Abstract:The semi-theoretical and empirical calibration curve,θ_v=(T/T_a-T_s/T_a)/(K_w^0.5-1),soil water content(θ_v) versus propagation time(T)of electromagnetic wave along TDR probe inserted in soil,is used to calculate soil water content.In this experiment TDR is used to measure T_s/T_a value of oven-dried soils with different texture and bulk density.The result showed that T_s/T_a value from 1.61 to 1.80 for four soils,and the larger bulk density,the larger T_s/T_a value.For three agricultural soils the average T_s/T_a can be used as 1.68.The column experiments on sandy loam and loam showed(water content from oven-dry to saturation) that different T_s/T_a values lead to water content deviation 0.001~-0.005 cm³ /cm³ and 0.007~-0.006cm³/cm³ respectively.For sandy loam with varied soil temperature,water content measured by TDR deviated from real values when it is higher than 0.30 cm³/cm³.The higher temperature,the lower water content measured.This paper also indicates the deviation range of measured water content with temperature increasing(or decreasing) 1℃ and its modification method.

Abstract:Three soils with different texture(sandy loam,eolian sand,warp clay) were selected in Huang-Huai-Hai Plain.Each treatment consisted of two 1.5m by 1.5m plots,one of which had been irrigated with about 56kg water two days before the dye experiment to achieve different initial water contents.Brilliant Blue was chosen as the dye tracer.One day after the irrigation,a vertical lm by lm soil profile was prepared.Photographs were taken for graphics analysis.And the relations between the occurrence of preferential flow and soil type,initial water content were studied.The results showed that susceptibility of different soils to preferential flow was different Structured soils were more prone to produce bypass flow.The initial water content had a pronounced effect in sandy loam soil and eolian sand soil and no effect in warp clay soil according to the deepest transport depth of the dye.The preferential transports of paclobutrazol and Cl^- were carried on sandy loam soil.Cl^- was detected at every site where preferential flow existed and had a much higher content than soil background content Paclobutrazol could also be detected even at the deepest transport depth of the dye.

Abstract:The status of soil aggregates is an important factor affecting soil fertility.In this work,the fractal model was used to study the soil aggregate structure under different stand management patterns and to inquiry the relation between fractal dimension and soil fertility.The results indicated that the higher the content of water stable aggregates and water stable big aggregates in soil,the smaller the fractal dimension of soil aggregates,and the higher the soil fertility.There were remarkable regression relationships between the fractal dimension of soil aggregates and the contents of water stable aggregates and water stable big aggregates.The fractal model could be a new tool for the research on soil fertility.

Abstract:Elemental composition,molecular structure,and physical and chemical properties of Ca bound and Fe/A1-bound humus in soil were determined by chemical and instrumental analyses.Results showed that the contents of C,H and N were higher in Fe/Al-bound humus than in Ca-bound humus,while the ratios of C/H and C/N were higher in Ca-bound humus.The aromaticity of humic acid in Fe/AI-bound complex was higher than in Ca-bound complex,but that of fulvic acid was higher in Ca-bound complex.Fe/Al-bound humus had the higher thermal stability and the stronger affinity for coordinating metal ions than Ca-bound humus.

Abstract:Effects of water-soluble products of rice straw,Chinese milk vetch and pig manure on precipitation and adsorption of Cu and Cd on a red soil and a fluvo-aquic soil were studied.Two opposite effects,pH^- raising effect and complexing effect,were observed.At same pH values,the water-soluble organic products depressed Cu and Cd precipitation and adsorption by forming soluble organic-metal complexes.Cu adsoprtion was more strongly inhibited than Cd adsorption because of the stronger complexation ability of copper.The adsorption isotherms showed that the water-soluble products enhanced Cu and Cd adsorption by raising pH values when the pH values were not adjusted.

Abstract:It was simulated that plant roots excreted different kinds of organic acids under phosphorus stress,and the effects of citric,malic,oxalic and tartaric acid on kinetics of phosphorus adsorption by calcareous soils have been investigated by flow technique method.Results show that all these acids can reduce phosphorus adsorption by the soils and the extent of reduction is closely Belated to the kinds of organic acids.The ability of organic acids to reduce phosphorus adsorption in calcareous soils is in the order of oxalic≥citric>malic≥tartaric acid.The effect of pH on reducing soil phosphorus adsorption by organic acids was very complicated.For example,the inhibiting effect of tartaric acid on phosphorus adsorption by soil 2,3,and 4 increased with increase in pH from 6.5 to 8.0,while the inhibiting effect of tartaric acid on phosphorus adsorption by soil 1 decreased with increase in pH.Regression analysis reveals that the first order Kinetic equation is the best one to describe the phosphorus adsorption kinetics as affected by organic acids,followed by Parabolic diffusion equation and Two-constant rate equation,and then by Elovich equation.According to the research,the influence of low-molecular weight organic acids on kinetics of phosphorus adsorption by the soils is a first order reaction.Organic acids inhibit adsorption mainly by eliminating the phosphorus sorption sites in the soils.Compared with control,All the four kinds of organic acids tested can dissolve a large amount of CaCO₃ in calcareous soils,thereby considerably reducing phosphorus adsorption by soils.

Abstract:For a long time past,We all think that the potential-determining ions are H⁺ and OH^- for hydrated oxide surface(variable charge surface).So the surface potential(Φ₀) is only the function of pH,and irrelative to the electrolyte concentration.Therefore,the surface of hydratied oxide is termed as constant potential surface.From the discussion in this paper,it is clear that the surface potential of variable charge surface is strongly dependent on the electrolyte concentration.So variable charge surface is not a constant potential surface.

Abstract:This is the second paper to study the fertility evolution of red soil derived from Quaternary red clay in low-hilly region in the middle subtropics from point of systematic view.The characteristics of soil chemical and biological fertility evolutions under various land use patterns were researched,then the evaluation indexes were selected with cluster analysis and their weight coefficients determined with factor analysis.Results showed that the chemical properties had dropped to the "Valley-bottom value" in forest and waste land systems without input.Soil chemical fertility in cultivated-land and garden systems increased with land reclamation and soil maturation process,the content of soil nutrient and exchangeable Ca and Mg raised,but exchangeable A1 dropped.The evolution of soil biological fertility was similar to that of soil chemical fertility.Similarly,the soil biological fertility in cultivated-land and garden systems increased with land reclamation and soil maturation process,it was shown by the raise of soil organic matter content,the improvement of humus quality,and the increase of microbe and activity of soil enzyme.The composition of exchangeable canon and the soil nutrient content can be used as the indexes to evaluate soil chemical fertility evolution,especially the former is more important.The changes of soil organic matter,humic acid,total amount of microbe,microbial biomass C,activity of urease and phosphatase reflected mainly the evolution of soil biological fertility.

Abstract:Release rates of non-exchangeable potassium(NE-K) in 25 selected soils of 12 primary soil types from northern China were studied using a continuous flow apparatus and 0.10mol/L HCl as extracting solution.Results indicated that NE-K was released slowly for a long time.Maximum release rate of NE-K varied from 0.195 to 2.30mg/(kg·min),average release rate of NE-K in 600 minutes ranged from 0.066 to 1.121mg/(kg·min),and the NE-K release lasted for more than 600 minutes in most soils.The NE-K released in 600 minutes accounted for 5.4% to 39.6% of the total NE-K in the soils.Generally speaking,the release rate and percentage of soil NE-K gradually increased from the east to the west of China,the release parameter of NE-K were the highest in northwest soils and the lowest in the northeast soils,on average.The release rate of NE-K was very closely and positively correlated with the potassium uptake by corn seedlings in the potassium depletion experiment in greenhouse.Therefore,it could be used as a reliable index of potassium-supplying power in soil.

Abstract:Based on the assemblage characteristics of bioclimatic zone,aridity,mean moisture content of sandy land,precipitation,etc,five zone,i.e.,desert,semidesert,steppe,subhumid and humid zone were divided for sandy lands and deserts of China.The moisture movement,stable moisture contents and available moisture storages in each zone are summed up and analysed.The main factors affecting moisture dynamical variations of sandy lands are discussed.The concrete measures for afforestation and selection of tree species in different sandy zones are put forward.Finally,the development and agricultural production directions,economic benefit of irrigation agriculture,and future development tendeney of different sandy lands are discussed.

Abstract:In the present paper the concept of the geo-zonal and unzonal distributions of soil water resouces is defined and the variation rules of the distribution of soil water resources in loess region,China is analyzed.Under homogeneous condition of vegetation and landfonn there is a geologically zonal distribution law which soil water content decreases from south to north and increases from the mountain top to bottom in loess region,China.In the ogeneous soil water zone the differences in land-types,variation of slope direction and mountain slope gradient soil water content,namely unzonal distribution of result in the local water resources.

Abstract:Huangtang township which is located in the catchment of Tai Lake,Jiangsu Province and also a developed economic area was selected as a test area for this project.A dynamic monitoring and pre-warning system were set up for the project based on GIS.It supported by personal computer,peripherals like digitizer,plotter,printer,some software such as ARC/INFO,MAPINFO,FOXPRO,and prewarning models which was developed by author.Two temporal(1984 and 1994) informations of land use,soil fertility,soil and water resource pollution were chosen for database construction and dynamic analysis.Result of this project showed that in the area of developed economy just like Huangtang township,with developing rural industries and increasing population,the farmland resources and farmland area per capita are decreasing,the land area for civil use are increasing,and the environment of soil and surface water are suffering from industry and chemical fertilizer pollution.Meanwhile,applying a large quantity of chemical fertilizers to soil results in N,P,K unbalance.Some measures have been put forward for keeping the dynamic balance of the sum of farmland area.

Abstract:The correlation and their concomitant factors between some metal element contents in the soils of Chaohekou Area,Liaoning Province,have been comprehensively studied by correlation and regression analysis.Results show that correlation coefficient for elements more or less similar in geochemical properties attained a significant or a very significant level.Four principal factors were selected by principal factor analysis,they represented 92% of measurement information for 14 elements.Taking the eigenvector corresponding to the first and the second principal factor as Axis X,Axis Y respectively,the 14 elements were divided into 5 groups,and regression equations were established for most the elements.It is also shown that the accumulation characteristic of the elements are affected by the source of elements and by external environmental conditions as well.

Abstract:The adsorption of chlordimeform on red soil and vegetable soil was studied in this work.The results showed that the clay fraction of the soil was principally responsible for the adsorption phenomenon,though oxides in the soil also played a certain role.Soil organic matter also had a high adsorption capacity for this pesticide,but its influence on the adsorption phenomenon was very slight because of its low content in the soil.The different characteristics of chlordimeform adsorption on two studied soils were also discussed in this paper.

Abstract:Amelioration experiments of marine medium-saline soil by mixed cultivation of sesbania growing in waterlogged soils with fish culture(MCSWFC) was carried out in soils improved with single fish culture(SFC) previously,with cultivating sesbania in upland as a control.Results obtained were as follows:1.Sesbania plants grew much better in waterlogged soils with fish culture than in upland.The fresh weight of lateral roots,root nodules and seeds yield of sesbania growing in waterlogged soils was 10 times,15 times and 1.5 times of that in upland respectively.2.Efficiency of salt leaching in soil depth of 0-20 cm in the three treatments was as following order:MCSWFC>cultivating sesbania in upland(CSU) SFC,while it in soil depth of 0~100 cm was MCSWFC>SFC>CSU and there were same tendencies for SAR and Na⁺/Ca²⁺ ratio.3.Total soil nitrogen and alkali-hydrolyzable nitrogen in soil depth of 0-10 cm in MCSWFC was almost the sum of those in the treatments of CSU and SFC and it was also taste for soil organic carbon.And the increase rates of soil available phosphorus and slowly available phosphorus were MCSWFC>CSU>SFC.

Abstract:Pot experiment for studying the status of K nutrition of tobacco plants was carried out in 1995 and 1996 by liming or adding FeSO₄ or sulfur powder to regulate the pH value of soils.The main results obtained are as follows:The average yield of tobacco leaves is higher in the soils with pH 5.33 or 6.1,but that is lower in the soils with pH above 6.1 or below 5.0.The absorbing capacity of potassium by tobacco plants and the efficiency of potassium fertilizer are highest in the soils with average pH 5.33,below or above this pH value the two indexes are lower.According to the study it is shown that the desirable yield of tobacco leaves with K content about 3.3% can be expected if tobacco is planted in soils with pH 5.33~6.1 range and N,P and K fertilizers is fully supplied.It is pointed out tentatively that soil pH 5.0 is a critical value that tobacco plants were injured by active Al.

Abstract:多孔介质传热传质过程在自然界和人类生活、生产中广泛存在,土壤就是一类最典型的多孔介质.随着农业工程化的进程,人们对土壤中水、肥、热的吸收、保持和迁移规律越来越重视,研究也越加深入.尽管目前多孔介质传递理论发展较快,有关的实验研究却相对滞后,热质迁移特性参数比较匮乏^[1].实验研究不仅为理论分析提供必须的参数,也为各种理论模型提供可靠的验证.未饱和土壤内热量与质量迁移不仅与土壤内部物性有关,还与外界自然环境条件有关.而且人们更加关心特定土壤的内部水、盐、热诸要素的迁移特性受当地气候条件的影响情况,以便在各类生产活动中采取措施.

Abstract:一般情况下,土壤学的研究重点是整个土体.但是,土壤是一个非均质体,其中某些微域环境不仅和整个土体有巨大变异,而且其重要意义往往不亚于整个土体,甚至,从某种意义上说,更为重要.这一微域环境过去或者研究得不够,或者研究很少.鉴于其重大意义,这些微域环境的研究有可能逐步形成一个土壤学的新分支——微域土壤学(Microzone soil science)(暂名).土壤微域是指土壤中某些具有和整个土体在性质上有巨大差异并对土壤生产力和植物营养有重大意义的区域.