Abstract:The contents,migration and profile distrjbution of natural radioactive elements in main groups of soils of loessial region are described in this paper.The results showed that contents,ratios and variance of radioactive elements in the soils were approaching to those in loessial parent materials.But certain variations were found among the soil groups,(gray-drab forest soil>stratified old manured loessial soil> drak loessial soil) sierozem>cultivated loessial soil>> aeolian sand soil).In alkalescent-oxidative condition of soil,uranium in the form of (UO₂)²⁺ was more active.Carbonate precipitated the luvic migration of U and organic matter fapoured the accumulation of U.Th and Ra accumulated in the soil layers rich in clay particle,but leaching trace of Th existed in the forest soils.In view of profile distribution,biological accumulation of radioactive elements exceeded leaching in the soil forming process.Under different la}iid utilization conditions,anthropic transfer of material intensified differentiation of the content and distribution of radioactive elements in soils.

Abstract:An evaluation method of soil integrated fertility was developed and used for evaluating soil fertility in the hilly and mountainous region of Southeastern China,with soil fertility being considered as a com plex of the state the capacity to regulate and transform the materials needed by of soil nutrients and plants.With systematic principle and the data of the Second National Soil General Survey,11 indexes were divided into two groups representing,separately,states of sail nutrients and environments of nutrient supplying,involving content of soil orgasie matter,total N,total P₂O₅,total K₂O,available P₂O₅ available K₂O,pH, CEC,physical clay,silt-clay ratio and thickness of epipedon.Then two types of membership functions of these indexes,S-type and parabola-type,were developed based on their effects on plants.Their values of function were also calculated. Through factor analysis of these vslucs with software STATGRAPHICS,weight values of these indexes were decided.Finally,IFI (Integrated Fertility Index) of different soils was calculated according to addition-multiplication principle.

Abstract:The specific adsorption of divalent Cu²⁺,Zn²⁺,Co²⁺,Ni²⁺ and Cd²⁺ on latosol,goethite,amorphous Al oride,and kaolinite was measured as a function of pH.The adsorption of heavy metals with increasing pH was in the order of Cu²⁺>Zn²⁺>Co²⁺>Ni²⁺>>Cd²⁺ on latosol,Cu²⁺>Zn²⁺>Cd²⁺>Ni²⁺>>Co²⁺ on goethite and data are consistent with the triple layer model.

Abstract:A method of soil moisture and wetland monitoring and mappiag at 1:50,000 scale using the satellite remote sensing data is described.Two TM images acquired on oct.18,1984 and Mar.6,1989 respectively were processed.The 3d principal components (PC3) resulted from K-L transformation of TM images of two dates were registered one to the other.Then a classification of land surface wetness was carried out by a hyperboxes classifier and five types of wetness were obtained: water body the Iand always wet,the land wet only in summer,the land wet only in winter,the land always dry.The results were checked against fields with a very good agreement.It meant that this method was suitable for mapping and monitoring of wetlands and soil moisture changes as well.

Abstract:Absorbability (Q) is a new concenpt which is derived from absorbance of determining nitrate nitrogen in soil by UV spectrophotometry for characterizing the contents of nitrate nitrogen and soluble organic nitrogen in soils.Absorbance indiGates only the concentration of a light-absorbing component in solution rather than the content of this component in sample (e.g.,soil sample).Absorbability may be used as an index of characterizing the content of a light-absorbing component in sample.When a soil is extracted by an extractant,the absorbability (Q) of the soil at a particular wave length is directly proportional to the absorbance (A) and volume (V) of soil extract but inversely proportional to the mass(m) of soil sample and the optical path length (b),
Soil-Q=AV/bm
within a certain range,the values of soil-Q possess additive property.

Abstract:In lysimeters,the transformation and accumulation of NO₃^--N in surface layer and its leaching loss out of 130cm solum column in chao soil in Beijing were studied by the routine analysis methods in combination with isotopic technique.The results showed that N transformation to NO₃^--N could be observed during the earlier growth stage.The significant differences existed among the treatments applied at 3 rates of urea but could not be found among the those with 3 kinds of N fertilizers. And the transformation to NO₃^--N was less strong during spring wheat growtk period than during summer corn growth period.Meanwhile immobilization and uncounted loss of fertilizer N could occur.NO₃^--N could be leached ont of 130cm soil body during rainy season with more than l Omg NO₃^--N/L in the fertilized lysimeters where the mean NO₃^--N content might be np to 33 mg/L.And NO₃^--N leaching loss was significantly correlated to the precipitation.However,the total leaching loss rate of fertilizer N was not high.

Abstract:The both sides of macro-and micro-symbionts were studied for host plant Bradyrhizobium strain compatibility of the cultivated peaunt.The results showed that (1) Bred cultivar was better than virginia type in nodulation and NZ fixation when the host plants were inoculated with strain 147-3 in greenhouse under condition of water culture.(2) Five serotype strains were determined by using agglutination in test tube and FA-indirect method.Nodulation competition and recovery were closely related to host cultivar.Rhizobium strain and indigenous rhizobium population.(3) The different host plant Bradyrhizobium strain combinations varied in the widely/sepecifically symbiotic compatibility and incompatibility.A widely compatible cultivalr,Xuzhou 68-4 with highly efficient nodulation and N fixation by strains tested,was identified,and a strong compatible strain 147-3 with broad host range was also indentified in greenhouse and field experiments.(4) The strong compatible cultivar-strain combinations produced significantly(P<0.05) higher pod yields than the incompatible combinations or uninoculated control.of 205 site trials for inoculation compatible combinations in the different parts of China from 1987-1990,the frequence of yield increase was 97%,the average yield increased by 421.5kg/ha,15.1%,compered with uninoculated control.

Abstract:Studies of the root eaudates of wheat shoots on the growing amount and denitrification activity of the dominant denitrifiers species were conducted by the sterile aquicultural experiments.The results indicated that the rhizosphere effects of the two different genotype wheats in the denitrifiers are significant.The total amount of the bacteria are larger and the activity of denitrification are more intensive in the rhizosphere of Zhenyin No.l than those in the rhizosphere of Baofen No.7228. The components of amino acid of the root esudates of Zhenyin No.l are similar to those of Baofen No.7228,but the quantity of amino acid,the former is larger. The Table of resistance to streptomycin on the denitrifiers has no effect on the activity of denitrification.

Abstract:Excessive salt in salt-affected soil affects the growth and development of crops.Although soil salinity affects the growth and development of crops at all the growth stages,the salt-sensitiveness of some crops differ remarkably at various stages.To lerance to salinity is not a fixed property of a species but varies with the growth stages of the crop.A pot culture experiment was conducted to determine salt tolerance of barley and wheat at various growth stages.The soils tested were salinized at various stages with distilled water containing salt at four levels.After salinized,the osmotic potential of soil solution increased by 0,-0.4,-0.8 and -1.6MPa,respectively.

Abstract:In this work,the forms and availability of Cu,Zn,Mn and Fe of principal agricultural soils in Gansu Province were studied.The results showed that the contents of Cu,Zn,Mn and Fe in the experimental soils were 22-24mg/kg,73-74mg/kg,542-772mg/kg and 25685-38355mg/kg respectively.Of the four soil types tested the contents of Cu,Zn,Mn and Fe were the lowest in irrigated desert soil but the highest in cinnamon soil.Most of Cu,Zn,Mn and Fe in the soil occur in residual mineral form and bound to iron oxide (amorphous and crystalline).Both biological experiment and statistical analysis pointed that the exchangeable form and the form loosly bound to organic matter were the most available forms of Cu,Zn,Mn and Fe for plants.

Abstract:A study on the soil-rice system pollution by the Cd-Zn mixture in nature was conducted using the pot-culture method.There existed some differences between the Cd-Zn combined pollution and single-factor pollution of Cd (or Zn) in the soil-rice systems.The differences included changes in the biological yield of riot and the concentrations of Cd and Zn in brown rice and relationship beFween biological yield of rice and Zn/Cd ratios of brown rice.According to the conclusion,.mathematical model for weighting combined pollution of Cd and Zn in soil-rice systema was deduced.The calculation results obtained by applying the model showed that the maximum allowable concentrations of Cd and Zn in the soil under the combined pollution condition were 1.0 and 400mg/kg,respectively.This provided a basis for working out the soil-environmental quality standards for Cd and Zn.

Abstract:The genetic characteristics of the warpic soils in the whole Chine were found in the present study to include;(1) Raising of land surface and thickening of the.cultivated layer;(2) Increase of organicmattcr and N,P,R and other nitrous elements;(3) Rising of soil moisture;(4) Leaching out of soluble salt and gypsum; (5) Leaching and replenishing of carbonates and clay;(6) Vanishing of warpic stratification and improvement of soil physical preperties.The paper also summarizes the characteristics of the diagostic horizon of warpic soils (warpic epipedon); and pointed out the position of warpic soils in the classification system.As anthropic soils,the warpic soils are much defferent from the arid soils,the udic soils, the Inceptisols and the Entisols.At last,the paper divides the warpic soils into eig subtypes:commonic,hydragric,Baltic,udic,fimic and frigic warpic soils,xnd puts forward the indexes to the warpic soils.

Abstract:The project "Management of B and Zn nutrition in oilseed crops in China",called ACIAR Project 9120,is supported by the Australian Center for International Agricultural Research (ACIAR).The project was carried out from July 1992 to July 1995,and the achievements of the project obtained have been highly appraised by the scientists both at home and abroad with major achievements summarized as follows:(1) Systematical study on the cultivar difference of oilseed rape in responses to B deficiency skowad that seedling mortality after transplanting,green leaf areas and root gro wth rate are the main plant traits for identifying B-efficientc genotypes of rape.