Abstract:Fields under corn rape rotation,soybean-winter wheat rotation,and fallow in Guizhou were selected as representative sub tropical upland soils for studying seasonal variations in N₂O flux and temperature synchronously.Furthermore,DNDC model was used to assess potential effect of the variation in air temperature in future on N₂O emissions from the fields.The results indicated that temperature was the key factor controling the diurnal regular variation in N₂O flux.Apart from that from the soybean field,N₂O fluxes from the crop fields and fallow land were positively related with the temperature,and N₂O fluxes from the fallow land in spring and winter were in exponential function with the temperature.DNDC modeling results showed,except from soybean field,N₂O fluxes from all the fields would increase with annual average temperature.The effect of temperature on N₂O fluxes would be greater in spring and winter than in summer and autumn,and from the fallow land than from the others in spring and autumn.

Abstract:A long-term field experiment of a triple cereal cropping system(barley-double rice)has been carried on for 26 yrs.Results showed that continuous application of FYM increased SOM successively and eventually reached such a high level as 60g kg^-1 in SOM content while maintaining high crop yield.The quantity of FYM applied was one of the most important factors which affected the rate of SOM accumulation.A model for the change in SOM was developed.Only 4.8 tons FYM was needed to keep SOM in balance in the barley-double rice cropping system.

Abstract:Changes of exchangeable acidity in the soil colloid of a latosol and a red soil with the presence of NaCl and Ba(NO₃)₂ solutions were studied quantitatively with an automatic pH control titration device.The results showed that in the two salt solutions only exchangeable acidity appeared in the range of pH measured.The amount of exchangeable acidity in the red soil is larger than that in the latosol.The increment of exchangeable acidity decreased with increase in concentration of the salt solutions.Turning points in the curve of the exchangeable acidity were observed when 300 mmol kg^-1 of NaCl and 120 mmol kg^-1 of Ba(NO₃)₂ was added respectively.The exchangeable acidity, which were significantly influenced by pH,increased with pH in the Ba(NO₃)₂ solution,but the peak value of the exchangeable acidity was found in the NaCl solution. A method of measuring the Cl^- exchangeable alkalinity was constructed.

Abstract:Pot experiment with rice on two typical purple soils shows that in red purple soil phosphorus could reduce arsenic poisoning to rice,while the effect was just the opposite in red brown purple soil.The research on distribution of arsenic fractions clarifies that there was higher content of arsenic of different fractions in rhizosphere than in nonrhizosphere in two soils,and arsenic existed in an accumulating state in the rhizosphere.In the red purple soil,arsenic was transformed from available arsenic(Fe-As,Al-As)to relatively inavailable one(O-As)when phosphorus was added,thus reducing the biotoxicity of arsenic.While in the red brown purple soil,arsenic was transformed from relatively inavailable arsenic(Fe-As,Al-As)to available one(Ca-As,A-As)when phosphorus was added.

Abstract:The process of cadmium adsorption and desorption on lndicotic Black(IB,Cambisols),Yellow Brown(YB,Luvisols)and Red(R,Ferrisols)soils as well as the influence of media's pH were investigated in detail.The presence of organic chemicals obviously influenced the processes of cadmium adsorption and desorption.Adsorption of Cd in YB and IB soils decreased in the presence of citric acid and EDTA,meanwhile,its desorption rate was lower than that obtained in the absence of organic chemicals,which suggests that the relatively unsaturated adsorption sites for Cd increased in the present of organic chemicals.For Red soil,Cd adsorption in the presence of citric acid and ED-TA increased with pH in low pH media but decreased in high pH one,which was very different from YB and IB soils.Further studies indicated that adsorbed Cd in red soil existed significantly as unex-changeable one,and desorption rate by 0.1 mol L^-1 NaNO₃ gave a peak-shape curve.

Abstract:Effect of external copper on enzyme activity in a soil and apple tree system was studied by us-ing cinnamon soil and Fuji apple young tree.The results showed that perioxidase,PPO and ascorbic acid oxidase act ivity in the leaves and perioxidase activity in the roots were reinforced at low external copper levels and reduced at high.Adding Ca of Fe at high copper levels could mitigate copper toxicity in some degree.A significant curuilinear correlation was observed between soil peri-oxidase activity and the external copper concentration(y=x/(-11.26+0.75x),r=0.9955^**).Soil sucrase activity was logistically correlated with the external copper level(y=2.95/(1+0.57exp(-5.02×10^-5x)),r=-0.9820^**).Urease was very sensitive to copper and it lost activity at levels> Cu100.

Abstract:The high efficiency degrading bacteria Pseudomonas and Bacilus were obtained by circulation culture.The conditions that influence degradative efficiency were studied.98.7% of pacloutrazol can be degraded naturally in sterile medium under vibration condition 99.8% of pacloutrazol can be degraded by degrading bacteria.Pacloutrazol can be degraded down to CO₂ by mixed degrading bacteria.If plenty of oxygen and light are adsorbed by soil,after 35d about 86.2% of pacloutrazol can be degraded and biomass can reach 89% of general level in soil.

Abstract:This paper introduces briefly techniques for preparing soil sections and digital images,with emphasis on influences of various experimental factors,such as image resolution,orientation of soil section,analyzed area and so on on the analysis of pore structure.Experimental results obtained by this method are subject to a deviation rate of 10%.The results showed that,for making analytical results reliable and comparable,it was very important to keep the experimental factors replicable and stable because any variation in the experimental factors could influence the analysis of pore structure.

Abstract:As Jiangxi Province stands out for its serious soil erosion in the hily red soil region of South China,research on its spatial and temporal changes was of true typicality.The combination of the remote sensing technique with the geographic information system technique showed significant advantages in the research.By using this technology,the change in soil erosion was studied in Xingguo and Yujiang of Jiangxi Province,with results indicating that soil erosion in the counties was gradually getting under control,both in area and in extent.The decreases in soil erosion area of the two counties were almost equal in percentage,with Xingguo County lagging slightly behind Yujiang County.However,soil erosion was still an outstanding problem in these counties.

Abstract:A six-step sequential chemical extraction experiment has been conducted on samples of loess and paleosols from Luochuo section,each for one of folowing:(1)soluble;(2)exchangeable;(3) carbonate bounded;(4)Fe-Mn-oxide bounded;(5)the organic mater bounded;and(6)residual forms of elements.Results show that elements,such as K and Rb,are predominantly associated with the residual,whereas Ca and Sr are mainly in carbonate bounded and residual forms.As Sr is preferentialy partitioned into Ca-rich minerals such as carbonates and plagioclase,its distribution is associated with Ca in loess and paleosols.Sr is likely to be leached when carbonates are eluviated and Ca-containing silicates are decomposed during weathering and pedogenesis,while Rb tends to stay in situ.Therefore,Rb Sr ratios can be used to indicate leaching degree that loess and paleosols have undergone,reflect precipitation variations in the Loess Plateau and serve as a proxy index of the summer monsoon intensity.

Abstract:Growing contour hedgerows on slopelands is an effective way to control soil erosion and nutrient loss.The experimental data of simulated rainfalls on a slope land(25°)of purplish soil in the Three-Gorge-Reservoir Region indicated that the Vetiveria zizanioides contour hedgerow plots decreased 82.2% in soil loss as compared with the cultivated plot.Fertilization did good to the growth of hedgerows and hence the effect of erosion control;which was comparable to the mulching treatment.The most distinct variation in slope shape between hedgerows was the formation nearly alluvial strips.With changing slope shape and increasing interception by hedgerows,the interacting time between soil and runoff was prolonged.As nutrient loss in runoffs,is an important way,hedgerows' function of controling runoff loss is helpful in decreasing soil erosion and nutrient loss by hedgerows.

Abstract:In this paper,the lower boundary flow of considered upper soil stratum was expressed into linear relation with infiltration ratio and saturated degree by introducing preferential flow coefficient.So according to principle of salt-water balance,the water deposit formula and salt deposit formula was conducted out by introducing leaching coefficient.Through discussing above formulas,the critical mineralization degree equation of irrigation water was presented.The physical significance and af ected factors of the preferential flow coefficient and leaching coefficient were discussed.The salt-water regime model is simple and suitable for farmland irrigation management,the critical mineralization degree equation of irrigation water maybe provide reference for option of mineralization degree of irrigation water.

Abstract:The effects of tillage and manure application on soil microbial biomass carbon(MBC),microbial biomass nitrogen(MBN),and microbial biomass phosphorus(MBP)were investigated in a field experiment,which consisted of two main treatments of conventional tillage and zero-tillage and five sub-treatments of control(no fertilizers),chemical fertilizers,chemical fertilizers plus straw,chemical fertilizers plus green manure,and chemical fertilizers plus pig manure and had continued for 16 years at the farm of Jurong Agricultural Science Institute.The crop rotation of the experiment was summer rice(Oryza Sativa L.)and winter wheat(Triticum aestivum).The results showed that MBC and MBN in zero-tillage treatment increased by 25.4% and 45.4%,respectively compared to those in conventional tillage treatment in 0~5cm depth layer after 16 years.However,there were no significant differences of MBC,MBN,and MBP in subsoil(5~10cm)between conventional tillage and zero-tillage.Although the application rate of N,P,and K in each sub-treatment were equal,the contents of MBC,MBN,and MBP in 0~5cm and 5~10cm depth layer followed the order in the treatments:fertilizers plus pig manure>fertilizers plus straw>fertilizers plus green manure>chemical fertilizers>control.

Abstract:144 soil samples were collected along the moisture gradient in grassland region of the Mongolian Plateau for investigating soil microbial biomass C(C_mic)and N(Nmic),and their relations to annu al average temperature and rainfal.The results are as followings:Soil microbial biomass C and N showed significant correlations with soil organic carbon,total nitrogen,precipitation,and tempera ture.C_mic ranged from 51.7 to 797mg kg^-1;Nmic from 11 to 118.6mg kg^-1;C_mic:Nmic from 5 to 9,and C_mic/C_org from 1.15% to 4.1%.C_mic/C_org was correlative negatively with soil organic C, total N,and annual average precipitation.Soil respiration showed a decreasing trend:meadow steppe>typical steppe>desert steppe,correlating positively with precipitation,and negatively with temperature.The relationship of metabolic quot ient CO₂(Q_CO2) with precipitation can fit in quadratic equation.Effect of grazing on soil microbial biomass depends on grassland types and grazing intensity.

Abstract:The available S content,as measured with Ca(H₂PO₄)₂ extraction and ICP-AES,in topsoils (0~20cm)of mulberry gardens in the area of the middle and lower reaches of the Yangtze River was found to be 2.51~87.73mg kg^-1)(Mean SE=18.34±15.25mg kg^-1 ).About 55.77% of the mulberry garden topsoils in six provinces of Jiangxi,Anhui,Hubai,Hunan,Jiangsu and Fujian have an available sulfur content below the critical value.The available sulfur content in the mulberry garden topsoil was commonly found to be lower that of the subsoil.Significant two-power function correlation was found between the available sulfur content in soil of mulberry gardens and the total sulfur content of mulberry leaves(Y=-0.001x²+0.017 9x+1.791 9,R²=8.1773^**,N=52).The curvilinear correlation(two-power function relationship)between sulfur contents in mul-berry leaves and cocoon shel was significant(Y=-0.694 2x²+2.996x-1.542 3,R²=0.210 1,n=26).Sulfur concentration in cocoon shel,pupa and silkworm excrement from high-yielding mulberry gardens was higher than that from low-yielding mulberry gardens,respectively.

Abstract:Eight plots with Artemisia halodendron,Populus and Pinus plantations and shift ing sandy land both four at leeward with similar slope and exposure and four on top of dune respectively,and three plots with similar Hedysarum fruticosum var.ligosum plantation at bottom,middle and top of sand dunes were chosen to monitor soil moisture to determine impacts of the plantation on both soil moisture regime and soil moisture spatial heterogeneity by using fractal dimension and semivariograms in Horqin Sandy Land.The results show that:(1)the soil moisture regime of the plots worsens in the order of Artemisia halodendron,Populus and Pinus plantation;(2)the soil moisture is significantly dependent on its position at the sand dunes;(3)horizontally,the soil moistures for Populus,Pinus plantations and shift ing sand land plots exhibits homogeneity within the scale of 4m,8m and 9m, respectively.However,that for Artemisia halodendron plantation plot show high heterogeneity within the scale of 4m,and homogeneity at the scale of 4m above.Vertically,the soil moisture for Artemisia halodendron,Pinus plantation and shifting sand land plot exhibits heterogeneity within the depth of 120cm,80cm,60cm,respectively,and homogeneity in the depth lower.However,Populus plantation plot shows great heterogeneity within the depth of 300cm.In a word,heterogeneity of soil moisture for plantation plots is higher than that for shifting sandy land plots both on horizontal and vertical scales.

Abstract:The multi-pin soil probe plays an important role in determination of soil water content with a variety of instruments,such as TDR(Time Domain Reflectrometry),FD(Frequency Decomposition) and SWR(Standing Wave Ratio).Therefore,it is critical to calculate the impedance of the soil probe in order to improve the measuring accuracy of these instruments.However,the electromagnetic characteristics of the multi-pin probe is too complex to describe due to the hard-to-define boundary conditions of Maxwell equation.Based on the theory of impedance transform of transmission line as well as a mathematical inequality from the parallel and coaxial transmission lines,a mathematical formula for the impedance of the soil probe was developed.By computing this formula,it was found that the impedance of the soil probe depends not only on the permitivity of soil-water-system,but also on length of the probe-pin and frequency of its measuring signal.Especialy,it is proved that the impedance characteristics of the soil probe may be turned into an inductance from a capacitance and vice versa as measurement conditions change.In addition,it was confirmed that the formula for impedance of the soil probe had a series of periodical disconnected dots.

Abstract:On an Artificial Soil Rapid Infiltration(ASRI)system,a new effective method for disposing domestic wastewater,mechanisms of COD removal in the system were studied.The result showed that COD removal in ASRI contributed to biodegradation and abiotic interception when wastewater was flooding the bed.Abiotic interception such as physical infiltration,adsorption and soil fixation intercepted and captured COD in the ASRI bed,in which the COD was decomposed when the water was drained.Periodic monitoring of organisms showed that both aerobe and anaerobe,which came from soil and sewage,played an important role in COD removal and aerobic biodegradation was the dominant action in the whole cycle of the ASRI system.

Abstract:A simple method for determination of total organic carbon in soil sediment samples using micro-wave digestion has been developed.The method shows the advantages of simple operation,less pollution,high analytical speed,better accuracy and precision over the traditional potassium dichromate oxidation method.F test and t test prove that the method is reliable.

Abstract:沸石作为土壤结构改良基质和缓释肥料基质,对改善土壤养分向植物的供应状况有十分重要的作用,在国内外的农业生产中得到较广泛的应用^[1～4]。据研究资料报道,在土壤中施用沸石不会引起有效磷和肥料中水溶性磷的固定,还能改善土壤供钾状况^[5]。在ＣＥＣ较小的土壤中施用,具有较好的保水蓄肥作用^[6],可使小麦、水稻等作物增产10%左右^[7]。研究资料表明,铵饱和沸石能显著增加粉砂质壤土中苏丹草的产量和对氮的吸收^[8],在壤土中随着沸石与磷矿石比例的增大,苏丹草对磷的吸收量增加^[9]。