Abstract:Based on a long-term (13 a) experiment on effect of hedgerows controlling soil and water loss, composition and fractal features of soil micro-aggregates in slope farmlands with established hedgerows were studied with mathematical statistics. Results show that compared to the pattern of traditional contour cropping, the pattern of contour cropping plus hedgerows obviously increased the content of soil micro-aggregates, <0. 2mm in particle size, especially the fraction of 0.2-0.05mm. Hedgerows significantly increased soil micro-aggregate fractal dimension (D) and aggregation degree, reduced relative enrichment of soil micro-aggregates small in particle size at lower slopes, and optimized slope distribution of soil large- and small-sized micro-aggregates. The soil micro-aggregate D values reflect soil physical properties, soil fertility, and erosion-resistance of slopelands under the pattern of contour cropping plus hedgerow in the purple hill region.

Abstract:Based on meteorological data and the Geographic Information System (GIS) database of the Nanjing area during the period from 2001 to 2010, and by means of soil sampling and analyzing, non-point source pollution and soil erosion in various districts of the Nanjing area in the past 10 years were quantitatively analyzed with models for overall monitoring of erosion and non-point source pollution from soil erosion and nutrient loss. Results show the following, (1) the data of total nitrogen, total phosphorus, ammonium nitrogen and available phosphorus of the various types of soils in the area better reflected soil nutrient and fertilization status of the area. In recent years, soil total nitrogen and available phosphorus increased significantly and total phosphorus decrease significantly in most parts of the area; (2) The non-point source pollution and soil erosion were characterized by annual and inter-annual variations; which show that soil erosion and pollution occurred mostly from Apr. to Aug. and was the most serious in 2003 and the least in 2001; (3) Significant spatial variation of the 10-year averages of non-point source pollution and soil erosion existed among different districts; Jiangning was the most seriously polluted area and was followed by Luhe; (4) For the past 10 years, the effect of the efforts of Nanjing to control non-point source pollution and soil erosion was significant. Increasing vegetation coverage and enforcing soil erosion control measures are effective in controlling non-point source pollution and soil erosion.

Abstract:As a potential pollution source, contaminated sites are located mostly in densely populated areas like cities, posing high environmental risks to the public and, what is more, tend to increase in number and area in recent years with the on-going industrial restructuring in cities of the country, thus arousing more and more concerns from the nation. Nowadays, in China and other countries of the world, a huge variety of technologies or techniques are available for remedying polluted sites technologies, so it’s of great significance to scientifically screen out technologies, technically applicable, economically feasible and environmentally friendly. Based on analysis of currently available approaches to screening the technologies for remedying polluted sites, and methods and tools to solve the multi-parameter problem in decision-making, an AHP-and-TOPSIS based remediation decision making process was worked and put forth and an index system established for the screening. Weights of the indices for the screening were worked out through investigation by experts in this field using AHP, and then the remediation technologies were collated with TOPSIS. This remediation decision making process was verified with the actual screening for a case of polluted site in China. AHP and TOPSIS were used in combination to solve the complicated multi-factor problem in decision making, thus not only overcoming the issue of subjectiveness of AHP in handling hard-to-quantify indices, but also avoiding the shortcoming of TOPSIS neglecting index weights. It is, therefore, a good tool for landowners and environmental researchers to screen remediation techniques for polluted sites.

Abstract:Natural evolution-based management mode, forestry-based management mode and agriculture-based management mode are three classical modes of management applied extensively to reclamation of coastal salt-affected land. To reveal effects of the three typical modes of management on soil quality, soil samples were taken from fields under the three modes of management, separately for analysis of laws of the dynamic variation of soil quality of the lands, using the soil single quality index (SSQI) method and the soil comprehensive quality index (SCQI) method. Results show that based on SSQI, the soil in the study zone on the whole could be sorted into the categories of excellent and good in soil bulk density, total porosity, aeration porosity, and salt content, into the category of moderate in soil pH, total phosphorus, available phosphorus, and available potassium, and into the categories of moderate and poor in soil texture, organic matter, total nitrogen, and micro biomass, indicating that the agriculture- and forestry-based managements could effectively improve the soil indices, such as salt content, organic matter, TN, TP, available P and available K. But based on SCQI, the mean value was 1.2±0.1, implying that the soil was ordinary in quality and unfavorable for plant growth. The mean SCQI value of the agriculture-based management, forestry-based management and natural evolution-based management was 1.24±0.11, 1.2±0.1 and 1.14±0.09, respectively, which indicates that differences exist between the three modes in soil quality. Though the differences were rather stable, they did not reach up to the significant level statistically. Artificial interferences, such as forestry- and agriculture-based managements, are the main factor inducing temporal and spatial variation of the soil quality within a short period of time, thus accelerating the evolution process of the coastal salt-affected land in soil quality.

Abstract:Micronutrient deficiency is commonly demonstrated in farmlands of fluvo-aquic soil, a typical soil type in the Huang-Huai-Hai Plain of China. The objectives of this study were to explore effects of different long-term fertilization practices on balance of micronutrients in the soil, and changes of soil micronutrients in fraction using the BCR sequential extraction method. A field experiment, designed to have 7 treatments, i.e. OM (Organic Manure), 1/2OM+1/2 ( Fertilizer)NPK, NPK, NP, PK, NK, and CK (No Fertilizer), was laid out and started in 1989. After more than 20 years of fertilization, various extents of accumulation of micronutrients were observed in the surface layer soil (0～20cm), and found to be greatly affected by their transfer between different soil layers. Results of sequential extraction show that the contents of soil available (DTPA-micronutrient) Fe, Cu and Zn were higher, while the content of soil available Mn was relatively lower than the critical levels in the other alkalic soils. The Residue-Fractions of soil Fe (>90%), Cu (>65%) and Zn (>70%) accounted for a high proportion of their respective total. Interestingly, DTPA, acid soluble and oxidizable fractions of soil micronutrients accumulated more with the increasing soil organic matter level, which was probably the driving factor for the changes of soil micronutrients in fraction. Long term application of K fertilizers also increased DTPA and acid soluble fractions of soil micronutrients, but decreased the total of Fe and Mn in the surface soil layer, while long-term application of P fertilizers decreased the contents of DTPA and acid soluble fractions of soil micronutrients through precipitation, but increased the totals of Cu and Zn.

Abstract:Cyanogen (C₂N₂) is a new type of fumigant, a potential replacement of methyl bromide. However, there is still no standard method available at home and abroad for detecting C₂N₂ and its degradation product, HCN (hydrogen cyanide) in soil. A method for the determination of residues of C₂N₂ fumigant and HCN in soil using head-space capillary gas chromatography (HS-GC) with a nitrogen-phosphorus detector (NPD) was developed; and headspace parameters for pretreatment of C₂N₂ and HCN in the soil was optimized in this study; and quality control parameters such as precision of standard, limit of detection and limit of quantification for the method were validated in experiments. Results showed that incubated in solution of 30% phosphoric acid at 50℃ for 1 h, the sample with C₂N₂ and HCN concentration in the range of 0.1~10 mg kg^-1 displayed a linear relationship with correlation coefficients >0.99 between C₂N₂ and HCN concentration and chromatographic peak area. The use of this method to determine C₂N₂ and HCN in soil is subject to a RSD of 4.58% and 6.32% (n=5) , respectively．Of the method, the limit of detection (LOD) and the limit of quantification (LOQ) of C₂N₂ and HCN was 0.016 and 0.028 mg kg^-1 ( S/N=3), 0.053 and 0.093 mg kg^-1 ( S/N =10), respectively. This method was also proved to be convenient in operation, high in sensitivity and least in outside interference, and therefore, applicable to determination of C₂N₂ and HCN residues in soil.

Abstract:Using the 15-nitrogen (¹⁵N) tracing method, potential of dissimilatory nitrate reduction to ammonium (DNRA) in Typic Hapli-Stagnic Anthrosols andEndogleyic Hapli-Stagnic Anthrosols soils of the Taihu Lake region as affected by tail water from pig rearing was studied. DNRA rates and relative potentials varied in the range of N 0.68 ~ 0.79 mg kg^-1 dry soil d^-1 and 34.61% ~ 44.45%, respectively, in Typic Hapli-Stagnic Anthrosols soli, and in the range of N 1.14 ~ 1.41 mg kg^-1 dry soil d^-1 and 54.24% ~ 106.70%, respectively in Endogleyic Hapli-Stagnic Anthrosols soil. Irrigation with tail water from pig rearing had little effect on DNRA rates in both soils and DNRA relative potential inTypic Hapli-Stagnic Anthrosolssoil, while it obviously reduced DNRA relative potential in Endogleyic Hapli-Stagnic Anthrosols soil. Correlation analysis indicates that soil DNRA relative potential was significantly positively correlated with the ratio of soil dissolved organic carbon to nitrate nitrogen (DOC / NO₃^-1 -N) at the start (r = 0.836，p< 0.05，n = 6) and the end (r = 0.936，p < 0.01，n = 6) of the incubation, but not significantly correlated with soil Eh or DOC at the start and the end of the incubation. The results indicate that Endogleyic Hapli-Stagnic Anthrosols soil is of much higher DRNA potential, therefore, in practice, it might be possible to enhance N retention through regulation of DNRA and hence to minimize N loss from paddy fields; and irrigation of the soils with tail water affects the contribution of DNRA to dissimilatory NO₃^-1 reduction mainly by changing soil DOC / NO₃^-1 -N and its effect varies with the soil types.

Abstract:After the completion of the Three Gorges Reservoir project, a 30-m height tidal zone is formed around the reservoir. Changes in P adsorption and fixation by the soils in the zone and in fate of the phosphorus directly affect the surrounding water environment. Through batch processing and indoor incubation of samples of the yellow soil and purple soil in the tidal zone, changes in form of the iron and adsorption and transformation of P in the soils were studied. Results show that flooding significantly decreased the content of crystalline iron oxides, while increasing the content of noncrystalline iron in both soils; Under flooding the content of Olsen-P in the soils displayed a declining trend, whereas the contents of Fe-P and Al-P turned upwards; Indoor simulation demonstrates that in the two yellow and purple soils under flooding for 15 days, P adsorption capacity increased by 70.8% and 9.5%, respectively; Incubated in 0.1 mol L^-1 CaCl₂, KCl and NH₄Cl solutions at pH 5 and pH 9, separately, for 15 days, the yellow soil increased its contents of Olsen-P, Fe-P and Al-P significantly, indicating that in the soils of the tidal zone, application of K, Ca or urea might increase the content of soil available P, which could eventually lead to increase in CaCl₂ extractable P, thus affecting the phosphorus content in the water body and water quality of the reservoir.

Abstract:Forms of P and P sorption parameters in soils under different crop rotation systems in a 26a long-term fertilization field experiment in an arid loess plateau were determined for study of effects of crop rotation and fertilization on forms and adsorption of the phosphorus in the soil and relationships between soil phosphorus adsorption parameters and phosphorus forms. Results show that both long-term crop rotation and long-term fertilization reduced the maximum P adsorption capacity(Qm) of the soil; relative to other crop rotation and continuous cropping systems, the application of nitrogen and phosphorus fertilizer (NP) reduced Qm of the soil under the Wheat-Corn-Pea crop rotation system, and the application of NP plus organic manure (NPM) had a similar effect on Qm of the soil under the Wheat-Corn crop rotation system. The same in fertilization, the Wheat-Corn rotation and Wheat-Pea rotation systems significantly increased the contents of various forms of inorganic phosphorus, and the soils were higher in available P under long-term crop rotation than under continuous cropping, especially in Ca₂-P. Correlation analysis shows that Qm and phosphorus sorption index (PSI) were significantly negatively related to total phosphorus (T-P), Olsen-P, CaCl₂-P, Ca₂-P, Ca₈-P, Fe-P, Ca₁₀-P and organic phosphorus(p<0.01), and to occluded phosphorus(O-P, p<0.05), too, but insignificantly to Al-P. Soil organic matter(SOM) was found to be in extremely significant negative relations to Qm, PSI and maximum buffer capacity(MBC), but in positive one related to the degree of P sorption saturation(DPSS). Path analysis and stepwise regression analysis show that among the inorganic phosphorus fractions in calcareous Heilu soil, Ca₂-P contributed the most to Olsen-P.

Abstract:Effects of low molecular weight organic acids (LMWOA) on K⁺ adsorption kinetic characteristics of Red Soil and Yellow-cinnamon Soil were studied with the continuous flowing method to explore an optimal model for describing K⁺ adsorption kinetics. Results show that the red soils in all the LMWOA treatments, except in the treatment of 0.1 mmol L^-1 oxalic acid, adsorbed less K⁺ than it did in CK (soil without addition of LMWOA), and the yellow-cinnamon soils varied in K⁺ absorption significantly with K⁺ concentration. When K⁺concentration was 0.1 mmol L^-1, the yellow-cinnamon soils adsorbed less K⁺ than it did in CK, but when K⁺ concentration was raised up to 1.0 mmol L^-1, they adsorbed more than it did in CK. The K⁺ adsorption capacities of the two soils varied with the type of organic acid, showing an order of oxalic > citric > malic. The reaction velocity of K⁺ adsorption in the two soils was found to be in a good linear relationship with the natural logarithm of time “lnt” (r_0.05=0.754, r_0.01=0.874). The treatment of 1.0 mmol L^-1 K⁺ was higher in initial adsorption rate, but dropped faster in reaction velocity. In fitting the data of K⁺ adsorption in the red soil and yellow-cinnamon, the two-constant, exponential and Elovich equations were all quite effective, reaching the level of extreme significance, but the first order equation was not so good. The correlation coefficient of the two-constant equation was higher than that of the exponential equation and the Elovich equation, which rendered two-constant equation the best-suited model to describe K⁺ adsorption kinetics in the soils treated with organic acids. Under the effect of organic acids, K⁺ adsorption in the two soils was mainly influenced by soil charge.

Abstract:A pot experiment and an incubation experiment were conducted to investigate effects of soil moisture content [percentage of water holding capacity (WHC)] on the fresh biomass of and Cd concentration in lettuce ( Lactuca sativa ), soil pH and Cd availability in soil. Results show that soil moisture affected significantly biomass of the plant. In Treatment 75%WHC, The plant was the highest in fresh biomass, and an inverse “V” shaped curve of relationship was observed between fresh biomass and soil moisture. Soil moisture also affected markedly Cd concentration in shoots and roots of lettuce, and what’s more, a significantly negative relationship was found between the former and the latter. When soil moisture was increased from 45%WHC to 65%WHC, Cd concentration in the shoots decreased by 41%, which means that the Cd concentration in the vegetable is lowered from the grade of higher-than-the-hazard-free- standard down to the grade of lower-than-the hazard-free-standard. Cd concentration was significantly higher in roots than in shoots in all the treatments except Treatments 55%WHC and 75%WHC through T test. It was also found in the pot experiment that concentration of NH₄OAc extractable Cd in the soil was insignificantly related with soil moisture and with Cd concentration in shoots of the plant, too. Besides, soil moisture did not have much effect on soil pH, either. But in the incubation experiment, concentration of NH₄OAc extractable Cd in soil was markedly correlated with soil moisture, showing a negative relationship. It is preliminarily assumed that the effect of soil moisture on Cd concentration in shoots is not rendered through its effect on pH and NH₄OAc extractable Cd concentration of the soil. Anyway, it is feasible to control Cd concentration in the edible part of leafy vegetables growing in greenhouses with soils slightly polluted with heavy metals by regulating soil moisture content, which is a green environment-friendly measure that enjoys broad prospect of application.

Abstract:With the aid of the Free-Air ozone Concentration Enrichment (O₃-FACE) system, effects of elevated atmospheric ozone (pO₃) on topsoil (0~20 cm) aggregate, bulk density, porosity and contents of nitrogen, phosphorus and potassium of paddy soil were investigated. The paddy field had been under rice/wheat rotation and exposed to elevated atmospheric ozone, 50% higher than the ambient pO₃, for three years. Results show that elevated pO₃ significantly increased 0.25~0.053 mm aggregates by 23.5% and significantly decreased < 0.053 mm slit +clay fraction by 24.6% in topsoil; obviously increased soil bulk density in the 0~10 cm soil layer and decreased the density in the 10~20 cm soil layer; decreased gas porosity by 39.8% and 32.4% in the 0~10 cm and 10~20 cm soil layers respectively, and increased capillary porosity by 9.1% in the 10~20 cm soil layer, thus altering the soil in proportion of solid, liquid and gas; reduced soil total nitrogen content by 10.5% and available potassium by 13.3%, increased available phosphorus by 40.8%, and however, did not affect much available nitrogen. It is quite obvious that long-term exposure to elevated atmospheric pO₃ will alter physical structure of the soil and biogeochemical cycle of nutrient substances therein.

Abstract:To study effect of long-term intensive management of Phyllostachys praecox stands on C and nutrients pools in the soil, soil samples were collected from two adjoint Phyllostachys praecox stands that had been subjected to intensive management for 1 and 15 years, separately, in Lin’an County, Zhejiang Province. Different forms of C, N, and P pools were determined and spectral characteristics of soil total organic carbon were analyzed using the nuclear magnetic resonance (NMR) technique. Results show that in comparison to the Phyllostachys praecox stand, 1 year under intensive management, the stand 15 years under intensive management was 248.5%, 197%, 81.8%, and 116% higher in soil total organic carbon, water-soluble organic C, hot water-soluble organic C, and readily oxidizable C (ROC), respectively, but 17.6% lower in MBC content. Solid-state NMR spectroscopy of soil samples showed that alkyl C and O-alkyl C dominated soil organic C in Phyllostachys praecox stands. Compared to the Phyllostachys praecox stand 1 year under intensive management, the stand 15 years under intensive management was significantly higher in soil alkyl C content and alkyl C to O-alkyl C ratio (A/O-A) (p < 0.05), but much lower in aromatic C content and organic matter aromaticity (p < 0.05), and however remained unchanged in O-alkyl C and carbonyl C. Moreover, in comparison to the Phyllostachys praecox stand 1 year under intensive management, the stand 15 years under intensive management was much higher in soil water-soluble organic N, NH₄⁺-N, NO₃^-1-N, available P, and organic P (p < 0.05), but 36.5% and 22.7% lower in microbial biomass N and microbial biomass P, respectively. In conclusion, long-term intensive management helps build up carbon pools and nutrients pools, but significantly affects activity of the soil microbial activity and stability of the organic carbon in the soil.

Abstract:In order to understand distribution characteristics of soil nitrogen and phosphorus in the Dianchi watershed at the watershed scale, soil pH, total nitrogen (TN), total phosphorus (TP), and soil organic matter were analyzed of 130 surface soil samples collected from lands different in land-use type in the Dianchi Basin. Results show that the soils in the major farming regions including Dounan, Majingpu and Jincheng in the basin east to Lake Dianchi and some of Xishan, were higher in total N, and those in Songhuaba in the north, Baoxiang River area in the northeast, and the mountains in the south of the watershed were lower. The highest and the lowest TN content was found in Dounan (2.21 g kg^-1) and Baoxiang River area (1.32 g kg^-1), respectively. And the soils in Shangsuan in the south and Majingpu, Dounan and Jincheng in the east of the watershed were the highest in total P, and followed by those in Xishan are Dongda River area, and those in Songhuaba in the north and Baoxiang River area in the northeast the lowest. The highest and lowest content of TP was found in Shangsuan (2.21 g kg^-1) and Baoxiang River area (0.80 g kg^-1), respectively. The findings suggest that in the greenhouse farming dominated regions, lakeside plains and flat tablelands, the application of large volumes of chemical fertilizers has led to high accumulation of N and P in the soil, thus making these areas highly potential non-point source agricultural pollution sources. It is, therefore, necessary to intensify control and management of non-point source pollution in those areas.

Abstract:Broad-leaved forest, Chinese fir forest, Mason pine forest and Bamboo grove are widely distributed in subtropical areas of South China. To investigate more information of soil bacterial community structures of natural forests, PCR-DGGE technology was applied to study structures of the soil bacterial communities in these four types of natural forests distributed in from the Tianmu Mountains and Linglong Mountains. Results show that the number of DGGE strips detected in the four kinds of forest soils in the Tianmu Mountains was 49, 45, 51 and 51, and in the Linglong Mountains, it was 42, 42, 44 and 48, respectively. DGGE analysis reveals little variation between the soils in fingerprint. The four soils in the Tianmu Mountains had 31 DGGE strips in common, while the soils in the Linglong Mountains had 23, accounting for 61% and 48% or more, respectively, of the total strips detected, and what is more, each type of forest had its own characteristic strips；Relatively speaking, the two sample lots of Chinese fir forest were both quite low in similarity to the other sample lots of other forest stands in soil bacterial structure, being 0.72 and 0.68 respectively in value, and diversity indices of their soil bacterial communities were obviously lower than the others’. However, Bamboo groves and Mason pine forests were not much different in soil bacteria diversity. DGGE analysis of soil bacteria from two sampling sites revealed that the effect of soil properties was greater than that of vegetation on soil bacterial community structure.

Abstract:Strains of biuret-degrading bacteria GW-1 were successfully isolated and labeled with green fluorescent protein with the triparental mating method and then the GFP-tagged strains were named GW-1-GFP. The expression of GFP in Strain GW-1-GFP was visualized under the fluorescent microscope and its dynamics was analyzed and stability tested. It was found that heterogenous plasmid did not bring any adverse effect to growth of the host strain GW-1-GFP and the strain was stable. HPLC analysis did not show any significant difference (p<0.05) between the origin stain GW-1 and the tagged strain GW-1-GFP in biuret-degrading ability. The tagged strain GW-1-GFP, proved by the antibiotics resistance screening and fluorescence tracing, could colonize well in the soil and was found to have degraded 50% of the biuret in soil in all the treatments on D25 after the application of Strain GW-1-GFP. It was also found in the experiment that the tagged strain was safe to the environment and vanished from the soil after 45 days. Good colonization of Strain GW-1-GFP in the rhizosphere of wheat seedlings which emerged from wheat seed inoculated with Strain GW-1-GFP was observed and the tagged strain could alleviate the toxic effects of biuret on wheat to a certain extent. The study provides a simple, intuitive method to trace functional microbial agents and corroborate their ecological effectiveness and affinity with crop roots in the soil.

Abstract:Soil samples were collected from three different types of underground root habitat typical of Karst area (Type I-dolomite of low oblique occurrence with multilayer space, Type II-dolomite of middle oblique occurrence with multilayer space and Type III-dolomite of high oblique occurrence with multilayer space types), for analysis of enzyme activity in the soils as affected by type of underground root habitat and level of soil layer, and correlation between soil enzyme and soil nutrients content. Results show that: 1) soil enzyme activity varied sharply between different habitat types and between different spatial soil layers(p<0.01). 2) Type I is conductive to cycling of soil carbon, Type II to transformation of N-containing compounds and Type III to oxidation of soil organic matter, and moreover, soil enzyme activity in all the three types decreased with soil depth. 3) soil enzyme activity was significantly related to soil nutrients content. So their correlation coefficient can be used as an indicator for evaluation of soil quality/fertility. Obviously, the finding of differences between the types of root underground habitat in soil enzyme activity may be very useful to evaluation of soil quality, study on technology for vegetation restoration and ecological remediation and management in the Karst rocky desertification region.

Abstract:Arable land is one of the most important resources for agriculture. Quality of the arable land is an important basis for food security of the nation, and quality safety of agricultural produce. Based on the literature available, the status quo of the study on conception of and evaluation methods for arable land quality was generalized and summarized. It is held that arable land quality is a multi-level conception, containing four levels of connotations, i.e. soil quality, geographic quality, management quality and economic quality, and its evaluation indices include natural and socio-economic factors. On such a basis, changes in the arable land quality of China was analyzed. It was found that on the whole the arable land quality of the country is quite low. However, its fertility quality，management quality and economic quality are gradually turning good while its health quality and environmental quality are getting worse and the problems of arable land quality in some areas are very serious. In light of the situation of the country, proposals are brought forward for construction and management of the arable land quality in China.

Abstract:Metaproteomics is a recently popped up new technology that based on proteomics is used in the study on microbial communities. It is defined as an instant broad-scaled analysis of all kinds of microbial proteins in a given environment. Though the study of metaproteomics is still at its primary stage, the technology has displayed its powerful function in the study of microorganisms in a given biotope. This paper is to compare the strategies and techniques commonly used in the study of metaproteomics, summarize the status quo of the research on extraction, purification, isolation and functional identification of soil metaproteome, and look into future significance of the study of soil metaproteomics. The development of soil metaproteomics is influenced strongly by extraction methods, while the methods currently available can hardly supply proteins that can be successfully isolated and easily identified as well. What is more, the major problems in identifying proteins reside in the fact that soil is a poor source of proteins and that there is not enough sequence-database information for identification of proteins with mass spectrometry. Once these obstacles are solved, the soil metaproteomics can find broader and deeper application in the study on ecological functions of soil microbe.

Abstract:Artificial shelterbelt is an important and effective measure for checking winds and fixing drifting sands and hence for controlling desertification. To build up windbreak forest belts in desert areas can effectively control soil erosion and promote accumulation of organic matter and clay in the soil and formation of crust at soil surface, thus fixing drifting sands and accelerating formation of aeolian sandy soil. Based on the theory of plant-soil interaction theory, an overview is presented of the effects of artificial shelterbelt on formation of aeolian sandy soil, from the aspects of the function of the aboveground parts of plants intercepting and accumulating nutrients and reducing surface soil evaporation, and the function of the underground parts of plants fixing drifting sands, decomposing organic matter and supplying nutrients. It was found from the researches in the past that during the soil forming process of aeolian sandy soil, the soil became finer in mechanical composition, lighter in bulk density, higher in soil porosity; more apparent in differentiation of soil profile structure, more in soil layer; more significant in nutrient enrichment, higher in population, species and activity of soil microbes, and higher in enzyme activity as well. In a word, with the establishment of artificial shelterbelts in desert, the aeolian sandy soil underneath altered significantly in soil properties, and developed gradually into fixed aeolian sandy soil, suggesting that windbreak forest belts and aeolian sandy soil develop synergically, which is beneficial not only to sustainable management of the forest belts, but also to control of desertification, and restoration and reestablishment of degraded ecosystems.

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Abstract:We described the relationship between soil solution concentration and electrical conductivity with the fuction of three spline in Tarim irrigation district..The result showed that C = 0.0003EC3 - 0.0099EC2 1.6988EC - 0.9881.We caculated out that the solubility of the soil solution salt in Tarim irrigation district was 8.99 under the condition of 11℃，100mL soil solution with the same soil and piecewise function. We also caculated out that the quality of dry soil should between 5.72g and 24g. The result showed that purified water could instead of aqua destillata in determining soil solution salt in Tarim irrigation district.The error of determination was less than 0.03 with purified water .The error which caused by purified water was no more than 0.005.The content of volume moisture is beter no less than 0.2cm3/cm3 to accurately determine the content of the soil solution salt in Tarim irrigation dictrict.This method was simple and obviously improved the efficiency of the experiment.The result of the determination was accurate.

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