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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 ...




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PEDOSPHERE
An International Peer-Reviewed Journal
(ISSN 1002-0160; Bimonthly)

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Contents and Abstracts
1991(1)--2011(6)
Tu, L. H., Hu, H. L., Hu, T. X., Zhang, J., Liu, L., Li, R. H., Dai, H. Z. and Luo, S. H. 2011. Decomposition of different litter fractions in a subtropical bamboo ecosystem as affected by experimental nitrogen deposition. Pedosphere. 21(6): 685--695.
ABSTRACT: As an important component of the global carbon (C) budget, litter decomposition in terrestrial ecosystems is greatly affected by the increasing nitrogen (N) deposition observed globally. We hypothesized that different litter fractions derived from a single tree species may respond to N deposition differently depending on the quality of the litter substrate. To test the hypothesis, a two-year field experiment was conducted using the litterbag method in a Pleioblastus amarus plantation in the rainy region of Southwest China. Four N treatment levels were applied: control (no N added), low-N (50 kg N ha–1 year–1), medium-N (150 kg N ha–1 year–1), and high-N (300 kg N ha–1 year–1). We observed different patterns of mass loss for the three P. amarus litter fractions (leaves, sheaths, and twigs) of varying substrate quality in the control plots. There were two decomposition stages with different decay rates (fast rate in early stages and slow rate in the later stages) for leaves and sheaths, while we did not observe a slower phase for the decay of twigs during the 2-year study period. The annual decomposition rate (k) of twigs was significantly lower than that of leaves or sheaths. Addition of N slowed the decomposition of leaves and twigs in the later stages of decomposition by inhibiting the decay of lignin and cellulose, while addition of N did not affect the mass loss of sheaths during the study period. In the decomposition of all three litter fractions, experimental N deposition reduced the net N accumulation in the early stages and also decreased the net N release in the later stages. The results of this study suggest that litter substrate quality may be an important factor affecting litter decomposition in a bamboo ecosystem affected by N deposition.

Xu, S. X., Shi, X. Z., Zhao, Y. C., Yu, D. S., Wang, S. H., Zhang, L. M., Li, C. S. and Tan, M. Z. 2011. Modeling carbon dynamics in paddy soils in Jiangsu Province of China with soil databases differing in spatial resolution. Pedosphere. 21(6): 696--705.
ABSTRACT: A number of process-based models have been developed for quantifying carbon (C) sequestration in agro-ecosystems. The DeNitrification-DeComposition (DNDC) model was used to simulate and quantify long-term (1980--2008) soil organic carbon (SOC) dynamics in the important rice-producing province, Jiangsu, China. Changes in SOC storages were estimated from two soil databases differing in spatial resolution: a county database consisting of 68 polygons and a soil patch-based database of 701 polygons for all 3.7 Mha of rice fields in Jiangsu. The simulated SOC storage with the coarse resolution county database ranged between 131.0--320.6 Tg C in 1980 and 170.3--305.1 Tg C in 2008, respectively, while that estimated with the fine resolution database was 201.6 and 216.2 Tg C in 1980 and 2008, respectively. The results modeled with the soil databases differing in spatial resolution indicated that using the soil input data with higher resolution substantially increased the accuracy of the modeled results; and when lacking detailed soil datasets, the DNDC model, parameterized with the most sensitive factor (MSF) method to cope with attribute uncertainty, could still produce acceptable results although with deviations of up to 60% for the case study reported in this paper.

Yang, Y. H., Yan, B. X. and Zhu, H. 2011. Estimating soil erosion in Northeast China using 137Cs and 210Pbex. Pedosphere. 21(6): 706--711.
ABSTRACT: Evaluation of soil erosion in agricultural fields is valuable to develop conservation practices for reducing agricultural nonpoint source pollution. Soil erosion rates were quantified using the fallout radionuclide tracer technique in Mojiagou Basin located on the outskirts of Changchun in Northeast China. The calculated soil erosion rates in the study area were 1.99 and 1.85 mm year-1 using 137Cs and excess 210Pb (210Pbex) measurements, respectively. Both fallout radionuclides showed a similar tendency at downslope sites. All measured sites have experienced net erosion during the past 50 to 100 years. 137Cs and 210Pbex measurements were useful to quantify soil erosion rates on field and small basin scales. At this rate of erosion, the current fertile topsoil layer would be entirely removed within 70 years.

Yang, L. J., Zhang, Y. L., Li, F. S. and Lemcoff, J. H. 2011. Soil phosphorus distribution as affected by irrigation methods in plastic film house. Pedosphere. 21(6): 712--718.
ABSTRACT: Water-saving irrigation methods have been increasingly used for vegetable cultivation in greenhouse or plastic film house. However, there is limited information concerning the effect of water-saving irrigation methods on soil phosphorus (P) behavior. In this experiment, drip and subsurface irrigation methods were applied, with furrow irrigation method as control, in Mollic Gleysols. Soil P distribution throughout the depth was significantly affected by irrigation methods. Total, Olsen, organic and inorganic P contents were greater in the topsoil (0--10 and 10--20 cm) than in the subsoil (20--30, 30--40, 40--50 and 50--60 cm). The Olsen P content throughout 0--60 cm layer under drip and subsurface irrigation treatments was lower than that under the furrow irrigation treatment. However, the total, organic and inorganic P contents from 20 to 60 cm under drip irrigation treatment were higher than or close to those under furrow irrigation treatment, but were lower under subsurface irrigation treatment than under furrow irrigation treatment. Under subsurface irrigation treatment, the contents of total, organic and inorganic P at the 0--10 cm layer were 78.0%, 1.3% and 3.7% greater than those at the 10--20 cm layer, respectively. But Olsen P content at the 10--20 cm layer was 5.7% larger than that at the 0--10 cm layer. These suggested that soil P behavior could be manipulated by soil water management to some extent.

Lichner, L., Eldridge, D. J., Schacht, K., Zhukova, N., Holko. L., Šír, M. and Pecho, J. 2011. Grass cover influences hydrophysical parameters and heterogeneity of water flow in a sandy soil. Pedosphere. 21(6): 719--729.
ABSTRACT: Vegetation cover has a major effect on water flow in soils. Two sites, separated by distance of about 50 m, were selected to quantify the influence of grass cover on hydrophysical parameters and heterogeneity of water flow in a sandy soil emerging during a heavy rain following a long hot, dry period. A control soil (pure sand) with limited impact of vegetation or organic matter was obtained by sampling at 50 cm depth beneath a glade area, and a grassland soil was covered in a 10 cm thick humic layer and colonised by grasses. The persistence of water repellency was measured using the water drop penetration time test, sorptivity and unsaturated hydraulic conductivity using a mini disk infiltrometer, and saturated hydraulic conductivity using a double-ring infiltrometer. Dye tracer experiments were used to assess the heterogeneity of water flow, and both the modified method for estimating effective cross section and an original method for assessing the degree of preferential flow were used to quantify this heterogeneity from the images of dyed soil profiles. Most hydrophysical parameters were substantially different between the two surfaces. The grassland soil had an index of water repellency about 10 times that of pure sand and the persistence of water repellency almost 350 times that of pure sand. Water and ethanol sorptivities in the grassland soil were 7% and 43%, respectively, of those of the pure sand. Hydraulic conductivity and saturated hydraulic conductivities in the grassland soil were 5% and 16% of those of the pure sand, respectively. Dye tracer experiments revealed a stable flow with “air-draining” condition in pure sand and well-developed preferential flow in grassland soil, corresponding to individual grass tussocks and small micro-depressions. The grassland soil was substantially more water repellent and had 3 times the degree of preferential flow compared to pure sand. The results of this study reinforce our view that the consequences of any change in climate, which will ultimately influence hydrology will be markedly different between grasslands and bare soils.

Cui, H. J., Liu, F., Tan, W. F. and Feng, X. H. 2011. Effect of cobalt-doped framework on formation of todorokite from layered manganese oxide with Mg2+/Co2+ ions as template. Pedosphere. 21(6): 730--737.
ABSTRACT: Cobalt (Co) exists in significant quantities in naturally occurring manganese (Mn) oxides and alters the growth of Mn oxide crystals. Four-layered Mn oxides, Na-buserite (Na-bus) and three Co-doped Na-buserite samples prepared from oxidation of Mn(OH)2 with 5%, 10%, and 20% Co/(Mn + Co) ratios (5Co-Na-bus, 10Co-Na-bus, and 20Co-Na-bus), were used to prepare todorokite, a common Mn oxide on the Earth’s surface, using Mg2+/Co2+ ions as a template. The results showed that todorokites could be obtained by reflux treatment of Mg2+-exchanged non-doped Na-buserite and three Co-doped Na-buserites at atmospheric pressure. However, the formation of todorokites was prohibited by reflux treatment of Co2+-exchanged Na-bus, 5Co-Na-bus, and 10Co-Na-bus samples. Instead, todorokite was obtained by the reflux treatment of Co2+-exchanged 20Co-Na-bus samples under atmospheric pressure. X-ray photoelectron spectroscopy analysis showed that doped Co existed as Co3+ in the MnO6 layers of doped Na-buserites. The amount of substituted Co3+ in the MnO6 layers may play a key role in the conversion of buserite to todorokite using Co2+ ions as a template.

Xiao, B., Wang, Q. H., Fan, J., Han, F. P. and Dai, Q. H. 2011. Application of the SCS-CN model to runoff estimation in a small watershed with high spatial heterogeneity. Pedosphere. 21(6): 738--749.
ABSTRACT: For reasons of simplicity, the most commonly used hydrological models are based on the Soil Conservation Service, Curve Number (SCS-CN) model, which is probably a good choice for the estimation of runoff on the Loess Plateau of China; however, the high spatial heterogeneity, mainly caused by a fragmented landform and variations in soil type, may limit its applicability to this region. Therefore, applicability of the SCS-CN model to a small watershed, Liudaogou on the plateau, was evaluated, and the most appropriate initial abstraction ratio (Ia/S) value in the model was quantified by the inverse method. The results showed that the standard SCS-CN model was applicable to the estimation of runoff in the Liudaogou watershed, and the model performance was acceptable according to the values of relative error and Nash-Sutcliffe efficiency. The most appropriate Ia/S value for the watershed was 0.22 because with this modified Ia/S value, the model performance was slightly improved. The model performance was not sensitive to the modification of the Ia/S values when one heavy rainfall event (50.1 mm) was not considered, which implied that the model, using a standard Ia/S value, can be recommended for the Liudaogou watershed because single rainfall events exceeding 50 mm seldom occurred in that region. The runoff amount predicted for the Liudaogou watershed by the SCS-CN model, using the modified Ia/S value, increased gradually with increasing rainfall when rainfall values were lower than 50 mm, whereas the predicted amount increased rapidly when the rainfall exceeded 50 mm. These findings may be helpful in solving the problem of serious soil and water loss on the Loess Plateau of China.

Veresoglou, S. D., Voulgari, O. K., Sen, R., Mamolos, A. P. and Veresoglou, D. S. 2011. Effects of nitrogen and phosphorus fertilization on soil pH-plant productivity relationships in upland grasslands of northern Greece. Pedosphere. 21(6): 750--752.
ABSTRACT: The potential role of soil pH in modulating plant productivity was assessed on the basis of dry mass, harvested in the form of 0.25 m2 quadrats, in two low-productivity upland grasslands of northern Greece subjected to annual factorial nitrogen (N) and phosphorus (P) fertilization (15 g N m-2 year-1 and 10 g P m-2 year-1) over a minimum period of 3 years. It was hypothesized that under these particular conditions, a positive relationship would exist between soil pH and plant productivity and, further, that N or P fertilizer application of a nutrient limited system, would result in a weakening of this positive relationship. A significant positive relationship was confirmed between soil pH and plant productivity in one of the two study areas and a positive trend in the other. Moreover, plant productivity increase, following fertilization, appeared to have a detrimental effect on the soil pH-plant productivity relationship. Findings support the original hypotheses and strengthen the idea that plant diversity-mediated soil pH-plant productivity relationships are a result of the more intense plant speciation that occurred under the more “typical” soil conditions of higher pH in temperate as opposed to tropical regions.

Ji, X. H., Zheng, S. X., Shi, L. H. and Liu, Z. B. 2011. Systematic studies of nitrogen loss from paddy soils through leaching in the Dongting Lake area of China. Pedosphere. 21(6): 753--762.
ABSTRACT: A two-year lysimeter study was conducted to study the effects of different fertilizers and soils on nitrogen leaching loss in a double rice cropping system by considering three major types of paddy soils from the Dongting Lake area. The results showed that N concentration in the leachate did not differ significantly among the treatments of urea, controlled release N fertilizer and pig manure and that all these fertilizers produced higher total nitrogen (TN) concentrations in the leachate compared to the case where no fertilizer was applied. The TN leaching loss following urea treatment accounted for 2.28%, 0.66%, and 1.50% of the amount of N applied in the alluvial sandy loamy paddy soil (ASL), purple calcareous clayey paddy soil (PCC), and reddish-yellow loamy paddy soil (RYL), respectively. Higher TN loss was found to be correlated with the increased leachate volume in ASL compared with RYL, and the lowest TN loss was observed in the PCC, in which the lowest leachate volume and TN concentration were observed. Organic N and NH4+-N were the major forms of N depleted through leachate, accounting for 56.8% and 39.7% of TN losses, respectively. Accordingly, soil-specific fertilization regimens are recommended; in particular, the maximum amount of fertilizer should be optimized for sandy soils with a high infiltration rate. To avoid a high N leaching loss from rice fields, organic N fertilizers such as urea or coated urea should primarily be used for surface topdressing or shallow-layer application and not for deep-layer application.

Li, G. H., Zhao, L. P., Zhang, S. X., Hosen, Y. and Yagi, K. 2011. Recovery and leaching of 15N-labeled coated urea in a lysimeter system in the North China Plain. Pedosphere. 21(6): 763--772.
ABSTRACT: The effectiveness of polyolefin-coated urea (Meister-5 and Meister-10; CU) in a wheat (Triticum aestivum L.)-maize (Zea mays L.) rotation system was studied in lysimeter plots located in the North China Plain for three consecutive maize-wheat-maize cropping seasons. An isotopic method was used to compare the fate of CU to that of non-coated urea (NCU), and N application rates of 0, 100, 150 and 225 kg N ha-1 were evaluated. The results showed that the nitrogen use efficiency (15NUE) of CU was 13.3%--21.4% greater than that of NCU for the first crop. Alternatively, when the difference method was applied (apparent NUE), no significant variations were observed among treatments in all three seasons. Although inorganic N leached from the 1.3 m layer was less than 1% of the total applied N, unidentified losses of 15N (losses of 15N = 15N applied as fertilizer – 15N absorbed by crops –15N remaining in the 0--0.2 m layer –15N leached from the 1.3 m layer) in CU-treated plots were 24.2%--26.5% lower than those of NCU-treated plots. The nitrate concentration in the 0--1.3 m layer of CU plots at the end of the experiment was 53% lower than that of NCU-treated plots. Thus, CU increased crop N uptake from fertilizer and reduced unidentified losses of applied N, which can reduce the risk of groundwater pollution.

Mahdy, A. M. 2011. Soil properties and wheat growth and nutrients as affected by compost amendment under saline water irrigation. Pedosphere. 21(6): 773--781.
ABSTRACT: A greenhouse experiment was conducted to test and compare the suitability of saline compost and saline irrigation water for nutrient status amendment of a slightly productive sandy clay loam soil, to study the macronutrients utilization and dry matter production of wheat (Triticum aestivum c.v. Gemmiza 7) grown in a modified soil environment and to determine effects of compost and saline irrigation water on soil productivity. The sandy clay loam soil was treated with compost of five rates (0, 24, 36, 48, and 60 m3 ha-1, equivalent to 0, 3, 4.5, and 6 g kg-1 soil, respectively) and irrigation water of four salinity levels (0.59 (tap water), 4.9, 6.3, and 8.7 dS m-1). The results indicated that at harvest, the electrical conductivity (EC) of the soil was significantly (P < 0.05) changed by the compost application as compared to the control. In general, the soil salinity was significantly increased with increasing application rate of compost. Soluble salts, K, Cl, HCO3, Na, Ca, and Mg, were significantly increased with the compost treatments. Soil sodium adsorption ratio (SAR) was significantly affected by the salinity levels of the irrigation water, and showed a slight response to the compost application. The soil organic carbon content was also significantly (P < 0.05) affected by application of compost, with a maximum value of 31.03 g kg-1 recorded at the compost rate of 60 m3 ha-1 and the irrigation water salinity level of 8.7 dS m-1 and a minimum value of 12.05 g kg-1 observed in the control. The compost application produced remarkable increases in wheat shoot dry matter production. The maximum dry matter production (75.11 g pot-1) occurred with 60 m3 ha-1 compost and normal irrigation water, with a minimum of 19.83 g pot-1 with no addition of compost and with irrigation water at a salinity level of 8.70 dS m-1. Significant increases in wheat shoot contents of K, N, P, Na, and Cl were observed with addition of compost. The relatively high shoot N values may be attributed to increases in its availability in the tested soil caused by the compost application. Similarly, significant increases in the shoot contents of Na and Cl may be ascribed to the increase in soil soluble K and Cl. The increases in shoot P, N, and K contributed to the growth stimulation since P supplied by the compost was probably responsible in saline and alkaline soils where P solubility was very low.

Wu, D. M., Yu, Y. C., Xia, L. Z., Yin, S. X. and Yang, L. Z. 2011. Soil fertility indices of citrus orchard land along topographic gradients in the Three Gorges area of China. Pedosphere. 21(6): 782--792.
ABSTRACT: In the Three Gorges Area of China, soil erosion and the resultant non-point source pollution and ecological degradation have endangered agricultural ecosystems and fresh water reservoirs. Although efforts have been undertaken to reduce soil and water losses from soils used for citrus production, information on the effects of management practices on soil fertility indices is either limited or nonexistent. This study was conducted to compare the effects of 10 years of various management practices, citrus intercropped with white clover (WC), citrus mulched with straw (SM), citrus intercropped with contour hedgerows (CH), citrus orchard land with impermeable membrane (IM), and citrus intercropped with wheat (Triticum aestivum), and peanut (Arachris hypogaea) (WP), as treatments on soil fertility indices with that of the conventional citrus management (CM). Results showed that the soil organic carbon, total and available nitrogen, available potassium, and water-stable aggregate (> 0.25 mm) contents at the 0--5 cm depth were higher for the WC and SM treatments than the CM treatment. There was also spatial variation in soil fertility along slopes of the WC and SM treatments. The soil total and available nitrogen, phosphorus, and potassium, and water-stable aggregate (> 0.25 mm) contents for the CH and IM treatments at both the 0--5 and 5--20 cm depths were higher than the CM treatment. The average soil available nitrogen and available potassium contents for the WP treatment were higher than the CM treatment, but the WP treatment had little effect on the soil organic carbon, total nitrogen, and water-stable aggregate (> 0.25 mm) contents. These suggested that white clover intercropping and straw mulching were the most effective approaches to improve soil fertility in citrus orchard land of the Three Gorges area.

Li, K. L., Chen, J., Tan, M. Z., Zhao, B. Z., Mi, S. X. and Shi, X. Z. 2011. Spatio-temporal variability of soil salinity in alluvial plain of the lower reaches of the Yellow River---A case study. Pedosphere. 21(6): 793--801.
ABSTRACT: Soil salinity and hydrologic datasets were assembled to analyze the spatio-temporal variability of salinization in Fengqiu County, Henan Province, China, in the alluvial plain of the lower reaches of the Yellow River. The saline soil and groundwater depth data of the county in 1981 were obtained to serve as a historical reference. Electrical conductivity (EC) of 293 surface soil samples taken from a 2 km × 2 km grid in 2007 and 40 soil profiles acquired in 2008 was analyzed and used for comparative mapping. Ordinary kriging was applied to predict EC at unobserved locations to derive the horizontal and vertical distribution patterns and variation of soil salinity. Groundwater table data from 22 observation wells in 2008 were collected, and used as input for regression kriging to predict the maximum groundwater depth of the county in 2008. Changes in the groundwater level of Fengqiu County in 27 years from 1981 to 2008 was calculated. Two quantitative criteria, the mean error or bias (ME) and the mean squared error (MSE), were computed to assess the estimation accuracy of the kriging predictions. The results demonstrated that the soil salinity in the upper soil layers decreased dramatically and the taxonomically defined saline soils were present only in a few micro-landscapes after 27 years. Presently, the soils with relatively elevated salt content were mainly distributed in depressions along the Yellow River bed. The reduction in surface soil salinity corresponded to the locations with deepened maximum groundwater depth. It could be concluded that groundwater table recession allowed water to move deeper into the soil profile, transporting salts with it, and thus played an important role in reducing soil salinity in this region. Accumulation of salts in the soil profiles at various depths below the surface indicated that secondary soil salinization would occur when the groundwater was not controlled at a safe depth.

Boojar, M. M. A. and Tavakkoli, Z. 2011. Antioxidative responses and metal accumulation in invasive plant species growing on mine tailings in Zanjan, Iran. Pedosphere. 21(6): 802--812.
ABSTRACT: Tailings of a Pb and Zn mine as a metal contaminated area (Zone 1) with two pioneer plant species, Peganum harmala and Zygophyllum fabago, were investigated and compared with a non-contaminated area (Zone 2) in the vicinity. Total concentrations of Pb, Zn, and Cu in the soil of Zone 1 were 1 416, 2 217, and 426 mg kg -1 DW, respectively, and all exceeded their ranges in the normal soils. The soil pH was in the neutral range and most of the physical and chemical characteristics of the soils from both zones were almost similar. The species Z. fabago accumulated higher Cu and Zn in its aerial part and roots than the normal plants. On the other hand, their concentrations did not reach the criteria that the species could be considered as a metal hyperaccumulator. The species P. harmala did not absorb metals in its roots; accordingly the accumulation factor of these metals were lower than 1. The contents of chlorophyll, biomass, malondialdehyde, and dityrosine in these two species did not vary significantly between the two zones studied. In Zone 1, leaf vacuoles of Z. fabago stored 35.6% and 43.2% of the total leaf Cu and Zn, respectively. However, in this species, the levels of phytochelatins (PCs) and glutathione (GSH) and antioxidant enzyme activities were significantly higher in Zone 1 than in Zone 2. In conclusion, metal exclusion in P. harmala and metal accumulation in Z. fabago were the basic strategies in the two studied pioneer species growing on the metal-contaminated zone. In response to metal stress, elevation in antioxidant enzyme activities, increases in the PCs and GSH levels in the aerial parts, and metal storage within vacuoles counteracted each other in the invasion mechanism of Z. fabago.

Niu, L. A., Hao, J. M., Zhang, B. Z. and Niu, X. S. 2011. Influences of long-term fertilizer and tillage management on soil fertility of the North China Plain. Pedosphere. 21(6): 813--820.
ABSTRACT: In the North China Plain, fertilizer management and tillage practices have been changing rapidly during the last three decades; however, the influences of long-term fertilizer applications and tillage systems on fertility of salt-affected soils have not been well understood under winter wheat (Triticum aestivum L.)-maize (Zea mays L.) annual double cropping system. A field study was established in 1985 on a Cambosol at the Quzhou Experimental Station, China Agricultural University, to investigate the responses of soil fertility to fertilizer and tillage practices. The experiment was established as an orthogonal design with nine treatments of different tillage methods and/or fertilizer applications. In October 2001, composite soil samples were collected from the 0--20 and 20--40 cm layers and analyzed for soil fertility indices. The results showed that after 17 years of nitrogen (N) and phosphorous (P) fertilizer and straw applications, soil organic matter (SOM) in the top layer was increased significantly from 7.00 to 9.3--13.14 g kg-1 in the 0--20 cm layer, and from 4.00 to 5.48--7.75 g kg-1 in the 20--40 cm layer. Soil total N (TN) was increased significantly from 0.37 and 0.22 to 0.79--1.11 and 0.61--0.73 g N kg-1 in the 0--20 cm and 20--40 cm layers, respectively, with N fertilizer application; however, there was no apparent effect of straw application on TN content. The amounts of soil total P (TP) and rapidly available P (RP) were increased significantly from 0.60 to 0.67--1.31 g kg-1 in the 0--20 cm layer, and from 0.52 to 0.60--0.73 g kg-1 in the 20--40 cm layer with P fertilizer application, but were decreased with combined N and P fertilizer applications. The applications of N and P fertilizers significantly increased the crop yields, but decreased the rapidly available potassium (RK) in the soil. Straw return could only meet part of the crop potassium requirements. Our results also suggested that though some soil fertility parameters were maintained or enhanced under the long-term fertilizer and straw applications, careful soil quality monitoring was necessary as other nutrients could be depleted. Spreading straw on soil surface before tillage and leaving straw at soil surface without tillage were two advantageous practices to increase SOM accumulation in the surface layer. Plowing the soil broke aggregates and increased aeration of the soil, which led to enhanced organic matter mineralization.

Jansen, B., Tonneijck, F. H. and Verstraten, J. M. 2011. Selective extraction methods for aluminium, iron and organic carbon from montane volcanic ash soils. Pedosphere. 21(5): 549--565.
ABSTRACT: Montane volcanic ash soils contain disproportionate amounts of soil organic carbon and thereby play an often underestimated role in the global carbon cycle. Given the central role of Al and Fe in stabilizing organic matter in volcanic ash soils, we assessed various extraction methods of Al, Fe, and C fractions from montane volcanic ash soils in northern Ecuador, aiming at elucidating the role of Al and Fe in stabilizing soil organic matter (SOM). We found extractions with cold sodium hydroxide, ammonium oxalate/oxalic acid, sodium pyrophosphate, and sodium tetraborate to be particularly useful. Combination of these methods yielded information about the role of the mineral phase in stabilizing organic matter and the differences in type and degree of complexation of organic matter with Al and Fe in the various horizons and soil profiles. Sodium tetraborate extraction proved the only soft extraction method that yielded simultaneous information about the Al, Fe, and C fractions extracted. It also appeared to differentiate between SOM fractions of different stability. The fractions of copper chloride- and potassium chloride-extractable Al were useful in assessing the total reactive and toxic Al fractions, respectively. The classical subdivision of organic matter in humic acids, fulvic acids, and humine added little useful information. The use of fulvic acids as a proxy for mobile organic matter as done in several model-based approaches seemed invalid in the soils studied.
Virto, I., Gartzia-Bengoetxea, N. and Fernández-Ugalde, O. 2011. Role of organic matter and carbonates in soil aggregation estimated using laser diffractometry. Pedosphere. 21(5): 566--572.
ABSTRACT: Aggregation in many soils in semi-arid land is affected by their high carbonate contents. The presence of lithogenic and/or primary carbonates can also influence the role of soil organic matter (SOM) in soil aggregation. The role of carbonates and SOM in aggregation was evaluated by comparing the grain-size distribution in two carbonate-rich soils (15% and 30% carbonates) under conventional tillage after different disaggregating treatments. We also compared the effect of no-tillage and conventional tillage on the role of these two aggregating agents in the soil with 30% of carbonates. Soil samples were treated as four different ways: shaking with water (control), adding hydrochloric acid (HCl) to remove carbonates, adding hydrogen peroxide (H2O2) to remove organic matter, and consecutive removal of carbonates and organic matter (HCl + H2O2), and then analyzed by laser diffraction grain-sizing. The results showed that different contributions of carbonates and SOM to aggregate formation and stability depended not only on their natural proportion, but also on the soil type, as expressed by the major role of carbonates in aggregation in the 15% carbonate-rich soil, with a greater SOC-to-SIC (soil organic C to soil inorganic C) ratio than the 30% carbonate-rich soil. The increased organic matter stocks under no-tillage could moderate the role of carbonates in aggregation in a given soil, which meant that no-tillage could affect the organic and the inorganic C cycles in the soil. In conclusion, the relative role of carbonates and SOM in aggregation could alter the aggregates hierarchy in carbonate-rich soils.
Chen, L., Long, X. H., Zhang, Z. H., Zheng, X. T., Rengel, Z. and Liu, Z. P. 2011. Cadmium accumulation and translocation in two Jerusalem artichoke (Helianthus tuberosus L.) cultivars. Pedosphere. 21(5): 573--580.
ABSTRACT: Jerusalem artichoke (Helianthus tuberosus L.) not just can be used for bioethanol production but may be potentially used in phytoremediation for the removal of heavy metal pollutants. Two Jerusalem artichoke cultivars, N2 and N5, were subjected to six cadmium (Cd) concentrations (0, 5, 25, 50, 100 and 200 mg L"1) to investigate Cd tolerance and accumulation. After 21 days of growth, the effects of Cd on growth, chlorophyll content, net photosynthetic rate, inter-cellular CO2 concentration and malondialdehyde content were evaluated. Most growth parameters were reduced under Cd stress. The two Jerusalem artichoke cultivars had relatively high Cd tolerance and accumulation capacity (> 100 mg kg-1), with N5 being more tolerant and having higher Cd accumulation than N2. Roots accumulated more Cd than stems and leaves. The bioconcentration factors (far higher than 1) and translocation factors (lower than 1) decreased with an increase in Cd applied. The results suggested that Jerusalem artichoke could be grown at relatively high Cd loads, and N5 could be an excellent candidate for phytoremediation of Cd-contaminated soils.
Jaiarree, S., Chidthaisong, A., Tangtham, N., Polprasert, C., Sarobol, E. and Tyler, S. C. 2011. Soil organic carbon loss and turnover resulting from forest conversion to maize fields in eastern Thailand. Pedosphere. 21(5): 581--590.
ABSTRACT: Soil organic carbon (SOC) content and its stable carbon isotopic composition (within the upper 1 m) were measured to determine the effect of land-use changes from dry evergreen forest to maize fields in eastern Thailand. Digital land cover maps, derived from aerial photography and satellite images for years 1989, 1996, and 2002 were used in association with field surveys and farmer interviews to derive land-use history and to assist in study site selection. Conversion from forest to maize cultivation for the duration of 12 years reduced SOC stocks at the rate of 6.97 Mg C ha-1 year-1. Reduction was most pronounced in the top 10 cm soil layer, which was 47% after 12 years of cultivation. Stable carbon isotope data revealed that the main fraction lost was forest-derived C. Generally low input rates of maize-derived C were not sufficient to maintain SOC at the level prior to forest conversion. After 12 years of continuous maize cultivation, the maize-derived C fraction made up about 20% of total SOC (5 Mg ha-1 of the total 25.31 Mg ha-1).
Dong, Y. W., Yang, S. Q., Xu, C. Y., Li, Y. Z., Bai, W., Fan, Z. N., Wang, Y. N. and Li, Q. Z. 2011. Determination of soil parameters in apple-growing regions by near- and mid-infrared Spectroscopy. Pedosphere. 21(5): 591--602.
ABSTRACT: Soil quality monitoring is important in precision agriculture. This study aimed to examine the possibility of assessing the soil parameters in apple-growing regions using spectroscopic methods. A total of 111 soil samples were collected from 11 typical sites of apple orchards, and the croplands surrounding them. Near-infrared (NIR) and mid-infrared (MIR) spectra, combined with partial least square regression, were used to predict the soil parameters, including organic matter (OM) content, pH, and the contents of As, Cu, Zn, Pb, and Cr. Organic matter and pH were closely correlated with As and the heavy metals. The NIR model showed a high prediction accuracy for the determination of OM, pH, and As, with correlation coefficients (r) values of 0.89, 0.89, and 0.90, respectively. The predictions of these three parameters by MIR showed reduced accuracy, with r values of 0.77, 0.84, and 0.92, respectively. The heavy metals could also be measured by spectroscopy due to their correlation with organic matter. Both NIR and MIR had high correlation coefficients for the determination of Cu, Zn, and Cr, with standard errors of prediction of 2.95, 10.48, and 9.49 mg kg-1 for NIR and 3.69, 5.84, and 6.94 mg kg-1 for MIR, respectively. Pb content behaved differently from the other parameters. Both NIR and MIR underestimated Pb content, with r values of 0.67 and 0.56 and standard errors of prediction of 3.46 and 2.99, respectively. Cu and Zn had a higher correlation with OM and pH and were better predicted than Pb and Cr. Thus, NIR spectra could accurately predict several soil parameters, metallic and nonmetallic, simultaneously, and was more feasible than MIR in analyzing soil parameters in the study area.
Cerqueira, B., Covelo, E. F., Andrade, M. L. and Vega, F. A. 2011. Retention and mobility of copper and lead in soils as influenced by soil horizon properties. Pedosphere. 21(5): 603--614.
ABSTRACT: The mobility and bioavailability of heavy metals in soils is largely governed by sorption and desorption phenomena. Cu2+ and Pb2+ are among the most potentially toxic heavy metals and they are present, often concomitantly, in many polluting spills and in agrochemicals. The objective was to assess and compare the competitive sorption and desorption capacities and sorption hysteresis of Cu2+ and Pb2+, as well as their migration through the profiles of four natural soils: a Humic Umbrisol, an Umbric Cambisol, an Endoleptic Luvisol and a Humic Cambisol. In all horizons Pb2+ was invariably sorbed and retained to a greater extent than Cu2+. The sorption and retention of Cu2+ were most influenced by pH, effective cation exchange capacity (CECe) and Mn oxides content. On the other hand, the fixation capacity of Pb2+ was most influenced by pH, CECe, and Mn oxide and organic matter contents. pH and CECe were the individual soil properties most markedly influencing Cu2+ and Pb2+ sorption and retention. In all the horizons Pb2+ exhibited greater hysteresis than Cu2+. In each soil the hysteresis in the A horizon was greater than that in the B horizon, except in the Bt horizon of Endoleptic Luvisol, due to its high pH and vermiculite content. Based on migration indices, Pb2+ was less mobile than Cu2+ in the studied soils.
Zhang, M., Zhang, X. K., Liang, W. J., Jiang, Y., Dai, G. H., Wang, X. G. and Han, S. J. 2011. Distribution of soil organic carbon fractions along the altitudinal gradient in Changbai Mountain, China. Pedosphere. 21(5): 615--620.
ABSTRACT: Understanding the responses of soil organic carbon (SOC) fractions to altitudinal gradient variation is important for understanding changes in the carbon balance of forest ecosystems. In our study the SOC and its fractions of readily oxidizable carbon (ROC), water-soluble carbon (WSC) and microbial biomass carbon (MBC) in the soil organic and mineral horizons were investigated for the four typical forest types, including mixed coniferous broad-leaved forest (MCB), dark coniferous spruce-fir forest (DCSF), dark coniferous spruce forest (DCS), and Ermans birch forest (EB), along an altitudinal gradient in the Changbai Mountain Nature Reserve in Northeast China. The results showed that there was no obvious altitudinal pattern in the SOC. Similar variation trends of SOC with altitude were observed between the organic and mineral horizons. Significant differences in the contents of SOC, WSC, MBC and ROC were found among the four forest types and between horizons. The contents of ROC in the mineral horizon, WSC in the organic horizon and MBC in both horizons in the MCB and EB forests were significantly greater than those in either DCSF or DCS forest. The proportion of soil WSC to SOC was the lowest among the three main fractions. The contents of WSC, MBC and ROC were significantly correlated with SOC content (P < 0.05). It can be concluded that vegetation types and climate were crucial factors in regulating the distribution of soil organic carbon fractions in Changbai Mountain.
Chung, B. Y., Song, C. H., Park, B. J. and Cho, J. Y. 2011. Heavy metals in brown rice (Oryza sativa L.) and soil after long-term irrigation of wastewater discharged from domestic sewage treatment plants. Pedosphere. 21(5): 621--627.
ABSTRACT: A pot experiment was conducted in a plastic film house to evaluate the translocation and uptake of heavy metals (Pb, Cd, Cu, and Zn) into brown rice (Oryza sativa L.) and the heavy metals residues in soils which had previously been irrigated with domestic wastewater for a long time (3 years). The range of Pb, Cd, Cu, and Zn was 5.10 ± 0.01, 0.105 ± 0.017, 5.76 ± 0.42, and 23.56 ± 1.40 mg kg-1, respectively in the domestic wastewater-irrigated soil, and 0.370 ± 0.006, 0.011 ± 0.001, 0.340 ± 0.04, and 2.05 ± 0.18 mg kg-1, respectively, in the domestic wastewater-irrigated brown rice was. The results indicated that application of domestic wastewater to arable land slightly increased the levels of Pb, Cd, Cu, and Zn in soil and brown rice (P < 0.01). The concentrations of heavy metals in brown rice were lower than the recommended tolerable levels proposed by the Joint FAO/WHO Expert Committee on Food Additives. However, the continuous monitoring and pollution control of hazardous materials from domestic wastewater are needed in order to prevent excessive build-up of heavy metals in the food chain.
Wang, A. P., Li, F. H. and Yang, S. M. 2011. Effect of polyacrylamide application on runoff, erosion, and soil nutrient loss under simulated rainfall. Pedosphere. 21(5): 628--638.
ABSTRACT: Soil erosion affects soil productivity and environmental quality. A laboratory research experiment under simulated heavy rainfall with tap water was conducted to investigate the effect of anionic polyacrylamide (PAM) application rates (0, 0.5, 1.0, and 2.0 g m-2) and molecular weights (12 and 18 Mg mol-1) on runoff, soil erosion, and soil nutrient loss at a slope of 5o. The results showed the two lower rates of PAM application decreased runoff while the highest rate increased runoff as compared with the control. Sediment concentration and soil mass loss increased significantly with the PAM application rate. Compared with the control, PAM application decreased K+, NH4+, and NO3- concentrations in sediment and K+ and NH4+ concentrations in runoff, but significantly increased the mass losses of K+, NH4+, and NO3- over soil surface except for the NH4+ at PAM application rate lower than 1.0 g m-2. PAM application decreased the proportion of K+ loss with runoff to its total mass loss over soil surface from 60.1% to 16.4%. However, it did not affect the NH4+ and NO3- losses with runoff, and more than 86% of them were lost with runoff. A higher PAM molecular weight resulted in less soil erosion and K+ mass loss but had little effect on runoff and NH4+ and NO3- losses. PAM application did not prevent soil erosion and the mass losses of K+ and NO3- under experimental conditions.
Wu, Y. Z., Huang, M. B. and Warrington, D. N. 2011. Responses of different physiological indices for maize (Zea mays) to soil water availability. Pedosphere. 21(5): 639--649.
ABSTRACT: Knowledge of plant responses to soil water availability is essential for the development of efficient irrigation strategies. However, notably different results have been obtained in the past on the responses of various physiological indices for different plants to soil water availability. In this study, the responses of various plant processes to soil water availability were compared with data from pot and field plot treatments conducted on maize (Zea mays L.). Consistent results were obtained between pot and field plot treatments for the responses of various relative plant indices to changes in the fraction of available soil water (FASW). A threshold value, where the relative plant indices began to decrease with soil drying, and a lower water limit, where the decline of relative plant indices changed to a very slow rate, were found. Evaporative demand not only influenced the transpiration rate over a daily scale but also determined the difference in transpirational response to soil water availability among the transient, daily and seasonal time scales. At the seasonal scale, cumulative transpiration decreased linearly with soil drying, but the decrease of transpiration from FASW = 1 in response to water deficits did not affect dry weight until FASW = 0.75. On the other hand, the decrease in dry weight was comparable with plant height and leaf area. Therefore, the plant responses to soil water availability were notably different among various plant indices of maize and were influenced by the weather conditions.
Guo, X. F., Wei, Z. B., Wu, Q. T., Qiu, J. R. and Zhou, J. L. 2011. Cadmium and zinc accumulation in maize grain as affected by cultivars and chemical fixation amendments. Pedosphere. 21(5): 650--656.
ABSTRACT: A field experiment was conducted to investigate the effects of soil amendments (lime, nano-Si foliar solution and used diatomite) on the growth and metal uptake of three maize (Zea mays L.) cultivars grown in a Cd and Zn-contaminated acidic soil. The addition of lime significantly increased the maize grain yields and decreased the concentrations of Zn and Cd in the grains and shoots of maize when compared with the control. Among the three maize cultivars, Yunshi-5 accumulated the lowest amounts of Cd and Zn in the grain. The concentrations of Zn and Cd in the grain of Yunshi-5 conformed to the Chinese feed standards. These data revealed that a combination of low metal-accumulating maize and chemical fixation could effectively provide a barrier to prevent metals from entering the human food chain.
Maqsood, M. A., Hussain, S., Aziz, T. and Ashraf, M. 2011. Wheat-exuded organic acids influence zinc release from calcareous soils. Pedosphere. 21(5): 657--665.
ABSTRACT: Rhizosphere drives plant uptake of sparingly soluble soil zinc (Zn). An investigation with three experiments was conducted to study organic acid exudation by two contrasting wheat genotypes (Sehar-06 and Vatan), Zn fractions in 10 different calcareous soils from Punjab, Pakistan, and release of different soil Zn fractions by organic acids. The two genotypes differed significantly in biomass production and Zn accumulation under deficient and optimum Zn levels in nutrient solution. At a deficient Zn level, Sehar-06 released more maleic acid in the rhizosphere than Vatan. Ten soils used in the present study had very different physicochemical properties; their total Zn and Zn distribution among different fractions varied significantly. Zinc release behaviour was determined by extracting the soils with 0.005 mol L-1 citric acid or maleic acid. The parabolic diffusion model best described Zn release as a function of time. Parabolic diffusion model fitting indicated more maleic acid-driven than citric acid-driven soil Zn mobility from different fractions. Cumulative Zn release in six consecutive extractions during 24 h ranged from 1.85 to 13.58 mg kg"1 using maleic acid and from 0.37 to 11.84 mg kg"1 using citric acid. In the selected calcareous soils, the results of stepwise linear regression indicated significant release of Fe-Mn oxide-bounded soil Zn by maleic acid and its availability to the Zn-efficient genotype. Hence, release of maleic acid by plants roots plays an important role in phytoavailability of Zn from calcareous soils.
Song, M. H., jiang, J., Xu, X. L. and Shi, P. L. 2011. Correlation between CO2 efflux and net nitrogen mineralization and its response to external C or N supply in an alpine meadow soil. Pedosphere. 21(5): 666--675.
ABSTRACT: In nutrient-limited alpine meadows, nitrogen (N) mineralization is prior to soil microbial immobilization; therefore, increased mineral N supply would be most likely immobilized by soil microbes due to nutrient shortage in alpine soils. In addition, low temperature in alpine meadows might be one of the primary factors limiting soil organic matter decomposition and thus N mineralization. A laboratory incubation experiment was performed using an alpine meadow soil from the Tibetan Plateau. Two levels of (NH4)2SO4 (N) or glucose (C) were added, with a blank without addition of C or N as the control, before incubation at 5, 15 or 25 °C for 28 d. CO2 efflux was measured during the 28-d incubation, and the mineral N was measured at the beginning and end of the incubation, in order to test two hypotheses: 1) net N mineralization is negatively correlated with CO2 efflux for the control and 2) the external labile N or C supply will shift the negative correlation to positive. The results showed a negative correlation between CO2 efflux and net N immobilization in the control. External inorganic N supply did not change the negative correlation. The external labile C supply shifted the linear correlation from negative to positive under the low C addition level. However, under the high C level, no correlation was found. These suggested that the correlation of CO2 efflux to net N mineralization strongly depend on soil labile C and C:N ratio regardless of temperatures. Further research should focus on the effects of the types and the amount of litter components on interactions of C and N during soil organic matter decomposition.
Zhang, G. H., Liu, G. B., Wang, G. L. and Wang, Y. X. 2011. Effects of vegetation cover and rainfall intensity on sediment-bound nutrient loss, size composition and volume fractal dimension of sediment particles. Pedosphere. 21(5): 676--684.
ABSTRACT: Vegetation and rainfall are two important factors affecting soil erosion and thus resulting nutrient loss in the Chinese Loess Plateau. A field experiment was conducted to investigate the effects of rainfall intensities (60, 100 and 140 mm h–1) and vegetation (Caragana korshinskii) coverages (0%, 30% and 80%) on soil loss, nutrient loss, and the composition and volume fractal dimension of eroded sediment particles under simulated rainfall conditions. The results showed that vegetation cover, rainfall intensity and their interaction all had significant effects on sediment transport and the sediment-bound nutrient loss. Higher rainfall intensity and lower coverage led to higher sediment and nutrient losses. Positive linear relationships were observed between soil loss and nutrient loss. The treatments showed more significant effects on the enrichment ratio (ER) of nitrogen (ERN) than on organic matter (EROM) and phosphorus (ERP). Compared with the original surface soil, the eroded sediment contained more fine particles. Under the same coverage, the clay content significantly decreased with increasing rainfall intensity. The ER of sediment-bound nutrients was positively correlated with that of clay, suggesting that the clay fraction was preferentially eroded and soil nutrients were mainly adsorbed onto or contained within this fraction. There were increments in the fractal dimension of the sediment particles compared to that of the original surface soil. Moreover, the fractal dimension was positively correlated with clay, silt, and sediment-bound OM, N, and P contents, whereas it was negatively correlated with sand content. This study demonstrated that fractal dimension analysis can be used to characterize differences in particle-size distribution and nutrient loss associated with soil erosion.

Liao, K. H., Xu, S. H., Wu, J. C., Ji, S. H. and Lin, Q. 2011. Assessing soil water retention characteristics and their spatial variability using pedotransfer functions. Pedosphere. 21(4): 413--422.
ABSTRACT: A total of 107 soil samples were taken from a site located in the city of Qingdao, Shandong Province, China. Soil water retention data at 2.5, 6, 10, 33, 100, 300, and 1 500 kPa matric potentials were measured using a pressure membrane apparatus. Multiple linear regression (MLR) was used to develop pedotransfer functions (PTFs) for single point estimation and van Genuchten parameter estimation based on readily measurable soil properties, i.e., MLR-based point (MLRP) PTF and MLR-based parametric (MLRV) PTF. The double cross-validation method was used to evaluate the accuracy of PTF estimates and the stability of the PTFs developed in this study. The performance of MLRP and MLRV PTFs in estimating water contents at matric potentials of -10, -33, and -1 500 kPa was compared with that of two existing PTFs, one developed by the Rawls PTF and the other by the Vereecken PTF. In addition, geostatistical analyses were conducted to assess the capabilities of these PTFs in describing the spatial variability of soil water retention characteristics. Results showed that among all PTFs only the Vereecken PTF failed to accurately estimate water retention characteristics. Although the MLRP PTF can be used to predict retention characteristics through traditional statistical analyses, it failed to describe the spatial variability of soil water retention characteristics. Although the MLRV and Rawls PTFs failed to describe the spatial variability of water contents at a matric potential of -10 kPa, they can be used to quantify the spatial variability of water contents at matric potentials of -33 and -1 500 kPa.

Song, Y., Wang, F., F. O. Kengara, Bian, Y. R., Yang, X. L., Liu, C. Y. and Jiang, X. 2011. Improved biodegradation of 1,2,4-trichlorobenzene by adapted microorganisms in agricultural soil and in soil suspension cultures. Pedosphere. 21(4): 423-431.
ABSTRACT: Inoculating soil with an adapted microbial community is a more effective bioaugmentation approach than inoculation with pure strains in bioremediation. However, information on the potential of different inocula from sites with varying contamination levels and pollution histories in soil remediation is lacking. The objective of the study was to investigate the potential of adapted microorganisms in soil inocula, with different contamination levels and pollution histories, to degrade 1,2,4-trichlorobenzene (1,2,4-TCB). Three different soils from chlorobenzene-contaminated sites were inoculated into agricultural soils and soil suspension cultures spiked with 1,2,4-TCB. The results showed that 36.52% of the initially applied 1,2,4-TCB was present in the non-inoculated soil, whereas about 19.00% of 1,2,4-TCB was present in the agricultural soils inoculated with contaminated soils after 28 days of incubation. The soils inoculated with adapted microbial biomass (in the soil inocula) showed higher respiration and lower 1,2,4-TCB volatilization than the non-inoculated soils, suggesting the existence of 1,2,4-TCB adapted degraders in the contaminated soils used for inoculation. It was further confirmed in the contaminated soil suspension cultures that the concentration of inorganic chloride ions increased continuously over the entire experimental period. Higher contamination of the inocula led not only to higher degradation potential but also to higher residue formation. However, even inocula of low-level contamination were effective in enhancing the degradation of 1,2,4-TCB. Therefore, applying adapted microorganisms in the form of soil inocula, especially with lower contamination levels, could be an effective and environment-friendly strategy for soil remediation.

Jin, H. R., Jiang, D. H. and Zhang, P. H. 2011. Effect of carbon and nitrogen availability on metabolism of amino acids in germinating spores of arbuscular mycorrhizal fungi. Pedosphere. 21(4): 432--442.
ABSTRACT: The effect of carbon (C) and nitrogen (N) sources on N utilization and biosynthesis of amino acids were examined in the germinating spores of the arbuscular mycorrhizal (AM) fungus Glomus intraradices Schenck & Smith after exposure to various N substrates, CO2, glucose, and/or root exudates. The N uptake and de novo biosynthesis of amino acids were analyzed using stable isotopic labeling with mass spectrometric detection. High-performance liquid chromatography-based analysis was used to measure amino acid levels. In the absence of exogenous N sources and in the presence of 25 mL L-1 CO2, the germinating AM fungal spores utilized internal N storage as well as C skeletons derived from the degradation of storage lipids to biosynthesize the free amino acids, in which serine and glycine were produced predominantly. The concentrations of internal amino acids increased gradually as the germination time increased from 0 to 1 or 2 weeks. However, asparagine and glutamine declined to the low levels; both degraded to provide the biosynthesis of other amino acids with C and N donors. The availability of exogenous inorganic N (ammonium and nitrate) and organic N (urea, arginine, and glutamine) to the AM fungal spores using only CO2 for germination generated more than 5 times more internal free amino acids than those in the absence of exogenous N. A supply of exogenous nitrate to the AM fungal spores with only CO2 gave rise to more than 10 times more asparagine than that without exogenous N. In contrast, the extra supply of exogenous glucose to the AM fungal spores generated a significant enhancement in the uptake of exogenous N sources, with more than 3 times more free amino acids being produced than those supplied with only exogenous CO2. Meanwhile, arginine was the most abundant free amino acid produced and it was incorporated into the proteins of AM fungal spores to serve as an N storage compound.

Herencia, J. F., García-Galavís, P. A. and Maqueda, C. 2011. Long-term effect of organic and mineral fertilization on soil physical properties under greenhouse and outdoor management practices. Pedosphere. 21(4): 443--453.
ABSTRACT: To evaluate the use of organic amendments as an alternative to conventional fertilization, a 10-year experiment on a loam soil was conducted in a crop rotation system in both greenhouse and outdoor plots applied with chemical fertilizers (NPK) and vegetal compost (organic fertilizer) in the Guadalquivir River Valley, Spain to evaluate the effect of two different fertilization regimes on soil physical properties. Soil organic carbon (OC), soil bulk density (BD), soil water retention (WR), available water content (AWC), aggregate stability (AS), and soil physical quality (Dexter’s index, S) were determined. The use of organic fertilizer increased OC and resulted in a significant increase in AS and a decrease in BD compared to the mineral fertilizer application in both greenhouse and outdoor plots. The outdoor plots showed the lowest BD values whereas the greenhouse plots showed the highest AS values. In the last years of the 10-year experiment the S parameter was significantly higher in organic fertilizer plots, especially for greenhouse plots. At the end of the study period, there were no significant differences in WR at field capacity (FC) between treatments in both systems; the AWC was also similar in the greenhouse plots but higher in the mineral outdoor plots. In mineral fertilizer treatments, a small improvement in the physical properties was also observed due to the utilization of less aggressive tillage compared with the previous intensive cropping system. Physical soil properties were correlated with soil OC. The sustainable management techniques such as the use of organic amendments and low or no tillage improved soil physical properties, despite the differences in management that logically significantly affected the results.

Zhu, W. L., Cui, L. H., Ouyang, Y., Long, C. F. and Tang, X. D. 2011. Kinetic adsorption of ammonium nitrogen by substrate materials for constructed wetlands. Pedosphere. 21(4): 454--463.
ABSTRACT: Constructed wetlands (CWs) are engineered systems that utilize natural systems including wetland vegetations, soils, and their associated microbial assemblages to assist in treating wastewater. The kinetic adsorption of ammonium nitrogen (NH4+-N) by CW substrate materials such as blast furnace slag (BFS), zeolite, ceramsite, vermiculite, gravel, paddy soil, red soil, and turf, was investigated using batch experiments and kinetic adsorption isotherms. Both Freundlich and Langmuir isotherms could adequately predict the NH4+-N adsorption process. The maximum adsorption capacities of NH4+-N, estimated from the Langmuir isotherm, ranked as: zeolite (33 333.33 mg kg-1) > turf (29 274.01 mg kg-1) > BFS (5 000 mg kg-1) > vermiculite (3 333.33 mg kg-1) > gravel (769.23 mg kg-1) > paddy soil (588.24 mg kg-1) > red soil (555.56 mg kg-1) > ceramsite (107.53 mg kg-1). Some properties of the substrate materials, including bulk density, specific gravity, hydraulic conductivity, uniformity coefficient (K60), curvature coefficient (Cc), organic matter, pH, exchangeable (or active) Cu, Fe, Zn and Mn, total Cu, and Fe, Mn, Zn, Cd, Pb and Ca, had negative correlations with NH4+-N adsorption. Other properties of the substrate materials like particle diameter values of D10, D30 and D60 (the diameters of particle sizes of a substrate material at which 10%, 30% and 60%, respectively, of the particles pass through the sieve based on the accumulative frequency), cation exchange capacity (CEC), exchangeable (or active) Ca and Mg, and total K and Mg had positive correlations with NH4+-N adsorption. In addition, active K and Na as well as the total Na had significant positive correlations with NH4+-N adsorption. This information would be useful for selection of suitable substrate materials for CWs.

Min, J., Zhao, X., Shi, W. M., Xing, G. X. and Zhu, Z. L. 2011. Nitrogen balance and loss in a greenhouse vegetable system in southeastern China. Pedosphere. 21(4): 464--472.
ABSTRACT: High rates of fertilizer nitrogen (N) are applied in greenhouse vegetable fields in southeastern China to maximize production; however, the N budgets of such intensive vegetable production remain to be explored. The goal of this study was to determine the annual N balance and loss in a greenhouse vegetable system of annual rotation of tomato, cucumber, and celery at five N (urea) application rates (0, 348, 522, 696, and 870 kg N ha-1 year-1). Total N input to the 0--50 cm soil layer ranged from 531--1 053 kg ha-1, and N fertilizer was the main source of N, accounting for 66%--83% of the total annual N input. In comparison, irrigation water, wet deposition, and seeds in total accounted for less than 1% of the total N input. The fertilizer N use efficiency was only 18% under the conventional application rate of 870 kg N ha-1 and decreased as the application rate increased from 522 to 870 kg N ha-1. Apparent N losses were 196.2--200.3 kg N ha-1, of which 71%--86% was lost by leaching at the application rates of 522--870 kg N ha-1. Thus, leaching was the primary N loss pathway at high N application rates and the amount of N leached was proportional to the N applied during the cucumber season. Moreover, dissolved organic N accounted for 10% of the leached N, whereas NH3 volatilization only contributed 0.1%--0.6% of the apparent N losses under the five N application rates in this greenhouse vegetable system.

Salehi, M. H., Hashemi Beni1, O., Beigi Harchegani, H., Esfandiarpour Borujeni, I. and MOTAGHIAN, H. R. 2011. Refining soil organic matter determination by loss-on-ignition. Pedosphere. 21(4): 473--482.
ABSTRACT: Wet oxidation procedure, i.e., Walkley-Black (WB) method, is a routine, relatively accurate, and popular method for the determination of SOM but it is time-consuming, costly and also has a high potential to cause environmental pollution because of disposal of chromium and strong acids used in this analysis. Therefore, loss-on-ignition (LOI) procedure, a simple and cheap method for SOM estimation, which also avoids chromic acid wastes, deserves more attention. The aims of this research were to study the statistical relationships between SOM determined with the LOI (SOMLOI) and WB (SOMWB) methods to compare the spatial variability of SOM in two major plains, Shahrekord and Koohrang plains, of Chaharmahal-va-Bakhtiari Province, Iran. Fifty surface soil samples (0--25 cm) were randomly collected in each plain to determine SOM using the WB method and the LOI procedure at 300, 360, 400, 500 and 550 oC for 2 h. The samples covered wide ranges of soil texture and calcium carbonate equivalent (CCE). The general linear form of the regression equation was calculated to estimate SOMLOI from SOM obtained by the WB method for both overall samples and individual plains. Forty soil samples were also randomly selected to compare the SOM and CCE before and after ignition at each temperature. Overall accuracy of the continuous maps generated for the LOI and WB methods was considered to determine the accordance of two procedures. Results showed a significant positive linear relationship between SOMLOI and SOMWB. Coefficients of determination (R2) of the equations for individual plains were higher than that of the overall equation. Coefficients of determination and line slopes decreased and root mean square error (RMSE) increased with increasing ignition temperature, which may be due to the mineral structural water loss and destruction of carbonates at higher temperatures. A temperature around 360 oC was identified as optimum as it burnt most organic carbon, destroyed less inorganic carbon, caused less clay structural water loss, and used less electrical energy. Although the trends of SOM in the kriged maps by two procedures accorded well, low overall accuracy was observed for the maps obtained by two methods. While not suitable for determination where high accuracy is required, determination of organic carbon through LOI is likely suitable for exploratory soil surveys where rough estimation of organic matter is required.

Ma, W., Li, X. X. and Li, C. J. 2011. Modulation of soil particle size and nutrient availability in the maize rhizosheath. Pedosphere. 21(4): 483--490.
ABSTRACT: Root exudates, microorganism colonization and soil aggregates together form the rhizosheath, a special cylinder of micro-ecosystem adhering to the root surface. To study how the rhizosheath affects soil structure and nutrient distribution, we analyzed the impact of maize rhizosheath on soil particle size and nutrient availability in an experiment with pot and field treatments. The results showed that there was a significant size decrease of soil particles in the rhizosheath. Meanwhile, the soil mineral nitrogen in the rhizosheath was significantly higher than that in the rhizosphere or bulk soil at tasseling and maturity stages of maize. The contents of Fe and Mn were also differentially altered in the rhizosheath. Rhizosheath development, indicated by a dry weight ratio of rhizosheath soil to the root, was relatively independent of root development during the whole experimental period. The formation of maize rhizosheath contributed to the modulation of soil particle size and nutrient availability. The subtle local changes of soil physical and chemical properties may have profound influence on soil formation, rhizospheric ecosystem initiation, and mineral nutrient mobilization over the long history of plant evolution and domestication.

Zhong, B. and Xu, Y. J. 2011. Scale effects of geographical soil datasets on soil carbon estimation in Louisiana, USA: A comparison of STATSGO and SSURGO. Pedosphere. 21(4): 491--501.
ABSTRACT: Estimation of soil organic carbon (SOC) pools and fluxes bear large uncertainties because SOC stocks vary greatly over geographical space and through time. Although development of the U.S. Soil Survey Geographic Database (SSURGO), currently the most detailed level with a map scale ranging from 1:12 000 to 1:63 360, has involved substantial government funds and coordinated network efforts, very few studies have utilized it for soil carbon assessment at the large landscape scale. The objectives of this study were to 1) compare estimates in soil organic matter among SSURGO, the State Soil Geographic Database (STATSGO), and referenced field measurements at the soil map unit; 2) examine the influence of missing data on SOC estimation by SSURGO and STATSGO; 3) quantify spatial differences in SOC estimation between SSURGO and STATSGO, specifically for the state of Louisiana; and 4) assess scale effects on soil organic carbon density (SOCD) estimates from a soil map unit to a watershed and a river basin scale. SOC was estimated using soil attributes of SSURGO and STATSGO including soil organic matter (SOM) content, soil layer depth, and bulk density. Paired t-test, correlation, and regression analyses were performed to investigate various relations of SOC and SOM among the datasets. There were positive relations of SOC estimates between SSURGO and STATSGO at the soil map unit (R2= 0.56, n = 86, t = 1.65, P = 0.102; depth: 30 cm). However, the SOC estimated by STATSGO were 9%, 33% and 36% lower for the upper 30-cm, the upper 1-m, and the maximal depth (up to 2.75 m) soils, respectively, than those from SSURGO. The difference tended to increase as the spatial scale changes from the soil map unit to the watershed and river basin scales. Compared with the referenced field measurements, the estimates in SOM by SSURGO showed a closer match than those of STATSGO, indicating that the former was more accurate than the latter in SOC estimation, both in spatial and temporal resolutions. Further applications of SSURGO in SOC estimation for the entire United States could improve the accuracy of soil carbon accounting in regional and national carbon balances.

Sharif, M. and Claassen, N. 2011. Action mechanisms of arbuscular mycorrhizal fungi in phosphorus uptake by Capsicum annuum L. Pedosphere. 21(4): 502--511.
ABSTRACT: A pot experiment was conducted to investigate the action mechanisms of arbuscular mycorrhizal (AM) fungi in phosphorus (P) uptake of Capsicum annuum L. in a sterilized fossil Oxisol. Three P levels of 0, 10 and 200 mg kg-1 soil (treatments P0, P10 and P200, respectively) without and with AM fungal inoculation were applied as Ca(H2PO4)2‡H2O. Shoot dry matter yields and shoot P uptake increased significantly (P > 0.05) by the inoculation of AM fungi in the treatments of P0 and P10. An increase of root length and P concentration in soil solution was observed with the inoculation of AM fungi but the root:shoot ratio decreased or remained constant. Around 50% roots of inoculated plants were infected by AM and the external hyphae amounted to 20 m g-1 soil at P10 and P200. The hyphae surface area of the infected root cylinder amounted to 11 and 2 cm2 cm-2 root at P0 and P10, respectively. The increased P uptake of inoculated plants was mainly because of an up to 5 times higher P influx of the infected root. Model calculations showed that the root alone could not have achieved the measured P influx in both infected and non-infected roots. But the P influx for hyphae calculated by the model was even much higher than the measured one. The P uptake capacity of hyphae introduced in the model was too high. Model calculations further showed that the depletion zone around roots or hyphae was very narrow. In the case of the root only 7% of the soil volume would contribute P to the plant, while in the case of hyphae it would be 100%. The results together with the model calculations showed that the increased P uptake of AM inoculated plants could be explained partly by the increased P concentration in the soil solution and by the increased P absorbing surface area coming from the external hyphae.

Shang, S. H. and Mao, X. M. 2011. A physicoempirical model for soil water simulation in crop root zone. Pedosphere. 21(4): 512--521.
ABSTRACT: To predict soil water variation in the crop root zone, a general exponential recession (GER) model was developed to depict the recession process of soil water storage. Incorporating the GER model into the mass balance model for soil water, a GER-based physicoempirical (PE-GER) model was proposed for simulating soil water variation in the crop root zone. The PE-GER model was calibrated and validated with experimental data of winter wheat in North China. Simulation results agreed well with the field experiment results, as well as were consistent with the simulation results from a more thoroughly developed soil water balance model which required more detailed parameters and inputs. Compared with a previously developed simple exponential recession (SER) based physicoempirical (PE-SER) model, PE-GER was more suitable for application in a broad range of soil texture, from light soil to heavy soil. Practical application of PE-GER showed that PE-GER could provide a convenient way to simulate and predict the variation of soil water storage in the crop root zone, especially in case of insufficient data for conceptual or hydrodynamic models.

Li, D. C., Velde, B., Li, F. M., Zhang, G. L., Zhao, M. S. and Huang, L. M. 2011. Impact of long-term alfalfa cropping on soil potassium content and clay minerals in a semi-arid loess soil in China. Pedosphere. 21(4): 522--531.
ABSTRACT: Alfalfa cropping has been considered an efficient method of increasing soil fertility. Usually nitrogen increase in root nodules is considered to be the major beneficial effect. A 21-year time series (five sampling periods) of alfalfa cultivation plots on a loess soil, initially containing illite and chlorite, in Lanzhou of northwestern China was selected to investigate the relationships among alfalfa cropping, soil potassium (K) content and soil clay minerals. The results indicated that soil K significantly accumulated after cropping, with a peak value at about 15 years, and decreased afterwards. The accumulated K was associated with the K increase in the well-crystallized illite mineral, which was not extracted by the traditional laboratory K extraction methods in assessing bioavailability. The steep decline in soil K content after 15-year cropping was in accord with the observed fertility loss in alfalfa soils. Plant biomass productivity peaked at near 9 years of culture, whereas soil K and clay minerals continued to increase until copping for 15 years. This suggested that K increased in the topsoil came from the deep root zone. Thus alfalfa continued to store K in clays even after peak production occurred. Nitrogen did not follow these trends, showing a general decline compared with the native prairie soils that had not been cropped. Therefore, the traditional alfalfa cropping can increase K content in the topsoil.

Amanullah and Khan, M. W. 2011. Interactive effect of potassium and phosphorus on grain quality and profitability of sunflower in Northwest Pakistan. Pedosphere. 21(4): 532--538.
ABSTRACT: A field experiment was conducted using a split plot randomized complete block design with three replications to study the effects of potassium (K) and phosphorus (P) application on sunflower (Helianthus annuus L.) growth at the New Developmental Research Farm of Khyber Pakhtunkhwa Agricultural University in Peshawar, Pakistan. Six levels of K (0, 25, 50, 75, 100 and 125 kg K ha-1) were main plots while four levels of P (0, 45, 90 and 135 kg P ha-1) were subplots. Increase in both K and P levels enhanced grain oil concentration of sunflower. Increase in P level increased grain protein concentration, while increase in K level decreased grain protein concentration. Both oil and protein yields increased significantly with increase in K and P levels. The increase in oil and protein yields of sunflower was mainly attributed to the improvement in yield components (grains per head, grain weight and head size) and the significant increase in grain yield. The highest net returns of 297 and 368 US$ ha-1 based on grain and oil yields, respectively, were obtained from a combination of 100 kg K ha-1 + 45 kg P ha-1.

Dou, C. Y., Kang, Y. H., Wan, S. Q. and Hu, W. 2011. Soil salinity changes under cropping with Lycium barbarum L. and irrigation with saline-sodic water. Pedosphere. 21(4): 539--548.
ABSTRACT: In order to utilize the wasted saline-sodic soils under shallow groundwater condition, a 3-year field study was carried in a field cropped with Lycium barbarum L. and irrigated by drip irrigation with saline groundwater under the water table depth of 30--40 cm in the northern Yinchuan Plain, China. Effects of cropping duration (one, two, and three years) on soil salinity, soil solution composition, and pH in three adjacent plots were investigated in 2008. Results showed that a high irrigation frequency maintained high soil water potential and subsequently facilitated infiltration and downward movement of water and salt in the crop root zone. Salt accumulated on the edges of the ridges, and soil saturated-paste electrical conductivity (ECe) was higher in the edge. Concentrations of Na+, Ca2+, Mg2+, Cl-, and SO42- in the soil increased with the soil depth as did the ECe, while HCO3- and pH had a relative uniform distribution in soil profile. As planting year increased, the ECe and soil salts in the field had a decreasing tendency, while in the root zone they decreased immediately after irrigation and then remained relatively stable in the following growing seasons. HCO3- and pH had little change with the planting year. Results suggested that the application of drip irrigation with saline water could ameliorate saline-sodic soil and provide a relatively feasible soil environment for the growth of salt-tolerant plant Lycium barbarum L. under the saline-sodic soils with shallow groundwater.

Wang, S. H., Shi, X. Z., Zhao, Y. C., Weindorf, D. C., Yu, D. S., Xu, S. X., Tan, M. Z. and Sun, W. X. 2011. Regional simulation of soil organic carbon dynamics for dry farmland in East China by coupling a 1:500 000 soil database with the Century model. Pedosphere. 21(3): 277--287.
ABSTRACT: Changes in soil organic carbon (SOC) in agricultural soils influence soil quality and greenhouse gas concentrations in the atmosphere. Dry farmland covers more than 70% of the whole cropland area in China and plays an important role in mitigating carbon dioxide (CO2) emissions. In this study, 4 109 dry farmland soil polygons were extracted using spatial overlay analysis of the soil layer (1: 500 000) and the land use layer (1: 500 000) to support Century model simulations of SOC dynamics for dry farmland in Anhui Province, East China from 1980 to 2008. Considering two field-validation sites, the Century model performed relatively well in modeling SOC dynamics for dry farmland in the province. The simulated results showed that the area-weighted mean soil organic carbon density (SOCD) of dry farmland increased from 18.77 Mg C ha-1 in 1980 to 23.99 Mg C ha-1 in 2008 with an average sequestration rate of 0.18 Mg C ha-1 year-1. Approximately 94.9% of the total dry farmland area sequestered carbon while 5.1% had carbon lost. Over the past 29 years, the net SOC gain in dry farmland soils of the province was 19.37 Tg, with an average sequestration rate of 0.67 Tg C year-1. Augmentation of SOC was primarily due to increased consumption of nitrogen fertilizer and farmyard manure. Moreover, SOC dynamics were highly differentiated among dry farmland soil groups. The integration of the Century model with a fine-scale soil database approach could be conveniently utilized as a tool for the accurate simulation of SOC dynamics at the regional scale.

Bernstein, N. Ioffe, M., Luria, G., Bruner, M., Nishri, Y., Philosoph-Hadas, S., Salim, S., Dori, I. and Matan, E. 2011. Effects of K and N Nutrition on function and production of Ranunculus asiaticus. Pedosphere. 21(3): 288--301.
ABSTRACT: Potassium (K) affects a range of physiological processes in the plant and is a key factor controlling crop productivity and yield quality. Little information is available concerning effects of K nutrition on function of cut flower plants. The present study was carried out to investigate the interaction between K and N nutrition, on flower quantity and quality of Ranunculus asiaticus L. The plants were supplied with three levels of K fertigation (60, 120, or 180 mg K L-1) under 50 mg N L-1 application, and at the intermediate level of 120 mg K L-1, to three levels of N applications (50, 100, or 150 mg N L-1). The two lowest K treatments and the lowest N treatment excelled in flower production due to the lower incidence of stem-toppling, a disorder associated with localized Ca deficiencies in rapidly expanding tissues of the flower stem. Detrimental effects in terms of yield quality were apparent already under supply of 180 mg K L-1 and 50 mg N L-1, and were not associated with changes in osmotic potential, relative water content or membrane stability of the plant tissue, or with changes in mineral contents of the leaves other than reduced Ca under high N application. Our results suggest a low nutritional requirement of R. asiaticus L. for K and N, a lack of involvement of tissue water relations in the reduced flower quality under the application of high concentrations of K and N, and an induction of stem toppling under high application of N and K by reduced availability of Ca to the expanding tissue of the flower stem.

Yuan, J. H., Xu, R. K., Wang, N. and Li, J. Y. 2011. Amendment of acid soils with crop residues and biochars. Pedosphere. 21(3): 302--308.
ABSTRACT: The liming potential of some crop residues and their biochars on an acid Ultisol were investigated using incubation experiments. Rice hulls showed greater liming potential than rice hull biochar, while soybean and pea straws had less liming potential than their biochars. Due to their higher alkalinity, biochars from legume materials increased soil pH much compared to biochars from non-legume materials. The alkalinity of biochars was a key factor affecting their liming potential, and the greater alkalinity of biochars led to greater reductions in soil acidity. The incorporation of biochars decreased soil exchangeable acidity and increased soil exchangeable base cations and base saturation, thus improving soil fertility.

Delgado-Baquerizo, M., Covelo, F. and Gallardo, A. 2011. Dissolved organic nitrogen in Mediterranean ecosystems. Pedosphere. 21(3): 309--318.
ABSTRACT: Dissolved organic nitrogen (DON) in soils has recently gained increasing interest because it may be both a direct N source for plants and the dominant available N form in nutrient-poor soils, however, its prevalence in Mediterranean ecosystems remains unclear. The aims of this study were to i) estimate soil DON in a wide set of Mediterranean ecosystems and compare this levels with those for other ecosystems; ii) describe temporal changes in DON and dissolved inorganic nitrogen (DIN) forms (NH4+ and NO3-), and characterize spatial heterogeneity within plant communities; and iii) study the relative proportion of soil DON and DIN forms as a test of Schimel and Bennett’s hypothesis that the prevalence of different N forms follows a gradient of nutrient availability. The study was carried out in eleven plant communities chosen to represent a wide spectrum of Mediterranean vegetation types, ranging from early to late successional status. DON concentrations in the studied Mediterranean plant communities (0--18.2 mg N kg-1) were consistently lower than those found in the literature for other ecosystems. We found high temporal and spatial variability in soil DON for all plant communities. As predicted by the Schimel and Bennett model for nutrient-poor ecosystems, DON dominance over ammonium and nitrate was observed for most plant communities in winter and spring soil samples. However, mineral-N dominated over DON in summer and autumn. Thus, soil water content may have an important effect on DON versus mineral N dominance in Mediterranean ecosystems.

Liu, L. Z., Gong, Z. Q., Zhang, Y. L. and Li, P. J. 2011. Growth, cadmium accumulation and physiology of marigold (Tagetes erecta L.) as affected by arbuscular mycorrhizal fungi. Pedosphere. 21(3): 319--327.
ABSTRACT: A pot experiment was carried out to study the effects of three arbuscular mycorrhizal fungi (AMF), including Glomus intraradices, Glomus constrictum and Glomus mosseae, on the growth, root colonization and Cd accumulation of marigold (Tagetes erecta L.) at Cd addition levels of 0, 5 and 50 mg kg-1 in soil. The physiological characteristics, such as chlorophyll content, soluble sugar content, soluble protein content and antioxidant enzyme activity, of Tagetes erecta L. were also investigated. Generally, the symbiotic relationship between the marigold plant and arbuscular mycorrhizal fungi was well established under Cd stress. The symbiotic relationship was reflected by the better physiobiochemical parameters of the marigold plants inoculated with the three AMF isolates where the colonization rates in the roots were between 34.3% and 88.8%. Compared with the non-inoculated marigold plants, the shoot and root biomass of the inoculated marigold plants increased by 15.2%--47.5% and 47.8%--130.1%, respectively, and the Cd concentration and accumulation decreased. The chlorophyll and soluble sugar contents in the mycorrhizal marigold plants increased with Cd addition, indicating that AMF inoculation helped the marigold plants to grow by resisting Cd stress. The antioxidant enzymes reacted differently with the three AMF under Cd stress. For plants inoculated with G. constrictum and G. mosseae, the activities of superoxide dismutase (SOD) and catalase (CAT) increased with increasing Cd addition, but peroxidase (POD) activity decreased with increasing Cd addition. For plants inoculated with G. intraradices, three of the antioxidant enzyme activities were significantly decreased at high levels of Cd addition. Overall, the activities of the three antioxidant enzymes in the plants inoculated with AMF were higher than those of the plants without AMF inoculation under Cd stress. Our results support the view that antioxidant enzymes have a great influence on the biomass of plants, and AMF can improve the capability of reactive oxygen species (ROS) scavenging and reduce Cd concentration in plants to alleviate Tagetes erecta L. from Cd stress.

Hu, G. Q., Dong, Y. J., Wang, H., Qiu, X. K. and Wang, Y. H. 2011. Laboratory testing of magnetic tracers for soil erosion measurement. Pedosphere. 21(3): 328--338.
ABSTRACT: Soil erosion, which includes soil detachment, transport, and deposition, is one of the important dynamic land surface processes. The magnetic tracer method is a useful method for studying soil erosion processes. In this study, five types of magnetic tracers were made with fine soil, fly ash, cement, bentonite, and magnetic powder (reduced iron powder) using the method of disk granulation. The tracers were uniformly mixed with soil and tested in the laboratory using simulated rainfall and inflow experiments to simulate the interrill and rill components of soil erosion, in order to select one or more tracers which could be used to study detachment and deposition by the erosive forces of raindrops and surface flow of water on a slope. The results showed that the five types of magnetic tracers with high magnetic susceptibility and a wide range of sizes had a range of 0.99--1.29 g cm-3 in bulk density. In the interrill and rill experiments, the tracers FC1 and FC2 which consisted of fly ash and cement at ratios of 1:1 and 2:1, respectively, were transported in phase with soil particles since the magnetic susceptibility of sediment was much near to that of the soil which was uneroded and the slopes of the regression equations between the detachment of sediment and the magnetic tracers FC1 and FC2 treatments were very close to the expected value of 20, which was the original soil/tracer ratio. The detachment and deposition on slopes could be accurately reflected by the magnetic susceptibility differences. The change in magnetic susceptibility depended on whether deposition or detachment occurred. However, the tracer FS which consisted of fine soil and the tracers FB1 and FB2 which consisted of fly ash and bentonite at ratios of 1:1 and 2:1, respectively, were all unsuitable for soil erosion study since there was no consistent relationship between sediment and tracer detachment for increasing amounts of runoff. Therefore, the tracers FC1 and FC2 could be used to study soil erosion by water.

Sun, X. L., Zhao, Y. G., Zhang, G. L., Wu, S. C., Man, Y. B. and Wong, M. H. 2011. Application of a digital soil mapping method in producing soil orders on mountain areas of Hong Kong based on legacy soil data. Pedosphere. 21(3): 339--350.
ABSTRACT: Based on legacy soil data from a soil survey conducted recently in the traditional manner in Hong Kong, a digital soil mapping method was applied to produce soil order information for mountain areas of Hong Kong. Two modeling methods, decision tree analysis and linear discriminant analysis were used, and their applications were compared. Much more effort was put on selecting soil covariates for modeling. First, analysis of variance (ANOVA) was used to test the variance of terrain attributes between soil orders. Then, a stepwise procedure was used to select soil covariates for linear discriminant analysis, and a backward removing procedure was developed to select soil covariates for tree modeling. In the same time, ANOVA results, as well as our knowledge and experience on soil mapping, were also taken into account for selecting soil covariates for tree modeling. Two linear discriminant models and four tree models were established finally, and their prediction performances were validated using a multiple jackknifing approach. Results showed that the discriminant model built on ANOVA results performed best, followed by the discriminant model built by stepwise, the tree model built by the backward removing procedure, the tree model built according to knowledge and experience on soil mapping, and the tree model built automatically. The results highlighted the importance of selecting soil covariates in modeling for soil mapping, and suggested the usefulness of methods used in this study for selecting soil covariates. The best discriminant model was finally selected to map soil orders for this area, and validation results showed that thus produced soil order map had a high accuracy.

Khan, S. Khan, M. A. and Rehman, S. 2011. Lead and cadmium contamination of different roadside soils and plants in Peshawar City, Pakistan. Pedosphere. 21(3): 351--357.
ABSTRACT: Soil and plant samples were collected from roadside sites (along with primary, secondary and tertiary roads) and reference site to investigate the contamination of soils and old common plant species with lead (Pb) and cadmium (Cd) in Peshawar City, Pakistan. All the data were analyzed using ANOVA analysis that showed a significant (P d" 0.01) variation in Pb and Cd concentrations in the roadside soils and plants as compared to the reference site. The mean concentrations of Pb and Cd were 53.9 and 6.0 mg kg-1 in soils and 49.1 and 10.9 mg kg-1 in plants, respectively. Significant variation ((P d" 0.01) in concentrations of Pb and Cd in soil and plant samples along with primary, secondary and tertiary roads might be due to different traffic densities. The highest value (9.4) of metal accumulation index (MAI) was observed for Eucalyptus camaldulensis. In selected plant species, the Pb and Cd accumulation was found in order of E. camaldulensis> Ficus elastica> Dalbergia sissoo> Alstonia scholaris. The roadside soils and plants were highly contaminated with Pb and Cd as compared to the reference site.

Zeng, Q. L., Chen, R. F., Zhao, X. Q., Wang, H. Y. and Shen, R. F. 2011. Aluminium uptake and accumulation in the hyperaccumulator Camellia oleifera Abel. Pedosphere. 21(3): 358--364.
ABSTRACT: Oiltea camellia (Camellia oleifera Abel.), an aluminium (Al) hyperaccumulator, grows well on acid soils in tropical or subtropical areas. In this study, the growth of oiltea camellia in response to Al application and the characteristics of Al uptake and accumulation were investigated using laboratory and field experiments. The growth of oiltea camellia seedlings in the nutrient solution tended to be stimulated by addition of Al. Results of the field experiment showed that oiltea camellia accumulated 11 000 mg kg-1 Al in leaves within 10 months, and the average rate of Al accumulation in new leaves was about 1 100 mg kg-1 month-1; however, the monthly rate varied and was highest in spring and autumn. The results of the laboratory experiment on Al uptake by oiltea camellia seedlings in CaCl2 nutrient solutions with various forms of Al showed that large amounts of Al supplied as Al3+ and Al complexes Al-malate (1:1) and Al-F (1:1) were influxed into oiltea camellia roots, whereas Al supplied as Al-citrate (1:1), Al-F (1:6), Al-oxalate (1:3), and Al-oxalate (1:1) complexes exhibited low affinity to oiltea camellia roots. The kinetics of Al3+ cumulative uptake in excised roots and intact plants showed a biphasic pattern, with an initial rapid phase followed by a slow phase. The Al cumulative uptake was unaffected by low temperature, which indicated that Al uptake in oiltea camellia was a passive process. The efficient influx of Al into the roots and the high transport rate in specific seasons were presumed to account for the plentiful Al accumulation in leaves of oiltea camellia.

Bortolon, L., Gianello, C., Welter, S., Almeida, R. G. O. and Giasson, E. 2011. Simultaneous extraction of phosphorus, potassium, calcium and magnesium from soils and potassium recommendations for crops in southern Brazil. Pedosphere. 21(3): 365--372.
ABSTRACT: Simultaneous multi-element extraction has been increasing worldwide to improve soil laboratory testing quality and efficiency. This study sought to investigate the applicability of the Mehlich-1, Mehlich-3, and resin methods for simultaneous extraction of soil available P, K, Ca and Mg as well as the effect of using conversion equations on nutrient recommendations for crops. Topsoil (0--20 cm) samples were taken from the most representative soils types used for crop production in southern Brazil with a wide range of chemical, physical, and mineralogical properties. Soil P, K, Ca, and Mg were simultaneously extracted using 1.0 mol L-1 KCl, Mehlich-1, and Mehlich-3 solutions, and membrane resin. The amounts of P extracted with the Mehlich-1 method were, on average, 50% lower than those extracted with the resin and Mehlich-3 methods. However, the resin method extracted the lowest amounts of K, Ca and Mg. The use of conversion equations was suitable and it did not affect negatively the K recommendations for crops grown on soils of southern Brazil.

Wang Z., Y., Shu, Q. S., Xie, L. Y., Liu, Z. X. and Si, B. C. 2011. Joint multifractal analysis of scaling relationships between soil water-retention parameters and soil texture. Pedosphere. 21(3): 373--379.
ABSTRACT: Soil water-retention characteristics at measurement scales are generally different from those at application scales, and there is scale disparity between them and soil physical properties. The relationships between two water-retention parameters, the scaling parameter related to the inverse of the air-entry pressure (±vG, cm-1) and the curve shape factor related to soil pore-size distribution (n) of the van Genuchten water-retention equation, and soil texture (sand, silt, and clay contents) were examined at multiple scales. One hundred twenty-eight undisturbed soil samples were collected from a 640-m transect located in Fuxin, China. Soil water-retention curves were measured and the van Genuchten parameters were obtained by curve fitting. The relationships between the two parameters and soil texture at the observed scale and at multiple scales were evaluated using Pearson correlation and joint multifractal analyses, respectively. The results of Pearson correlation analysis showed that the parameter ±vG was significantly correlated with sand, silt, and clay contents at the observed scale. Joint multifractal analyses, however, indicated that the parameter ±vG was not correlated with silt and sand contents at multiple scales. The parameter n was positively correlated with clay content at multiple scales. Sand content was significantly correlated with the parameter n at the observed scale but not at multiple scales. Clay contents were strongly correlated to both water-retention parameters because clay content was relatively low in the soil studied, indicating that water retention was dominated by clay content in the field of this study at all scales. These suggested that multiple-scale analyses were necessary to fully grasp the spatial variability of soil water-retention characteristics.

Wu, C. X., Wang, J. J., Zhang, S. Z. and Zhang, Z. M. 2011. Adsorption and desorption of methiopyrsulfuron in soils. Pedosphere. 21(3): 380--388.
ABSTRACT: Methiopyrsulfuron is a new, low-rate, sulfonylurea herbicide for weed control in wheat; however, there is a lack of published information on its behavior in soils. In this study, methiopyrsulfuron adsorption and desorption were measured in seven soil samples from Heilongjiang, Shandong, Jiangxi, Sichuan, Anhui, and Chongqing provinces of China using a batch equilibrium method. The Freundlich equation was used to described its adsorption and desorption. Adsorption isotherms were nonlinear with the values of Kf-ads, the Freundlich empirical constant indicative of the adsorption capacity, ranging from 0.75 to 2.46, suggesting that little of this herbicide was adsorbed by any of the seven soils. Soil pH and organic matter content (OM) were the main factors influencing adsorption; adsorption was negatively correlated with pH and positively correlated with OM. Methiopyrsulfuron desorption was hysteretic on the soils with high OM content and low pH.

Mohammadi, J. and Motaghian, M. H. 2011. Spatial prediction of soil aggregate stability and aggregate-associated organic carbon content at the catchment scale using geostatistical techniques. Pedosphere. 21(3): 389--399.
ABSTRACT: The association of organic carbon with secondary particles (aggregates) results in its storage and retention in soil. A study was carried out at a catchment covering about 92 km2 to predict spatial variability of soil water-stable aggregates (WSA), mean weight diameter (MWD) of aggregates and organic carbon (OC) content in macro- (> 2 mm), meso- (1--2 mm), and micro-aggregate (< 1 mm) fractions, using geostatistical methods. One hundred and eleven soil samples were collected at the 0--10 cm depth and fractionated into macro-, meso-, and micro-aggregates by wet sieving. The OC content was determined for each fraction. A greater percentage of water-stable aggregates was found for micro-aggregates, followed by meso-aggregates. Aggregate OC content was greatest in meso-aggregates (9 g kg-1), followed by micro-aggregates (7 g kg-1), while the least OC content was found in macro-aggregates (3 g kg-1). Although a significant effect (P = 0.000) of aggregate size on aggregate OC content was found, however, our findings did not support the model of aggregate hierarchy. Land use had a significant effect (P = 0.073) on aggregate OC content. The coefficients of variation (CVs) for OC contents associated with each aggregate fraction indicated macro-aggregates as the most variable (CV = 71%). Among the aggregate fractions, the micro-aggregate fraction had a lower CV value of 27%. The mean content of WSA ranged from 15% for macro-aggregates to 84% for micro-aggregates. Geostatistical analysis showed that the measured soil variables exhibited differences in their spatial patterns in both magnitude and space at each aggregate size fraction. The relative nugget variance for most aggregate-associated properties was lower than 45%. The range value for the variogram of water-stable aggregates was almost similar (about 3 km) for the three studied aggregate size classes. The range value for the variogram of aggregate-associated OC contents ranged from about 3 km for macro-aggregates to about 6.5 km for meso-aggregates. Kriged maps of predicted WSA, OC and MWD for the three studied aggregate size fractions showed clear spatial patterns. However, a close spatial similarity (co-regionalization) was observed between WSA and MWD.

Wang, J., Huang, Y. and Jiang, X. Y. 2011. Influence of ectomycorrhizal fungi on absorption and balance of essential elements of Pinus tabulaeformis seedlings in saline soil. Pedosphere. 21(3): 400-406.
ABSTRACT: Pinus tabulaeformis seedlings were grown under a factorial design to measure biomass accumulation and P, Na and K concentrations of plants, with 3 different ectomycorrhizal fungus (EMF) strains (Boletus edulis, Xerocomus chrysenteron and Gomphidius viscidus) and two P treatments (with or without extra P). Growth and mineral nutrition of pine seedlings were stimulated by three EMF under salinity stress. Na concentrations were changed and plant K and P concentrations were increased significantly by EMF. Adding extra P made no difference in accumulation of seedlings biomass, and did not assist element absorption of plants. Although three strains of EMF can all enhance the tolerance of pine seedlings to salinity stress, they may utilize different mechanisms because of different performance in absorption of elements. The increased P and K accumulation and the balance of ion concentrations might be due to the enhanced tolerance of EMF--inoculated plants to saline conditions.

Wu, G. L., Li, W., Zhao, L. P. and Shi, Z. H. 2011. Artificial management improves soil moisture, C, N and P in an alpine sandy meadow of western China. Pedosphere. 21(3): 407--412.
ABSTRACT: Regeneration of degraded grassland ecosystems is a significant issue in restoration ecology globally. To understand the effects of artificial management measures on alpine meadows, we surveyed topsoil properties including moisture, organic carbon (SOC), nitrogen (N), and phosphorus (P) contents five years after fencing and fencing + reseeding management practices in a sandy meadow in the eastern Qinghai-Tibetan Plateau, northwestern China. Both the fencing and fencing + reseeding management practices significantly increased soil moisture storage, SOC, total N, available N, total P, and available P, as compared to the unmanaged control. Fencing plus reseeding was more effective than fencing alone for improving soil C, N, and P contents. These suggested that rehabilitation by reseeding and fencing generally had favorable effects on the soil properties in degraded sandy alpine meadows, and was an effective approach for restoration of degraded meadow ecosystems of the Qinghai-Tibetan Plateau.

Zhou, D. M., Wang, Q. Y. and Cang, L. 2011. Free Cu2+ ions, Cu fractionation and microbial parameters in soils from apple orchards following long-term application of copper fungicides (-N‡eÂS€Ç{˜˜ÿ•gO(u+Tܔ@gw̃BRù[ù‚œgíVWäX-Nê1u`ܔ»yP[0úVøvܔb_`R§~åNÊS®_uir;m'`„vq_ÍT). Pedosphere. 21(2): 139--145.
ABSTRACT: Soil samples were collected from apple orchards 5, 15, 20, 30, and 45 years old, and one adjacent forest soil was used as reference to investigate the free Cu2+ ion activity in soil solution and the soil Cu fractionation in the solid phase following long-term application of copper fungicide, Bordeaux mixture, in apple orchards of different ages and to investigate the relationships among soil free Cu2+ ions, Cu fractionation and soil microbial parameters. The total Cu concentration in the orchard soils varied from 21.8 to 141 mg kg"1, increasing with the orchard age. The value for the reference soil was 12.5 mg kg-1. The free Cu2+ ion concentrations in the soil solutions extracted by 0.01 mol L-1 KNO3 ranged from 3.13 × 10-8 (reference) to 4.08 × 10-6 mol L-1 (45 years-old orchard). The concentration of Cu complexed in the fulvic fraction increased with orchard age from 5.16 to 52.5 mg kg-1. This was also the case for other soil Cu fractions except the residual one. The residual soil Cu remained practically constant, ranging from 4.28 to 5.66 mg kg"1, suggesting that anthropogenic soil Cu mainly existed in the more labile active fractions. Regression analyses revealed that both the free Cu2+ ions in the soil solution and the humic acid-complexed Cu fraction in the solid phase were strongly related with soil microbial parameters.

Zied, D. C., Minhoni, M. T. A., Kopytowski-Filho, J., Barbosa, L. and Andrade, M. C. N. 2011. Medicinal mushroom growth as affected by non-axenic casing soil (-N‡eÂS€Ç{˜˜ÿ^—àẽ†‰Wù[oƒ(ũ„vžX•„vq_ÍT). Pedosphere. 21(2): 146--153.
ABSTRACT: Five different soil combinations were collected from two soils at two depths (0.2 and 2.0 m below soil surface) to examine the relationships between the physical properties of non-axenic casing soil and yield, number and weight of the medicinal mushroom Agaricus blazei ss. Heinemann. The results showed that soil clay content and bulk density were negatively correlated with the mushroom yield, respectively, but soil silt content and water-holding capacity were found to be positively correlated with the yield. The number of mushrooms was negatively correlated with soil water-holding capacity but positively correlated with soil clay, bulk density and porosity. The weight of mushroom was positively correlated with the content of soil fine sand and negatively correlated with the contents of soil coarse sand, total sand and clay. Neither soil depth nor different soil combinations affected the yield and number of mushrooms, but the mushroom weight was affected by the soil combinations and soil depth, so interplay in the fructification process with the physical characteristics of casing is complicated.

Zhang, H. M., Yang, X. Y., He, X. H., Xu, M. G., Huang, S. M., Liu, H. and Wang, B. R. 2011. Effect of long-term potassium fertilization on crop yield and potassium efficiency and balance under wheat-maize rotation in China (-N‡eÂS€Ç{˜˜ÿ\¦ž
ÿ‰ss|n\Oû|ß~ N•g½e¾”ù[\Oir§Nϑ0¾” })R(u‡sŒT¾” }s^aˆ„vq_ÍT). Pedosphere. 21(2): 154--163.
ABSTRACT: Sustainable potassium (K) management at different soil sites requires understanding the relationships between crop productivity and long-term K fertilizations on a regional or national scale. We analyzed responses of grain yield of wheat (Triticum aestivum L.) and maize (Zea mays L.), K efficiency, and partial balance (difference between K input through fertilizer and K output in the aboveground biomass) during 15- (1990--2005) or 18-year (1990--2008) K fertilizations at five distinctive agroecological zones across China. Compared to the inorganic nitrogen (N) and phosphorus (P) fertilization, the inorganic NPK fertilization significantly increased grain yields of wheat (21%) and maize (16%--72%) at Qiyang and Changping, where soils have low exchangeable and non-exchangeable K contents, but not at Ürümqi, Yangling and Zhengzhou, where soils have a high exchangeable and non-exchangeable K and/or low N/K ratio in crop plants. Compared to the inorganic NPK fertilization, the inorganic NPK (30% N) and organic manure (70% N) fertilization (NPKM) increased grain yields of wheat (14%--40%) and maize (9%–61%) at four sites, but not at Zhengzhou. For a productivity of wheat at 2--5 t ha-1 or maize at 3--6 t ha-1, 13--26 or 9--17 kg K ha-1 were required to produce 1.0 t wheat or maize. The NP fertilization resulted in the lowest negative partial K balance and accumulated 52 kg K ha-1 year-1 less than the NPK fertilization, which accumulated 28 kg ha-1 year-1 less K than the NPKM fertilization. A re-evaluation of the site-specific fertilization effects on N/K ratio in crop plants and soil K accumulation under current NPK and NPKM fertilization is urgently needed to increase both crop yield and K use efficiency at different agroecological zones across China.

Ge, C. R. and Zhang, Q. C. 2011. Microbial community structure and enzyme activities in a sequence of copper-polluted soils (-N‡eÂS€Ç{˜˜ÿܔalÓgWäX®_uir¤=„ÊSv‘;m'`xvz). Pedosphere. 21(2): 164--169.
ABSTRACT: The microbial community structure and enzyme activities of seven paddy soils with different Cu concentrations were investigated in the vicinity of a Cu smelter in Fuyang County, Zhejiang Province in Southeast China. The microbial community structure was analyzed using the phospholipid fatty acid (PLFA) and multiplex-terminal restriction fragment length polymorphism (M-TRFLP) techniques. There was no clear dose-response relationship between Cu pollution and soil enzyme activity except for urease. Both PLFA and M-TRFLP methods showed that Cu contamination had a large effect on the soil microbial community structure. PLFA indicators of gram-positive bacteria (16:0i, 15:0i) and fungi (18:2w6,9) relatively decreased with increasing Cu concentration, whereas indicators of gram-negative bacteria (19:0cy, 16:1w7) increased. The M-TRFLP results suggested that there was a dose-dependent response between Cu pollution and bacterial community or fungal community. The fungal community was more sensitive to Cu pollution than the bacterial community. There were no significant differences in archaeal community structure between the different Cu pollution plots and archaea might be more tolerant to Cu pollution than both bacteria and fungi.

Motaghian, H. R. and Mohammadi, J. 2011. Spatial estimation of saturated hydraulic conductivity from terrain attributes using regression, kriging, and artificial neural networks (-N‡eÂS€Ç{˜˜ÿúWŽN0Wb_^\'`O(uÞVR_ ÿKQ̑ flagella > N-acyl-homoserine lactones (AHLs) signaling molecules > extracellular protein > swarming motility.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Liang, W. J., Li, Q., Jiang, Y., Chen, W. B. and Wen, D. Z. 2003. Effect of cultivation on spatial distribution of nematode trophic groups in black soil. Pedosphere. 13(2): 97--102
ABSTRACT: Geostatistics combined with geographical information system was applied to assess the spatial distributio
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