Abstract:Spatial data of soil temperature is one of the basic datasets of many large scale researches, such as the International Geosphere-Biosphere Program and DIVERSITAS. Thus, it is really meaningful to derive spatial continuous data of soil temperature from discrete data using the spatial estimation method. Based on the data of mean annual soil and air temperatures in the period from 1971 to 2000 collected from 698 meteorological stations in China and the data of the digital elevation model of China, analysis was conducted of effects of meteorological and topographic factors on mean annual soil temperature. In light of different sources of data, three groups of affecting factors, that is, 1) mean annual air temperature; 2) longitude, latitude and elevation; and 3) mean annual air temperature, longitude, latitude and elevation; were designed as auxiliary variable, and the regression kriging method was adopted to predict the spatial patterns of mean annual soil temperatures across the country. Results showed that mean annual air temperature, longitude, latitude and elevation all displayed significant impacts on spatial variation of mean annual soil temperatures. Validation of the results revealed that prediction with auxiliary variable of group 2 was in the lead in accuracy, and followed by that with Group 3 and then with Group 1. Data accuracy of the auxiliary variables and their relativity with mean annual soil temperature would significantly affect precision of the prediction.

Abstract:Use of fuzzy membership values obtained with the fuzzy –c means clustering (FCM) method was explored to predict soil properties over space. First, environmental factors were fuzzy-clustered. Then, soil samples were collected at modeling points in the fields to determine soil-environment relationship and fuzzy membership of each pixel point to soil type in the study region was calculated. Finally, the weighted average model was applied to fuzzy membership, thus acquiring soil properties. To evaluate effectiveness of this method, it was compared with the multiple linear regression model based on environmental factors in soil property and terrain attributes. Four indices were set up for evaluation of the performance of these two models, i.e. correlation coefficient between predicted and observed values, mean absolute error (MAE), root mean square (RMSE) and agreement coefficient (AC). To validate the method, it was applied to a study area, in the Laolai River Valley, Heshan Farm of Nenjiang County in Heilongjiang Province of China Two soil properties were chosen, i.e. A-horizon organic matter and soil thickness. Results show that the fuzzy membership weighted method produced reasonably better performance than the regression model by using less modeling points, while the linear regression model demonstrated its limitations in the study area. Although R² of the regression equations based on modeling points was high, the equation does not fit other sampling points of the area. It is, therefore, concluded that the weighted average method using fuzzy membership was an efficient way to predict soil properties, and it is more extendable than the regression approach.

Abstract:The knowledge about characteristics and erosion effect of the development of soil crust is very important to exploration of soil erosion mechanism and construction of accurate prediction model for soil erosion Through experiments of events of simulated rainfall, development process of soil crust with or without raindrop impact and dynamic soil erosion effect of crusting in the initial period with or without soil crust on loess was discussed Results show that (1) with rainfall going on, bulk density and shear strength (with moisture content at 20%) of the crust genetic horizon increased steadily; a stable crust, 3～4 mm thick, formed within 30 min; (2) soil crust development process remained more or less the same with or without raindrop impact, except for variation in degree, and the contribution of raindrop impact to crust formation was basically similar to that of soil humidification; (3) shear strength of the soil surface varied sharply between with crust and without crust at the initial period of rainfall, and the difference narrowed rapidly and tended to merge Therefore, the effect of crust development on anti-erodibility was very weak. Variation of cumulative splash erosion was attributed to variation of the starting time of splash erosion; (4) the existence of soil crust on loess significantly decreased infiltration but increased runoff. But the effect of crust disappeared gradually with rainfall going on The function of splash erosion is expressed as C = 0.667 0 ln(t) -3.245 9, which, coupled with the splash erosion model (S_c= S_uc /(1-C)), can be used to accurately predict the cumulative splash erosion within a certain period during the rainfall in loess without crust.

Abstract:A new method is proposed to calculate integrated index of soil erosion (EI) and the mean soil erosion modulus for most serious erosion worked out to be 18 700 t km^-2 a^-1 by using the polynomial equation modeling method, and then the weight for each grade of soil erosion determined. Based on the EIscalculated with the new method, comparison was made between 1986, 1996 and 2002 in soil erosion status of the whole red soil region in South China and of each of the 476 counties (cities) therein. Results show that the EI of the whole region decreased from 3.81 in 1986 to 3.02 in 2002, which suggests that soil erosion was declining in both area and intensity. The results also show that of the 476 counties (cities) in the region, 163 increased, 285 decreased, and 28 remained unchanged in EI in the period from 1996 to 2002. Areas with decreasing EI were mostly distributed in Jiangxi, Fujian and Zhejiang Provinces, while areas with increasing EI in Guangdong and Hunan Provinces. Particularly in Guangdong Province, the area with increasing EI was larger in acreage, suggesting that though it used to be slight in soil erosion, the situation has been getting worse and worse in the recent years.

Abstract:Purple soils different in texture were selected in a study to calculate fractal dimension of soil particle size distribution (PSD) on the basis of accumulative quantity or weight distribution of soil particles. And the fractal dimension of PSD was compared with the fitted fractal dimension of the soil water retention curve (SWRC) model which was developed by Tyler and Wheatcraft. Results indicate that fractal dimensions obtained by three different means were all closely related to soil texture, with the higher content of clay, the finer soil texture and the higher fractal dimension. Although the difference between the fractal dimension of accumulative quantity distribution of soil particles (which ranged from 2.98 to 3.26) and the fractal dimension of accumulative weight distribution of soil particles (which ranged from 2.73 to 2.81) was obvious, a significant linear relationship was observed between them. A significant linear relationship was always observed between the fractal dimension of PSD and the fractal dimension of SWRC (which ranged from 2.72 to 2.84), especially between the fractal dimension of accumulative quantity distribution of soil particles and the fractal dimension of SWRC. They were quite approximate in value. Based on the linear function between the fractal dimension of PSD and the fractal dimension of SWRC, SWRC was predicted through Tyler and Wheatcraft’s model. It was quite obvious that the predicted SWRC agreed well with the measured data. So, estimating soil water retention curve of the purple soil based on the fractal dimension of PSD is feasible.

Abstract:A field experiment that combined iodidestarch staining with conservative ions as water flow tracers were conducted to investigate the heterogeneity of water flow and solute transport. The active region model (ARM) was applied to characterize heterogeneous water flow and solute transport in soilsHeterogeneous flow patterns were visualized from the iodidestarch staining and distributions of Br^-, Cl^-and NO₃ ^-racers. The ARM described the fractal characteristics of the heterogeneous water flow. A relationship between the proportion of active region within the whole region and the effective saturation of soil water was established with a power function, in which the power was related to the fractal dimension. Results indicated that simulations of water flow and solute transport using the ARM matched the measured data better than those using the continuum model. The results also showed that the concentration distributions of the ion tracers were normal or lognormal distributions and the dispersion degree of solute concentrations decreased with soil depth. Based on the analyses, it was concluded that the ARM was useful to characterize the macroscopic features of heterogeneous water flow and solute transport in soils.

Abstract:The dynamics of soil moisture distribution and thawingfreezing process of stipa steppe in central Mongolia during the seasonal transition period (2003~2004) were analyzed with the measurement of temperature and moisture in the soil profile combined with the meteorological data. The results show that there is a completely frozen period about 154~ 160 d in the soil profile of 0~150 cm. The diurnal freeze/thaw cycle mainly takes place at the ground surface of 0~ 5 cm. The soil moisture in 0~30 cm layer changes intensively in the thawingfreezing processes, as well as the soil temperature. In general, the soil water content at 10 cm depth is always higher than those of other depths. The seasonal variation of soil moisture weakened gradually with the increasing soil depth. The frozen soil is favor of keep water, which benefits the regreening of grass in spring.

Abstract:Study was carried out on spatial variability and transfer of heavy metals and their driving factors in cropsoil systems around three different types of factories in southern part of Jiangsu Province. Results show that wastewater irrigation led to Pb and Cd accumulation in soils around F1 (a lead oxide factory) and F2 (a chemical factory), respectively, and concentrations of heavy metals in crops were also increased. Although F3 (a metallurgical plant) did not cause any significant heavy metal accumulation in the soils around, its waste gas emission greatly raised Pb concentration in the crops. Spatially soils and plants high in heavy metal concentration were distributed maily within the radius of about 50 m from the waste water outlet, and decreased exponentially with the distance from the factory. Soil with heavy metal contents higher than the local soil background values were found within the radius of about 400 m (F1) and 100 m (F2). In soil profile, Pb and Cd were accumulated mainly in 0～20 cm soil layer. Affected by wastewater irrigation, there were significant exponential relationship between Pb in rice and Pb in soil and between Cd in rice and Cd in soil, and significant linear relationship between Cd in wheat and Cd in soil When soil available Cd and total Cd in the soil was 0.319 mg kg^-1 and 1.42 mg kg^-1, respectively, Cd concentration in wheat would exceed the criterion of the national food safety standard (0.2 mg kg^-1); and when soil available Cd and total Cd in soil reached 0.360 mg kg^-1 and 1.50 mg kg^-1, respectively, Cd concentration in rice would exceed the criterion. Under the air pollution, no significant relationship was found between the heavy metal in crops and in soil.

Abstract:As the largest fertilizer user, China consumes one third of the total the world does. In despite of its role in increasing agriculture production and ensuring food security, fertilizer utilization contributes to a series of negative global and regional eco-environmental impacts, such as quality degeneration of farm produce, damage to ecological quality and harm to human health. Hereby, the authors estimated the environmental cost of utilization of mineral fertilizers in China, by means of emergy analysis(EMA) and disability adjusted life years(DALY). Results reveal that the environmental cost of fertilizer utilization in China was considerable:(1) the total costs in the year of 2005 reached ￥18.8 billions, accounting for about 1.5% of the increment of the value added of farm in the same year;(2) the annual cost growth rates averaged 7.1% in the period of 1990~2005, and fortunately, the rate is decreasing remarkably in the 21st century; and (3) provinces, more developed in economy, are also regions more intensively under fertilization environmental impact.

Abstract:Change in distribution of C, N, P and K in particlesize fractions of a cultivation chronosequence of paddy soils in subtropical China was investigated by particlesize fractionating with the sedimentation method Results show that contents of organic C, N, P and K in various fractions decreased with increasing particle size, and that their distribution in the fractions varied significantly in percentage. Organic Carbon in fractions of<0.002 mm, 0.002~0.02 mm, 0.02~0.05 mm and >0.05 mm accounted for 29.2%, 30.7%, 11.9% and 15.4%, N for 36.7%, 31.9%, 10.2% and 14.0%, P for 49.2%, 26.5%, 11.1% and 12.4%, and K for 36.9%, 33.4%, 12.9% and 20.0%, respectively of the total in the soil. Generally, a high percentage of organic C, N, P and K was distributed in clay and silt as well. Besides, their distribution in the fractions differed obviously with the cultivation history of paddy soils. In paddy fields less than 10 years in rice cultivation, the contents of soil organic C, N, P and K were relatively lower and mainly distributed in Fraction<0.002 mm, whereas in paddy fields more than 10 years in rice cultivation, the distribution of organic C and nutrients in silt (0.002～0.05 mm) exceeded 50%. Silt (0.02～0.05 mm) was also the highest in C/N ratio regardless of cultivation history, but it did decrease with rice cultivation going on, which suggests that the observed changes indicate improvement of soil fertility and soil nutrient availability.

Abstract:Profiles of paddy soils were sampled in Longjing of Jilin Province, Fengqiu of Henan Province, Cixi of Zhejiang Province and Jinxian of Jiangxi Province, which are in different climatic zones. Distribution of organic carbon (OC) andδ¹³C in profiles and organomineral complex of the paddy soils was studied, and structure and functional group composition of humic acid (HA) in different paddy soils was explored with the aid of infrared spectrum (IR). Its aim was to provide some scientific data for reference for the study on organic carbon dynamics and its mechanism. With increasing soil depth in profiles of paddy soils, δ¹³Cof OC increased gradually, and with increasing latitude of the locations of the profiles, δ¹³C of OC increased gradually, too, in the topsoil of the paddy soils. Topsoil OC of paddy soils was mostly concentrated in organomineral complex in the size fraction<10 μm, and their OC abundance was over 50%. With decreasing particlesize, δ¹³C of topsoil complex increased continually, and old OC high in ¹³C natural abundance accumulated in fine particles. In terms of degradation degree of OC in soil complex<10 μm, the four profiles were in a decreasing order of Fengqiu > Cixi > Jinxian > Longjing. Structure of the HA differed slightly between paddy soils. Compared to paddy soils sampled in Cixi and Jinxian, paddy soils sampled in Fengqiu and Longjing contained HA high in C=O groups, and in oxidation, aromatization and polymerization degrees.

Abstract:For better understanding the mechanism regulating availability of phosphorus (P) in red earth, a study was carried out to investigate P fractions (Olsen-P; absorbed inorganic-P fractionated in Fe-P, Al-P, Ca-P, and O-P, and organic-P fractionated in labile, moderately labile, moderately stable and highly stable organic-P) in aggregates (>2 mm, 2～0.2 mm, 0.2～0.02 mm, 0.02～0.002 mm,＜0.002 mm) of upland and paddy red earths. Results indicate that in the upland soil about 72% of the aggregates were>0.2 mm, while in the paddy soil 67.5% were. In the two soils, inorganic P in aggregates>0.2 mm was dominated by Fe-P, but in aggregates<0.02 mm by O-P, while organic P in aggregates>0.2 mm and<0.002 mm in the paddy soil was much higher than that in the upland soil. In conclusion, the distribution of P in the soils of red earth was closely associated to particle size fractions of their aggregates, and the lower availability of P in the upland soil (P 3.9 mg g^-1, Olsen-P) as compared to the paddy soil (P 7.9 mg g^-1, Olsen-P) was presumably attributed to higher free-Fe and lower organic-P in its aggregates.

Abstract:An indoor simulation experiment was carried out to study effects of monochlorobenzene on activities of three major hydrolyzable soil enzymes (urease, invertase and phosphatase). Results showed that the three enzymes had ativities within the range of 20.81～162.00μgg^-1h^-1, 64.60～582.10μgg^-1h^-1 and 5.80～89.75μgg^-1h^-1 separately when the monochlorobenzene was in the designed concentration from 5.53 gkg^-1 to 110.58gkg^-1, which stimulate soil urease activity, while inhibit soil invertase and phosphatase activities by 1.11%～118%, 0.74%～25.43% and 2.02%～35.63%, respectively. It indicated that the three soil enzymes could be used to a certain extent as indicators of soil pollution by monochlorobenzene. The reaction style of soil phosphatase with monochlorobenzene obtained from regression equation of U =B/ ( 1 +A x ) was full inhibition. The monochlorobenzene concentrations that may characterize slight pollution of Lou soil and red soil were 33.9 g kg^-1 and 16.7 g kg^-1.

Abstract:To study impact of climate and fertilization on soil microbial community, a transplant experiment of black soil (Phaeozem) was conducted at Hailun, Fengqiu and Yingtan Experiment Stations located separately in the temperate, warm temperate and midsubtropical zone in East China. Soil microbial communities were measured by Biolog ECOPlate^TM. In different climate conditions, balance application of N, P and K increased soil microbial metabolic activity （expressed as AWCD, average well color development）in black soilsIn the teaseling stage of maize, AWCD of black soil followed a sequence of Yingtan station>Hailun station>Fengqiu station with fertilization (NPK), and in a sequence of: Yingtan station>Fengqiu station>Hailun station without fertilization (CK). The soil bacterial metabolic activity increased with the monthly mean temperature without fertilization, while the interaction of rainfall and fertilization increased soil bacterial metabolic activity and affected the impact of temperature. Principal component analysis of soil microbial communities showed that the metabolic fingerprint of soil microbial communities varied slightly between black soils in Hailun station and Fengqiu station, but significantly from that in Yingtan station under midsubtropical monsoon climate. The effect of climate on variation of the carbon source of soil microbial communities was displayed in αKetobutyric Acid, Putrescine, D,L-α-Glycerol and L-Threonine (R＞0.9), while the effect of fertilization was in β-Methyl-D-Glucoside, Glucose-1- Phosphate and Pyruvic Acid Methyl Ester. To sum up, variation of the hydrothermal conditions in different climate zones and fertilization affects integrally metabolic activity and metabolic fingerprint of microbial communities in black soil.

Abstract:Soil samples were collected from various treatments of a longterm fertilization experiment in Mollisol, and analyzed for variation of basic soil properties, phospholipids fatty acids (PLFAs), neutral lipid fatty acids (NLFAs), acidic (alkaline) phosphatase activities and soil microbial biomass C or N (SMB-C or N). Results show that 26 years of combined application of organic manure and chemical fertilizers significantly increased the contents of OM, TN, and readily available N, P and K, as well as the values of SMB-C or N, and SMB-C/OM ratio, and improved phosphatase activity and PLFA content of various microbial communities. The activity of soil microbe in Treatment N was obviously lower than in CK, whereas Treatment P was the lowest in effect on activity and community structure of soil microbes. Variation of the relative NLFA content in various soil bacteria was just contrary to that of living microbial biomarkers, suggesting that in Treatments MN, MP and MNP, rich in nutrient content, hypopodes of various bacterial communities or accumulation of storage substances was limited. PCA of PLFA, NLFA and NLFA/PLFA revealed that the community structure of soil microbe varied sharply between organic manure treatments and chemical fertilizer treatments Analysis of the loading values of some individual PLFAs or NLFAs showed that fungal C18∶2ω6,9 was significantly affected by manure application, while G+ iC15∶0, iC17∶0, iC16∶0 were apt to be affected by chemical fertilizer application. PCA also demonstrated that NLFA/PLFA ratio is more applicable than PLFA or NLFA in distinguishing treatments different in fertilization.

Abstract:Bacteria, when high in cell density, will produce chemical signal molecules, called atuoinducers (AI), to regulate gene expression. Autoinducers of high activity in the spent culture supernatant of Mesorhizobium tianshanense CCBAU060A were detected with the aid of AI bioassay strain JZA1. One autoinducerdeficient mutant was obtained by screening Mesorhizobium tianshanense CCBAU060A mutated with mariner transposon Analysis of the flanking region of transposon insertion found a LuxItype synthase gene, mrtI2, which wascloned into the broad host range expression vectors pYC12, and transformed into Escherichia coliDH5α . The putative AHL synthase gene was overexpressed in Escherichia coli, and four different autoinducers could be detected in the supernatant of the positive recombinant.

Abstract:Influence of compound pollution of Rac-metolachlor or S-metolachlor with Cd on soil catalase and dehydrogenase activity was studied in laboratory. Rac-metolachlor and S-metolachlor were added separately to the tested soil at a dosage (6.8 mg kg^-1) recommended for crop field and at a dosage (68 mg kg^-1) ten times of the recommended one; Cd was designed to have three different concentrations (0, 50, 100 mg kg^-1). Catalase and dehydrogenase activities were tested under single stress of Rac-metolachlor or S-metolachlor and its combination with Cd. Difference between Rac-metolachlor and S-metolachlor in enantioselectivity towards catalase and dehydrogenase activities was also investigated. Results indicate that stress of Rac-metolachlor or S-metolachlor was imposed, catalase activity was first enhanced and then inhibited; while dehydrogenase activity followed a similar trend, but eventually rose up again Rac-metolachlor and S-metolachlor showed different enantioselectivity toward catalase activity, while no significant difference was found in enantioselectivity toward dehydrogenase activity. Under the combined pollution of Rac-metolachlor or S-metolachlor with Cd, catalase and dehydrogenase activities showed the same trend as under the single metolachlor pollution. With the same level of metolachlor, catalase and dehydrogenase activities were greatly influenced by increase in concentration of Cd， showing that compound pollution of metolachlor and Cd had certain interaction effect on catalase and dehydrogenase activities.

Abstract:Since organoarsenicals, copper and zinc additives are widely used in modern intensive animal production, animal manures are commonly high in As, Cu and Zn content. A pot experiment with amaranth was conducted to investigate As, Cu and Zn bioavailability in a paddy soil (PS) and a lateritic red soil (LRS) applied with 2% and 4% (w/w) chicken manure (CM) and pig manure (PM), respectively. Soils without any fertilizer were included as the checks (CK). Results show that application of the two manures increased biomass of the shoots of amaranth, but decreased its As, Cu and Zn content. Variation of the contents of As, Cu and Zn and uptake rates of three elements in amaranth among treatments with manures didn’t show any distinct rule two soils. However, though the initial contents of total and available As, Cu and Zn were much lower in LRS than in PD, As, Cu and Zn contents and As, Zn uptake rates of amaranth were significantly higher in LRS than in PD at the level of 0.01, with the exception that significant difference wasn’t observed in Cu uptake rates between two soils. Soil total and available As in all treatments reduced after the harvest of amaranth, but soil total and available Cu and Zn increased in treatments applied with higher rates of two manures as compared to their initial values. And, soil total and available As, Cu and Zn and percent available As, Cu and Zn over total As, Cu and Zn increased by the application of manures compared to CK. It was assumed that the bioavailability of heavy metals be measured by the increments of available content and percent available content over total content, availability of soil As was enhanced by CM than by PM, but that of soil Cu and Zn was increased by PM than by CM. The availability of soil As, Cu and Zn was higher in treatments with higher manure rates than those with lower ones, and higher in LRS than in PS.

Abstract:Soil is a complicated historical natural continuum, which gradually changes in both attributive and geographic spaces. Hence, the theoretical basis of the conventional soil survey and cartography, based on the “double crisp model” is obviously inadequate. With the rapid development of precision agriculture and the improvement of the accuracy of the environmental model, the demand for contents and accuracy of the output of soil surveys is objectively getting higher and higher. The application of fuzzy logic to soil classification and cartography is another innovative approach in pedometrology after the introduction of geo-statistics in soil classification and mapping. Though researches in this field have been reported in a number of countries, little has been done in China. In this paper, a systematic introduction is presented to the inevitability and scientific significance of the application of fuzzy logic to the study on soil continuous classification, and the advancement in the study on application of fuzzy logic to soil continuous classification and cartography at home and abroad And, shortcomings of the fuzzy-logic-based continuous soil cartography and outlook of its research are analyzed.

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