adsorption processes for Freundlich and Temkin isotherm models were deduced according to the relationship between the thermodynamic equilibrium constants and the temperature.

Hu, X. F. and Gong, Z. T. 1999. A "yellow cap" on Quaternary red clay in Jiujiang, Jiangxi Province. Pedosphere. 9(4): 311--318
ABSTRACT: A thin layer of yellow-brown-coloured earth was generally found on Quaternary red clay in Jiujiang, Jiangxi Province, China. A typical profile was established. Both particle size distribution and rare earth elements characteristics of the yellow-brown-coloured earth suggest its aeolian origin and close similarity to Nanjing Xiashu loess. The study also implied aeolian origin of the underlying Quaternary red clay. Compared with the red clay, the yellow-brown-coloured earth was less weathered because of its lower content of free iron and higher mole ratios of SiO2:Al2O3 and SiO2:(Fe2O3+Al2O3) as well as its less developed chemical microtextures of quartz grains. In order to study the ages of the two deposits comparatively, the thermoluminescent dating method was used. As a result, the bottom of the yellow-brown-coloured earth was dated to 60thin? ka B.P. and the upper part of the red clay 388thin?4 ka B.P. It was suggested that the yellow-brown-coloured earth was formed in the Late Pleistocene and was probably the aeolian deposit of the Last Glacial, which corresponded with the Malan loess in the Loess Plateau of the northwestern part of China; while the underlying red clay was formed in the Middle Pleistocene. A 'yellow cap' on Quaternary red clay in Jiujiang implied a great climatic and environmental variation in the beginning of the Late Pleistocene in the southern part of China, especially in the middle and lower reaches of the Yangtze River. The event not only halted the rubification, once dominating the region, but also produced a widespread covering of aeolian deposit, as only occurred in the cold and dry environment.

Yin, S. X., Cheng, L. M. and Shen, Q. R. 1999. Denitrification and nitrate reduction to ammonium in Taihu Lake and Yellow Sea inter-tidal marine sediments. Pedosphere. 9(4): 305--309
ABSTRACT: Denitrification and nitrate reduction to ammonium in Taihu Lake and Yellow Sea inter-tidal marine sediments in Jiangsu, China, were studied. The sediment samples were made into slurry containing 150 g dry matter/litre. Various amounts of glucose and 5 mmol potassium nitrate/litre were added in order to achieve different ratios of glucose-C:nitrate-N. Acetylene inhibition technique was applied to measure denitrification in the slurries. All samples were incubated anaerobically under argon atmosphere. Data showed that Taihu Lake sediment produced more N2O than marine sediment. Denitrification potential was higher in Taihu Lake sediment than in the marine one. Glucose added increased denitrification activity but not the denitrification potential of the sediments. Dissimilatory nitrate reduction to ammonium seemed to occur in marine sediment, but not in the freshwater one. When the marine sediment was treated with 25 mmol glucose/litre, its denitrification potential, as indicated by maximum N2O production by acetylene blockage, was lower than that treated with no or 2.5 mmol glucose/litre. Acetylene was suspected to have an inhibitory effect on dissimilatory nitrate reduction to ammonium.

Zhuang, S. Y., Yin, B. and Zhu, Z. L. 1999. Model estimation of volatilization of ammonia applied with surface film-forming material. Pedosphere. 9(4): 299--304
ABSTRACT: Greenhouse experiments were conducted to determine the ammonia volatilization loss with or without application of surface film-forming material (SFFM). Ammonia volatilization loss was estimated by the model developed by Jayaweera and Mikkelsen. The results showed that the model could estimate and predict well ammonia volatilization loss also in the case of SFFM addition. There was an emended factor B introduced to the model calculation when SFFM was used. Simulated calculation showed that the effect of factor B on NH3 loss was obvious. The value of B was governed by SFFM and the environmental conditions. Sensitivity analysis suggested that pH was the main factor controlling NH3 volatilization loss from the floodwater.

Lin, C. 1999. Acid sulfate soils in Australia: characteristics, problems and management. Pedosphere. 9(4): 289--298
ABSTRACT: Acid sulfate soils are widely distributed in Australia. This paper reviews aspects concerning (a) the distribution and acid potential, (b) controls on acidic status, and (c) problems and management of acid sulfate soils in Australia.

Xu, Y. C., Jiang, T. H., Zheng, S. J. and Zhou, L. X. 1999. Effect of irradiated sewage sludge on crop yield and soil nitrogen. Pedosphere. 9(3): 281--288
ABSTRACT: A field experiment was conducted in Jiangsu Province, China, to study the feasibility of irradiated and non-irradiated sewage sludge as a fertilizer for the growth of wheat and rice. The irradiated and non-irradiated sewage sludge were applied at rates of 0 (CK), 75, 150, 225 and 300 kg N/ha for wheat, and 0 (CK), 112.5, 225, 337.5 and 450 kg N/ha for rice, respectively. (NH4)2SO4 at a rate of 150 kg N/ha for wheat, and 225 kg N/per ha for rice were added to the control treatments. Additionally, 20 kg 15N/ha in the form of (NH4)2SO4 was added to each treatment for wheat to study the effect of sewage sludge on chemical nitrogen fertilizer recovery. The results showed that the irradiation of sewage sludge by gamma ray at a dosage of 5 kGy increased crop yield by 11-27% as compared to the non-irradiated treatments. Irradiation stimulated mineralization of organic nitrogen in the sludge and improved seedling growth. The addition of irradiated sludge could reduce the leaching loss of chemical nitrogen fertilizer. Both irradiated and non-irradiated sewage sludge could increase the content of soil total nitrogen. Based on the preliminary results, it was concluded that irradiated sewage sludge could partly substitute for chemical nitrogen fertilizer in crop production.

Wang, Z. M., Zhu, P. L. and Huang, D. M. 1999. Straw 14C decomposition and distribution in humus fractions as influenced by soil moisture regimes. Pedosphere. 9(3): 275--280
ABSTRACT: 14C-tracer technique and closed incubation method were used to study straw 14C decomposition and distribution in different fractions of newly formed humus under different moisture regimes. Decomposition of straw 14C was faster during the initial days, and slower thereafter. Decay rate constants of straw 14C varied from 3.29X10-3 d-1 to 7.06X10-3 d-1. After 112 d incubation, the amount of straw 14C mineralized was 1.17-1.46 times greater in submerged soils than in upland soils. Of the soil residual 14C, 9.08%-15.73% was present in humic acid (HA) and 31.01%-37.62% in fulvic acid (FA). Submerged condition favored the formation of HA, and the HA:FA ratio of newly formed humus (labelled) was greater in submerged soils than in upland soils. Clay minerals affected the distribution of straw 14C in different humus fractions. The proportion of 14C present in HA to 14C remaining in soil was greater in Vertisol than in Ultisol.

Yang, Z. M., Zheng, S. J. and Hu, A. T. 1999. Zinc nutrition and metabolism of plants as influenced by supply of phosphorus and zinc. Pedosphere. 9(3): 265--274
ABSTRACT: A solution culture experiment was conducted to investigate the growth, the accumulation and translocation of Zn, and the metabolic changes of 24 days old plants of maize and wheat with the varied supply of phosphorus (0, 0.12, 0.6 and 3.0 mmol litre-1) and zinc (0.1 and 2.0 umol litre-1) under controlled environmental conditions. The results showed the highest dry matter production of both maize and wheat under the moderate combination of phosphorus (0.6 mmol litre-1) and zinc (2.0 umol litre-1) as compared with other imbalance applications of phosphorus and zinc. Excessive P supply significantly inhibited the translocation of Zn from maize roots to the aboveground part, thus decreasing the content of Zn in the shoots. Application of 3.0 mmol P litre-1 could also reduce the water-soluble Zn in plant tissues, leading to an increase in the cell plasma membrane permeability, a decrease in the dehydrogenase activity in roots and the activity of nitrate reductase in leaves, and a decline in the uptake of nitrate by plants. A similar decrease occurred in superoxide dismutase and plasma membrane adenosine triphosphatase (ATPase) activity in Zn-deficient plants. But, with increasing P supply, the activity of ATPase in both maize and wheat increased and reached the maximum at the P-supplying level of 3.0 mmol litre-1. Similar to the effect of high P supply, no or low P (0.12 mmol litre-1) supply could be detrimental to dry matter production and physiological functioning of the plants. Maize plants showed a more significant response to the imbalance supply of P and Zn than wheat plants. The possible physiological and biochemical mechanism of phosphorus-zinc antagonistic interaction in maize and wheat might be attributed to decrease in physiological availability and activation of Zn.

Wang, B. L., Liu, X. N., Yu, G. R., Wang, S. and Zou, B. J. 1999. Effect of cultural measures on nutrient contents in rice plants with erect panicles. Pedosphere. 9(3): 259--264
ABSTRACT: Field experiments were carried out with rice cv. Shennong 91 having short culms and erect panicles to study nutrient contents in high-yielding rice plants and to increase rice yield by appropriate fertilization. Nitrogen, phosphorus, potassium, magnesium, zinc, manganese, iron and copper contents in rice plants varied with different treatment factors. The relationship between the nutrient contents and treatment factors could be simulated using a multiple quadratic equation. The nutrient contents in plants should be appropriate for high-yielding rice. If the mean nutrient content in rice plants producing 11 t ha-1 or more of grain (uj) was set as the standard value and the standard deviation (sigmaj) was set as the range of variation, the nutrient content in high-yielding rice plants should be uj±1.99sigmaj. Rice leaves were sensitive to the nutrient elements. Heavy nitrogen dressing increased the content of nitrogen in rice plants. Sparse transplanting also increased nitrogen content. Improper application of nitrogen, phosphorus and potassium could affect the nutrient contents and decrease the grain yield.

Zheng, C. R., Tu, C. and Chen, H. M. 1999. Effect of combined heavy metal pollution on nitrogen mineralization potential, urease and phosphatase activities in a Typic Udic Ferrisol. Pedosphere. 9(3): 251--258
ABSTRACT: Individual and combined effects of Cu, Pb, Zn and Cd on N mineralization, urease and phosphatase were examined in a red soil in the laboratory using an uniform design and a single factor design. Soil pollution caused by heavy metals inhibited N mineralization and urease and phosphatase activities. The combined pollution of metals alleviated their toxicity to N mineralization to some extent, whereas it aggravated the toxicity to urease and phosphatase. Phosphorus application could mitigate the toxic effect of heavy metals on phosphatase activities, whilst the alleviating effect of N application on the toxicity of heavy metals to urease was inconsistent. However, the mitigating effect of the fertilizers was limited in heavily polluted soils.

Zhu, D. W., Shi, L. and Liu, W. D. 1999. Temperature effect on boron adsorption-desorption kinetics in soils. Pedosphere. 9(3): 243--250
ABSTRACT: The effect of temperature on the properties of boron adsorption-desorption in brown-red soil, yellow-brown soil and calcareous alluvial soil of Hubei Province, China, was investigated with the mobile displacement technique. The experimental data of B adsorption-desorption amounts and reaction time at 25 and 40! were fitted by the zero-order, first-order and parabolic diffusion kinetic equations. The adsorption process was in conformity with the parabolic diffusion law at both temperatures, and the values of rate constant of the parabolic diffusion equation in B adsorption were 0.138, 0.124 and 0.105 mg kg-1 min-1/2 at 25!, and 0.147, 0.146 and 0.135 mg kg-1 min-1/2 at 40! for the brown-red soil, yellow-brown soil, and calcareous alluvial soil, respectively. The relationship between amount of B desorption and reaction time could be described by the first-order kinetic equation, and the corresponding values of rate constant were 0.042 2, 0.056 3 and 0.038 4 min-1 at 25!, and 0.040 8, 0.042 3 and 0.040 1 min-1 at 40! for the brown-red soil, the yellow-brown soil and the calcareous alluvial soil, respectively. Therefore, the desorption process of B might be related to the amount of B adsorbed in soil. The higher the temperature, the lower the amount of B adsorption for the same soil in the same reaction time. The values of the apparent activation energy of B adsorption in the three soils calculated with the rate constants of parabolic diffusion equation were 3.27, 8.44 and 12.99 kJ mol-1, respectively, based on the experimental data of B adsorption amounts and reaction time at 25 and 40!.

Zhou, D. M. and Chen, H. M. 1999. Effect of Cr(VI) and p-chloroaniline interaction on their reaction behaviors on soil colloids. Pedosphere. 9(3): 233--242
ABSTRACT: Adsorption of Cr(VI) and p-chloroaniline on three typical soil colloids and pH influence were studied using batch equilibrium method. Both of Cr(VI) and p-chloroaniline adsorption on the colloids could be well described by general adsorption simulation equations. The adsorption processes changed with media pH. When Cr(VI) and p-chloroaniline coexisted on soil colloids, their interactions could be observed in a certain pH range to be accompanied with Cr(VI) reduction, which clearly suggested that a surface catalytic reaction occurred in this system. Soil colloid acted as an efficient catalyst for the interaction of Cr(VI) and p-chloroaniline. The pH values at which no interaction was observed were 4.0, 4.5 and 5.0 for the colloids of indigotic black soil (Aquic Cambisol), yellow-brown soil (Udic Luvisol) and latosol (Udic Ferralsol), respectively. Capillary electrophoresis used to analyse p-chloroaniline provided a high separation efficiency and short separation time, and needed no more extensive pretreatment of samples.

Zhang, G. Y. and Zhang, X. N. 1999. Sulfate-exchange alkalinity of ferralsol colloid. Pedosphere. 9(3): 227--232
ABSTRACT: The amount of OH- replaced by sulfate, i.e. sulfate-exchange alkalinity, from the electric double layer of a Ferralsol colloid was measured quantitatively in different conditions with automatic titration equipment. The amount of OH- release increased with the amount of Na2SO4 added and decreased with rising pH in the colloid suspension. Exchange acidity was displayed as the pH was >5.6. If the negative effect of sodium ions was offset, the amount of OH- replaced by sulfate was larger than the original amount of OH- released in the pH range of 6.0 and dropped to zero when pH reached 6.5. In the solution of 2.0 mol NaClO4 litre-1, the amount of OH- replaced by sulfate from the surface of the colloid could be considered as the amount of OH- adsorbed by ligand exchange reaction. The amount of OH- released in the solution of NaClO4 concentration below 2.0 mol litre-1 from which the amount of OH- adsorbed by ligand exchange reaction was subtracted, could be considered as the OH- adsorbed by electrostatic force. The OH- adsorbed by electrostatic force decreased with increases in the concentration of NaClO4 and pH and increased almost linearly with the increasing amount of Na2SO4 added. The percentages of OH- adsorbed by electrostatic force in water and in the electrolyte solutions of 0.05 and 0.5 mol NaClO4 litre-1 in the total OH- released were calculated.

Chen, X. Q. and Zhou, J. M. 1999. Effect of potash application patterns on crop yields under different cultivation systems. Pedosphere. 9(3): 219--226
ABSTRACT: Three patterns of potash application were used in the maize-wheat and rice-wheat rotation experiments, which were conducted in the upland and wetland of Siyang County, northern Jiangsu Province, and the wetland of Liyang City, southern Jiangsu Province, China. The results of 5 cropping seasons (2 seasons/year) showed that the direct response of maize to K was larger than that of wheat, but no difference was found between rice and wheat in Siyang when the total annual amount of K was applied only in one cropping season. However, the response of wheat was much greater than that of rice in Liyang. If potash was applied in the preceding season, the residual effect of K on wheat was larger than that on rice both in Siyang and Liyang, but less than that on maize. The total effect (direct and residual effects) of K applied to maize or rice was greater than that to wheat in Siyang, but that to wheat was greater in Liyang. The direct and total effects of K application in the upland were larger than those in the wetland of Siyang; but for the wetland, the effects were larger in Liyang than in Siyang, especially in the wheat season. The results demonstrated that the most profitable practice to be recommended to the local farmers was to apply a limited amount of potash to only rice or maize but not to wheat. Equally applying half of the total annual amount of K to each of the crops may be advisable in order to lessen possible fertilization risks.

Zhang, Z. Q. and Zhang, Y. P. 1999. Similarities and differences between Freundlich kinetic equation and two-constant equation. Pedosphere. 9(3): 213--218
ABSTRACT: A mathematical expression of the Freundlich kinetic equation, lnS=A'+B'lnt (where S is the amount of ions adsorbed by the solid, A and B are parameters, and t is time) is presented, and the physical meanings of its parameters are indicated. Although the Freundlich kinetic equation and the two-constant equation are of the same form, the derivation of the Freundlich kinetic equation is precise, while the derivation of the two-constant equation has some contradictions and is unsatisfactory. It is suggested that the Freundlich kinetic equation should have priority over the use of the two-constant equation.

Sun, B., Zhang, T. L. and Zhao, Q. G. 1999. Fertility restoration of red soils in low-hilly region of middle subtropical China. Pedosphere. 9(3): 205--212
ABSTRACT: There are about 1.27 million ha of upland red soils (Acrisols) derived from Quaternary red clay facing degradation in the low-hilly region of the middle subtropical China. From the aspects of chemistry, physics and microbiology, the processes of soil fertility restoration in the surface layer (0-20 cm) under three types of land use (I.e. citrus orchard, tea garden and upland) in two provinces were studied. Results showed that the reclamation of eroded wasteland improved most of the soil properties. Soil organic matter, total N and P, available P and K, and exchangeable Ca and Mg increased, but soil total K and exchangeable Al decreased. Soil pH decreased by 0.5 unit in the tea plantation for 20 years. Soil reclamation increased the percentage of soil microaggregates ( goethite > N-AlOH > bayerite > N-FeOH. No correlation was found between enzyme adsorption and the specific surface area of minerals examined. The differences in the surface structure of minerals and the arrangement of enzymatic molecules on mineral surfaces led to the different capacities of minerals for enzyme adsorption. The adsorption of invertase on bayerite, N-AlOH, goethite, N-FeOH and kaolinite was differently affected by pH. The order for the activity of invertase adsorbed on minerals was N-FeOH > N-AlOH > bayerite > goethite > kaolinite. The inhibition effect of minerals on enzyme activity was kaolinite > crystalline oxides > non-crystalline oxides. The pH optimum of iron oxide- and aluminium oxide-invertase complexes was similar to that of free enzyme (pH 4.0), whereas the pH optimum of kaolinite-invertase complex was one pH unit higher than that of free enzyme. The affinity to substrate and the maximum reaction velocity as well as the thermal stability of combined invertase were lower than those of the free enzyme.

Zhang, G. Y., Brummer, G. W. and Zhang, X. N. 1998. Effect of sulfate on adsorption of zinc and cadmium by variable charge soils. Pedosphere. 8(3): 245--250
ABSTRACT: Sulfate (SO2-4) and Zn2+ or Cd2+ were added to three variable charge soils in different sequences. In one sequence sulfate was added first, and in the other, Zn2+ or Cd2+ first. The addition of sulfate to the system invariably caused an increase in adsorption of the heavy metal added, with the effect more remarkable when the soil reacted with the sulfate prior to the metal. The shift in pH50 (the pH at which 50% of the metal ion-adsorption capacity was reached) for both Zn and Cd adsorption was also comparatively larger in the first sequence of reactions. It is suggested that the increase in negative charge density and the resultant negative potential of the soil were the primary cause of the pronounced effect of sulfate on adsorption of Zn or Cd, and the formation of the ternary surface complex -S-SO4-M, where S represents the soil surface and M denotes Zn or Cd, might also play a role in the effect.

Chen, H. M., Lin, Q. and Zheng, C. R. 1998. Interaction of Pb and Cd in soil-water-plant system and its mechanism: II. Pb-Cd interaction in rhizosphere. Pedosphere. 8(3): 237--244
ABSTRACT: The changes in extractable Cd and Pb concentrations in the rhizosphere soil of rice plants, root exudates from wheat and wheat plant and their complexing capacity with Pb and Cd were investigated under different Pb and Cd treatments. Results showed that the concentration of extractable Cd in the rhizosphere of rice in red soil was markedly increased by Pb-Cd interaction. It increased by 56% in the treatment with Pb and Cd added compared to that in the treatment with only Cd added in soil. Considerable differences in both composition and amount of root exudate from wheat and rice were found among different treatments. Lead and Cd might be complexed by root exudates. The concentrations of free Pb and Cd in the solution were markedly increased by adding root exudate from wheat and decreased by that from rice due to Pb-Cd interaction. The distribution patterns of Pb and Cd in roots were affected by Pb-Cd interaction, which accelerated transport of Pb into internal tissue and retarded accumulation of Cd in external tissue.

Xiao, F. H. 1998. Changes of protective enzymes and accumulation of polyamines induced by boron deficiency in roots of rape seedlings. Pedosphere. 8(3): 229--236
ABSTRACT: Rape cv. Zhongyou 821 plants were grown in nutrient solution containing 2 (deficient) or 20 (control) mmol B m-3. Boron deficiency decreased root dry weight and increased the rate of solute leakage and malondialdehyde (MDA) concentration in the roots. It is suggested that membrane composition altered under B deficiency. The concentration of putrescine and the ratio of putrescine to spermidine + spermine in rape roots increased, and the activities of superoxide dismutase and catalase decreased, during B deficiency. Peroxidase activity was higher in roots of B-deficient plants.

Yin, S. X., Shen, Q. R., Tang, Y. and Cheng, L. M. 1998. Reduction of nitrate to ammonium in selected paddy soils of China. Pedosphere. 8(3): 221--228
ABSTRACT: Three paddy soils were examined for their capacities of dissimilatory reduction of nitrate to ammonium (DRNA). 15N-labelled KNO3 was added at the rate of 100 mg N/kg. Either glucose or rice straw powder was incorporated at the rate of 1.0 or 2.0 mg C/kg respectively. Three treatments were designed to keep the soil saturated with water: (1) a 2-cm water layer on soil surface (with beaker mouth open); (2) a 2-cm water layer and a 1-cm liquid paraffin layer (with beaker mouth open); and (3) water saturated under an O2-free Ar atmosphere. The soils were incubated at 28! for 5 days. There was almost no 15N-labelled NH4+-N detected in Treatment 1. However, there was 1.4 to 3.4 mg N/kg 15N-labelled NH4+-N in Treatment 2, and 2.1 to 13.8 mg N/kg in Treatment 3. Glucose was more effective than straw powder in ammonium production. Because there was sufficient amount of non-labelled NH4+-N in the original soils, 15N-labelled NH4+-N produced as such should be the result of dissimilatory reduction. Studies on microbial population showed that there were plenty of bacteria responsible for DRNA process (DRNA bacteria) in the soils examined, indicating that number of DRNA bacteria was not a limiting factor for ammonium production. However, DRNA bacteria were inferior in number to denitrifiers. The DRNA process in soil suspension started after 5 days of incubation. Glycerol and sodium succinate, though both are readily available carbon sources to organisms, did not facilitate DRNA process. DRNA occurred only when glucose was available and at a C:NO3--N ratio >12. Both availability and quality of the carbon sources affected DRNA.

Yang, H., Du, M. Y., Chang, Q., Minami, K. and Hatta, T. 1998. Quantitative model for estimating soil erosion rates using 137Cs. Pedosphere. 8(3): 211--220
ABSTRACT: A quantitative model was developed to relate the amount of 137Cs loss from the soil profile to the rate of soil erosion. According to the mass balance model, the depth distribution pattern of 137Cs in the soil profile, the radioactive decay of 137Cs, sampling year and the difference of 137Cs fallout amount among years were taken into consideration. By introducing typical depth distribution functions of 137Cs into the model, detailed equations for the model were found for different soils. The model shows that the rate of soil erosion was mainly controlled by the depth distribution pattern of 137Cs, the year of sampling, and the percentage reduction in total 137Cs. The relationship between the rate of soil loss and 137Cs depletion was neither linear nor logarithmic. The depth distribution pattern of 137Cs was a major factor for estimating the rate of soil loss. The soil erosion rate was directly related with the fraction of 137Cs content near the soil surface. The influence of the radioactive decay of 137Cs, sampling year and 137Cs input fraction were not large compared with others.

Pu, L. J., Bao, H. S., Peng, B. Z. and Higgitt, D. L. 1998. Distribution and assessment of soil and land degradation in subtropical China--a case study of Dongxi River Basin, Fujian Province. Pedosphere. 8(3): 201--210
ABSTRACT: Some alternative methods for the rapid estimation of soil erosion rates were used to study the relationship between land use types and land degradation. The 137Cs content, magnetic susceptibility, aggregate stability, and soil properties were studied in the title area of China. A plot of 137Cs inventory (Y) against slope angle (X) showed a strong inverse log-log relationship (r=-0.83), indicating that much more soil erosion occurs on steeper slopes. Average soil loss (in thickness of topsoil per year) in the past 30 years for arable slope crest, arable slopes and tea plantation slopes was 1.6, 10.4 and 8.0 mm/year respectively. The surface layer enrichment factor of magnetic susceptibility (Y) in soil also shows an inverse log-log relationship (r=-0.63), indicating a similar tendency with the relationship between the 137Cs inventory (Y) against slope angle (X). The physical and chemical properties of soils among different land use types show different degraded characteristics at different significant levels.

Zhang, Z. G., Xu, Q. and Blevins, R. L. 1998. Effects of tillage management systems on residue cover and decomposition. Pedosphere. 8(3): 193--200
ABSTRACT: The effects of tillage methods on percentage surface residue cover remaining and decomposition rates of crop residues were evaluated in Kentucky, USA. The line transect method was used to measure residue cover percentage on continuous maize plots under no-tillage (NT), conventional tillage (CT), chisel plough (CH), and disc tillage (DT). Samples of rye (Secale cereale) and hairy vetch (Vicia villosa) were used for residue decomposition study. Results showed that the percentage of residue cover remaining was significantly higher for NT than for CH and DT and that for CT was the lowest ( isohumisols > Aridisols. The correlation analysis between Av-Se and the soil physicochemical properties showed that the correlations between Av-Se and organic matter, cation exchange capacity, Fe2O3, Al2O3, ignition loss, Co and Zn were positive at a highly significant level, but those between Av-Se and pH, base saturation, CaO, Ba and Sr were all negative at a highly significant level. The reason for some diseases related to the Se deficiency might be the leaching loss of selenium in some soils.

Liu, F., Tan, W. F., He, J. Z., Li, X. Y. and Violante, A. 1998. Changes of clay mineral association after high-gradient magnetic separation. Pedosphere. 8(1): 79--84
ABSTRACT: The changes of clay mineral association after high-gradient magnetic separation (HGMS) treatment, and the effects of chemical and physical technologies on concentrating Fe oxides for main soils in central and southern China were investigated by means of X-ray diffraction and chemical analysis. Results indicated that the concentrating times of Fe oxides by HGMS treatment were the largest for 0.2-2 um size fractions in the examined soils. For the soils in which 2:1 phyllosilicates were dominant, concentrating times of iron oxides by HGMS treatment were larger than by the 5 mol/litre NaOH treatment. Phyllosilicates were decreased after HGMS treatment; however, the decrease was less than that of kaolinite. The goethite/(goethite+haematite) values in Fe oxides of the soils kept virtually constant after HGMS treatment.

Pan, J. J. and Bergsma, E. 1998. Flood hazard prediction from soil properties by remote sensing and geographic information system: a case study of Mae Rim watershed, Chiang Mai Province, Thailand. Pedosphere. 8(1): 71--78
ABSTRACT: Physiography and soil in Mae Rim watershed, Chiang Mai Province, Thailand were investigated by using aerial photographs and satellite imagery in conjunction with field work. Soil infiltration rate and soil shear resistance were measured in the field. Many factors affecting runoff were analysed using the Integrated Land and Water Information System (ILWIS). A model determining flood hazard was developed. Three maps including runoff curve number map, runoff coefficient map, and flood inundation map were created, and the time of concentration was predicted.

Qian, J. L., Yin, Z. S., Ke, S. Z. and Xian, C. X. 1998. Application and verification of logarithmic linear correlation model of element contents between tree rings and soils near the tree roots. Pedosphere. 8(1): 65--70
ABSTRACT: Nine Platanus acerifolia trees growing in Nanjing, China, were selected to determine the contents of Li, Al, K, V, Mn, Co, Ni, Cu, Zn, Sr, Cd, Ba and Pb both in the 1994 growth rings, C(Z,t), and in the soils near the roots, C'(Z,t), of the trees. The results showed that the relationship between C(Z,t) followed the logarithmic linear correlation model, lgC'(Z,t)=a(Z)+b(Z) lgC(Z,t). Based on this model the chronosequences of element contents in the soils were reproduced from those in the tree rings; i.e. the dynamic variations in the element contents of the soils at the sites were traced. The chronosequences of elements including Cd, Pb, Mn, Co and Zn in the soils near the roots of P. acerifolia from 1957 to 1994 were established, and the background values of Cd, Pb, Mn, Co and Zn in the soil were calculated by taking the lowest values of the chronosequences of the element contents as upper limits of the background values.

Fu, G. M., Yuan, F. M., Yao, Z. H. and Liu, Y. J. 1998. Downward movement and leaching of NO3--N from nitrogen-fertilized corn on dryland soil. Pedosphere. 8(1): 59--64
ABSTRACT: A field lysimeter was used to investigate the downward movement and leaching of N applied to summer maize on cinnamon alluvial soil in Beijing, China. A N-fertilizer (120 kg N/hm2 ) and a control treatment were arranged for the study. Soil solution was collected at depths of 20, 40, 60, 120 and 170 cm, while leachate was collected at the bottom (200 cm) of the lysimeter. The results showed that the downward movement of NO3--N in soil profile was greatly affected by rainfall pattern. The peak of leached NO3--N from both treatments coincided with the peak of the rainfall. In addition, leached NO3--N from both treatments and rainfall were significantly correlated (P WG > WF, and it correlated significantly with Se availability.

Hu, F., Li, H. X. and Wu, S. M. 1997. Differentiation of soil fauna populations in conventional tillage and no-tillage red soil ecosystems. Pedosphere. 7(4): 339--348
ABSTRACT: In a field experiment in Jiangxi Province, China, the populations of major soil fauna groups including earthworms, enchytraeids, arthropods and nematodes were examined in conventional tillage (CT) and no-tillage (NT) red soil ecosystems. Earthworms, macro- and micro-arthropods were stimulated by NT, with earthworms showing the highest population increase by four times, while enchytraeids and nematodes favoured CT system, indicating the adaptability of these animals to a plough-disturbed soil environment. On the basis of relative response index, soil fauna was more sensitive to tillage than the soil resource base (C and N pools) and microflora. The population structure of soil fauna was also affected by tillage treatments. Analysis of nematode trophic groups showed that bacteria-feeding and plant parasitic nematodes were more abundant in CT soil whereas the proportions of fungivores and omnivore-predators increased in NT soil. Possible reasons for the differentiation in both size and structure of the fauna population are discussed and the ecological significance involved in these changes emphasized.

Xu, R. K. and Ji, G. L. 1997. Effect of electrolyte on the dissolution of aluminum from acid soils and the distribution of aluminum forms in soil solution. Pedosphere. 7(4): 331--338
ABSTRACT: Potassium chloride, CaCl2, NH4Cl, NaCl, K2SO4 and KF solutions were used for studying the effects of cations and anions on the dissolution of Al and the distribution of Al forms respectively. Power of exchanging and releasing Al from four kinds of cations was in the order: Ca2+ > K+ > NH4+ > Na+. The dissolution of Al increased with the cation concentration. The adsorption affinity of various soils for Al was different. Soil Al with a stronger adsorption affinity was difficult to be exchanged and released by cations. The Al-F complexes were main species of inorganic Al at a low concentration of cations, while Al3+ became major species of inorganic Al at a high concentration of cations. The results on the effect of anions indicated that the concentrations of total Al, three kinds of inorganic Al (Al3+, Al-F and Al-OH complexes) and organic Al complexes (Al-OM) when SO42- was added into soil suspension, were lower than those when Cl- was added. The dissolution of Al from soils and the distribution of Al forms in solution were affected by the adsorption of F- on the soil. For soils with strong affinity for F-, the concentrations of the three inorganic Al species in soil solution after addition of F- were lower than those after addition of Cl-; but for soils with weak affinity for F-, the concentrations of Al3+ and Al-OM were lower and the concentrations of Al-F complexes and total inorganic Al after addition of F- were higher than those after addition of Cl-. The increase of F- concentration in soil solution accelerated the dissolution of Al from soils.

Lu, Q. M. and Liao, Z. W. 1997. Comparative study on characteristics of P fixation by Mn, Fe and Al. Pedosphere. 7(4): 325--330
ABSTRACT: An experiment was conducted to examine the role of Mn in P fixation through comparing with Al and Fe. Hydroxides and oxides of Al, Fe and Mn were prepared in the laboratory under opened and closed conditions to react with phosphate. The newly formed Mn hydroxide showed the strongest P-fixing ability, even several times higher than Fe hydroxide, but became the lowest rapidly due to ageing when exposed to air. Mn oxide showed the lowest P-fixing ability. Therefore, a sound consideration on P fixation should be based on both quantities and P-fixing abilities of the compounds of Fe, Al and Mn. The importance of Mn to P availability should receive more attention especially under oxidation-reduction dynamic conditions.

Tu, S. H., Goh, T. B. and Banerjee, M. R. 1997. Vesicular arbuscular mycorrhizae-mediated uptake and translocation of P and Zn by wheat in calcareous soil. Pedosphere. 7(4): 317--324
ABSTRACT: Vesicular-arbuscular mycorrhizal (VAM) fungi have improved the growth and mineral nutrition of many host plants but these effects are moderated by soil factors and nutrient balance. The combined effects of VAM, Zn and P application on the growth and translocation of nutrients in wheat were investigated using a calcareous soil marginal in P and Zn concentrations. Wheat was grown in a growth chamber under various combinations of VAM, P and Zn with measurements done at heading stage and maturity. Vegetative dry matter accumulation was increased by P application and reduced by VAM treatments. Both P and VAM increased grain yield. Zinc concentration and uptake were generally reduced by P addition and VAM infection. There were no antagonistic effects of Zn on P acquisition in the plant. The role of VAM in enhancing the translocation of Zn and P from root to grain would be beneficial to seed setting and yield.

Zhou, L. Y. and Chen, Z. X. 1997. Study on rational irrigation for wheat production in Fengqui Region: II. A model of rational irrigation for wheat and its evaluation. Pedosphere. 7(4): 311--316
ABSTRACT: A 5-year experiment on water balance was conducted in a flat rainfed wheat field with an area of 66 m X 100 m in Fengqui, Henan Province, China. Based on the results of the 5-consecutive-year experiments, an irrigation model for wheat cultivation is suggested according to the principle of maintaining the water balance. The irrigation programme was designed by simulating the ideal soil moisture regimes during a wheat season. The deviation from the ideal soil moisture was kept within ± 50 mm. Implementation of this model would produce a grain yield of 5.25 t/ha under optimum fertilization. Compared with the traditional irrigation scheme, the suggested model saved irrigation water by 18%.

Chen, T. B., Struwe, S. and Kjoller, A. 1997. Effect of replacement of headspace gas on N2O and CO2 emissions in anaerobic incubation of soil. Pedosphere. 7(4): 303--310
ABSTRACT: The effect of C2H2 and change of headspace gas on N2O emission, denitrification, as well as CO2 emission was studied by anaerobically incubating slurries of an agricultural soil for 7 days at 25!. Both N2O reduction and CO2 emissions were inhibited by the addition of 100 ml/litre of C2H2. However, the inhibition to CO2 emission was alleviated by the replacement of headspace gas, and the N2O emission was enhanced by the replacement. Acetylene disappeared from the soil slurries during the incubation. Results obtained from the traditional C2H2 blocking technique for determination of denitrification rate, especially in a long-time incubation, should be treated with care because of the side-effect existing in the incubation environments without change of headspace gas. To reduce the possible side-effect on the processes other than denitrification, it is suggested that headspace gas should be replaced several times during a long-time incubation.

Shen, R. F., Brookes, P. C. and Powlson, D. S. 1997. Effect of long-term straw incorporation on soil microbial biomass and C and N dynamics. Pedosphere. 7(4): 297--302
ABSTRACT: The long-term effect of straw incorporation on soil microbial biomass C contents, C and N dynamics in both Rothamsted and Woburn soils, UK, was studied. The results showed that for both soils, the microbial biomass C contents were significantly different among all the treatments, and followed the sequence in the treatments: straw chopped and incorporated into 10 cm (CI10) > straw burnt and incorporated into 10 cm (BI10) > straw chopped and incorporated into 20 cm (CI20) > straw burnt and incorporated into 20 cm (BI20). Laboratory incubation of soils showed that the cumulative CO2 evolution was closely related to the soil microbial biomass C content. Carbon dioxide evolution rates (CO2-C, ”“ (g.d)-1) decreased rapidly in the first two weeks' incubation, then decreased more slowly. The initial K2SO4-extractable NH4-N and NO3-N contents were low and similar in all the treatments, and all increased gradually with the incubation time. However, net N immobilization was observed in chopped treatments for Rothamsted soils during the first 4 weeks. Nevertheless, more N mineralization occurred in Treatment CI10 than any other treatment at the end of incubation for both soils. The Woburn soils could be more prone to nitrate leaching because the soils were more permeable and more N was mineralized during the incubation compared to the Rothamsted soils.

Wang, F. L. and Huang, P. M. 1997. Mineralogy of selected paddy soils in southeastern China. Pedosphere. 7(4): 289--296
ABSTRACT: The mineral composition of three paddy soils: Jinghua (paddy soil on Quaternary red clay), Fuyang (alluvial loamy paddy soil), and Shaoxing (marine gleyic clayey paddy soil), was studied. All the soils contained quartz, mica, vermiculite, chlorite and kaolinite, and the distribution of these minerals varied with soil particle size fractions. The clay fraction of the Fuyang and Shaoxing soils also contained smectite. Although X-ray data did not show the presence of smectite in the Jinghua soil, this mineral was identified by the chemical method, suggesting a transitional property of the mineral in the soil. Hydroxy-Al interlayered minerals were also present in the clay fraction. The amount of smectite in the soils was 31.6 (Shaoxing), 16.5 (Fuyang), and 21.4 (Jinghua) g/kg; for vermiculite it was 33.3 (Shaoxing), 16.5 (Fuyang), and 8.5 (Jinghua) g/kg. Smectite was only found in the clay fraction. In contrast, amounts of vermiculite in soil particle size fractions were 3.0-11.4 (sand), 2.1-6.0 (coarse silt), 4.6-18.9 (medium silt), 0.9-40.0 (fine silt), and 17.0-108 (clay) g/kg. Non-crystalline aluminosilicates in the soils in g/kg were: 2.4 (Shaoxing), 1.9 (Jinghua) and 1.7 (Fuyang).

Wang, Z. Y. and Chen, Y. C. 1997. Alleviation of copper toxicity to maize by phosphorus fertilizer in purple soil. Pedosphere. 7(3): 281--288
ABSTRACT: A pot experiment was conducted to evaluate the effects of P fertilizer in inhibiting Cu toxicity to maize in neutral purple soils (Entisol) from China. Results indicated that the growth of shoots and roots was reduced by Cu and the height and biomass were significantly negatively correlated to application levels of Cu at no and low P (100 mg/kg) levels. However, maize biomass was increased and Cu-toxicity alleviated in treatments with P at 300 and 500 mg/kg. To maintain the normal maize growth the critical application rates of P fertilizer should be 160, 210, 300, and 500 mg P/kg at 10, 50, 100, and 200 mg Cu/kg, respectively. The increases in polyphenol oxidase [catechol oxidase] and catalase activities in maize leaves, and dehydrogenase activity in the roots due to P fertilizer were in the order of medium P > high P > low P > no P. Activities of polyphenol oxidase and catalase were significantly positively correlated to the application levels of Cu, whereas that of dehydrogenase was the reverse. Medium and high P repressed the influence of Cu on the activities of the three enzymes. P fertilizer reduced the Cu concentrations of maize roots and leaves and the change ranges of the P:Cu ratio of maize roots and the P:Cu, N:Cu, and K:Cu ratios of maize leaves. Soil available Cu could be reduced by application of P fertilizer, especially at high P level.

Wang, X. J., Hu, X. F. and Chen, H. Z. 1997. Some biogeochemical characteristics of tea soils. Pedosphere. 7(3): 275--280
ABSTRACT: Characteristics of element abundance, cycling, and element budget in tea soils were discussed based on investigations of 6 tea plantations and the adjacent waste lands in the Three Gorges region, Hubei Province, China. The plantations had different soil-forming parent materials, but similar landforms, and the same tea variety and age. The results showed that tea growing increased the organic matter, total and available N, P, Al, and Mn contents; elements enriched by tea trees were, in descending order; P > Ca > K > Mn > Mg > Zn > Al > Fe. Elements returned through tea litter were; Ca > Mn > P > Zn > Mg > K > Al > Fe. In the nutrient budget of the soil-tea system, P and K were in deficit, whereas Al, Ca, Fe, and Mn were in surplus.

Zhu, D. W., Pi, M. M. and Liu, W. D. 1997. Relationship between soil boron adsorption kinetics and rape plant boron response. Pedosphere. 7(3): 269--274
ABSTRACT: A boron (B) adsorption kinetic experiment in soil using a flow displacement technique showed that the kinetic data could be described with some mathematical equations. The average values of the correlation coefficient for zero-order, first-order, parabolic diffusion, Elovich, power function, and exponential equations were 0.957, 0.982, 0.981, 0.984, 0.981, and 0.902, respectively. The correlation between adsorbed B or its other expression form and time were the highest for first-order, parabolic diffusion, Elovich, and power function equations, the second for the zero order equation, and the lowest for the exponential equation. The parabolic diffusion equation fitted well the experimental results, with the least standard error among the six kinetic equations, showing that the movement of B from soil solution to soil colloid surface may be controlled by B diffusion speed. The B content of rape (Brassica napus) seedlings obtained from soil cultivation was correlated with the rate constants of the kinetic equations. The constants of first-order, parabolic diffusion, and exponential equations were significantly correlated with the B content of the crop and NPK treatment at a 95% probability level, with correlation coefficients being 0.686, 0.691, and 0.641, respectively. The zero-order equation was significant at 99% probability level (r =0.736). These results showed that the adsorption kinetic constants of soil B were closely related with the rape plant response to B.

Bai, Z. G., Wan, G. J., Wang, C. S., Wan, X. and Huang, R. G. 1997. Geochemical speciation of soil 7Be, 137Cs, 226Ra and 228Ra as tracers to particle transport. Pedosphere. 7(3): 263--268
ABSTRACT: A brunisolic soil collected from an erosive forest land (HF-1-1) and a yellow soil from an accumulative shallow basin (HF-6-1) in the watershed of Lake Hongfeng (HF), China, were used for activity measurements of 7Be, 137Cs, 226Ra, and 228Ra in different geochemical speciation. More than 85% of 7Be, 137Cs, 226Ra, and 228Ra in the soils were bound to organic, Fe-Mn oxy-hydroxide, and residual fractions. They could move with soil particles and be used as tracers for the erosion and/or accumulation of soil particles. 7Be geochemical speciation in the soils agreed with its trace for seasonal particle transport. 137Cs geochemical speciation was suitable for tracing soil particle accumulation and for sediment dating. 226Ra and 228Ra were combined in the crystalline skeleton of clay minerals and mainly remained as residues in the soils and little was bound to the soluble, exchangeable, and carbonate fractions. The differentiation of 226Ra:228Ra activity ratios in different geochemical fractions in the soils could be used as a parameter to trace accumulation and/or erosion of soil particles.

Xu, M. G., Zhang, Y. P. and Liu, W. N. 1997. Diffusion of chloride ions in soils: II. Kinetic and thermodynamic characteristics. Pedosphere. 7(3): 257--262
ABSTRACT: The amounts of chloride ions diffused in four soils of different textures at the same water content but under different temperatures and at varied time were measured by the diffusion cell method using 36Cl-labelled CaCl2 solution. Five kinetic models were used to fit the dynamic process of the diffusion of chloride ions in the soils. Results showed that the Elovich equation or power function equation was the best model to describe the process. The pseudothermodynamic parameters (the net reaction energy, the activation entropy, activation enthalpy, and activation free energy of the diffusion) were derived from the absolute reaction-rate theory. The results showed that these parameters decreased in the order of loessal soil > black lu soil > lou soil (manured loess soil) > yellow cinnamon soil, which indicated that as the force and the heat-energy barrier to be overcome for diffusion decreased, the diffusion rate increased and the disorder of the soil-solution-ion system due to diffusion decreased successively with the texture becoming heavier in the four soils.

Zhou, L. Y. and Chen, Z. X. 1997. Study on rational irrigation for wheat production in Fengqiu Region: I. Analysis of the relation between soil water supply and wheat yield. Pedosphere. 7(3): 251--256
ABSTRACT: A 5-year experiment on water balance was conducted in a flat rainfed wheat (Triticum aestivum) field with an area of 66 X 100 m in Fengqiu, Henan Province, China. Results showed that the correlation between wheat yield and water consumption was not significant, but that between wheat yield and the ratio of water supply to Penman evaporation was significant, following a parabolic curve. The water consumption process, as well as the growing season of wheat, could be divided into three periods. The first (154 days) was vegetative growth period, during which the water consumption accounted for 35% of the total; the second (65 days) was the reproductive growth period, during which water consumption occupied 57%, indicating the importance of water consumption in this period; and the third (5-9 days) was the maturation period, during which water supply was not important to yield formation.

Chen, H. J., Li, Y. Q., Chen, D. D. and Hu, S. C. 1997. Growth responses of young slash pine (Pinus elliotti Engelm.) to N, P and K fertilizers in red-yellow soil in Jiangxi Province, China. Pedosphere. 7(3): 243--249
ABSTRACT: Between 1991 and 1995 the growth responses of young slash pine (Pinus elliottii) to N, P, and K fertilizers in yellow-red soil in the title region were studied. N fertilizer decreased the growth, while P not only significantly improved the increment of bottom diameter, height, and crown diameter, but also caused earlier canopy closure of the stand. It also had a sustainable effect in the next two years. Slash pine had the most significant response to the treatment of 200 kg P2O5/ha, in which tree height, bottom diameter, and crown diameter were increased by 22%, 35%, 20%, and 18% in 1994 and 21%, 25%, 10%, and 10% in 1995, respectively, compared to the control. Although there was no remarkable response to K fertilizer, good growth response to the application of 100 kg P2O5 plus 100 kg K2O/ha was shown, and tree height, bottom diameter, and crown diameter were increased by 31%, 14%, 23% and 21%, respectively, in 1993, compared to the control.

Zeng, Z. Y. and Pan, X. Z. 1997. Application of remote sensing in study of slope land use and soil erosion in subtropic region of China. Pedosphere. 7(3): 237--242
ABSTRACT: Two remote sensing case studies are described on land use in the subtropical region of China. The first was on slope land use in the Yangtze River Three Gorges area (60 497 km2). Geometric correction and supervised classification were conducted for ten scenes of Landsat-5 thematic mapper or multiple spectral scanner (MSS) images. The resolution of the processed images was 50 X 50 m on the ground. From the classification, land use/cover categories in this area were discriminated. Then the croplands, including rice fields and upland fields, were extracted from the land use/cover maps. Simultaneously, the slope grade maps were prepared based on the topographic maps. Overlaying the slope grade maps and the cropland maps, the area and percentage of the croplands in different slope grades were determined. This case study showed that 71.5% of the uplands had slopes of >15 and 25% had slopes >25 On which urgent engineering works should be undertaken to prevent/reduce erosion. The second case study was on soil erosion in Linshan County of Guangxi Province. Aerial photograph interpretation and supervised classification of a Landsat TM image were carried out to discriminating land cover/use categories in an area of 3557.8 km2. Soil erosion intensity grades were determined according to the land cover/use maps and slope maps. It was shown that land suffering soil erosion accounted for 2404.0 km2 (67.6%) of the total area of the county. Necessary measures to control soil erosion are needed across this area.

Khan, K. S., Xie, Z. M. and Huang, C. Y. 1997. Effect of anions on toxicity of cadmium applied to microbial biomass in red soil. Pedosphere. 7(3): 231--235
ABSTRACT: A laboratory incubation experiment was conducted to elucidate the effects of associated anions on toxicity of Cd applied to microbial biomass in a red soil (Ultisol from Zhejiang Province, China). Cd was applied at six different levels (0, 5, 15, 30, 60, and 100 ¼g/g soil) in the form of either cadmium acetate or cadmium chloride. Application of Cd as cadmium acetate markedly reduced the soil microbial biomass C compared to Cd applied as cadmium chloride at all the tested levels. Similarly, organic C to biomass C ratio in the soil was increased by increasing the level of the Cd in the soil as cadmium acetate, while the change was much smaller in the case of cadmium chloride at the same Cd levels. The results suggested that due consideration should be given to the source of Cd when deciding the Cd levels in experiments.

Shen, Q. R., Wang, Y., Chen, W. and Shi, R. H. 1997. Changes of soil microbial biomass C and P during wheat growth after application of fertilizers. Pedosphere. 7(3): 225--230
ABSTRACT: A pot experiment was carried out with a clay loam from Jiangsu Province, China. The results showed that soil microbial biomass C increased with the application of organic manure at the beginning of the experiment and then gradually decreased with a decrease in the temperature. The soil biomass C increased at the tillering stage when the temperature gradually increased, and rose to the highest value at the anthesis stage, being about 554.9-794.4 mg C/kg. The application of organic manure resulted in the highest increase in biomass C, whilst application of ammonium sulfate gave the lowest. At harvest time the soil biomass C decreased to the presowing level. Like soil biomass C, the amount of biomass P increased with incorporation of organic manure, and again, ammonium sulfate treatment gave the lowest increase. The changing patterns of the C:P ratio of soil microbial biomass at the stages of wheat growth were also described.

Zeng, Z. Y. and Pan, X. Z. 1997. Study on soil gleization in subtropic region of China using LBV transformed landsat images. Pedosphere. 7(3): 219--224
ABSTRACT: A new type of transformed Landsat images (LBV images) and their application in discriminating soil gleyification in subtropical regions of China is described. LBV transformation was worked out for extracting useful information from original landsat images. Using this method, three black and white images, L image, B image, and V image, were computer generated from original bands of a Landsat scene, which covered a large area of 34528 km2 in Hubei and Hunan provinces in south China. Then a colour composite was produced from these three images. These kinds of black-and-white and colour images contained rich and definite geographic information. Using field work, the relationship between the colours on the composite and the land use/cover categories on the ground was established. Thirty-seven composite colours and 70 ground feature categories could be discriminated altogether. Finally, 17 land use/cover categories and 10 subregions affected by soil gleyification were determined, and the gleyification area for the study area was estimated to be 731.3 km2.

Wang, Y. J., Yang, H. and Gao, W. L. 1997. Particle size distribution of kaolinite and halloysite in weathering products of granite and its implications for pedogenesis. Pedosphere. 7(3): 211--218
ABSTRACT: The kaolins collected from a profile of weathered granite at Yichun County, Jiangxi Province, China, were subjected to particle size fractionation by the conventional sedimentation method and examined by x-ray diffraction, scanning and transmission electron microscopy. All of them exhibited a mixture phase of poorly crystallized kaolinites and halloysites (0.7 nm) occurring as the main clay minerals. Electron micrographs showed that plate kaolinites were the principal constitution in the coarse fraction, with more tubular and curled halloysite (0.7 nm) in the fine fraction. Both of them showed normal probability curves in particle size distributions. The ratios of kaolinite and halloysite (0.7 nm) in different size fractions were examined by X-ray diffraction with a series of X-ray patterns characterized by three main peaks at d(001), d(002), and d(020), varying in intensity. An index, Qhm, expressed as (Id(001) + Id(002))/(2 X Id(020)) was designed to indicate relative ratios of the two clay minerals in a number of mixture phases. Because kaolinite and halloysite (0.7 nm) commonly occurred, respectively, in low and medium leaching micro-environments, the index Qhm could be used to indicate weathering and pedogenic conditions of a weathering crust.

Tang, S. R., Huang, C. Y. and Zhu, Z. X. 1997. Commelina communis L.: Copper hyperaccumulator found in Anhui Province of China. Pedosphere. 7(3): 207--210
ABSTRACT: Commelina communis L. growing over some new copper mining wastelangds at Bijiashan,Tongling City of Anhui Province,China,was found to be a copper hyperaccumulator,Its copper concentrations were 2707-6159( 4439±2434) mg kg^-1 ,369-831,(731±142)mg kg^-1 ,and 429-587(547±57)mg kg^-1 ,respectively,in the roots,stems,and leaves.The soils supporting the growth of the species had a copper concentration ranging from 4620 to 5020 mg kg^-1 and averaging 4835±262 mg kg^-1 ,suggesting that the species could not only grow on heavily copper-contaminated soils but aslo accumulate extraordinarily high concentration of copper, thus,it shows great potential in the phytoremediation of copper-contaminated soils,the restoration of mined land,geochemical prospecting ,and the study of environmental pollution changes.

Cheng, L. L., Wen, Q. X. and Chen, B. Y. 1997. Nitrogen forms of maillard polymers derived from xylose and 15N-labelled glycine. Pedosphere. 7(3): 199--206
ABSTRACT: Water-soluble,nondialyzable Maillard polymers were prepared by reacting D-xylose with ^15N-glycine (and /or glycine)at 68! and pH 8.0 at equimolar concentrations of 1,0.5 and 0.1 mol L^-1,respectively, for 13 days and partitioned into acid-insoluble(MHA) and acid-soluble(MFA) fractions.The nitrogen froms in these polymers were studied by using the ^15N cross polartisation-magic angle spinning nuclear magnetic resonance(CPMAS NMR) technique in combination with chemical methods .The ^15N nuclear magnetic resonance(NMR) data showed that while the yield,especially the MHA /MFA ratio,varied considerably with the concentrations of the reactants,the nitrogen distribution patterns of these polymers were quite similar. From 65% to 70% of nitrogen in them was in the secondary amide and /or indole form with 24%-25% present as aliphatic and /or aromatic amines and 5% to 11% as pyrrole and /or pyrrole-like nitrogen,More than half (50%-77%) of the N in these polymers were nonhydrolyzable,The role of Maillard reacion in the formation of nonhydrolyzable nitrogen in soil organic matter is discussed.

Zhu, H. X., Ma, L. W. and Selim, H. M. 1997. Application of a kinetic multireaction model for studying metolachlor adsorption in soil. Pedosphere. 7(3): 193--198
ABSTRACT: Metolachlor retention on a Sharkey clay soil (Vertic Haplaquept from Louisiana, USA) was quantified using a kinetic batch method for different initial solution concentrations. Time-dependent adsorption was carried out by monitoring solution concentration at different reaction times. Adsorption was highly kinetic in nature. Attempts were made to describe metolachlor retention based on a kinetic multi-reaction model which included reversible and irreversible retention processes of the equilibrium and kinetic types. The predictive capability of the model for the description of experimental results for metolachlor retention was examined and proved to be adequate.

Chen, Y. X., Chen, Y. Y., Lin, Q., Hu, Z. Q., Hu, H. and Wu, J. Y. 1997. Factors affecting Cr(III) oxidation by manganese oxides. Pedosphere. 7(2): 185--192
ABSTRACT: The high oxidation ability of manganese oxides or soils was used to study effects of pH and coating on Cr(III) oxidation. The results indicated that Cr(III) oxidation peaked in pH 4.0-6.5. The amount and rate of Cr(III) being oxidized by uncoated delta-MnO2 were larger than those by Fe oxide- or CaCO3-coated one. Inorganic Cr(III) was more easily oxidized by MnO2 than organic complex Cr(III) due to different surface affinities. Precipitated Cr(III) and adsorbed Cr(III) might be transferred onto MnO2 surface and then oxidized to Cr(VI).

Zhou, J. H., Zhu, X. L. and Wang, D. M. 1997. Effect of fertilizer N forms on physiological metabolism and potassium uptake of fluecured tobacco. Pedosphere. 7(2): 177--184
ABSTRACT: Tobacco cv. Honghuadajinyuan seedlings were grown in sand culture and supplied with Hoagland solution containing 3 to 15 mmol N/litre as urea, NaNO3 or NH4NO3. Plant growth, chlorophyll content, photosynthesis and respiration rates, K uptake and root K+ secretion were studied. Total plant biomass, net respiration rate, and K uptake (g/kg dry matter) were highest with supplying 6 mmol N/litre as urea, 15 mmol N/litre as NaNO3, and 12 mmol N/litre as NH4NO3. K+ secretion from roots increased with N concentration in the nutrient medium with all N forms.

Zhang, R. X., Shen, Z. G. and Guan, H. Y. 1997. Influences of root zone restriction and nitrogen nutrition on hybrid wheat growth. Pedosphere. 7(2): 171--176
ABSTRACT: To study the physiological effects of a small root zone, plants of hybrid wheat cv. Meiyou 4 were grown in small pots (1 litre) or large pots (8 litre) with low nitrogen (50 mg kg-1 soil) and high nitrogen (200 mg kg-1 soil). Restricting the root zone decreased plant dry weight at the stages of stem elongation and flowering, compared with control plants grown in the large pots (P feather cockscomb (Celosia argentea) > alligator alternanthera (Alternanthera philoxeroides) > tobacco > sesbania (Sesbania cannabina) > wheat > broad bean (Vicia faba). Ethiopian guizotia showed very high K-enrichment capability at different soil K levels, and the K content in its dry matter was >110 mg/kg when soil K was fully supplied, and ?0 mg/kg when no K fertilizer was applied. For alligator alternanthera, the capability to accumulate K was closely related with its growth medium. When it was grown on soils, both the K content and K uptake rate of the plant were similar to those of tobacco. Evident K depletion was observed in the rhizosphere of all plant species, and the depletion rate was related to the capability of K enrichment of plant.

Wei, S. Q., Sommar, J., Lindqvist, O. and Xiao, Z. F. 1997. Effect of mercury deposition on mercury content and distribution in rye grass. Pedosphere. 7(2): 155--164
ABSTRACT: Lolium multiflorum was grown in the greenhouse or exposed to the atmosphere, in soil with or without 5 mg Hg/kg. The relative importance of foliar absorption, root uptake and atmospheric deposition to Hg contamination of the grass was investigated. Hg deposition accounted for 27-32% of Hg content in the above-ground parts of grass plants when Hg was not added to the soil. Hg deposition varied between 0.01 and 0.07 ¼g/pot over a 2-week period, contributing 17-48% of the total Hg load in exposed grass plants.

Zhang, B., Gao, G. Z., Zhang, T. L. and Sun, Y. L. 1997. Determination of water content in clayey red soil using techniques based on measurement of dielectric constant. Pedosphere. 7(2): 149--154
ABSTRACT: Two time-domain reflectometry (TDR) systems and a new impedance measuring instrument, Thetaprobe, which are based on determination of soil dielectric constant, were used to measure water content of clayey red soil to evaluate the accuracy of these instruments. The results indicated that these instruments should be carefully re-calibrated before being applied in clayey red soil. With a new calibration curve fed into one of the TDR systems tested, Trase system, the measured data compared well with those by standard oven-drying method.

Yuan, L., Huang, J. G. and Yu, S. Q. 1997. Responses of nitrogen and related enzyme activities to fertilization in rhizosphere of wheat. Pedosphere. 7(2): 141--148
ABSTRACT: In the present experiment, wheat seedlings (Triticum aestivum) were grown on a purple soil with various fertilizer treatments in order to investigate the responses of nitrogen and related enzyme activities in the rhizosphere. The results revealed the increments of both organic matter and total N in the soil with the proximity to the growing roots, especially in the treatment of supplying pig manure in combination with chemical fertilizer, suggesting that they could come from root and microorganism exudation which could be intensified by inorganic-organic fertilization, being of benefit to improving the physical and biological environment in the rhizosphere of wheat. Much more inorganic N was observed in the fertilized soils surrounding wheat roots than in the CK treatment, indicating the improvement of crop N supply in the rhizosphere of wheat by fertilization. The activities of invertase, urease and protease in the root zone were greatly enhanced as compared to those in the other parts of soils except that the urease activities were similar in the rhizosphere and nonrhizosphere of the CK and pig manure treatments, indicating that invertase and protease could be produced by growing roots and rhizosphere microorganisms, in contrast to urease which could be stimulated by urea. Also, significant increment of these three enzyme activities in the rhizosphere of wheat by fertilization, especially by application of chemical fertilizer combined with pig manure, suggested that fertilization not only accelerated the renewal of organic matter but also enhanced bioavailability of organic N in that soil zone. This could be the reason why the total amount of inorganic N available for plants was increased more obviously in the rhizosphere of wheat of the fertilization treatments than in that of the CK treatment.

Huang, M. B., Kang, S. Z., Zhang, F. C. and Li, Y. S. 1997. Behaviours of soil-root interface and their variations with wheat varieties. Pedosphere. 7(2): 133--140
ABSTRACT: Water movement into and out of roots depends on the water potential difference between the bulk soil and the root xylem and the total hydraulic conductance of the pathway, which can be divided into three parts, I.e. soil conductance, soil-root conductance and root conductance. The values and relative importance vary with soil water content. The general rule is that water uptake by roots is mainly limited by radial hydraulic conductance of roots in wet soils, the soil-root interface becomes a major limiting factor to water uptake in moderately dry soils, and the water uptake is limited by the rapidly decreasing soil hydraulic conductance in seriously dry soils. Meanwhile these limiting factors vary with crop variety, and these variations can be used to evaluate the drought-resistance and water use efficiency of crops.

Yin, S. X., Tang, Y., Liang, Y. C. and Feng, K. 1997. Effect of ammonium fixation on determination of N mineralized from soil microbial biomass. Pedosphere. 7(2): 127--132
ABSTRACT: Two soils with relatively high (Soil 1) and low (Soil 2) ammonium fixation capacities were used to examine the effect of ammonium fixation on the determination of N mineralized from soil microbial biomass. Organism suspension was quantitatively introduced to Soil 1 at various rates. Both fumigation-incubation (FI) and fumigation-extraction (FE) methods were used to treat the soil. The amount of fixed NH4+-N increased with increasing rate of organism-N addition. A close correlation was found between the amount of fixed ammonium and the rate of organism-N addition. The net increases of fixed NH4+-N were equivalent to 38 and 12% of the added organism-N for FI and FE treatments, respectively, in this specific soil. To provide isotopic evidence, 15N-labelled organism-N was added to Soils 1 and 2 at 121.4 mg N/kg. In FI treatment, 22 and 3 mg N/kg of labelled N were found in the fraction of fixed NH4+-N in Soils 1 and 2 respectively; while in FE treatment, 9 mg N/kg of labelled N was found in the fraction of fixed NH4+-N in Soil 1 only. There was no labelled N in the fraction of fixed NH4+-N in Soil 2. In all of the unfumigated (check) soils, there was little or no labelled N in the fixed fractions, probably because the organism-N added was easily mineralized and nitrified. A mean of 0.64 for KN value, the fraction of N mineralized in the killed microbial biomass, was obtained with inclusion of the net increase of fixed NH4+-N. The corresponding value calculated with exclusion of the net increase of fixed NH4+-N was 0.46. It was concluded that ammonium fixation was a problem in determination of KN, particularly for soils with a high ammonium fixation capacity. Results also showed that microbial biomass N measurement by FE method was less affected by ammonium process than that by FI method.

Wang, Z. S., Zhang, S. M. and Liu, D. S. 1997. Kinetic modelling of degradation of organic compounds in soils. Pedosphere. 7(2): 119--126
ABSTRACT: A set of equations is suggested to describe the kinetics of degradation of organic compounds applied to soils and the kinetics of growth of the involved microorganisms: -(dx/dt) = jx + kxm and dm/dt = -fm + gxm where x is the concentration of organic compound at time t, m is the number of microorganisms capable of degrading the organic compound at time t, while j, k, f and g are positive constants. This model can satisfactorily be used to explain the degradation curve of organic compounds and the growth curve of the involved microorganisms.

Xiong, L. M., Fardeau, J. C. and Zhou, Z. G. 1997. Suitability of isotope kinetic approach to assess phosphorus status and bioavailability of major acidic soils in subtropical China. Pedosphere. 7(2): 111--118
ABSTRACT: A 32P isotope kinetic approach was used to describe the chemical status and bioavailability of phosphorus in 32 acidic soils from subtropical China. By determining the residual radioactivity, rt, in soil solution at different time, t, after introduction of the isotope in an amount of R into the steady soil-water system, a well-defined isotope kinetic model was established, and upon this model the decrease rate, n, of log(rt/R) with respect to log t, the mean sojourn time of phosphate ions in solution, the mean exchange rate and the mean flux of phosphate ions between soil solid and solution phases were calculated. Other parameters, such as the exchangeable P within the first minute of isotope exchange (E1), and P in various compartments that could be exchanged with solution phosphate ions at different periods of time, were also obtained. For these acidic soils, the r1/R had a significant correlation with the contents of clay and free Al2O3 where r1 is the radioactivity in solution 1 minute after introduction of the isotope into the system. Parameter n also had a significant correlation with clay content and a negative correlation with soil pH. E1 values and Cp, the P concentration in soil solution, also significantly correlated with clay and sesquioxide contents of the soils. These indicated that these isotope kinetic parameters were largely influenced by P-fixing components of the soils. For the soils with strong P-fixing ability, the E1 values overestimated labile P pools and hence their correlations with A values and plant P uptake were not significant. The other isotope kinetic parameters also had no significant correlation with plant P uptake. On the other hand, the conventional chemical-extracted P correlated better with plant P uptake. It was concluded that the isotope kinetic method could assess the P chemical status yet it would be inappropriate in predicting plant available P for soils with a high P-fixing ability as the problem of an overestimation of soil labile P in these soils was inevitable.

Huang, X. and Evangelou, V. P. 1997. Iron phosphate coating: a novel approach to controlling pyrite oxidation. Pedosphere. 7(2): 103--110
ABSTRACT: A novel coating technique was developed for controlling pyrite oxidation. The technique involved leaching pyrite particles with a solution containing low concentrations of phosphate and hydrogen peroxide. During the leaching process, the iron released from pyrite by hydrogen peroxide was precipitated by phosphate as a ferric phosphate coating. This coating effectively prevented pyrite oxidation and it could be established at the expense of only surface portions of pyrite. The emergence of this technique could provide a unique potential route for abating acid mine drainage and reclaiming sulfide-containing degraded mining land.

Lin, C. X. and Melville, M. D. 1997. Controls of soluble Al in experimental acid sulfate conditions and acid sulfate soils. Pedosphere. 7(2): 97--102
ABSTRACT: The controls of soluble Al concentration were examined in three situations of acid sulfate conditions: (1) experimental acid sulfate conditions by addition of varying amounts of Al(OH)3 (gibbsite) into a sequence of H2SO4 solutions; (2) experimental acid sulfate conditions by addition of the same sequence of H2SO4 solutions into two non-acid sulfate soil samples with known amounts of acid oxalate extractable Al; and (3) actual acid sulfate soil conditions. The experiment using gibbsite as an Al-bearing mineral showed that increase in the concentration of H2SO4 solution increased the soluble Al concentration, accompanied by a decrease in the solution pH. Increasing the amount of gibbsite added to the H2SO4 solutions also increased soluble Al concentration, but resulted in an increase in solution pH. Within the H2SO4 concentration range of 0.0005-0.5 mol/litre and the Al(OH)3 range of 0.01-0.5 g (in 25 ml of H2SO4 solutions), the input of H2SO4 had the major control on soluble Al concentration and pH. The availability of Al(OH)3, however, was responsible for the spread of the various sample points, with a tendency that the samples containing more gibbsite had a higher soluble Al concentration than those containing less gibbsite at equivalent pH levels. The experimental results from treatment of soil samples with H2SO4 solutions and the analytical results of acid sulfate soils also showed a similar trend.

Chen, G. C., He, Z. L., Zhu, J. and Zhang, M. K. 1997. Fumigation-extraction method for measurement of microbial biomass-N in red soils. Pedosphere. 7(1): 87--91
ABSTRACT:

Shen, A. L., Li, X. Y., Kanamori, T., Ono, S. and Arao, T. 1997. Low-molecular-weight aliphatic acids in soils incubated with plant residues under different moisture conditions. Pedosphere. 7(1): 79--86
ABSTRACT: Incubation experiments were conducted to investigate the dynamics of low-molecular-weight aliphatic acids in two Andosols with and without plant materials. Results showed that amount of low-molecular-weight aliphatic acids in soils alone varied considerably with water regime under which the soil was incubated, duration of incubation and soil organic matter content, ranging from 257-860 ¼mol / kg soil, of which 19-33% was in a free state. Incorporation of plant materials increased greatly the amount and diversity of low-molecular-weight aliphatic acids, as well as the proportion occurring in the free state. Generally, among the aliphatic acids detected, acetic, propionic, glyoxalic and formic acids were predominant.

Liu, Z. G. and Ma, X. H. 1997. Effect of reclamation on soil environment in Sanjiang Plain. Pedosphere. 7(1): 73--78
ABSTRACT: The soil environment in the title area of Heilongjiang Province, China, has changed greatly because of large-scale reclamation. The physical and chemical properties of soil have changed, and soil erosion, soil saline-alkalization and soil pollution has occurred in some areas. These problems have obstructed the sustainable development of agriculture. Suggestions for the sustainable use of these soils are given.

Xu, M. G., Zhang, Y. P. and Liu, W. N. 1997. Diffusion of chloride ions in soils: I. Influences of soil moisture, bulk density and temperature. Pedosphere. 7(1): 65--72
ABSTRACT: Diffusion coefficients of chloride ions in four soils of different texture with varying effective moisture content and bulk density from 1.1 to 1.6 g/cm3 under three different temperatures, were determined by the diffusion-cell method using 36Cl-labelled CaCl2 solution. The results showed that activation energy decreased with water content, which indicated that the threshold for diffusion was lower at a higher soil moisture rate. The diffusion coefficient (D) of chloride ions in soil increased consistently with soil moisture. Although a near linear increase in the diffusion coefficient with increasing soil moisture or bulk density in all the soils was observed, the increase rate in different soils was not the same. The D value increased with temperature, and with temperature increased by 10! in the range 5-45!, the D valve increased by 10-30%, averaging 20%. Chloride diffusion in soil at 200 g/kg moisture was in the order: loessial soil > black lu soil > lou soil (manured loess soil) > yellow cinnamon soil; I.e. the heavier the soil texture the higher the chloride diffusion.

Ni, W. Z. and He, N. Z. 1997. Effect of excess fertilizer phosphorus on some chemical properties of paddy soil derived from red soil and its relation to rice growth. Pedosphere. 7(1): 59--64
ABSTRACT: A field experiment with an early rice-late rice rotation was conducted on a paddy soil derived from red soil in southern Zhejiang Province, China, to determine the effect of excess P application on some soil properties and its relation to nutrient status and grain yields of rice. The experimental results indicated that adequate fertilizer P (15 kg P/hm2) could increase the content of soil available P at the tillering stage of early rice, the N, P and K concentrations in the shoots of early rice at primary growth stages, and grain yield in early rice by increasing valid ears per hectare and weight per thousand grains. The latter was mainly related to the higher contents of reduced, non-reduced and total sugar in the shoots at the heading stage. Early rice supplied with excessive P did not yield more than that supplied with adequate P, due to the reduction in the valid grain percentage and weight per thousand grains. In addition, a single excess P application of
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