Abstract:The rhiizosphere is the microhabitat where plant roots are contacted with soils, and aria the region where soils, roots and microbes are closely combined and interacted on each other. The rhizosphere microorganisms may act as a "microbememlbrane" in the exchanges of nutrients between soils The dynamics of rhizosphere bacteria related to nitrogen transformation and their enzyme activities were investigated applying simulating pot culture tests with two kinds of soil and two genmtypes of wheat in order to understand the regularities of growth and decline of hacteria and their enzyme activities as well as the relations between them and nitrogen transformation.

Abstract:Three different tillage methods in 5 different farming regions of diangsu were surveyed by location test examine how these tillage methods effect the soil fertility and the yields of rice and wheat. The results show that sowing at the same term, the yield of wheat with minimumor no-tillage was more prebable to increase, with a greater increment on clay loam than on sandy foam; the yield of hand transplanted rice in no-tillage treatment tended to decrease, with:greater decrement on clay loam than on sandy loam also; and both the change ranges tended to increase grandually from raised south to north (32°10'N-34°30'N).Minimumor no-tillage notably the nutrient contents of the surface soil, but the soil bulk density below 7cm also,increased. Organic matter, available nitrogen, phosphorus and potassium all tended to decrease. Comprehensive analysis of soil fertility indicates that as for fertility enhancement, minimum-or ao-tillage was more advantageous for clay loam than for sandy loam. Based on extensive survey and comprehensive analysis, a new rotation-tillage system was put forward, in which minimum tillage is the principal part, minimum and no-tillage alternate and deep, shallow and no-tillage rotate periodically. This new system continued and developed the merits of different tillage methods, and correctly handled the contradictions between multiple cropping and farming season, farming and promoting the soil fertility, high yield and high efficiency, thus promoting the development of agronomics in Jiangsu. In recent years, this new tillage system has been extended to a total area of 794000ha in Jiangsu. The application of this new rotation-tillage system has increased yield by 7.5×10⁹g and net income by 3.98×10⁹ yuan and gained significant social, economic and ecologic benefits.

Abstract:The pot experiments were carried out to investigate the availity of the residual N from rabbit excreta and ammonium sulfate and its relationsliip with the residual N components by using the isotopic ¹⁵N tracer technique. The results indicated that the residual effect of fertilizer N was low. The residual N from rabbu excreta utilized by wheat plant was 3.6-4.8%. Most of the residual N (82-89%) was left in the soil and 7-14% of the residual N was lost; while the corresponding values for the residual N from ammonium sulfate were 3.6-5.3%, 69-76% and 19-28% respectively. The amounts of amino acid-N and acid hydrolyzed-unidentified N fractions from these two fertilizers were relatively high. However, the residual N from ammonium sulfate in these two fractions was much more than that from rabbit excreta. Ninety-five percent of the mineralized N from the ammonium sulfate left in the soil came from these two N components while that for rabbit excreta was only 66-84%.In the paper the signific;ince and application of the ¹⁵N% dff value are also discussed.

Abstract:A comparative experiment was systemarically conducted to study the response of corn to different rates of Mn application under the conditions of soilless culture, pot experiment and field trial. The results indicated that there were no significant differences in the shoot dry weight and grain yield of corn between the treatmews with Mn input rate as high as 55 mg/L (500 times higher than normal) in nutrient solution and MnSO₄·H₂O rates of 5g/kg soil in pot Gut 1500 g/m² in field trials and their respective control treatment. Also, no remarkable change in the Mn uptake by the plant as recorded when Mn concentration in nutrient solution was below 1.1mg/L and MnSO₄·H₂O races were 0.17g/kg soil or lower in pot culture and 1500g/m² in field trials as compared with CK treatments. The plant Mn content increased linearly as the medium (rockwool and pot soil) Mn content increased over the above-mentioned Mn rates, showing a characteristic passive Mn absorption of the corn.

Abstract:The present paper deals with the production, variation rhythm, decomposition rate and mineral contents of litter in the subtropical monsoon evergreen broad-leaved forest in the Dinghu Mountain. The organic matter and the nutrient elements in the leaffall of the main edificators in this forest were also studied. The 5-year observation results show that the annual litter ranges from 7t/ha to 11t/ha, with an average of 9.2 t/ha. The variation rhythm of the litter is remarkable; there are 2 peaks in each year: one occurs at the beginning of the rainy sezsan (April or May), the other appears at the end of the rainy season (Septembet or Dctober). But in dry season the litter production is low and has little annual variation. In the total litter, the rhythm is conspicuous in the leaf fraction, while it is imperceptible in twig and miscellany fractions.

Abstract:Thirteen satttples of typical zonal soil were collected from whole China to study the distribution of the organemineral complexes separated by the fractional peptization method. The total amount of organo-mineral complexes (G₀+G₁+G₂) was significantly correlated with the content of clay particles in soil. The content of G₁ fraction decreased but that of G₂ fraction increased from north to south. The ratio of G₁ to G₂, ranging from 0.25 to 12.35, gradually decreased from north to south. The correlation coefficients between organo,mineral complexes and soil-forming factors, mineral elements, humus composition and basic properties of different soils were calculated. G₁/G₂ ratio was positively related to latitude, but negatively to the mean annual temperature and rainfall, the content of Gl fraction was positively correlated with total Mg and Ca, degree of Ca saturation, pH and CEC, and G₂ fraction was positively related with total Fe and Al, free and complex Fe and Al, but negatively with degree of Ca saturation, pH, and CEC. In addition, G₁/G₂ ratio was positively related to HA/FA ratio. It was thus revealed that the distribution of organo-mineral complexes (G₁ and G₂)was related to the forming conditions and properties of zonal soils. Therefore, the content of organo-mineral complexes and G₁/G₂ ratio could be used as a reference for soil classification.

Abstract:Jia hu plain is looted at the lower Yan}tse River Delta. paddy soils occupy about 88% of the cultivated lands. Historically, most of the paddy soils were used for rice-wheat rotation. At the present time, laree areas have been adopted for rice-rice-barley (or rape) rotation.The present article deals with the interelation between Soil development and sedimentary environments in Holocene period. In order to study the sedimentary substances, We chose four kinds of representative paddy soils (lacustrine loamy albic paddy soil, silt-clayey yellow motrled paddy soil, silt. paddy soil, submgergic clayey paddy soil) as testing samples, dating of ¹⁴C, distribution of ancient ruins, particle parameter analysis, combination of microfossil and spore-pollen, clay mineral and mineral composition test were used to indicate the kinds of sedimentary substances. The results obtained show that the formation of different paddy soils are deeply influenced by the sedimentary environments. There are four sediments in the Jia hu plain, they are Tai hu lake coastal deposits, continental deposits, marinecontimental deposits and laeustrine deposits respectively The different sediments affect significantly the distribution, characteristics and development of paddy soils.

Abstract:The variabilities of soil moisture, Salinity and infiltration and their inter relation were aoalyed by using the theoretical method of serial analysis in this paper. Satisfactor results were obtained by the method. The maximun entropy spectral method ometry estimation used had a high resolution ratio and could expose: the superior eperiod. The intwer relations among the series were exposed by the mutual spectral analysis. The resualts obtained by a multidimension AR(p) model could fit well with the mtaswied results.

Abstract:Spatial variability of saturated hydraulic conductivity, clay and physical clay particles, water-stable aggregate and porosity of red soil were studied using a geostatistical method. Field experiments were undertaken on a red soil at Yingtan, Jiangxi Province, Clhina. There were thirty sampling locations in the experimental field with an area of 50×100 m. The autocor relation distances of various physical parameters determined in field were different according to the analysis of sermivariogram and autocorrelogram: saturated hydraulic conductivity of soil 42.0 m, clay 43.5m, physical clay 56.0 m, macroaggregate 47.0 m, total porosity 65.0m,porosity in diameter of > 0.03 mm 37.5 m and clay in layer B (20-30 cm) 45.0 m. The estimation of seven soil parameters by using Kriging interpolation method shows chat Kriging method was obviously better than Jackkniffing technology. Its estimated error was lust 67.5-30.5% of Jackniffings. Tlae saturated hydraulic conductivity of soil was esti0 mated by porosity in diameter of >0.01 mm and the clay content in B layer was estiamted by clay content in A layer in terms of Colcringing technology. Its estimated error was only 54.1-65.5% of that of linear regression method arid 36.2-86% of Kriging's respectively.

Abstract:The effect of magnetic plLouph on ploughing resistance was studied. The results show chat magnetic plough could reduce ploughing resistance markedly. Magnetic two-share plouph reduced ploughing resistantce by about 21%,While magnetic four-share plough decreased ploughing resistance by about 10% and saved oil by about 10%. The principal mechanism is that magnetic field could cause the changes of soil physical chemical properties. For example, magnetic field could cause a reduction in the specific surface, cohesive force, shear force, zeta-potential etc. of soil and an. increase in the aggregation and water potential The results show that magnetic plough would be efficieat in reducing ploughing resistance, saving energy and improving soil physical and chemical properties.

Abstract:In the study, an isolation of soil particles in different sizes in terms of the dry sieve method and gravitational dry sedimentation meshed was carried out to explore the relationship among the contents of DIET and BHC, the size of soil particle and the content of organic matter in different types of topsails in Beijing region during windy and dusty seasons. The results obtained show that DDT and BHC remaining in the soils were mainly distributed in the soil particles of <0.25mrn in size and the amounts of DDT and BHC in <0.05 mm soil particles that could be earily floated by air current accounted for 41-89 and 30-81 percent, respectively, of the total amounts in the original topsails. It was found that within a certain size range, the smaller 21ae size of soil particle, the higher the contents of DDT and BHC were, and that the contents of DDT and BHC were positively correlated to the content of organic matter (P<0.01) and that the proportions of DDT, BHC and some of their metabolites and isomers in soil particles changed with the soil size.

Abstract:Advances in soil potassiurn(K) research in the last decade was reviewed. Soil Potassium is usually divided into water soluble. K, exchangeable K, non-exchangeable K and mineral K. The exchangeable K can be further divided into surface adsorbed K and specifically adsorbed K. The contents of K in various forms and their transformation processes determine the K-supplying pawer of soils. Methods commonly used to derermine thermodynamic parameters of soil K exchange processes are the equilibrium method and kinetics approach, The thermodynamic parameters obtamed can be used to explain the mechanisms of soil K transformation. For kinetics study of soil K, batch equilibrium technique, miscible displacenment techmique, and ion exchange resin method have been used. The results can be descrihed by using the first order equation, Parabolic: diffusion equation and other functions.Potassium dynamics in rhizosphere has received great attention in recent years. The results have been used to evaluate the characteristics of soils in K supply.

Abstract:Three-Gorges Project has multipie influences on ecology and environment, including good and bad ones. This paper lay emphasis on the factor analysis of sudden and gradual changes and their effects. The exploitation of Yangtze Basin is of great significance in the development of our national economiy. The effects of Three-Gorges Project on ecology and environment must be thoroughly studied so as to provide the countermeasures, make the most of Yangtze Basin resources, harmonize the relationship between economic development and envira nmental improvement and give full play to the project benefit.

Abstract:帕·劳斯特(Bad Lauchstadt)土壤肥力试验地位于柏林西南部,土壤是黄土母质发育的黑土。它建于1902年,是德国最古老和最重要的土壤肥料研究基地之一,它的试验设计方案实际上是八项方案的六项减缩方案。这项典型的方案目前世界各地仍在沿用其中有机无机肥料配合更有独到和预见性,这对提高土壤肥力和增加产量是有深远意义,作物种植的时间空间重复也是设计的重要特点。试验表明有机肥料对土壤有机质的平衡、氮素平衡、磷钾平衡和微量元素平衡都起重要作用^[5].施肥措施刘一改良土壤结构、改善微形态特征以及容重、持水量等都有明显效果。

Abstract:研究非饱和土壤水分运动的基本途径是数值模拟和实验。用计算机模拟非饱和土壤水分运动从60年代以来不断有研究成果,非饱和土壤水分运动的研究经验到理论,由定性到定量的深刻变化。