Abstract:Soil serves as one of the most important sources and sinks of trace gases.However,as a source and a sink as well,soil is being changed because of human activities,such as changing land use and applying fertilizers.Being concerned about human health and global change,reseatch on trace gases will not be limitel in greenhouse gases and their greenhouse effect.A new branch,research on soil trace gases will play an important part.

Abstract:The characteristics and biolnaical mechanism of methane reliase in paddy soil were studied by the soil column and in situ field methods.The results obtained showed that the amounts of methane released were the highest during full-tillering stage of both early and late rice; the amount of methane released was higher during night and morning and lower during afternoon;fertilizers could stimulate the release of methane in paddy soil and the methane release of organic manure plot was more than that of urea plot; there active part of methane formation was the root system which was undisturbed and combined,closely with soil; more than 80% of mrthane was released by rice plants; methanogenie bacteria adhered to surfaee of roots.The result also showed that the amounts of methanogenic bacteria,anaerobic celluloclastic and methane-oxidizing bacteria as well as TVFA were higher in rhizosphere soil were than in non rhizosnhere soil.

Abstract:The present study was carried out on paddy osils under conditions of coutinuous application of organic manures.We found that organic manuer applied could provide nutrients deficient in rhizospherea enchanced the formation of chelated compounds of Fc and Mn in root horizon and play a significan role in decreasing the lignifcation of mechanical tissue and in increasing the stelar cathether diameter of roots.Therefore,it could faver the absorption of water part and the coordiation of the growth of plant and mictrobes.Therefore the application of organic manure proved to be of great significance for improning the root horizon environment and enhancing the root system function in paddy soils.

Abstract:Changes in the physical properties of high-yield paddy soil in.Tiaxing,Zhejiang Province after seven-year application of organic materials were analyzed.Different physical properties of soils in different treatments and the effect of application time of organic materical were compared after wheat hardiest and later rice harvest.Results show that although the organic matter content of the soil used in the experiment was as high as 35.5 g/kg,the physical properties of high-yield paddy soil were improved significantly by applying organic material.The soil bulk density and rupture modules decreased but the soil porosity and 1-0.05 mm micraag gregates increased.Meanwhile,its effectiveness was elosely related to different moisture cola ditions.Applying organic material into waterunsatutated.soil in wheat season was more effecrive than that into water-saturated soil in early rice season.Moreover,soils treated with orgenie materials,were moxe loose and had a quicker increase of air-filled porosity than the soil of control treatment,which wa}uld he beneficial to the sowing of upland crop as early as posBible after rice harvest.

Abstract:The characteristics of phosphate(P) adsorption and desorption by 4 albic soils collected from the Three-River Plain.The experimental results showed that the soils had very strong ability to adsorb P.The whole process of adsorption was divided into the initially fast reaction (within 24 hours) and the slow reaction thereof ter.In all kinetic models examined in this study, the Langmuir-type equation most perfectly modeled the kinetic processes of P sorption.The properties of P adsorption suggested that there were two populations of adsorbed sites which differed in the affinity for P,and therefore the sorption of P may be described using two-surface Langmuir equation.The process of P desorption had high P concentration.The characteristics of succe.ssrve an evident hysteresis phenomenonn at desorption further indicated the presence of two forms of adsorbed sites or regions,one adsorbed P tightly,another loosely.Organic matter (O.M.) significantly affected P sorbtion by soils.The addition of O.M.could increase the amount of P adsorbed but it could be conductive to P desorption as well.The higher the content of O.M.the more easily the adsorbed P,especially at low P concentration.After O.M.was removed,P was more tightly adsorbed by soils,and therefore the desorption rate decreased evidently.

Abstract:Three pedons of typical albic soils in the Three River Plain of Heilongjiang Provence were chosen far the study of elemental geochemistry.The background levels of trace element and rare earth element were established for these undisturbed soils.The redistribution and differentiation of these elements during soil forming process were analyzed.We found that Br,Cl,I and Hg were possibly accumulated in Ah Horizons,due to dust deposition and their affinity for soil organic matter.Mn,As,Sb,Th and U were associated with amounts of oxalate and dithionite extractable Mn and Fe in E horizons.The Cr,Rb,Sc,V and Zn Were closely related to clay particles and enriched in Ba horizons.The B,Ba,Hf,Sr,Ti and Zr exist generally in weathering-resistant minerals and have a relatively even distribution in soil profiles.

Abstract:Indoor soil column simulating experiment was carried,out to study salt-water dynamics in homogeneous sandy loam,sandy loam with interbedded caly layer and sandy loam with surface clay layer under conditions of different groundwater depths.The results obtained show that the evaporation of groundwater is involved in the two stages,i.e.the wetting of dry soil and the evaporation of soil water in moist soil.fJnder the condition of same groundwater depth the speed of wetting front reaching soil surface in soil column and the amount of daily groundwater evaporaxion followed the order:homogeneous sandy loam>soil with surface clay layer>sandy loam with interbedded clay layer.It was also found that within 1-2m variation range of groundwater table,the influence of interbedded clay layer on groundwater evaporation was greater than that of groundwater depth,and two salt peaks occurred in soil profiles.Under evaporation condition,water content increased gradually from top soil to bottom soil in homogeneuns sandy loam,and interbeded clay layer only affected the water regime in soil above the interbedded clay layer.Under the experimental condition of using groundwater containg 3g/L NaCl for evaporation,secondary alkalization could occur owing to the for anation of Na₂CO₃ and NaHCO₃ in bottom soils.

Abstract:The secondary salinization of grassland soil is the mam reason for the formation of secondary saline-alkaline soil pathes in grasslands in Songnen Plain.Inthe presence of potential salinization factors such as dry climate and high underground water level the secondary salinization of grassland soil was induced because vegetation had been ruined due to strong anthropogenic interference.Therefore,the secondary saline-alkaline soil in grassland had its special profile and physical and chemical characterstics.It is suggested that to protect and recover vegetation is an effective way to prevent and improve secondary saline-alkaline grassland soil in Songnen Plain.

Abstract:Soils derived from the loess-like sediments in 5 hill areas of Jiangsu Province were studied.The examination results of the contents of TiO₂ and Fe₂O₃ in non-clay fraction and the silt/clay ratio of subsoil samples showed that the properties of loess-like parent materials within Jiangsu Province varied gradually with location,and the boundary between Xiashu group and Qizui group of loess-like sediments was hard to ascertain.Such variation was one of the reasoms that diversified soils from the loess-like sediments.In the hill areas of Jiangsu Province,referring to Chinese Soil Taxonomic Classifition (1 st scheme),soils derived from loess-like sediments could be allocated into 6 soil great groups under 2 soil orders,i.e.,cinnamon soil,brown earth,acidic brown earth of Siallisols and yellow cinnaman soil,yellow-brown soil and brown-red soil of Ferosiallisols.Soil numerical classificatioci based on the principal component analysis reached a similar conclusion except that brown earth was absent.

Abstract:Through experiments,this paper verifies a rate model for microbial degradation of pesticides:-dx/dt=kxm,where x is the concentration of pesticide at time t,k the rate constant,and n the number of pesticide-degrading microorganisms at time t.For microbial degradation of r-BHC in a submerged soil,there was a strong positive correlation between -dx/dt and xm (the product of x and m)where x is the concentration of r-BHC,and m thr bacterial coupe.According to a nonlinear relation between m and m=ζ₁+ζ₂x+ζ₃x²(ζ₁,ζ₂ and ζ₃ are constants),there was a significarnr correlation between the bacterial count and the concentration of r-BHC.This paper further discusses kinetic models describing the effect of pesticide concentration and temperature on the loss rate of pesticides in soil.

Abstract:Both field and labor atory experiments of different soils show that the hysteresis phenomenon of soil water movement existed in almast all kinds of soils.However,it has a greater effect on water flow in linht soils.The maximum soil water content due to hystersis was about 20 %(vol./vol)in medium and find sandy soils,11.l% in.silty soil,but only 3% in silty clayey doam.At present,four differenr approaches——domain theory algorithm,linear alborithm,interpolation algorithm and analytical algorithm are commonly introduced in considering hysteresis in numerical simulation of water flow.It is shown that the linear algorithm has the advantages of simplicity,ease and sufficient accuracy,parficularly in the higher order scaning process.

Abstract:近几年来,随着氮、磷肥施用量的不断增加,小麦单位面积产量不断提高,我市土壤中钾素含量也发生了很大变化。据1990年抽测化验,我市土壤速效钾含量在100mg/kg以下的面积就达30%以上,已成为制约小麦产量提高的重要因素之一。为了探讨增施钾肥对小麦生长发育及产量的影响,特设置本试验。

Abstract:近年来,我国在研制与应用人工合成土壤结构改良剂方面,取得了不少科技成果^[1-4]。这些资料表明,应用土壤结构改良剂是培肥与改良土壤的有效措施,为了合理应用改良剂,进一步提高其经济效益,有必要对影响凝聚效应的化学条件进行研究。作者选用离子型的PAA与非离子型的PVA为材料进行了室内试验研究,现将部分试验结果整理成文,简报如下。

Abstract:本试验研究水稻的生长发育和标记¹⁵N硫铵氮素的有效性与施用的肥料组合(稻秆+硫铵)不同碳氮比的关系;对碳氮比值可否作为指导合理配合施用稻秆和硫铵的定量指标作了初步的评价;同时也探讨了延长植稻前土壤淹水时间的不同对肥料组合(稻秆+硫铵)中硫铵氮有效性影响的问题。