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Estimation of the van Genuchten soil water retention properties from soil textural data. ...... Ge, T. D., Huang, D. F., Roberts, P., Jones, D. L. and Song, S. W. 2010. ...... Zhang, J., Blackmer, A. M., Kyveryga, P. M., Van De Woestyne, B. and ...

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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; HYPERLINK "http://www.elsevier.com/locate/pedosphere" www.elsevier.com/locate/pedosphere

Contents and Abstracts
1991(1)-2010(5)
Nogueira, T. A. R., Melo, W. J., Fonseca, I. M., Marcussi, S. A., Melo, G. M. P. and Marques, M. O. 2010. Fractionation of Zn, Cd and Pb in a tropical soil after nine-year sewage sludge applications. Pedosphere. 20(5): 545-556.
ABSTRACT: A long-term field experiment was carried out in the experiment farm of the State University of São Paulo, Brazil, to evaluate the phytoavailability of Zn, Cd and Pb in a Typic Eutrorthox soil treated with sewage sludge for nine consecutive years, using the sequential extraction and organic matter fractionation methods. During 2005--2006, maize (Zea mays L.) was used as test plants and the experimental design was in randomized complete blocks with four treatments and five replicates. The treatments consisted of four sewage sludge rates (in a dry basis): 0.0 (control, with mineral fertilization), 45.0, 90.0 and 127.5 t ha-1, annually for nine years. Before maize sowing, the sewage sludge was manually applied to the soil and incorporated at 10 cm depth. Soil samples (0--20 cm layer) for Zn, Cd and Pb analysis were collected 60 days after sowing. The successive applications of sewage sludge to the soil did not affect heavy metal (Cd and Pb) fractions in the soil, with exception of Zn fractions. The Zn, Cd and Pb distributions in the soil were strongly associated with humin and residual fraction, which are characterized by stable chemical bonds. Zinc, Cd and Pb in the soil showed low phytoavailability after nine-year successive applications of sewage sludge to the soil.

Zhang, J., Zhang, H. W. and Zhang, C. G. 2010. Effect of groundwater irrigation on soil PAHs pollution abatement and soil microbial characteristics: A case study in Northeast China. Pedosphere. 20(5): 557--567.
ABSTRACT: To evaluate the effect of groundwater irrigation on the polycyclic aromatic hydrocarbons (PAHs) pollution abatement and soil microbial characteristics, a case study was performed in the Shenfu irrigation area of Shenyang, Northeast China, where the irrigation with petroleum wastewater had lasted for more than fifty years, and then groundwater irrigation instead of wastewater irrigation was applied due to the gradually serious PAHs pollution in soil. Soil chemical properties, including PAHs and nutrients contents, and soil microbial characteristics, including microbial biomass carbon, substrate-induced respiration, microbial quotient (qM), metabolic quotient (qCO2), dehydrogenase (DH), polyphenol oxidase (PO), urease (UR) and cellulase (CE) in surface and subsurface were determined. Total organic C, total N, total P, and available K were significant differences between the sites studied. The PAHs concentrations ranged from 610.9 to 6 362.8 ¼g kg-1 in the surface layers (0--20 cm) and from 404.6 to 4 318.5 ¼g kg-1 in the subsurface layers (20--40 cm). From the principal component analysis, the first principal component was primarily weighed by total PAHs, total organic C, total N, total P and available K, and it was the main factor that influencing the soil microbial characteristics. Among the tested microbial characteristics, DH, PO, UR, CE, qM and qCO2 were more sensitive to the PAHs stress than the others, thus they could serve as useful ecological assessment indicators for soil PAHs pollution.

Dayani, M. and Mohammadi, J. 2010. Geostatistical assessment of Pb, Zn and Cd contamination in near-surface soils of the urban-mining transitional region of Isfahan, Iran. Pedosphere. 20(5): 568--577.
ABSTRACT: Due to the lack of regulation and environmental education and awareness, Sepahanshahr located in vicinity of Isfahan City, central Iran, is now a rapid growing residential area suffering from the considerable consequences of poorly regulated mining activities operating in its vicinity. A survey was carried out on soil Pb, Zn and Cd concentrations around Sepahanshahr Town to explore the spatial structure of Pb, Zn and Cd distribution and to map their concentrations using geostatistical techniques. 100 near-surface soil samples were collected and analyzed for Pb, Zn and Cd and some related soil physical and chemical variables such as pH, organic matter content, electrical conductivity, and clay, silt and sand contents. The variography results showed a strong spatial dependency in heavy metals concentration due to the dilution effects of natural factors including atmospheric dispersion and precipitation. The almost same range values calculated for both ln-transformed Pb and sand data suggested presence of spatial co-regionalization. However, ln-transformed Zn data showed a shorter spatial dependency among the three tested heavy metals. Kriged maps of all three heavy metals showed a strong gradient of contamination around the three mining sites activating in the area. The results of this study provide insight into identification of the extent and spatial variability of Pb, Zn and Cd pollution in the mining sites and surrounding urban areas.

Zhang, W. T., Yu, D. S., Shi, X. Z., Tan, M. Z. and Liu, L. S. 2010. Variation of sediment concentration and its drivers under different soil management systems. Pedosphere. 20(5): 578--585.
ABSTRACT: In order to prevent soil erosion in southern China, a study was performed to determine the drivers of sediment concentration variation using simulated rainfall and four soil management systems under field condition. Four soil management systems, i.e., forest and grass coverage (FG), forest coverage with disturbed soil surface (FD), contour tillage (CT) and downslope tillage (DT), were exposed to two rainfall intensities (40 and 54 mm h-1) using a portable rainfall simulator. The drivers of sediment concentration variation were detected by process-based variations of runoff rate and sediment concentration as well as their relationships. The effects of the four soil management systems in preventing water and soil losses were compared using runoff rates and sediment concentrations at steady state. At runoff initial stage, sediment concentration variation was mainly driven by rainfall and management. The degree of sediment concentration variation driven by flow varied with different soil management systems. Three best relationships between runoff rate and sediment concentration were identified, i.e., reciprocal (CT), quadratic (FG and FD) and exponential (DT). At steady state, runoff rates of the four soil management systems varied slightly, whereas their sediment concentrations varied greatly. FG and CT were recommended as the best soil management systems for preventing water and soil losses.

Hu, J. L., Lin, X. G., Wang, J. H., Shen, W. S., Wu, S., Peng, S. P. and Mao, T. T. 2010. Arbuscular mycorrhizal fungal inoculation enhances suppression of cucumber Fusarium wilt in greenhouse soils. Pedosphere. 20(5): 586--593.
ABSTRACT: A pot experiment was conducted to study the plant growth and fruit yields of cucumber (Cucumis sativus L.) on a greenhouse soil with or without inoculation of arbuscular mycorrhizal fungi (AMFs) and Fusarium oxysporum f. sp. cucumerinum under unsterilized conditions. Two AMF inocula were tested: only one AMF strain Glomus caledonium 90036 and an AMF consortium mainly consisting of Glomus spp. and Acaulospora spp. There were four treatments including no inoculation (control), inoculation with F. oxysporum but without mycorrhizae (FO), inoculation with F. oxysporum and G. caledonium (FA+M1), and inoculation with F. oxysporum and the AMF consortium (FO+M2). Cucumber plants were harvested at weeks 3 and 9 after transplanting. Compared with the control, the FO treatment without AMF inoculation had less biomass both at weeks 3 and 9 (P < 0.05) and had higher incidence of Fusarium wilt and produced no cucumber fruit at week 9. Both FO+M1 and FO+M2 treatments had higher mycorrhizal colonization than the treatments which received no AMF inoculation at week 3 (P < 0.05), but only the FO+M2 treatment elevated plant biomass, decreased the incidence of Fusarium wilt, and improved cucumber yields to the same level as the control at week 9. The results indicated that the AMF consortium could suppress Fusarium wilt of cucumber and, therefore, showed potential as a biological control agent in greenhouse agroecosystems.

Zhu, Q. and Lin, H. S. 2010. Comparing ordinary kriging and regression kriging for soil properties in contrasting landscapes. Pedosphere. 20(5): 594--606.
ABSTRACT: The accuracy between ordinary kriging and regression kriging was compared based on the combined consideration of sample size, spatial structure, and auxiliary variables (terrain indices and electromagnetic induction surveys) for a variety of soil properties in two contrasting landscapes (agricultural vs. forested). When spatial structure could not be well captured by point-based observations (e.g., when the ratio of sample spacing over correlation range was > 0.5), or when a strong relationship existed between target soil properties and auxiliary variables (e.g., their R2 was > 0.6), regression kriging (RK) was more accurate for interpolating soil properties in both the landscapes studied. Otherwise, ordinary kriging (OK) was better. Soil depth and wetness condition did not appear to affect the selection of kriging for soil moisture interpolation, because they did not significantly change the ratio of sample spacing over correlation range and the relationship with the auxiliary variables. Because of a smaller ratio of elevation change over total study area (E/A = 1.2) and multiple parent materials in the agricultural land, OK was generally more accurate in that landscape. In contrast, a larger E/A ratio of 6.8 and a single parent material led to RK being preferable in the steep-sloped forested catchment. The results from this study can be useful for selecting kriging for various soil properties and landscapes.

Xing, X. L., Qi, S. H., Zhang, Y., Yang, D. and Odhiambo, J. O. 2010. Organochlorine pesticides (OCPs) in soils along the eastern slope of the Tibetan Plateau. Pedosphere. 20(5): 607--615.
ABSTRACT: Soils samples collected from several sites along an altitudinal transect on the eastern slope of the Tibetan Plateau were analyzed for hexachlorobenzenes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs). The results showed that HCHs and DDTs were found in the soil samples from the remote high altitude areas away from source regions, which confirmed the long-range atmospheric transport phenomenon of these insecticides. The OCP concentrations in the soils had a significant negative correlation with altitude; they showed a trend to increase with decreasing altitude, but the increase was not continuous, being interrupted at some moderate-altitude sites on the transect. The distances from the source region, landforms, soil properties, and physical-chemical properties of OCPs were more important than content of TOC to the distribution of OCPs in soils disturbed by human activities. An analysis of the compositions of HCH isomers and DDTs revealed predominantly low ratios of ±-HCH to ³-HCH, ranging from 0.06 to 4.79, which suggested current lindane inputs. On the other hand, low p,p¢ð-DDT/p,p¢ð-DDE and o,p¢ð-DDT/p,p¢ð-DDT ratios were observed, indicating mainly aged historical DDT residues in the study area.

Liang, T., Song, W. C., Wang, L. Q., Kleinman, P. J. A. and Cao, H. Y. 2010. Interactions between exogenous rare earth elements and phosphorus leaching in packed soil columns. Pedosphere. 20(5): 616--622.
ABSTRACT: Rare earth elements (REEs) increasingly used in agriculture as an amendment for crop growth may help to lessen environmental losses of phosphorus (P) from heavily fertilized soils. The vertical transport characteristics of P and REEs, lanthanum (La), neodymium (Nd), samarium (Sm), and cerium (Ce), were investigated with addition of exogenous REEs at various doses to packed soil columns (20 cm deep). Vertical transfers of REEs and P were relatively small, with transport depths less than 6 cm for most REEs and P. Export of applied REEs in leachate accounted for less that 5% of inputs. The addition of Ce, Nd and Sm to soil columns significantly decreased concentrations of extractable soil P up to a depth of 4 cm, with soil P concentrations unaffected at depths > 4 cm. In general, REEs had little effect on the vertical leaching of P in packed soil columns.

Teng, Y. B., Li, Y. J., Fang, P. and La, G. X. 2010. Characterization of nitrogen metabolism in the low-nitrogen tolerant lnt1 mutant of Arabidopsis thaliana under nitrogen stress. Pedosphere. 20(5): 623--632.
ABSTRACT: A growth experiment on agar medium and a hydroponics experiment were carried out to study the nitrogen (N) metabolism of a low-N tolerant mutant (lnt1) of Arabidopsis thaliana under different N levels as compared with the wild-type (WT) Arabidopsis. On the agar medium, no apparent growth differences were observed between the lnt1 and WT plants under a normal N level of 9 mmol L-1 NO3-. However, under a low N level of 0.18 mmol L-1 NO3-, the growth of the WT plants was greatly retarded, while the lnt1 plants were not affected by low-N stress and showed similar growth with those grown under a normal N level. In the hydroponics experiment, the lnt1 mutant had higher activities of glutamine synthetase (GS) and NADH-dependent glutamate synthase (NADH-GOGAT) in both leaves and roots under N-deficient conditions. Moreover, they accumulated less ammonium (NH4+) but more free amino acids in leaves compared with the WT plants. These observations suggest that better N assimilation might contribute to the low-N tolerant phenotype of the lnt1 mutant.

Ju, C. H., Tian, Y. C., Yao, X., Cao, W. X., Zhu, Y. and Hannaway, D. 2010. Estimating leaf chlorophyll content using red edge parameters. Pedosphere. 20(5): 633--644.
ABSTRACT: Hyperspectral remote sensing makes it possible to non-destructively monitor leaf chlorophyll content (LCC). This study characterized the geometric patterns of the first derivative reflectance spectra in the red edge region of rapeseed (Brassica napus L.) and wheat (Triticum aestivum L.) crops. The ratio of the red edge area less than 718 nm to the entire red edge area was negatively correlated with LCC. This finding allowed the construction of a new red edge parameter, defined as red edge symmetry (RES). Compared to the commonly used red edge parameters (red edge position, red edge amplitude, and red edge area), RES was a better predictor of LCC. Furthermore, RES was easily calculated using the reflectance of red edge boundary wavebands at 675 and 755 nm (R675 and R755) and reflectance of red edge center wavelength at 718 nm (R718), with the equation RES = (R718
ÿR675)/( R755
ÿR675). In addition, RES was simulated effectively with wide wavebands from the airborne hyperspectral sensor AVIRIS and satellite hyperspectral sensor Hyperion. The close relationships between the simulated RES and LCC indicated a high feasibility of estimating LCC with simulated RES from AVIRIS and Hyperion data. This made RES readily applicable to common airborne and satellite hyperspectral data derived from AVIRIS and Hyperion sources, as well as ground-based spectral reflectance data.

Li, J. Y., Wang, N., Xu, R. K. and Tiwari, D. 2010. Potential of industrial byproducts in ameliorating acidity and aluminum toxicity of soils under tea plantation. Pedosphere. 20(5): 645--654.
ABSTRACT: It is imperative to choose some low cost, available and effective ameliorants to correct soil acidity in southern China for sustainable agriculture. The present investigation dealt with the possible role of industrial byproducts, i.e., coal fly ash (CFA), alkaline slag (AS), red mud (RM) and phosphogypsum (PG) in correcting acidity and aluminum (Al) toxicity of soils under tea plantation using an indoor incubation experiment. Results indicated that CFA, AS and RM increased soil pH, while PG decreased the pH of an Ultisol and an Alfisol. The increment of soil pH followed the order of RM > AS > CFA. All the industrial byproducts invariably decreased exchangeable Al and hence increased exchangeable Ca, Mg, K and Na and effective cation exchange capacity. RM, AS and lime decreased total soluble Al, exchangeable Al and organically bound Al. Formation and retention of hydroxyl-Al polymers were the principal mechanism through which Al phytotoxicity was alleviated by application of these amendments. In addition, the heavy metal contents in the four industrial byproducts constituted a limited environmental hazard in a short time at the rates normally used in agriculture. Therefore, the short-term use of the byproducts, especially AS and RM, as amendments for soil acidity and Al toxicity in acid soils may be potential alternatives to the traditional use of mined gypsum and lime.

Qi, Y. C., Dong, Y. S., Jin, Z., Peng, Q., Xiao, S. S. and He, Y. T. 2010. Spatial heterogeneity of soil nutrients and respiration in the desertified grasslands of Inner Mongolia, China. Pedosphere. 20(5): 655--665.
ABSTRACT: There is a limited knowledge of spatial heterogeneity in soil nutrients and soil respiration in the semi-arid and arid grasslands of China. This study investigated the spatial differences in soil nutrients and soil respiration among three desertified grasslands and within two shrub-dominated communities on the Ordos Plateau of Inner Mongolia, China in 2006. Both soil organic carbon (SOC) and total nitrogen (TN) were significantly different (P < 0.01) among the three desertified grasslands along a degradation gradient. Within the two shrub-dominated communities, the SOC and TN contents decreased with increasing distance from the main stems of the shrub, and this fertile island effect was most pronounced in the surface soil. The total soil respirations during the growing season were 131.26, 95.95, and 118.66 g C m-2, respectively, for the steppe, shrub, and shrub-perennial grass communities. The coefficient of variability of soil respiration was the highest in the shrub community and lowest in the steppe community. CO2 effluxes from the soil under the canopy of shrub were significantly higher than those from the soil covered with biological crusts and the bare soil in the interplant spaces in the shrub community. However, soil respiration beneath the shrubs was not different from that of the soil in the inter-shrub of the shrub-perennial grass community. This is probably due to the smaller shrub size. In the two shrub-dominated communities, spatial variability in soil respiration was found to depend on soil water content and C:N ratio.

Liu, X. L., He, Y. Q., Zhang, H. L., Schroder, J. K., Li, C. L., Zhou, J. and Zhang, Z. Y. 2010. Impact of land use and soil fertility on distributions of soil aggregate fractions and some nutrients. Pedosphere. 20(5): 666-673.
ABSTRACT: The size distribution of water-stable aggregates and the variability of organic C, N and P contents over aggregate size fractions were studied for orchard, upland, paddy, and grassland soils with high, medium, and low fertility levels. The results showed that > 5 mm aggregates in the cultivated upland and paddy soils were 44.0% and 32.0%, respectively, less than those in the un-tilled orchard soil. Organic C and soil N in different size aggregate fractions in orchard soil with high fertility were significantly higher than those of other land uses. However, the contents of soil P in different size aggregates were significantly greater in the paddy soil as compared to the other land uses. Soil organic C, N and P contents were higher in larger aggregates than those in smaller ones. The amount of water-stable aggregates was positively correlated to their contribution to soil organic C, N and P. For orchard and grassland soils, the > 5 mm aggregate made the greatest contribution to soil nutrients, while for upland soil, the 0.25--0.053 mm aggregates contributed the most to soil nutrients. Therefore, the land use with minimum disturbance was beneficial for the formation of a better soil structure. The dominant soil aggregates in different land use types determined the distribution of soil nutrients. Utilization efficiency of soil P could be improved by converting other land uses to the paddy soil.

Amanullah and Khan, M. W. 2010. Interactive effects of potassium and phosphorus on phenology and grain yield of sunflower in Northwest Pakistan. Pedosphere. 20(5): 674--680.
ABSTRACT: Potassium (K) and phosphorus (P) applications improve growth, increase yield and yield components of sunflower (Helianthus annuus L.) on K and P-deficient soils in Northwest Pakistan. A field experiment was conducted using sunflower cv. Hysun-33 at the New Developmental Research Farm of KPK Agricultural University, Peshawar, Pakistan, during summer 2006. The experimental design was a randomized complete block in split plot arrangements, with six levels of K (0, 25, 50, 75, 100, and 125 kg K ha-1) as main plots and four levels of P (0, 45, 90, and 135 kg P ha-1) as sub-plots with three replications. Sunflower yield and yield components responded positively to K and P fertilization but the magnitude of response varied with the levels of K and P. Days to flowering and maturity, grains per head , 1000-grain weight, shelling percentage, and grain yield increased tremendously in the K and P-fertilized plots as compared to the control with no K and P applied. The combined application of 100 kg K and 45 kg P ha-1 significantly increased yield components, grain yield, harvest index, and shelling percentage of sunflower, suggesting that 100 kg K ha-1 in combination with 45 kg P ha-1 could maximize productivity of sunflower planted after wheat on the K and P-deficient soils in the study area.

Weindorf, D. C., Bakr, N., Zhu, Y., Haggard, B., Johnson, S. and Daigle, J. 2010. Characterization of placic horizons in ironstone soils of Louisiana, USA. Pedosphere. 20(4): 409--418.
ABSTRACT: Placic horizons, defined as thin, wavy, hardened layers of iron and organic matter, are rare within the United States, occurring only in Washington, Alaska, and Hawaii. While ironstone is common in many soils of the southeastern United States, it is not known to contain appreciable organic matter. As a pilot study evaluating the justification for a larger study on ironstone in Louisiana, a 40 m lateral exposure with suspected placic horizons was evaluated in Vernon Parish, Louisiana. Results of laboratory analysis show elevated levels of iron and organic matter in the suspect horizons that meet the criteria of placic horizons as defined by the Soil Survey Staff. Based on the results of this study, additional evaluation of multiple pedons with similar features is warranted. Should additional pedons demonstrate similar properties, a new great group of Petrudepts would be needed to describe both the placic horizons in the pedon and the udic moisture regime in which they occur.

Sun, Z. Q., Kang, Y. H. and Jiang, S. F. 2010. Effect of sprinkler and border irrigation on topsoil structure in winter wheat field. Pedosphere. 20(4): 419--426.
ABSTRACT: A two-year experiment was carried out on the effect of sprinkler irrigation on the topsoil structure in a winter wheat field. A border-irrigated field was used as the control group. The total soil porosity, pore size distribution, pore shape distribution, soil cracks and soil compaction were measured. The sprinkler irrigation brought significant changes to the total soil porosity, capillary porosity, air-filled porosity and pore shape of topsoil layers in comparison with the border irrigation. The total porosity and air-filled porosity of the topsoil in the sprinkler irrigation were higher than those in the border irrigation. The changes in the air-filled and elongated pores were the main reasons for the changes in total porosity. The porosities of round and irregular pores in topsoil under sprinkler irrigation were lower than those under border irrigation. Sprinkler irrigation produced smaller soil cracks than border irrigation did, so sprinkler irrigation may restrain the development of macropore flow in comparison with border irrigation. The topsoil was looser under sprinkler irrigation than under border irrigation. According to the conditions of topsoil structure, it is preferable for crops to grow under sprinkler irrigation than under border irrigation.

Zheng, J. Q., Han, S. J., Zhou, Y. M., Ren, F. R., Xin, L. H. and Zhang, Y. 2010. Microbial activity in a temperate forest soil as affected by elevated atmospheric CO2. Pedosphere. 20(4): 427--435.
ABSTRACT: Microorganisms play a key role in the response of soil ecosystems to the rising atmospheric carbon dioxide (CO2) as they mineralize organic matter and drive nutrient cycling. To assess the effects of elevated CO2 on soil microbial C and N immobilization and on soil enzyme activities, in years 8 (2006) and 9 (2007) of an open-top chamber experiment that begun in spring of 1999, soil was sampled in summer, and microbial biomass and enzyme activity related to the carbon (C), nitrogen (N) and phosphorus (P) cycling were measured. Although no effects on microbial biomass C were detected, changes in microbial biomass N and metabolic activity involving C, N and P were observed under elevated CO2. Invertase and dehydrogenase activities were significantly enhanced by different degrees of elevated CO2. Nitrifying enzyme activity was significantly (P < 0.01) increased in the August 2006 samples that received the elevated CO2 treatment, as compared to the samples that received the ambient treatment. Denitrifying enzyme activity was significantly (P < 0.04) decreased by elevated CO2 treatments in the August 2006 and June 2007 (P 2 000 ¼m) was higher in NT than that in CT, while small macroaggregates (250--2 000 ¼m) showed an opposite trend. Therefore, the total proportion of macroaggregates (> 2 000 and 250--2 000 ¼m) was not affected by tillage management. However, C concentrations of macroaggregates on a whole soil basis were higher under NT relative to CT, indicating that both the amount of aggregation and aggregate turnover affected C stabilization. Carbon concentrations of intra-aggregate particulate organic matter associated with microaggregates (iPOM_m) and microaggregates occluded within macroaggregates (iPOM_mM) in NT were 1.6 and 1.8 times greater than those in CT, respectively. Carbon proportions of iPOM_m and iPOM_mM in the total SOC increased from 5.4% and 6.3% in CT to 7.2% and 9.7% in NT, respectively. Furthermore, the difference in the microaggregate protected C (i.e., iPOM_m and iPOM_mM) between NT and CT could explain 45.4% of the difference in the whole SOC. The above results indicate that NT stimulates C accumulation within microaggregates which then are further acted upon in the soil to form macroaggregates. The shift of SOC within microaggregates is beneficial for long-term C sequestration in soil. We also corroborate that the microaggregate protected C is useful as a pool for assessing the impact of tillage management on SOC storage.

Jalali, M. 2010. Multivariate statistical analysis of potassium status in agricultural soils in Hamadan, western Iran. Pedosphere. 20(3): 293--303.
ABSTRACT: Multivariate statistical technique was used to determine the K+ status and to assess soil fertility and K leaching potential in some calcareous soils. Water-soluble K+ (H2O-K) and ammonium acetate-extractable K+ (NH4OAc-K) ranged from 0.019 to 0.59 (mean value 0.095) and 0.390 to 3.32 (mean value 0.954) cmolc kg-1, respectively. The nitric acid-extractable K+ (HNO3-K) varied from 1.03 to 13.63 (mean value 5.37) cmolc kg-1. The proportion of H2O-K ranged from 0.34% to 14.8% of HNO3-K, and 2.2% to 53.2% of NH4OAc-K. The proportion of NH4OAc-K ranged from 5.8% to 80% of HNO3-K (mean value 23% of HNO3-K). The tendency of the soil to lose K+ by leaching was examined by determining K+-Ca2+ exchange isotherms. The soils mostly had moderate to high values of K+ sorption capacity, ranging from 10% to 58% (mean value 28%) of added K+. The Gapon coefficient varied widely from 1.1 to 12.0 (L mol-1)-1/2. Clay minerals were dominated by illite, smectites and vermiculite with small amounts of kaolinite. Principal component analysis (PCA) showed that the first four components accounted for 27.7%, 21.4.3%, 13.8%, and 8.9% of total variation, respectively. The non-hierarchical cluster analysis (k-means clustering) grouped 75 sampling sites into six clusters, based on the similarity of soil quality characteristics. The results suggested that such classes could form a basis for variable-rate application to maintain an adequate K+ status for crop production and to reduce potential K+ loss from soil by leaching.

Wang, J., Liu, W. Z., Mu, H. F. and Dang, T. H. 2010. Inorganic phosphorus fractions and phosphorus availability in a calcareous soil receiving 21-year superphosphate application. Pedosphere. 20(3): 304--310.
ABSTRACT: A long-term (21-year) field experiment was performed to study the responses of soil inorganic P fractions and P availability to annual fertilizer P application in a calcareous soil on the Loess Plateau of China. Soil Olsen-P contents increased by 3.7, 5.2, 11.2 and 20.6 mg P kg-1 after 21-year annual fertilizer P application at 20, 39, 59, and 79 kg P ha-1, respectively. Long-term fertilizer P addition also increased soil total P and inorganic P (Pi) contents significantly. The contents of inorganic P fractions were in the order of Ca10-P > Ca8-P > Fe-P > Al-P > occluded P > Ca2-P in the soil receiving annual fertilizer P application. Fertilizer P application increased Ca8-P, Al-P and Ca2-P contents as well as their percentages relative to Pi. Pi application increased Fe-P and occluded P contents but nor their percentages. Soil Ca10-P content remained unchanged after fertilizer P application while its percentage relative to Pi declined with increasing fertilizer P rate. All Pi fractions but Ca10-P were correlated with Olsen-P significantly. 90% of variations in Olsen-P could be explained by Pi fractions, and the direct contribution of Ca8-P was predominant. Long-term annual superphosphate application would facilitate the accumulation of soil Ca8-P, and thus improve soil P availability.

Kudo, N. and Fujiyama, H. 2010. Responses of halophyte Salicornia bigelovii to different forms of nitrogen source. Pedosphere. 20(3): 311--317.
ABSTRACT: Salt-affected soils are agricultural and environmental problems on a global scale. Plants suffer from saline stresses in these soils and show nitrogen (N) deficiency symptoms. However, halophytes grow soundly under saline conditions. In order to clarify the N nutrition of the halophyte Salicornia bigelovii, it was grown at several N levels (1, 2, 3, and 4 mmol L-1), supplied in the form of NO3- or ammonium (NH4+), under high NaCl conditions (200 mmol L-1).. NH4+-fed plants showed better growth than NO3--fed plants at 1--3 mmol L-1 N, and plants in both treatments showed the same growth at 4 mmol L-1 N. Nitrogen content in NO3--fed plants increased with the N concentration in solution; competitive inhibition of NO3- absorption by Cl- was observed under lower N conditions. In addition, shoot dry weight significantly correlated only with shoot N content. Therefore, growth of NO3--fed plants was regulated by N absorption. In contrast, N content of shoots in NH4+-fed plants did not change with N concentration. Shoot Na content decreased with increasing N concentration, while K content increased. Dry weight was highly correlated only with K content in NH4+-fed plants. These observations indicate that growth of NH4+-fed plants is mainly regulated by K absorption.

Gu, Z. J., Zeng, Z. Y., Shi, X. Z., Li, L., Weindorf, D. C., Zha, Y., Yu, D. S. and Liu, Y. M. 2010. A model for estimating total forest coverage with ground-based digital photography. Pedosphere. 20(3): 318--325.
ABSTRACT: Vegetation fractional coverage (VFC) is one of the key indicators of vegetation distribution. In the work a measurement-based model was developed to derive total forest VFC (TG) as well as the VFC of trees (T) and shrub-grasses (G) separately in a subtropical forest area in Nanjing, China. Both upward and downward photographs were taken with a digital camera in 72 quadrats (10 m × 10 m each). Fifteen models were established and validated. Models jointly using both T and G performed better than those using the T and G separately. The best model, TG = T + G 1.134 × T × G 0.025 (R2 = 0.9115, P < 0.01, root mean squared error = 0.0789), is recommended for application. This model provides a good way to obtain total forest VFC values through taking tree and shrub-grass photos on ground below tree canopy rather than above tree canopy.

Zhang, L. L., Wu, Z. J., Shi, Y. F., Chen, L. J., Song, Y. C. and Juan, Y. H. 2010. Inhibitory effects of aromatic compounds on soil nitrification. Pedosphere. 20(3): 326--333.
ABSTRACT: Aromatic compounds (ACs) in soil can induce competitive inhibition for soil NH3 oxidation, and nitrification inhibitors can be used to this end. A laboratory incubation experiment was performed with 12 nitroaromatic compounds (NACs), 15 amidoaromatic compounds (AACs) and 20 hydroxyaromatic compounds (HACs) to assess the inhibitory effects of the ACs on soil nitrification. Based on these results, the critical and optimal concentrations of ACs were determined for better inhibitory effects. Most of the test ACs were able to inhibit soil nitrification; the effectiveness differed with soil type. Among the ACs, the NACs with m-nitryl, amino or hydroxyl and the AACs with a nitro group or a chlorine atom on aromatic ring or with a p-hydroxyl were more effective. 3-nitroaniline, 4-aminophenol and 3-nitrophenol showed the greatest potential as nitrification inhibitors. The critical concentration of these compounds in brown soil and cinnamon soil was found to be 0.5 mg kg-1 soil. Due to the toxicity, carcinogenicity and mutagenicity of ACs, further toxicological and ecotoxicological research is necessary before ACs are used as nitrification inhibitors in agricultural and horticultural practices.

Xue, Y. J., Liu, S. G., Hu, Y. M. and Yang, J. F. 2010. Soil quality assessment using weighted fuzzy association rules. Pedosphere. 20(3): 334--341.
ABSTRACT: Fuzzy association rules (FARs) can be powerful in assessing regional soil quality, a critical step prior to land planning and utilization; however, traditional FARs mined from soil quality database, ignoring the importance variability of the rules, can be redundant and far from optimal. In this study, we developed a method applying different weights to traditional FARs to improve accuracy of soil quality assessment. After the FARs for soil quality assessment were mined, redundant rules were eliminated according to whether the rules were significant or not in reducing the complexity of the soil quality assessment models and in improving the comprehensibility of FARs. The global weights, each representing the importance of a FAR in soil quality assessment, were then introduced and refined using a gradient descent optimization method. This method was applied to the assessment of soil resources conditions in Guangdong Province, China. The new approach had an accuracy of 87%, when 15 rules were mined, as compared with 76% from the traditional approach. The accuracy increased to 96% when 32 rules were mined, in contrast to 88% from the traditional approach. These results demonstrated an improved comprehensibility of FARs and a high accuracy of the proposed method.

Yu, L., Zhou, L., Liu, W. and Zhou, H. K. 2010. Using remote sensing and GIS technologies to estimate grass yield and livestock carrying capacity of alpine grasslands in Golog Prefecture, China Pedosphere. 20(3): 342--351.
ABSTRACT: Remote sensing data from the Terra Moderate-Resolution Imaging Spectroradiometer (MODIS) and geospatial data were used to estimate grass yield and livestock carrying capacity in the Tibetan Autonomous Prefecture of Golog, Qinghai, China. The MODIS-derived normalized difference vegetation index (MODIS-NDVI) data were correlated with the aboveground green biomass (AGGB) data from the aboveground harvest method. Regional regression model between the MODIS-NDVI and the common logarithm (LOG10) of the AGGB was significant (r2 = 0.51, P < 0.001), it was, therefore, used to calculate the maximum carrying capacity in sheep-unit year per hectare. The maximum livestock carrying capacity was then adjusted to the theoretical livestock carrying capacity by the reduction factors (slope, distance to water, soil erosion, and vegetation cover). Results indicated that the grassland conditions became worse, with lower aboveground palatable grass yield, plant height, and cover compared with the results obtained in 1981. At the same time, although the actual livestock numbers decreased, they still exceeded the proper theoretical livestock carrying capacity, and overgrazing rates ranged from 39.89% in Madoi County to 517.25% in Baima County. Integrating remote sensing and geographical information system technologies, the spatial and temporal conditions of the alpine grassland, trend, and projected stocking rates could be forecasted for decision making.

Jia, G. M., Zhang, P. D., Wang, G., Cao, J., Han, J. C. and Huang, Y. P. 2010. Relationship between microbial community and soil properties during natural succession of abandoned agricultural land. Pedosphere. 20(3): 352--360.
ABSTRACT: The changes of microbial biomass carbon (MBC) and nitrogen (MBN) and microbial community in the topsoil of the abandoned agricultural land on the semi-arid Loess Plateau in China during the natural succession were evaluated to understand the relationship between microbial community and soil properties. MBC and MBN were measured using fumigation extraction, and microbial community was analyzed by the method of fatty acid methyl ester (FAME). The contents of organic C, total N, MBC, MBN, total FAME, fungal FAME, bacterial FAME and Gram-negative bacterial FAME at the natural succession sites were higher than those of the agricultural land, but lower than those of the natural vegetation sites. The MBC, MBN and total FAME were closely correlated with organic C and total N. Furthermore, organic C and total N were found to be positively correlated with fungal FAME, bacterial FAME, fungal/bacterial and Gram-negative bacterial FAME. Natural succession would be useful for improving soil microbial properties and might be an important alternative for sustaining soil quality on the semi-arid Loess Plateau in China.

Ziadat, F. M. 2010. Prediction of soil depth from digital terrain data by integrating statistical and visual approaches. Pedosphere. 20(3): 361--367.
ABSTRACT: Information about the spatial distribution of soil attributes is indispensable for many land resource management applications; however, the ability of soil maps to supply such information for modern modeling tools is questionable. The objectives of this study were to investigate the possibility of predicting soil depth using some terrain attributes derived from digital elevation models (DEMs) with geographic information systems (GIS) and to suggest an approach to predict other soil attributes. Soil depth was determined at 652 field observations over the Al-Muwaqqar Watershed (70 km2) in Jordan. Terrain attributes derived from 30-m resolution DEMs were utilized to predict soil depth. The results indicated that the use of multiple linear regression models within small watershed subdivisions enabled the prediction of soil depth with a difference of 50 cm for 77% of the field observations. The spatial distribution of the predicted soil depth was visually coincided and had good correlations with the spatial distribution of the classes amalgamating three terrain attributes, slope steepness, slope shape, and compound topographic index. These suggested that the modeling of soil-landscape relationships within small watershed subdivisions using the three terrain attributes was a promising approach to predict other soil attributes.

Wang, H. Y., Zhou. J. M., Du, C. W. and Chen, X. Q. 2010. Potassium fractions in soils as affected by monocalcium phosphate, ammonium sulfate, and potassium chloride application. Pedosphere. 20(3): 368--377.
ABSTRACT: Soil K deficiency has been increasing over recent decades as a result of higher inputs of N and P fertilizers concomitant with lower inputs of K fertilizers in China; however, the effects of interactions between N, P, and K of fertilizers on K status in soils have not been thoroughly investigated for optimizing N, P and K fertilizer use efficiency. The influence of ammonium sulfate (AS), monocalcium phosphate (MCP), and potassium chloride application on potassium (K) fractions in three typical soils of China was evaluated during 90 d laboratory soil incubation. The presence of AS significantly altered the distribution of native and added K in soils, while addition of MCP did not significantly affected K equilibrium in most cases. Addition of AS significantly increased water-soluble K (WSK), decreased exchangeable K (EK) in almost all the soils except the paddy soil that contained considerable amounts of 2:1 type clay minerals with K added, retarded the formation of fixed K in the soils with K added, and suppressed the release of fixed K in the three soils without K added. These interactions might be expected to influence the K availability to plants when the soil was fertilized with AS. To improve K fertilizer use efficiency, whether combined application of AS and K was to be recommended or avoided should depend on K status of the soil, soil properties, and cropping systems.

Weng, Y. L., Gong, P. and Zhu, Z. L. 2010. A spectral index for estimating soil salinity in the Yellow River Delta region of China using EO-1 Hyperion data. Pedosphere. 20(3): 378--388.
ABSTRACT: Soil salinization is one of the most common land degradation processes. In this study, spectral measurements of saline soil samples collected from the Yellow River Delta region of China were conducted in laboratory and hyperspectral data were acquired from a EO-1 Hyperion sensor to quantitatively map soil salinity in the region. A soil salinity spectral index (SSI) was constructed from continuum-removed reflectance (CR-reflectance) at 2 052 and 2 203 nm, to analyze the spectral absorption features of the salt-affected soils. There existed a strong correlation (r = 0.91) between the SSI and soil salt content (SSC). Then, a model for estimation of SSC with SSI was established using univariate regression and validation of the model yielded a root mean square error (RMSE) of 0.986 (SSC of the soil samples ranging from 0.06 to 12.30 g kg-1) and an R2 of 0.873. The model was applied to a Hyperion reflectance image on a pixel-by-pixel basis and the resulting quantitative salinity map was validated successfully with RMSE = 1.921 and R2 = 0.627. These suggested that the satellite hyperspectral data had the potential for predicting SSC in a large area.

Shen, W. S., Yin, R., Lin, X. G. and Cao, Z. H. 2010. Bacterial communities in a buried ancient paddy soil from the Neolithic age. Pedosphere. 20(3): 389--398.
ABSTRACT: An ancient irrigated paddy soil from the Neolithic age was excavated at Chuodunshan Site in the Yangtze River Delta, close to Suzhou, China. The soil organic matter (SOM) content in the prehistoric rice soil is comparable to the average SOM content of present rice soils in this region, but it is about 5 times higher than that in the parent materials. As possible biomarkers to indicate the presence of the prehistoric paddy soil, the bacterial communities were investigated using the techniques of aerobic and anaerobic oligotrophic bacteria enumeration, Biolog analysis, and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The results showed that in the buried soil layers, the prehistoric paddy soil had the largest number of aerobic and anaerobic oligotrophic bacteria, up to 6.12 and 5.86 log cfu g-1 dry soil, respectively. The prehistoric paddy soil displayed better carbon utilization potential and higher functional diversity compared to the parent materials and a prehistoric loess layer. The Shannon index and richness based on DGGE profiles of bacterial 16S rRNA genes were higher in prehistoric paddy soil than those in the prehistoric loess soil. It might be concluded that the prehistoric irrigated rice cultivation accumulated the SOM in plowed soil layer, and thus increased soil bacterial populations, metabolic activity, functional diversity and genetic diversity. Bacterial communities might be considered as the sensitive indicators of the presence of the prehistoric paddy soil in Chinas Yangtze River Delta.

Liu, K. H., Fang, Y. T., Yu, F. M., Liu, Q., Li, F. R. and Peng, S. L. 2010. Soil acidification in response to acid deposition in three subtropical forests of subtropical China. Pedosphere. 20(3): 399--408.
ABSTRACT: Long-term changes in soil pH, the current status of soil acidification, and the response of bulk soil and soil water pH to experimental nitrogen addition under three subtropical forests were investigated in Dinghushan Biosphere Reserve of subtropical China. The results showed that the mineral soil pH at 0--20 cm depth declined significantly from 4.60--4.75 in 1980s to 3.84--4.02 in 2005. Nitrogen addition resulted in the decrease of pH in both bulk soil and soil water collected at 20-cm depth. The rapid decline of soil pH was attributed to long-term high atmospheric acid deposition (nitrogen and sulphur) therein. The forest at earlier succession stage with originally higher soil pH appeared to be more vulnerable to acid deposition than that at later succession stage with originally low soil pH.

Darilek, J. L., Huang, B., Li, D. C., Wang, Z. G., Zhao, Y. C., Sun, W. X. and Shi, X. Z. 2010. Effect of land use conversion from rice paddies to vegetable fields on soil phosphorus fractions. Pedosphere. 20(2): 137--145.
ABSTRACT: Excess phosphorus (P) from agricultural soils contributes to eutrophication in water bodies. Samples (n = 60) were taken from sites where rice paddies have been converted to vegetable fields for 0, < 10, 10--20, and > 20 years and analyzed for five inorganic P (Pi) fractions, three organic P (Po) fractions, and several soil parameters to investigate how land use conversion affects Pi and Po fractions in a peri-urban area of China with soils characteristic of many agricultural areas of Asia. Significant increases of 33, 281, 293, and 438 mg kg-1 were found for soluble and loosely bound Pi (SL-Pi), aluminum-bound Pi (Al-Pi), calcium-bound Pi (Ca-Pi), and iron-bound Pi (Fe-Pi), respectively, after conversion from rice paddies to vegetable fields. Most of the increase in Pi was in the form of Fe-Pi, which increased from 8% of total P (TP) on paddy soil to 31% on the soil with > 20-year vegetable cultivation, followed by Al-Pi, which increased from 2% to 19% of TP. For Po fractions, there was no significant change in P concentrations. The conversion of land use from paddy fields to high intensity vegetable fields was causing significant changes in soil P fractions. Management practices were causing a buildup of soil P, primarily in the Fe-Pi fraction, followed by Ca-Pi and Al-Pi fractions. If current trends continue, a 30%--70% increase in TP could be expected in the next 20 years. Farmers in the area should reduce P application and use to maximize P uptake.

Liu, X., Li, F. M., Liu, D. Q. and Sun, G. J. 2010. Soil organic carbon, carbon fractions and nutrients as affected by land use in semi-arid region of Loess Plateau of China. Pedosphere. 20(2): 146--152.
ABSTRACT: Cropland (CP), native grassland (NG) and two shrub land treatments which were converted from cropland in 1985: seabuckthorn (Hippophae rhamnoides L.) (ST), and branchy tamarisk (Tamarix ramosissima) (BT) were investigated to evaluate effects of land use conversion on soil organic carbon (SOC) and soil nutrients in the semi-arid region of the Loess Plateau of China. Total organic carbon (TOC), light fraction organic carbon (LFOC), heavy fraction organic carbon (HFOC), total N (TN), nitrate nitrogen (NO3-N) and nitrite nitrogen (NO2-N), ammonium nitrogen (NH4-N), total P, and available P (AP) were measured. The results showed that SOC in NG, ST and BT were 12.7%, 27.7% and 34.8% higher than that of the cropland, respectively. LFOC, light fraction (LF) dry matter, ratio of TOC to TN (C/N)) and ratio of TOC to AP (C/P) were higher in the shrub land or native grassland than in the cropland. Cropland had the highest TN, the total of NO3-N and NO2-N, TP and AP due to the use of chemical fertilizers. TOC significantly correlated with LFOC, HFOC and C/N. LFOC significantly correlated with dry matter of the LF and C/N. TN, the total of NO3-N and NO2-N and AP were significantly negatively correlated with TOC and LFOC. Therefore, land use conversion from cropland to shrub land or maybe grassland, contributed to SOC sequestration and improved soil nutrients stabilization.

Ashraf, M., Rahmatullah, Ahmad, R., Bhatti, A. S., Afzal, M., Sarwar, A., Maqsood, M. A. and Kanwal, S. 2010. Amelioration of salt stress in sugarcane (Saccharum officinarum L.) by supplying potassium and silicon in hydroponics. Pedosphere. 20(2): 153--162.
ABSTRACT: A hydroponics experiment was conducted to evaluate the role of potassium (K) and silicon (Si) in mitigating the deleterious effects of NaCl on sugarcane genotypes differing in salt tolerance. Two salt-sensitive (CPF 243 and SPF 213) and two salt-tolerant (HSF 240 and CP 77-400) sugarcane genotypes were grown for six weeks in ½ strength Johnsons nutrient solution. The nutrient solution was salinized by two NaCl levels (0 and 100 mmol L-1 NaCl) and supplied with two levels of K (0 and 3 mmol L-1) and Si (0 and 2 mmol L-1). Applied NaCl enhanced Na+ concentration in plant tissues and significantly (P d" 0.05) reduced shoot and root dry matter in four sugarcane genotypes. However, the magnitude of reduction was much greater in salt-sensitive genotypes than salt-tolerant genotypes. The salts interfered with the absorption of K+ and Ca2+ and significantly (P d" 0.05) decreased their uptake in sugarcane genotypes. Addition of K and Si either alone or in combination significantly (P d" 0.05) inhibited the uptake and transport of Na+ from roots to shoots and improved dry matter yields under NaCl conditions. Potassium uptake, K+/Na+ ratios, and Ca2+ and Si uptake were also significantly (P d" 0.05) increased by the addition of K and/or Si to the root medium. In this study, K and Si-enhanced salt tolerance in sugarcane genotypes was ascribed to decreased Na+ concentration and increased K+ with a resultant improvement in K+/Na+ ratio, which is a good indicator to assess plant tolerance to salt stress. However, further verification of these results is warranted under field conditions.

Hua, J. F., Lin, X. G., Bai, J. F., Shao, Y. F., Yin, R. and Jiang, Q. 2010. Effects of arbuscular mycorrhizal fungi and earthworm on nematode communities and arsenic uptake by maize in arsenic-contaminated soils. Pedosphere. 20(2): 163--173.
ABSTRACT: The influences of arbuscular mycorrhizal fungi (MF, Acaulospora spp. and Glomus spp.), rice straw and earthworms (RE, Eisenia foetida) on nematode communities and arsenic (As) uptake by maize (Zea mays L.) in As-contaminated soils were examined in a field experiment conducted in Wujiang, Jiangsu Province, China. The experiment was designed as a 2 × 2 factorial with the factors of MF (inoculated or uninoculated) and RE (added or not added). The results demonstrated that MF inoculation led to significantly higher root colonization of MF and root dry weight. Plants inoculated with both MF and RE had the highest As concentrations in root. The number of total nematodes increased with MF inoculation when RE was absent, and decreased with RE addition when MF was inoculated. The improved abundance of nematodes with the MF treatment implied that the tested MF acted as food sources for fungivores. The abundances of omnivores-predators and plant parasites were reduced by earthworm activity. Twenty-seven genera of nematodes were identified, with Filenchus dominant in all treatments. Trophic diversity (TD), Shannon-Weaver diversity (H2 ), Simpson dominance index (»), and species richness (SR) indicated higher species diversity, more proportionate species composition, evenly distributed species, and more food sources in the MF, RE, and their interaction treatments. Maturity index (MI) showed a moderately disturbed environment due to As pollution. Besides enhancing plant uptake of contaminants, MF and RE amendments could also improve soil health by restoring the structure of soil communities, as reflected by more stable nematode community structure.

Yuan, H. P., Min, H., Liu, J., Yan, B. and Lü, Z. M. 2010. Variations in laboratory-scale actinomycete communities exposed to cadmium as assessed by denaturing gradient gel electrophoresis profiles. Pedosphere. 20(2): 174--184.
ABSTRACT: The actinomycete populations and functions in cadmium (Cd) contaminated soil were investigated by using cultivation-independent molecular methods. The genomic DNA was extracted and purified from soil adulterated with various concentrations of Cd in the laboratory. The partial 16S rDNA genes were amplified by polymerase chain reaction (PCR) using specific primers bound to evolutionarily conserved regions within these actinomycete genes. The diversity in PCR-amplified products, as measured by denaturing gradient gel electrophoresis (EGGE), was used as a genetic fingerprint of the population. Principle component analysis and Shannon-Weaver diversity index (H) analyses were used to analyze the DGGE results. Results showed that the two principal components accounted for only a low level of the total variance. The value H in contaminated soil was lower than that in the control at later stages of cultivation, whereas at earlier stages it was higher. Among the six sampling time points, the first, fifth and sixth weeks had the highest values of H. Significantly negative correlations between bioavailable Cd concentration and H values existed in the samples from week 2 (R = 0.929, P < 0.05) and week 4 (R = 0.909, P < 0.05). These results may shed light on the effect of Cd on the soil environment and the chemical behavior and toxicity of Cd to actinomycetes.

Weindorf, D. C. and Zhu, Y. 2010. Spatial variability of soil properties at Capulin Volcano, New Mexico, USA: Implications for sampling strategy. Pedosphere. 20(2): 185--197.
ABSTRACT: Non-agricultural lands are surveyed sparsely in general. Meanwhile, soils in these areas usually exhibit strong spatial variability which requires more samples for producing acceptable estimates. Capulin Volcano National Monument, as a typical sparsely-surveyed area, was chosen to assess spatial variability of a variety of soil properties, and furthermore, to investigate its implications for sampling design. One hundred and forty one composited soil samples were collected across the Monument and the surrounding areas. Soil properties including pH, organic matter content, extractable elements such as calcium (Ca), magnesium (Mg), potassium (K), sodium (Na), phosphorus (P), sulfur (S), zinc (Zn), and copper (Cu), as well as sand, silt and clay percentages were analyzed for each sample. Semivariograms of all properties were constructed, standardized, and compared to estimate the spatial variability of the soil properties in the area. Based on the similarity among standardized semivariograms, we found that the semivariograms could be generalized for physical and chemical properties, respectively. The generalized semivariogram for physical properties had a much greater sill value (2.635) and effective range (7 500 m) than that for chemical properties. Optimal sampling density (OSD), which is derived from the generalized semivariogram and defines the relationship between sampling density and expected error percentage, was proposed to represent, interpret and compare soil spatial variability and to provide guidance for sample scheme design. OSDs showed that chemical properties exhibit a stronger local spatial variability than soil texture parameters, implying more samples or analysis are required to achieve a similar level of precision.

Chen, Y., Tang, X., Yang, S. M., Wu, C. Y. and Wang, J. Y. 2010. Contributions of different N sources to crop N nutrition in a Chinese rice field. Pedosphere. 20(2): 198--208.
ABSTRACT: Among the various factors that affect crop yields, N availability is one of the most important factors limiting crop yield enhancement. In this study, the recovery of applications of 15N-labeled fertilizer and crop residues in a rice-wheat cropping system was determined for up to 6 consecutive growing seasons. The crop residues from the previous season were either incorporated or removed as two different treatments. Our results showed that 16.55%--17.79%% (17.17%on average) of the fertilizer N was recovered in the crop during the first growing season, suggesting that more than 80% of crop N was not directly from the N fertilizer. When 15N-labeled residues were applied, 12.01% was recovered in the crop in the first growing season. The average recoveries of fertilizer N and crop residue N in the soil after the first growing season were 33.46% and 85.64%, respectively. N from soil organic matter contributed approximately 83% of the N in the crop when 15N fertilizer was applied or 88% when crop residues were applied. There was a larger difference in the total 15N recovery in plant and soil between N applications in the forms of fertilizer and crop residues. Incorporation of crop residues following the 15N fertilizer application did not significantly promote 15N recovery in the crop or soil. On average, only additional 1.94% of N for the fertilizer-applied field or 5.97% of N for the crop residue-applied field was recovered by the crops during the 2nd and 3rd growing seasons. The total recoveries of 15N in crop and soil were approximately 64.38% for the fertilizer-applied field after 6 growing seasons and 79.11% for the crop residue-applied field after 5 growing seasons. Although fertilizer N appeared to be more readily available to crops than crop residue N, crop residue N replenished soil N pool, especially N from soil organic matter, much more than fertilizer N. Therefore, crop residue N was a better source for sustaining soil organic matter. Our results suggested that the long-term effect of fertilizer or crop residues on N recovery in the crop and soil were different. However, there was little difference between the practices of crop residue incorporation and residue removal following the N fertilizer application.

Xiong, Z. Q., Ma, Y. C., Huang, T. Q., Xing, G. X. and Zhu, Z. L. 2010. Nitrate and ammonium leaching in variable- and permanent-charge paddy soils. Pedosphere. 20(2): 209--216.
ABSTRACT: A variable-charge (VC) and a permanent-charge paddy soil (PC) were selected to study nitrate (NO3--N) and ammonium (NH4+-N) leaching with N isotopes for one consecutive year. An irrigation and intermittent drainage pattern was adopted to mimic natural occurrence of rainfall during the upland crop season and drainage management during the flooded rice season. Treatments to each soil type were no-N controls (CK), 15N-labeled (NH4)2SO4 (NS) and milk vetch (NV) applied at a rate equivalent to 238 kg N ha1 to unplanted lysimeters, totaling six treatments replicated in triplicates. Results indicated that the soil type dominated N leaching characteristics. In the case of PC, NO3--N accounted for 78% of the total leached inorganic N; NS was prone to leach three times more than the NV, being 8.2% and 2.4% of added 15N respectively; and > 85% of leached NO3--N came from native N in the soil. In the case of VC, NH4+-N made up to 92% of the total inorganic N in leachate. Moreover, NH4+-N leaching was detected throughout the whole incubation, and was particularly high during the flooded season. NO3--N leaching in VC occurred later at a lower rate compared to that in PC. The findings of this study indicate that NO3--N leaching during the drained season in permanent-charge paddy soils and NH4+-N leaching in variable-charge soils deserve more attention for regional environmental control.

Beavers, B. W., Liu, Z., Cox, M. S., Kingery, W. L., Brink, G. E., Gerard, P. D. and Mcgregor, K. C. 2010. Phosphorus dynamics in two poultry-litter amended soils of Mississippi under three management systems. Pedosphere. 20(2): 217--228.
ABSTRACT: An experiment arranged in a randomized complete block design with three replications was conducted on a Lexington soil (fine-silty, mixed, active, thermic, Ultic Hapludalfs) and a Loring soil (fine-silty, mixed, active, thermic, Oxyaquic Fragiudalfs) in Mississippi from September 1997 to September 2000 on 18 runoff plots under natural rainfall condition to study the P dynamics in poultry litter amended soils under three management systems combining tillage and planting date treatments to identify effective management practices in southern U.S.A. The management systems in the study were: 1) tillage in the fall prior to litter application followed by a delayed planting of fall forages (CT-DP); 2) tillage followed by immediate planting of the fall forage with subsequent litter application (CT-IP); and 3) no-till with planting prior to litter application (NT-IP). The results indicated that there was significant increase in soil P after 3 years of poultry litter application for both Lexington and Loring soils (P < 0.05). Based on P budget analysis, the majority of P from poultry litter application (> 90%), was accumulated in both soils. In Loring soil, soluble P mass in the runoff was significantly higher from NT-IP than from CT-DP and CT-IP over the entire study period (P < 0.01). For both soils, there were no significant differences in sediment P mass between management systems. For Loring soil, CT-DP and CT-IP were effective management practices to mitigate negative effects due to poultry litter application.

Zhang, N., He, X. D., Gao, Y. B., Li, Y. H., Wang, H. T., Ma, D., Zhang, R. and Yang, S. 2010. Pedogenic carbonate and soil dehydrogenase activity in response to soil organic matter in Artemisia ordosica community. Pedosphere. 20(2): 229--235.
ABSTRACT: Little attention has been paid to the role of soil organic matter (OM) in the formation of pedogenic carbonate in desert soils. The relationships among soil OM, soil dehydrogenase activity (DHA), and soil CaCO3 in a plant community dominated by Artemisia ordosica, located on the eastern boundary of Tengger Desert in the Alxa League, Inner Mongolia, China, were studied to understand whether OM was directly involved in the formation of pedogenic carbonate. The results showed that DHA and CaCO3 positively correlated with OM content, and DHA, OM, and CaCO3 were correlated with each other in their spatial distribution, indicating that abundant OM content contributed to the formation of CaCO3. Therefore, the formation of pedogenic CaCO3 was a biotic process in the plant community dominated by A. ordosica.

Zhang, K., Xu, X. N. and Wang, Q. 2010. Characteristics of N mineralization in urban soils of Hefei, East China. Pedosphere. 20(2): 236--244.
ABSTRACT: Nitrogen cycling has been poorly characterized in urban ecosystems. In this study, the in-situ buried bag incubation technique was used to quantify net rates of N mineralization and nitrification in soils of two urban sites, a street greening belt and a university campus, and a suburban site , a forest park, in Hefei, East China. The average concentration of extractable NO3- in the surface soil (0--10 cm) was significantly higher at the urban sites than the suburban park site, whereas extractable NH4+ concentration was significantly higher at the suburban park site than the urban sites. The forest park soil had greater potential N mineralization (148.1 ¼g N cm-3) than the soils from the campus (138.3 ¼g N cm-3) and street (99.8 ¼g N cm-3). It was estimated that the net mineralization rates varied between 1.63 and 2.69 ¼g N cm-3 d-1 and net nitrification rates between 0.82 and 1.02 ¼g N cm-3 d-1 at the suburban forest park site, but the rates varied from 1.27 to 2.41 ¼g N cm-3 d-1 and from 1.07 to 1.49 ¼g N cm-3 d-1, respectively, at the urban campus site. Both net mineralization and nitrification rates were lower during dry seasons. Results from regression analysis indicated that net N mineralization was significantly and positively correlated with soil moisture and soil C/N ratio, and was negatively correlated with soil pH. Relative nitrification was, however, significantly and negatively correlated with soil moisture and soil C/N ratio, and was positively correlated with soil pH. Mean relative nitrification was 0.763, indicating the dominance of nitrate cycling relative to ammonium cycling at the urban sites. The urban soils had the great potential for N losses compared to the suburban soils.

Wang, X. D., Chen, X. N., Ali, A. S., Liu, S. and Lu, L. L. 2010. Dynamics of humic substance-complexed copper and copper leaching during composting of chicken manure. Pedosphere. 20(2): 245--251.
ABSTRACT: Chicken manure was composted for 110 d to evaluate changes in organic carbon (C) and humic substance-complexed copper (HS-Cu) extracted with water, sodium hydroxide (NaOH), and sodium pyrophosphate and sodium hydroxide mixture (Na4P2O7-NaOH). The average HS-Cu content from the Na4P2O7-NaOH extraction accounted for 46.8% of the total Cu in the compost, followed by those from the NaOH and water extractions, which accounted for 34.5% and 6% of the total Cu in the compost, respectively. NaOH-Na4P2O7-extractable HS-Cu increased throughout the composting process. NaOH-extractable HS-Cu increased during the first 50 d of composting and then leveled off. Water-extractable HS-Cu enhanced during the first 21 d and then decreased. Water-extractable HS-Cu was not correlated to NaOH or NaOH-Na4P2O7-extractable organic C. The average amount of Cu leached from the compost was about 20% of the total Cu in the chicken manure and Cu leaching increased during the first 35 d of composting and then decreased. Leaching of Cu was significantly correlated to the concentrations of HS-Cu extracted with NaOH and water, but was not correlated to the concentration of HS-Cu extracted with NaOH-Na4P2O7. Thus, NaOH and water-extractable HS-Cu were relatively labile and NaOH-Na4P2O7-extractable HS-Cu was relatively immobile. Composting process after rapid decomposition could result in low potential of Cu leaching because of formation of more NaOH-Na4P2O7-extractable HS-Cu.

Ajayi, A. E., Dias Junior, M. S., Curi, N., Okunola, A., Teixeira Souza, T. T. and Silva Pires, B. 2010. Assessment of vulnerability of Oxisols to compaction in the Cerrado region of Brazil. Pedosphere. 20(2): 252--260.
ABSTRACT: The Cerrado region of Brazil, one of the fastest-growing agricultural areas in the world, is undergoing very rapid mechanization; this development is good for the countrys economy but may also snowball into substantial loss of agricultural land and other environmental degradation if the soil susceptibility and vulnerability to compaction is not well understood. In this study we explored different techniques for estimating soil intrinsic abilities to withstand applied pressure using the prevalent Oxisols of the Cerrado region under native vegetation. Undisturbed samples were collected from three sites within the region and subjected to 1) compressibility test: 2) manual penetration resistance test; 3) automated penetration resistance test; and 4) packing density analysis. The four methods produced analogous results. Our results showed the significant influence of soil structure on the inherent strength and compaction susceptibility of the soils. We also established the association of soil structure with the mineralogy of the soil. It is noteworthy that the packing density which was developed from very simple and easily obtained parameters could give a picture of the tendency of the soil to compact. Thus, this approach would be useful in developing compaction susceptibility maps for the region. It could be concluded that most of the Oxisols in the Cerrado region would support mechanized agricultural production very successfully. However, there is need for careful management of the mechanization process to avert degradation. The management techniques should include conservationist practices such as no till in order to maintain as much as possible the favorable structure and drainage of these very old soils.

Ge, T. D., Huang, D. F., Roberts, P., Jones, D. L. and Song, S. W. 2010. Dynamics of nitrogen speciation in horticultural soils in suburbs of Shanghai, China. Pedosphere. 20(2): 261--272.
ABSTRACT: Dissolved organic nitrogen (DON) represents a significant pool of soluble nitrogen (N) in soil ecosystems. In this study, soils samples under three different horticultural management practices were collected from the Xiaxiyang Organic Vegetable and Fruit Farm, Shanghai, China. The objectives were: 1) to investigate the dynamics of N speciation during 2 months of aerobic incubation, 2) to compare the effects of different soils on the mineralization of 14C-labeled amino acids and peptides, and 3) to determine which of the pathways in the decomposition and subsequent ammonification and nitrification of organic N represented a significant blockage in soil N supply. The dynamics of N speciation was found to be significantly affected by mineralization and immobilization. DON, total free amino acids, and NH4+-N were maintained at very low levels and did not accumulate, whereas NO3--N gradually accumulated in these soils. The conversion of insoluble organic N to low-molecular-weight (LMW) DON represented a main constraint to N supply, while conversions of LMW-DON to NH4+-N and NH4+-N to NO3--N did not. Free amino acids and peptides were rapidly mineralized in the soils by the microbial community and consequently did not accumulate in soil. Turnover rates of the additional amino acids and peptides were soil-dependent and generally followed the order of organic soil > transitional soil > conventional soil. The turnover of high-molecular-weight DON was very slow and represented the major DON loss. Further studies are needed to investigate the pathways and bottlenecks of organic N degradation.

Jiao, J. G., Yang, L. Z., Wu, J. X., Wang, H. Q., Li, H. X. and Ellis, E. C. 2010. Land use and soil organic carbon in Chinas village landscapes. Pedosphere. 20(1): 1--14.
ABSTRACT: Village landscapes, which integrate small-scale agriculture with housing, forestry, and a host of other land use practices, cover more than 2 million square kilometers across China. Village lands tend to be managed at very fine spatial scales (d" 30 m), with managers both adapting their practices to existing variation in soils and terrain (e.g., fertile plains vs. infertile slopes) and also altering soil fertility and even terrain by terracing, irrigation, fertilizing, and other land use practices. Relationships between fine-scale land management patterns and soil organic carbon (SOC) in the top 30 cm of village soils were studied by sampling soils within fine-scale landscape features using a regionally weighted landscape sampling design across five environmentally distinct sites in China. SOC stocks across Chinas village regions (5 Pg C in the top 30 cm of 2 × 106 km2) represent roughly 4% of the total SOC stocks in global croplands. Although macroclimate varied from temperate to tropical in this study, SOC density did not vary significantly with climate, though it was negatively correlated with regional mean elevation. The highest SOC densities within landscapes were found in agricultural lands, especially paddy, the lowest SOC densities were found in nonproductive lands, and forest lands tended toward moderate SOC densities. Due to the high SOC densities of agricultural lands and their predominance in village landscapes, most village SOC was found in agricultural land, except in the tropical hilly region, where forestry accounted for about 45% of the SOC stocks. A surprisingly large portion of village SOC was associated with built structures and with the disturbed lands surrounding these structures, ranging from > 18% in the North China Plain to about 9% in the tropical hilly region. These results confirmed that local land use practices, combined with local and regional variation in terrain, were associated with most of the SOC variation within and across Chinas village landscapes and may be an important cause of regional variation in SOC.

Zhang, J., Blackmer, A. M., Kyveryga, P. M., Glady, M. J. and Blackmer, T. M. 2010. Temporal patterns in symptoms of nitrogen deficiency as revealed by remote sensing of corn canopy. Pedosphere. 20(1): 15--22.
ABSTRACT: To evaluate the temporal patterns in N deficiencies in corn and assess the ability of remote sensing to diagnose N deficiencies during the vegetative growth of corn, three field-scale experiments were conducted with various rates (56, 112, and 168 kg N ha-1), timing (early and late applications) and placement (injected into soil and dribbled on soil surface) of N fertilization in a split-plot design. Relationships between canopy reflectance during the growing season and yield data at the end of growing season were studied for different treatments. Results showed significant variation in both grain yields and canopy reflectance among the three cornfields. The N fertilization made in early June resulted in low canopy reflectance in early July, but the differences disappeared as the season progressed. The effect of N rates on canopy reflectance was not significant in early July but it gradually became detectable in mid-July and thereafter. The fertilizer placement had a significant effect on grain yields only in one field but not on canopy reflectance in all three fields. These observations suggest that the deficiency of N developed under field conditions is a dynamic phenomenon, which adds complexity for accurately defining N deficiency and effectively developing management strategies for in-season correction. Remote sensing throughout the season helps collect information about important interactions that have not been given enough attention in the past.

Murtaza, G., Ghafoor, A., Qadir, M., Owens, G., Aziz, M. A., Zia, M. H. and Saifullah. 2010. Disposal and use of sewage on agricultural lands in Pakistan: A review. Pedosphere. 20(1): 23--34.
ABSTRACT: Raw sewage is widely used on agricultural soils in urban areas of developing countries to meet water shortages. Although it is a good source of plant nutrients, such sewage also increases the heavy metal load to soils, which may impact the food chain. Management options for sewage contaminated soils includes addition of nontoxic compounds such as lime, calcium sulfate and organic matter, which form insoluble metal complexes, thus reducing metal phytoavailability to plants. In this paper we review the variation in irrigation quality of sewage at different sites and its impact on the quality of soils and vegetables. Although quality of sewage was highly variable at source, yet the effluent from food industries was relatively safe for irrigation. In comparison effluent samples collected from textile, dyeing, calendaring, steel industry, hospitals and clinical laboratories, foundries and tanneries were hazardous with respect to soluble salts, sodium adsorption ratio and heavy metals like zinc, copper, iron, manganese, nickel, cobalt and cadmium. The sewage quality in main drains was better than that at the industry outlet, but was still not safe for irrigation. In general, higher accumulation of metals in fruits and vegetable roots was recorded compared to that in plant leaves. Edible parts of vegetables (fruits and/or leaves) accumulated metals more than the permissible limits despite the soils contained ammonium bicarbonate diethylenetriaminepentaacetic acid extractable metals within a safe range. In either case further scientific investigations are needed to ensure safe management strategies. Cadmium appeared to be the most threatening metal especially in leafy vegetables. It is advisable to avoid leafy vegetables cultivation in sewage irrigated areas everywhere to restrict its entry into food chain.

Li, F. H. and Zhang, L. J. 2010. Combined effects of water quality and furrow gradient on runoff and soil erosion in North China. Pedosphere. 20(1): 35--42.
ABSTRACT: Irrigation-induced soil erosion seriously affects the sustainability of irrigated agriculture. The effects of irrigation water quality and furrow gradient on runoff and soil loss were studied under simulated furrow irrigation in laboratory using a soil collected from an experimental station of China Agricultural University, North China. The experimental treatments were different combinations of irrigation water salt concentrations of 5, 10, 20, and 30 mmolc L-1, sodium adsorption ratios (SAR) of 0.5, 5.0, and 10.0 (mmolc L-1)0.5, and furrow gradients of 1%, 3%, and 5%, with distilled water for irrigation at 3 furrow gradients as controls. The experimental data indicated that total runoff amount, sediment concentration in runoff, and total soil loss amount generally decreased with salt concentration in irrigation water but increased with its sodicity and furrow gradient. The effects of water quality and furrow gradient on soil loss were greater than those on runoff, and the increase of furrow gradient decreased the influence of water quality on soil loss. When the salt concentration increased from 5 to 30 mmolc L-1 at SAR of 10.0 (mmolc L-1)0.5, total runoff amount, sediment concentration, and total soil loss amount decreased by 3.89%, 52.1%, and 53.92%, and 10.57%, 38.86%, and 42.03% at the furrow gradients of 1% and 5%, respectively. However, they respectively increased by 3.37%, 45.34%, and 55.36%, and 3.86%, 10.77%, and 13.91% when SAR increased from 0.5 to 10.0 (mmolc L-1)0.5 at the salt concentration of 5 mmolc L-1. Irrigation water quality and furrow gradient should be comprehensively considered in the planning and management of furrow irrigation practices to decrease soil loss and improve water utilization efficiency.

Wang, X. Y., Zhao, Y. and Horn, R. 2010. Soil wettability as affected by soil characteristics and land use. Pedosphere. 20(1): 43--54.
ABSTRACT: Depth distribution of soil wettability and its correlations with vegetation type, soil texture, and pH were investigated under various land use (cropland, grassland, and forestland) and soil management systems. Wettability was evaluated by contact angle with the Wilhelmy plate method. Water repellency was likely to be present under permanently vegetated land, but less common on tilled agricultural land. It was mostly prevalent in the topsoil, especially in coarse-textured soils, and decreased in the subsoil. However, the depth dependency of wettability could not be derived from the investigated wide range of soils. The correlation and multiple regression analysis revealed that the wettability in repellent soils was affected more by soil organic carbon (SOC) than by soil texture and pH, whereas in wettable soils, soil texture and pH were more effective than SOC. Furthermore, the quality of SOC seemed to be more important in determining wettability than its quantity, as proofed by stronger hydrophobicity under coniferous than under deciduous forestland. Soil management had a minor effect on wettability if conventional and conservation tillage or different grazing intensities were considered.

Han, X. W., Shao, M. A. and Horton, R. 2010. Estimating van Genuchten model parameters of undisturbed soils using an integral method. Pedosphere. 20(1): 55--62.
ABSTRACT: The van Genuchten model is the most widely used soil water retention curve (SWRC) model. Two undisturbed soils (clay and loam) were used to evaluate the accuracy of the integral method to estimate van Genuchten model parameters and to determine SWRCs of undisturbed soils. SWRCs calculated by the integral method were compared with those measured by a high speed centrifuge technique. The accuracy of the calculated results was evaluated graphically, as well as by root mean square error (RMSE), normalized root mean square error (NRMSE) and Willmotts index of agreement (l). The results obtained from the integral method were quite similar to those by the centrifuge technique. The RMSEs (4.61 × 10-5 for Eum-Orthic Anthrosol and 2.74 × 10-4 for Los-Orthic Entisol) and NRMSEs (1.56 × 10-4 for Eum-Orthic Anthrosol and 1.45 × 10-3 for Los-Orthic Entisol) were relatively small. The l values were 0.973 and 0.943 for Eum-Orthic Anthrosol and Los-Orthic Entisol, respectively, indicating a good agreement between the integral method values and the centrifuge values. Therefore, the integral method could be used to estimate SWRCs of undisturbed clay and loam soils.

Chen, H. S., Huang, Q. Y., Liu, L. N., Cai, P., Liang, W. and Li, M. 2010. Poultry manure compost alleviates the phytotoxicity of soil cadmium: Influence on growth of pakchoi (Brassica chinensis L.). Pedosphere. 20(1): 63--70.
ABSTRACT: The growth performance of pakchoi (Brassica chinensis L.) in relation to soil cadmium (Cd) fractionations was investigated to evaluate the remediating effect of poultry manure compost on Cd-contaminated soil. A yellow-brown soil (Alfisol) treated with various levels of Cd (0--50 mg Cd kg-1 soil) was amended with increasing amounts of compost from 0 to 120 g kg-1. Compost application transformed 47.8%--69.8% of soluble/exchangeable Cd to the organic-bound fraction, and consequently decreased Cd uptake of pakchoi by 56.2%--62.5% when compared to unamended soil. Alleviation of Cd bioavailability by compost was attributed primarily to the increase of soil pH and complexation of Cd by organic matter including dissolved organic matter. In general, the improvement of pakchoi performance was more pronounced in higher Cd contaminated soil. Addition of large amount of compost also favored the anti-oxidative capability of pakchoi against Cd toxicity. This low cost remediation method seems to be very effective in the restoration of Cd-contaminated soils.

Yang, Z. H., Stöven, K., Haneklaus, S., Singh, B. R. and Schnug, E. 2010. Elemental sulfur oxidation by Thiobacillus spp. and aerobic heterotrophic sulfur-oxidizing bacteria. Pedosphere. 20(1): 71--79.
ABSTRACT: The prediction of the oxidation rate of elemental sulfur (S0) is a critical step in sulfur (S) fertilizer strategy to supply plant-available sulfur. An incubation experiment was conducted to determine the rate and amount of S0 oxidation in relation to the contribution of Thiobacillus spp. and aerobic heterotrophic S-oxidizing bacteria. After 84 days, 16.3% and 22.4% of the total S0 applied to the soil were oxidized at 20 and 30 °ðC, respectively. The oxidation of S0 proved to be a two-step process with a rapid oxidation during the first 28 days and a slow oxidation from then on. The highest oxidation rate of 12.8 mðg S cm-2 d-1 was measured during the first two weeks at 30 °C. At 20 °C the highest oxidation rate of 10.2 mðg S cm-2 d-1 was obtained from two to four weeks after start of the experiment. On an average the soil pH declined by 3.6 and 4.0 units after two weeks of experiment. At the same time the electric conductivity increased nine times. With the oxidation of S0 the population of Thiobacillus spp. and aerobic heterotrophic S-oxidizing bacteria increased. The corresponding values for Thiobacillus spp. and aerobic heterotrophic S-oxidizing bacteria increased from 2.9 × 105 and 1.4 × 105 g-1 soil at the start of the experiment to 4 × 108 and 5.6 × 108 g-1 soil 14 days after S0 application, respectively. No Thiobacillus spp. was present eight weeks after S0 application. The results suggested that oxidation of residual S0 completely relied on aerobic heterotrophic S-oxidizing bacteria.

Wang, Z. M., Zhang, B., Song, K. S., Liu, D. W. and Ren, C. Y. 2010. Spatial variability of soil organic carbon under maize monoculture in the Song-Nen Plain, Northeast China. Pedosphere. 20(1): 80--89.
ABSTRACT: Soil organic carbon (SOC) and its relationship with landscape attributes are important for evaluating current regional, continental, and global carbon stores. Data of SOC in surface soils (0--20 cm) of the four main soils, Cambisol, Arenosol, Phaeozem, and Chernozem, were collected at 451 locations in Nongan County under maize monoculture in the Songnen Plain, Northeast China. The spatial characteristics of soil organic carbon were studied, using geographic information systems (GIS) and geostatistics. Effects of other soil physical and chemical properties, elevation, slope, and soil type on SOC were explored. SOC concentrations followed a normal distribution, with an arithmetic mean of 14.91 g kg-1. The experimental variogram of SOC was fitted with a spherical model. There were significant correlations between soil organic carbon and bulk density (BD) (r = -0.374**), pH (r =0.549**), total N (r = 0.781**), extractable phosphorus (r = -0.109*), exchangeable potassium (r = 0.565**), and cation exchange capacity (r = 0.313**). Generally, lower SOC concentrations were significantly associated with high elevation (r = -0.429**). Soil organic carbon was significantly negatively correlated with slope gradient (r = -0.195**). Samples of the Cambisol statistically had the highest SOC concentrations, and samples of the Arenosol had the lowest SOC value.

Su, D. C., Jiao, W. P., Zhou, M. and Chen, X. 2010. Can cadmium uptake by Chinese cabbage be reduced after growing Cd-accumulating rapeseed?. Pedosphere. 20(1): 90--95.
ABSTRACT: Rapeseed (Brassica campestris L.), a Cd-accumulating crop, is effective in reducing plant-available Cd from soil. A pot experiment was conducted to test the hypothesis that the Cd uptake by Chinese cabbage (Brassica pekinensis Rupr.) grown in rotation with rapeseed would be reduced due to the efficient removal of bioavailable Cd from soil solution by the rapeseed crops. The Cd removal by shoot for the rapeseed cultivar Zhucang Huazi ranged from 0.24% to 1.0% in natural Cd-contaminated soil (soil A) and from 0.63% to 1.2% in artificial Cd-contaminated soil (soil B) during the growth period of 4--7 weeks; whereas that for the rapeseed cultivar Chuanyou II-93 ranged from 0.25% to 0.61% and from 0.38% to 0.90%, respectively. Chinese cabbage grown in the pots with soil A for five weeks after harvesting rapeseed exhibited a significantly lower Cd concentration compared to that grown in the control pots (uncropped with rapeseed). However, the rotation of rapeseed did not lower the Cd concentration of Chinese cabbage on soil B. Although an increase of Cd uptake was observed in the rapeseed cultivars with growth time, and the decrease of soil NH4OAc-extractable Cd was found only in the natural rather than artificial Cd-contaminated soil.

Liu, J. G., Li, G. H., Shao, W. C., Xu, J. K. and Wang, D. K. 2010. Variations in uptake and translocation of copper, chromium, and nickel among nineteen wetland plant species. Pedosphere. 20(1): 96--103.
ABSTRACT: An experiment was carried out to investigate the variations in metal uptake and translocation among 19 wetland plant species in small-scale plots of constructed wetland using artificial wastewater containing 2.0 mg L-1 copper (Cu), 1.0 mg L-1 chromium (Cr), and 2.0 mg L-1 nickel (Ni). More than 97% of Cu, Cr, and Ni were removed from the wastewater by the wetland plant species. There were more than 100-fold differences in the metal accumulation and more than ten-fold differences in the metal concentrations among the 19 plant species. These plants accumulated as high as 8.8% of Cu, 20.5% of Cr, and 14.4% of Ni when they were grown in the wetland soaked with the wastewater. Several plant species were found to be highly capable of accumulating one, two or all the three metals. The results indicated considerable variations in the metal removal abilities through phytoextraction among the 19 wetland plant species. It can be concluded that the selection of appropriate plant species in constructed wetland can be crucial for the improvement of metal removal efficiency of the wetland system..

Gao, H. J. and Jiang, X. 2010. Effect of initial concentration on adsorption-desorption characteristics and desorption hysteresis of hexachlorobenzene in soils. Pedosphere. 20(1): 104--110.
ABSTRACT: Adsorption and desorption are important processes that influence the transport, transformation, and bioavailability of hexachlorobenzene (HCB) in soils. To examine the adsorption-desorption characteristics of HCB, equilibrium batch experiments were carried out using two soils (red soil and paddy soil) with different initial HCB concentrations (0.25, 0.50, 0.75, 1.00, 1.50, 2.50, 3.50, and 5.00 mg L-1) by using 0.01 mol L-1 calcium chloride as the background solution. The successive desorption experiments (48, 96, 144, 192, and 240 h) were conducted after each adsorption equilibrium experiment. The results revealed that adsorption and desorption isotherms of HCB on two soils were nonlinear, which can be best described by the Freundlich equation with the square of the correlation coefficient (r2) ranging from 0.97 to 0.99. Desorption of HCB from two soils exhibited hysteresis at all HCB concentrations because the Freundlich desorption coefficients were always higher than the Freundlich adsorption coefficients. The hysteretic effect was enhanced with increasing initial HCB concentration, and positive hysteresis was observed at different concentrations.

Lin, X. Y., Wang, Y., Wang, H. L., Chirko, T., Ding, H. T. and Zhao, Y. H. 2010. Isolation and characterization of a bensulfuron-methyl-degrading strain L1 of Bacillus. Pedosphere. 20(1): 111--119.
ABSTRACT: The objectives of this study were to isolate a bensulfuron-methyl (BSM)-degrading strain of Bacillus spp. and to evaluate its effectiveness in remediation of a BSM-contaminated soil. A BSM-degrading bacterium, strain L1, was successfully isolated in this study. Strain L1 was identified as Bacillus megaterium based on its morphological, physiological, and biochemical properties, G+C content, phylogenetic similarity of 16S rDNA, and fatty acid compositions. Two experiments were used to examine BSM degradation by strain L1. When BSM was used as a sole carbon source in a mineral salt medium, the average degradation rate of BSM by strain L1 was 12.8%, which suggested that the strain was able to utilize BSM as a sole carbon and energy source. In addition, supplement of yeast extract (200 mg L-1) significantly (P d" 0.01) accelerated the degradation of BSM by strain L1. Almost complete degradation (97.7%) of BSM could be achieved in 84 h with addition of yeast extract. In addition, when a sterile soil was supplemented with BSM (50 mg L-l), BSM degradation rate was 94.3% in 42 d, indicating the potential of using microbes for the remediation of BSM-contaminated soils in fields.

Baglieri, A., Ioppolo, A., Nègre, M., Abbate, C. and Gennari, M. 2010. Characterization of glycerol-extractable organic matter from Etna soils of different ages. Pedosphere. 20(1): 120--128.
ABSTRACT: We characterized humic acids (HAs) and glycerol-extractable organic fractions (GEOFs) extracted from four Andisols, taken from comparable soil-climate conditions on the east side of Mount Etna. The soils were formed on old lava (about 9 000 years ago), old tephra (about 8 700 years ago), recent lava (about 2 600 years ago) and recent tephra (about 3 600 years ago). A part of the organic matter of the soils, deprived of HAs and fulvic acids (FAs), was isolated by glycerol extraction. The GEOF can not be extracted with alkaline solutions, probably because it is closely bound to the mineral component of the soil. The characterization of the extracted organic fraction was carried out using elementary and functional group analysis and Fourier transform infrared (FT-IR) spectroscopy. About 20 extractions were necessary to extract the HA and FA from the older soils and about 10 extractions to extract them from the younger soils. Data showed that the GEOFs had a greater ash content and a smaller N content, as well as a greater presence of aliphatic compounds and carboxylic groups as compared to the HA extracted from the same soil. The GEOFs extracted from younger soils also had a lower yield, ash and COOH-group content, and was more aliphatic than the GEOF extracted from older soils. Finally, the GEOFs were more closely bound to the amorphous component of the soil (short-range minerals) and consequently less subject to biodegradation.

Yan, F. L., Shi, Z. H., Cai, C. F. and Li, Z. X. 2010. Wetting rate and clay content effects on interrill erosion in Ultisols of southeastern China. Pedosphere. 20(1): 129--136.
ABSTRACT: In this study, an aggregate stability test and a simulated rainfall test were conducted on four representative Ultisols from Southeast China. The soils selected, with clay contents ranging between 117 and 580 g kg-1, were derived from shale and Quaternary red clay. The stability of aggregates (2--5 mm in diameter) obtained from the soil samples were determined by the Le Bissonnais method. For determination of infiltration, runoff, and erosion, the soil samples were packed in 30 cm x 60 cm trays, wetted at rates of 2, 10, and 60 mm h-1, and then exposed to simulated rainfall at 60 mm h-1 for 1 h. The results indicated that both aggregate stability and slaking caused by fast wetting increased with increasing clay content. The effect of WR on infiltration and seal formation varied with clay contents. In the soil with low clay content (sandy loam), the infiltration rate was affected slightly by WR due to low aggregate stability and slaking. In the soils with medium clay content (silt clay loam and clay), WR affected infiltration significantly due to the high aggregate slaking force. In the soil with high clay content, the effect of WR on infiltration was significant, but not as evident as in the soils with medium clay content, which may be related to high aggregate stability by wetting partially compensating for slaking force. The effect of WR on soil loss was similar to that of runoff, but more pronounced. The findings from this study indicated that the relationship between wetting rate and clay content should be considered when predicting interrill erosion in Ultisols.

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 m2 s1, which was 8 times the flux value before wetting, and in the pine forest, the averaged peak flux was 135 ng N m2 s1, 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 m2 in the broadleaf forest and 22.2 mg N m2 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 Chinas 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.

Santanna, 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 rangelands 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., Ongor, 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)2H2O, 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, Jennys 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 Jennys equation. With Jennys 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 Chinas 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 Chinas 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 worlds 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 Chinas 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 Chinas 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 models 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 worlds largest producer and user of industrial fertilizers and manures. Consequently China plays a substantial role in global N cycle dynamics and in mans 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 Chinas 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.
Chinas 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 co

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