Abstract:The dynamics of chemical types and main components in vertical profile of soil and groundwater in salt-affected soil area are focused in this paper.The results from the typical sites of soil-groundwater during 4 years show that most of the dynamics classes for soil chemical types in this area are seasonal variation class,the next is relative steady class.For the chemical types of groundwater,most of the dynamics classes are relative steady class,the next is transform class and no seasonal variation class.The dynamics of chemical types for groundwater is steadier than that for soil and the chemical type of groundwater is not always coincident with that of soil at same site.The dynamics of the vertical variations for main component in the soil-groundwater reflects the influences of landform,climate,man-made measures and the migration law of geochemical components. The principles of the classification for the dynamics of chemical types of salt-affected soil and groundwater,the simplified indexes for determining the main components and the unity of the indexes and nomenclature of chemical classification for the salt- affected soils and groundwater with other disciplines are put forward in this paper.

Abstract:In this paper,three typical Holocene soil profiles in the Loess Plateau are studied.The analytical results show that Sr concentration is higher in the loess beds than that in the paleosol beds and that Rb concentration and Rb/Sr ratio is lower in the loess beds than that,respectively,in the paleosol beds.The change in Rb/Sr ratio reflects changes in pedogenic environment during the Holocene,and spatial-temporal changes in monsoon circulation over the Loess Plateau,as well.In the early Holocene(11500~8500 years B.P.),dust deposition reduced because of climate warming,and biological weathering began.In the mid-Holocene(8500~3100 years B.P.),as the climate became warmer and wetter;the effect of pedogenesis was getting stronger and stronger than that of the eolian dust deposition,and thus black loessial soil developed on the surface of the plateau,and cinnamon soil in the Guanzhong Basin. But beginning form 3 100 years BP,the climate has become dry,and dust storms and dust-fall occurred frequently.Recent loess(L₀) has begun to accumulate and gradually covered the mid-Holocene soil (S₀).As a result,the S₀ has become buried paleosoil,The change from soil formation to loess accumulation indicates environment deterioration and soil degradation.In the Loess Plateau,the environmental effect of the winter monsoon on the south is much stronger than that of the summer monsoon on the north, and so is the amplitude of the change in monsoon on the south than on the north.

Abstract:Wind erosion is the first step to land desertification,and it is obvious that accurate measurement and estimation of wind erosion rate appears urgent and essential.Owing to the complexity,randomness and boundlessness of the processes,it is difficult to measure or estimate wind erosion rate precisely at present. Current methods that include field observation,wind tunnel tests and wind erosion model have numerous limitations in their practicability,cost and accuracy.Meanwhile,the world-fallout of ¹³⁷Cs associated with the nuclear tests during 1950s and 1970s has provided a valuable man-made tracer for studies of soil erosion and sediment delivery,and since its first introduction in the 1970s,¹³⁷Cs technique has found application in water erosion research,with profound accomplishments.But it was not applied to wind erosion until the 1990s and still remains inadequate in this respect.Taking the Gonghe Basin in Qinghai Province as the study area,the paper attempts to introduce the ¹³⁷Cs method to study soil wind erosion.After field survey and analysis of a large number of soil samples,the characteristics of ¹³⁷Cs distribution over the whole study area and along the soil profile were found out,and the ¹³⁷Cs reference inventory of the area was calculated to be 2 691178±196108 Bq m^-2.By means of the ¹³⁷Cs model,the rate of wind erosion on the four sampling plots was estimated,and then the estimation method at the four points was extrapolated to the whole area.Thus the rate of wind erosion in the Gonghe Basin was figured out averaging 121556 t hm^-2 a^-1,which passed the test of erosion-deposition equilibrium at a relatively small error rate being less than 10%.

Abstract:Polyacrylamide(PAM),as a new effective soil amendment,applied on to soil surface,can significantly reduce runoff and erosion.With a series of rainfall simulation tests,effects of slope degree,slope length,PAM coverage and rain intensity on soil sediment loss of steep cultivated slope land are approached.The experiment is designed to have 3 levels of rain intensity:50 mm h^-1,100 mm h^-1 and 150 mm h^-1;4 slope degree:5°,10°,20°and 25°(8.74%,17.63%,36.4%and 46.63%);4 equivalent slope length:8 m,16 m,24 m and 40 m;and 5 treatments:control,straw coverage,3 PAM coverage-A,B and C(A

Abstract:Based on data of different soil types,the conversion of soil texture by mathematical methods including cubic spline interpolation,square spline interpolation and linear interpolation was studied.The result showed that cubic spline interpolation is superlative and the minimum relative error is 0.6%,the maximum error 3.5%,average 2.48%.The development of the texture conversion by mathematical method is valuable for calculating soil erodibility K based on data of soil properties and is meaningful for calibrating soil erodibility nomograph.

Abstract:Soil mechanical composition,physical features,chemical properties,and total composition of chemical elements of soils are measured for studying the land desertification.The results indicate that fine soil grains decrease progressively by wind and water erosion.Surface layer of soil vanished and it is covered with the sand layer.Soil texture tends sandification,and the contents of organic matter and nutrients reduce progressively.Ability in preserving moisture and fert ility fall down.Soil formation is in the stage of modern erosion and sand deposition,leaching and weathering are weak.The evolution coexists with the degeneration in the development of land resources.

Abstract:This paper mainly introduced the technique of serial digital images for analyzing pore characteristics on a small scale.Soil samples are impregnated by resins containing fluorescent dye,and grinded consecutively at an interval of 1 mm in order to obtain the serial images of pore space.By using this technique, we analyzed pore characterist ics on a small scale from a cultivated soil from USA and a cultivated soil from France,and the results showed that there were differences in image pore area,image pore size,image pore variability,pore connectivity,pore overlapped extent and pore circulating ability in those two soils, which were considered to be related with their different organic material contents.

Abstract:Accumulation and movement of NO₃^--N in soil profile in winter wheat/summer maize rotation system was studied in field experiments.The results showed that nitrification completed in 7d after urea was applied into soil.High concentration of NH₄⁺-N only appeared in short period after fert ilization and NH₄⁺-N concentration in other t imes was 1~3 mg kg^-1.NH₄⁺-N concentration in different soil layers was lower than 4 mg kg^-1 generally.So the content of NH₄⁺-N could not reflect soil available nitrogen level.NO₃^--N in soil profile was significantly increased with nitrogen fertilizer rate increasing.NO₃^--N movement mainly occurred in 0~40 cm with low nitrogen rate(N<120 kg hm^-2),but large amount of NO₃^--N moved below 100 cm even in winter wheat growth season with high nitrogen rate.The movement of NO₃^--N had a great different between years.In drought year,the possibility of NO₃^--N moving to deeper layer was low even in summer maize growth season.Except large amount of gas loss occurred in 1999 summer maize season(extremely drought in this season),the loss nitrogen fertilizer mainly accumulated in deeper layer in other season,which was consistent in two sites.

Abstract:A field experiment for studying water and salt movement in soil after basin irrigated by saline ground water was conducted in the center of Takelamakan Desert.A series of data about soil water potential,soil water content and EC value of soil solution at different depths along the soil profile were obtained at different times after stopping irrigation.By analyzing these data using method of water and salt balance,some results of water and salt movement in soil were obtained as follows:(1)After stopping irrigation 24 hours, 8.85% of the amount of irrigation water would be contained in the soil layer of 0~150 cm.After stopping irrigation 72 h,3.4% of the amount of irrigation water would be contained in layer of 0~150 cm,and average soil water content in this soil layer was 5.3%.After this time,soil water content in this layer reduced slowly.(2)During the time from stopping irrigation to seventh day after stopping irrigation in autumn,the daily evaporation water amount was between 2~6 mm.2 hours after stopping irrigation,soil water contained in the layer of 0~20 cm moved upward to the surface of ground,while 72~144 hours after stopping irrigation,the upward region of soil water extended to the depth of 90 cm underground. (3)When irrigated by saline water with EC value of 6.3 mS cm^-1,The EC value of soil solution reduced obviously in upper part of the layer and was almost same as that of before irrigation in lower part of the layer.24 h after stopping irrigation,the amount of salt contained in solution of layer of 0~150 cm was less than that of before irrigation,while 144 h after stopping irrigation,it was only 53.46% of that of before irrigation.(4)After stopping irrigation,the daily amount of salt accumulated on ground surface with area of 100 cm×100 cm would be 13~35 g in autumn.

Abstract:Kinetics of humic acids interactions with proton and calciumions were studied using modified potentiometric titration.Solutions of 1 and 2 g L^-1 humic acids in 0.1 mol L^-1 NaClO₄ or KCl were titrated with 0.1 mol L^-1 HClO₄ or HCl from pH 7.5 to about 2.6 at 24℃ under carefully controlled anaerobic conditions.The reaction kinetics were well described by a traditional relaxation equation Y=Y₀EXP(-t/S). In each titration point occurred an initial fast relaxation of redox potential(E_R)and glass electrode potential(E_G),followed by further slow relaxation and/or oscillations of E_R.And eventually,the reaction reached a steady state,indicating the non-equilibrium nature of humic acid solution system.The analyses of time-resolved data of E_G for the stepwise addition of calcium ions to humic acid solutions revealed that the overall reaction rates were diffusion-controlled rather than reaction-controlled.After relaxation down to a steady state E_R showed a linear pH dependence with an almost constant slope of 45.3? 1mV/pH unit despite the differences of humic acid concentrations and supporting electrolytes,which then could be applied as an index of the arrival at a steady state of the humic acid interactions with metations.The characteristics of proton reactions with humic acids were studied using the suggested index,and well reproducible results were obtained.Four types of binding sites HA,H₂A,H₃A and HA₂ with accordingly apparent pK values of 5.79~5.82,3.77~3.84,1.64~1.71 and 2.75~2.79 were found existing in the studied humic acids.

Abstract:Exchang-eadsorption of aluminum and manganousions by red soils continued being studied.It was shown that the nonelectrical adsorption of aluminum and manganousions was related to either adsorption capacity of solid phase or adsorption intensity of ion;For the ion exchange reaction in soils,it seemed impossible to obtain equilibrium constant k;K and 1/n were also not fixed values;The change in standard free energy ΔG^o of exchange-adsorption between aluminum and potasium was greater than that between it and calcium,it was also the greatest in laterite system.Changes in k,K,1/n and ΔG^o were affected both by the property of solid phase surface and by the nature of ion itself.

Abstract:Study of Cu adsorption and desorption processes on Red soil(R) and Sajong black soil(SB) is carried out.The results exhibit that SB has higher Cu adsorption quantity than R,and Cu desorption percentage from SB is also higher than that from R.It means that Cu is more easily exchanged by MgCl₂ from IB than from R.In the pH range from 3.5 to 7.5,Cu adsorption in the two soils increases with increasing pH,and shows as of S-shape.Effect of o-Phenylenediamine(o-PD) on Cu adsorption and desorption in the two soils shows that presence of o-PD increases Cu adsorption in R but not changes it obviously in SB, meanwhile,Cu desorption percentage increased correspondingly.Although o-PD does not change Cu adsorption quantity in SB,it changes Cu adsorption process strongly,which can be recognized from Cu desorption percentage from SB.

Abstract:The site-energy distribution function offers a method to evaluate heterogeneous properties of sorbents. The sorption of selected acetanilide herbicides on six different soils is examined by using batch equilibrium methods,and sorption data were fitted with the Freundlich equation.The site-energy distributions and mean-value of partitioning coefficients normalized to organic matter for each herbicide on six soils was obtained.The results indicated that the herbicide was firstly adsorbed on the high-energy sites of soil surface when adsorbed at the lower concentration.The herbicide properties can influent the site-energy distribution of soils.The number of sites or the sorption capacity on soils was related to the content of organic matter in soils,the clay also contributed to sorption to limited extent.The hydrophobic binding may be relatively important in the process of the four herbicides adsorbed by soils.

Abstract:Successive extraction method was adopted to study the relationship between characteristics of chemical forms of cadmium and lead and four soil enzymatic activities(Calatase,Urease,Invertase,Alkalin phosphatase) in alluvial meadow soil and meadow cinnamon soil by field sampling.The result showed that the most contributions to inhibiting effect of soil enzymatic activities,especially to Urease activities in lowly polluted soils,were the exchangeable Cd and Pb,the next were the Fe-Mn oxide Cd and Pb.When the Urease activities was decreased by 10% in meadow cinnamon soil,the concentration of exchangeable Cd, Pb were 0.09 mg kg^-1,0.12 mg kg^-1 respectively and in alluvial meadow soil,the concentration of the exchangeable Pb was 0.92 mg kg^-1.In calcareous soils,it was feasible to use the exchangeable Cd,Pb and Urease activities as primary biochemical index to evaluate Cd,Pb polluted soils.

Abstract:¹⁵N-labell fertilizer was used to study on N competition between tree and peanuts,and to test the potential of tree roots acting as safety-net on Choerospondias axillaris cropped with peanut(Arachis hypogaea) in subtropical China.Five-year-old and nine-yea-rold Choerospondias axillaris recovered 9.66% and 30.15% of the N applied at topsoil of peanut area,respectively.Compared with sole peanut system,N recovery by peanut was decreased by 37.8%in 5-year-old and 59.1% in 9-yea-rold Choerospondias axillaris alley cropping system,respectively.The role of 5-yea-rold Choerospondias axillaris acting as a safetynet was not obvious,since it recovered little N from subsoil and did not decrease N residual in the soils. With increasing tree age,9-yea-rold Choerospondias axillaris showed its potential to act as a safety-net, since it recovered 33.79% N from 35cm soil layer and 14.74% N from 55 cm soil layer,respectively,and N residual in 0~60 cm soil layer was decreased by 24.1%,compared with that in sole peanut system.

Abstract:The effects of manure application on the contents and distributions of fractions of organic P in soil and soil particle sizes were investigated in a field experiment,which consisted five 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 14 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 compared with the treatments of control or single application of chemical fertilizers,the combined application of organic manures with chemical fertilizers could significantly increase soil organic P.The contents of soil organic P in different soil particle size fractions were in the following order:0~2 m>2~10 m>50~100 m>10~50 m.Long-term fertilization mainly increased the contents of moderately labile organic P which was a little bit available to plant absorption and accounted for a largest percentage of soil organic P no matter in soil itself or in different soil fractions.The labile organic P was also increased in long-term fertilization but its contribution to plant P nutrition was small since it accounted for only 3% of total organic P in soils.Furthermore,long-term fertilization could decrease the percentage of highly resistant organic P showing that fertilization could also activate the nat ive soil P to improve plant P nutrition.

Abstract:Atmospheric CO₂ levels are expected to exceed 700 L mol mol^-1 by the end of 21st century.Therefore the influence of increased CO₂ concentration on crop plants is of major concern.This study is an analysis of growth of and N and P concentrations in winter wheat(Triticum aestivum L.cv.Xinong 8727) grown under two levels of atmospheric CO₂ concentration(350 L mol mol^-1 and 700 Lmol mol^-1)and of nitrogen fert ilizer(45 kg hm^-2 and 90 kg hm^-2).Results showed that plant height,leaf area index (LAI)and net assimilation rate(NAR)increased,while leaf area ratio(LAR)reduced and specific leaf weight(SLW)remained unchanged under the high atmospheric CO₂ concentration.The influence of CO₂ enrichment on relative growth rate(RGR)was dependent on N level.Higher CO₂ concentration increased RGR significantly in the high N treatment,but did not increase in the low N treatment.Tasseling of winter wheat advanced by 7~8 days and masses of leaf sheaths,stalks and shoots also increased with CO₂ concentration increasing.Higher CO₂ decreased N and P concentrations in leaves,leaf sheaths and stalks, however it increased N uptake by winter wheat slightly.Higher CO₂ concentration increased use efficiencies of N and P(NUE and PUE),but did not affect relative nitrogen and phosphorus accumulation rates (RNAR and RPAR).Dilution of N and P due to increased dry mass and the enhancement of the use efficiencies of N and P can explain the decline in plant N content in the present experiment.

Abstract:Differences in the population of culturable microorganisms and the enzymatic activities between soils amended with Bt-transgenic rice straw and non Bt-transgenic rice straw,respectively,were invest igated under laboratory conditions No significant differences(p<0.05) were observed in CFU(colony forming units) of culturable bacteria,act inomycetes and fungi between the two soils Although some apparent differences were observed in the populations of ammonifying bacteria,nitrogen fixing bacteria and cellulose-decomposing bacteria in the middle of the incubation,they did not last long Responses of various soil enzymes to the incorporation of Bt-transgenic rice straw and non Bt-transgenic rice straw varied No significant differences(p<0.05) in protease activities,neutral phosphatase activities,urease activities and respiration activities were found between the soil amended with Bt-transgenic rice straw and the soil blended with non Bt-transgenic rice straw Soil dehydrogenase was more sensitive than the other enzymes to amendment of the Bt-transgenic rice straw into soil Dehydrogenase activities in the soil amended with Bttransgenic rice straw were significantly higher(p<0.05) as compared to those in the soil with non Bt transgenic rice straw,and the apparent differences in the soil dehydrogenase activities,however,disappeared after incubation for 63 days Results indicate that the cry 1Ab toxin in straws of Bt-transgenic rice appears to be in toxic to the culturable microorganisms in upland soil.

Abstract:The survival dynamics of recombinant Sinorhizobium fredii HN01DL,Bradyrhizobium japonicum TA113QD both of which marked with luxAB gene and its wild-type strain HN01,TA11 in sterilized and non-sterilized soil microcosm were studied respectively1 The results showed that the population dynamics of HN01Dl and TA113QD in sterilized and non-sterilized soil microcosm was obviously different1 The survival population of the marked rhizobia decreased slightly at an early stage after inoculation and then kept a relatively stable high survival level in sterilized soil microcosm,and its survival population in non-sterilized soil microcosm decreased regularly at a high speed until reaching about 4.5 log cfu g^-1 soil1 No significant difference in soil survival was found between the recombinant marked strains and the wild-type stains.

Abstract:Experiment was carried out with flouvo-aguic soils of low fertility coming from Qihe,Shandong Province.The results of 15 years application showed that matching use of straw and chemical fert ilizer is an effective measure to increase yield and improve soil fertility.As straw application rate at the range of 2250,4500,6750 kg hm^-2,the accumulation of O.M.,available nutrient and activity of urease have markedly positive correlation to amount of straw and are effected by climate,growing season,soil texture et al.

Abstract:This paper presents an overview of currently available literature on the physiology and biochemistry of nitrate reducing microorganisms in anaerobic soils,with emphasis on electron transport chains in assimilatory reduction,dissimilatory nitrate reduction to ammonium,respiratory denitrification and non-respiratory denitrification.

Abstract:玄武岩台地,是地幔中基性或超基性熔浆沿深(大)断裂上升、喷溢到地表,在低洼区冷却、固化成岩,再经新构造运动区域性差异抬升和流水侵蚀切割,出现地形倒置,形成不同海拔高程上的面平、边陡的台桌状地貌^[1,2].玄武岩台地因其平坦的台面、肥沃的土壤而成为我国南方山地丘陵区的优质耕地资源,也是村镇建设的常选基地.然而,就在这类台地上时有岩层滑坡发生,严重威胁着当地人民的生命财产安全.作为深层的玄武岩台地滑坡,一旦发生就很难治理.

Abstract:植物根系养分吸收性能与土壤养分、水分、pH值和温度等环境条件有着密切的关系,同时又影响着近根微区(根际)土壤中养分的迁移和有效性.土壤中磷素在土壤中的迁移和吸收直接与土壤性质有关.在石灰性土壤中,由于土壤中存在着大量的碳酸钙和粘粒矿物,土壤的pH较高,土壤中磷的化学有效性较低^[1,2].因此,通过降低石灰性土壤的pH值以提高土壤中磷的生物有效性是研究者普遍关注的问题.近些年来,研究者发现施氮肥对土壤根际的pH值有较大影响.用NH₄⁺-N处理的根际土壤pH值为4.8,而NO₃^--N处理的根际pH为7.1^[3].