Abstract:The general direction of research work on soil science should be "to study the material composition, properties, cycling and energy transformation of materials in pedosphere and their effects on human living environment, especially on the sustainable development of agriculture",which is a new proposed tendency of studies on soil science under influences of current situation of natural science development and resource environment. Soil science must make an important contribution to that mankind enjoys enough foods and a clean environment. Soil fertility is a primary material base for the establishment of sustained agriculture, and continuously promoting soil fertility to get stable high crop yields via regulating the deterioration and rebuilding processes of soil fertility is the fundamental measure to establish sustained agriculture. Much attention should be paid to the regulation of N, P and K fertilizer ratio and balance fertilization, to the promotion of nutrients recycling in farmlands and to the prevention of soil fertility deterioration. Most important researches of modern soil science in promoting the sustainable development of agriculture in China should involve systematic and long-term experimental studies in many aspects such as sustained agriculture and material cycling in pedosphere, soil fertility and sustainable development of agriculture, and soil water balance and regulation.

Abstract:The water problem of red soil in the hilly region of Central China and its effective management are described in this paper. Results show that in this area the drought in summer and autumn is severe due to unequal distribution of rainfall during a year though there is rich, precipitation annually, becoming one of the primary barriers affecting agricultural production. The water-storage capacity, especially the available water-storage capaciaty, in red soil is smaller and the water content available to plant growth is limited, which promote the progressive development of drought situation. Developing trickle irrigation in a planned way and soil surface mulching and use of storing water in deep layer of red soil by adopting the intercropping or rotation cropping with deep rooted plants could be effective in increasing water use efficiency of red soil.

Abstract:This paper propounds an improved kinetic model of monthly potential evapotranspiration E_Ti:

where i is a number of month, P_i the monthly mean atmospheric pressure(mb),t_i the monthly mean air temperature(℃),d_i the number of days in a month,U_i the monthly mean wind velocity measured at height 10-12m (m/s),w_oi the saturated water vapour pressure at t_i(mmHg),and h_i the monthly mean relative humidity. The monthly aridity k_i=E_Ti/r_i, where r_i is the monthly precipitation (mm);and the annual aridity K=(ΣE_Ti)/r_α,where r_α is the annual precipitation (mm).The soil moisture regime is udic when K<1, ustic when 1≤K<3.5, and aridic when K≥3.5. If k_i<0.7 for 8-12 months including May-September and t_i>1.5 for other months, then the soil moisture regime is perudic.

Abstract:Nitrogen leaching loss from double cropping rice fields was observed using a lysimeter system during 1991-1994. The main results are summarized as follows:1.The basic form of nitrogen leached from rice fields-was nitrate nitrogen(NO₃^--N) rather than ammonium nitrogen (NH₄⁺-N),so the N fertilizer applied in rice fields could result in the nitrate pollution to underground water due to N leaching.2. N application showed an obvious effect on NH₄-N concentrations in the percolateing soil depth of at 10-16cm, and a rather high NH₄⁺-N concentration occurred in urea plot compared with the NH₄HC0₃ plot, suggesting the possibility of more N-leaching in NH₄HC0₃ plot than in urea plot.3. The NO₃^--N level in the percolating at water soil depth of 90-96cm was consistently higher in the NH₄HCO₃ plot than in the urea plot, which may be ascribed to the obvious dif ference of transformation dynamics between NH₄HCO₃ and urea. 4. Under the conditions of an application rate of 300 kg urea-Nha^-1 and a percolation of 540 mm, a NO₃^--N leaching of about 23 kg ha^-1 and a NO₃^--N+NH₄⁺-N leaching load of nearly 27 kg ha^-1 were estimated for double-rice cropping paddy. 5. Based on the observed peak levels of 9 to 11 mg NO₃^--N L^-1 during a certain period of time and the limit of 10 mg NO₃^--N L^-1 in drinking water derived from underground water, we recommended a application limit of 150 kg Nha^-1 per rice-cropping season.

Abstract:Vertisol is greatly different from lateritic red earth, which is an extensively distributed zonal soil in Fujian Province, not only in soil properties but in soil fertility and agricultural production characters such as nutrient status, soil adsorption, moisture capacity, tillage, cropping system, fertilization effect, irrigation measures and crop yield and quality. The productivity of the vertisol exceeded that of the lateritic red earth. The yields of rice, sweet potato, peanut, sorghum and sugarcane grown on the vertisol were obviously higher than those grown on the lateritic red earth, and some of the crops mentioned above grown on the vertisol also displayed a better quality, because the former soil possesses higher contents of nutrients, stronger nutrient and water retention ability, and more appropriate aeration status in the soil surface than the latter, which caused a series of good agricultural production characters of the vertisol in drought resistance, fertilizer saving, suitability for intercropping etc..

Abstract:This paper describes the mechanism of dynamic monitoring of soil erosion with remote sensing technology, and establishes the interpretation keys for soil erosion degrees in Southern China. Analytical results based on the dynamic monitoring maps of soil erosion at three historical periods and the investigation and statistic data from Xingguo and Yuexi counties showed a parabolical type change of soil erosion in the mountainous and hilly areas of south China. It has an evident decreasing tendency of the soil erosion area in Jiangxi, Fujian, Hunan and Guangdong provinces of China.

Abstract:In the five types of soils on the north slope of the Shennongis Natural Conservation area, 2:1 type clay mineral was predominant, and there were few kaolinites. There existed a weak desilicification in the soils. For the yellow-brown soil and mountain yellow-borwn soil, the main clay mineral was hydromica, and there was a certain amount of vermiculite, as well as a few 1.4nm intergrade minerals and kaolinites. In the mountain brown soil, mountain dark brown soil and mountain brown coniferous forest soil, 1.4nm minerals (being mostiy 1.4nm intergrade mineral) were the major clay minerals, and there were certain amounts of hydromica and chlorite and a few kaolinites or vermiculites. For soils examined, the higher the sampling site, the stronger the eluvial depotassification process of clay mineral in soil was. The contents of various noncrystalline iron, aluminum oxide, increased obviously with increasing altitude in the area. The enrichment of noncrystalline iron and aluminum in case of higher altitude, which could play a main role in influencing the surface properties of soils, resulted mainly from the leaching losses of base and silica under the conditions of low temperature, high moisture and the complex or chelation eluviation of organic acid.

Abstract:The content of soil complexing in paddy soils developed from purple soils appears in the sequence of neutral soils > calcareous soils > acid soils and decreases with depth of soil layer, while the degree of organo-mineral complexing is in the order of calcareous soils > neutral and acid soils and increases with the depth of soil layer. The content and degree of <0.01mm soil particle aggregation are in the sequence of calcareous soil > neutral soils > acid soils. The content of soil complexing is positively related with the contents of organic matter, physical clay, Fe oxide and <0.01mm soil particle aggregation. But the degree of organo-mineral complexing is negatively related to content of organic matter, but insigificantly related to the combined forms of humus, the content of physical clay and the degree of <0.01mm soil particle aggregation. The complexing humus with mineral (content of soil complexing) in soil organic matter plays an important role.in soil particle aggregation. The content of <0.01mm soil particle aggregation depends on the content of soil complexing to a great extent. The relationship between complexing of organo-mineral and aggregation of soil particle is reflected by the relationship between the content of soil complexing and the content of <0.01 mm soil particle aggregation.

Abstract:The sorption of Cu, Zn,Ni, and Co in unit metal and binary Cu-Zn or Ni-Co systems was examined in 0.05 mol/L KClO₄ solution as a function of pH. At higher pH values, copper sorption was not affected by Zn but slightly decreased at lower pH. Zn sorption decreased in the presence of Cu, especialy when a high initial concentrations of metal were used. Co and Ni coexistence caused increases of pK_Co(int) and pK_Ni (int) and with a higher initial concentration pK_Co(int) incresed to a greater extent.

Abstract:The total and available contents of several heavy metal elements in thirty-seven Profiles of Fimus soils, different vegetable cultivated mellow soils and corresponding grain crop soils derived from different original soils in China were studied. The distribution characteristics of heavy metals, the relationships between total and available element contents, between elements and some soil properties, and among elements were elucidated. Results showed that as the ripening degree increased, there was an evident increase tendency of increase in the contents of Zn, Pb, Cu and Cd. Total and available metal element contents decreased with the soil depth. In Fimus soils, the elemental contents were higher in the upper horizon of 0 to 40 cm and decreased dramatically below the transitional horizons due to the thicker fimic epipedons. In the moderately and slightly ripening vegetable cultivated soils, element contents were higher only in the surface horizons and decreased sharply below surface horizons, but there were no evident changes in the profiles of grain crop soils.

Abstract:A simulated experiment and a pot test were conducted to study the time-dependent changes of soil mercury fractions and the influence of liming on them. the acid purple soil and the yellow soil were treated on different lime levels but the same HgClz level. Hg fractionation was carried out by using the sequential extraction method at 5, 14 and 30 days after treatment in the simulated experiment and at 35, 320, 610 days in the pot test. The different mercury fractions were distributed in the order of residual Hg > acid soluble Hg > alkaline soluble Hg and active Hg after HgCl₂ application. Their stability decreased in the same trend, and the other three fractions would gradually transform into residual Hg. The influence of liming on the distribution of mercury fractions occurred only within a certain time range and a proper dose range.

Abstract:在前文^[4]中确定了风干水稻土淹水密闭培养矿化氮有效积温式中K, n值计算方法后,我们对自己及其他作者来源于浙江、江苏、上海、湖南等省市共81个土壤矿化氮淹培试验资料作了分析,发现将矿化量转化为相对量形式后,不同土样间的氮矿化过程具有较高的相对稳定性,现报道如下。

Abstract:在黄土高原以及其他干旱半干旱地区,水分是影响农业生产的主要原因之一。冬小麦根系发达,最深可达5m^[1]生育期内耗水的40-50%主要来自土壤的有效储水^[2-3]因此储水状况在很大程度上影响冬小麦生长发育。建立土壤水分预测模型,预报土壤水分变化状况,对冬小麦品种选择,施肥量确定等农艺措施可以提出更合理的建议。本文的目的旨在充分供水的土壤水分预测模型研究的基础上^[4-5],建立非充分供水条件下土壤水分预测模型。

Abstract:众所周知,重金属进人土壤后,其活性受到土壤诸多因素的影响和控制,例如pH,温度、Eh、有机质、粘土矿物以及金属氧化物等,其中金属氧化物吸持重金属的性能对重金属的环境效应有着特殊的意义^[1]。我国南方土壤含有一定数量的金属氧化物,其中氧化铁是相当普遍的,而且有不同类型的氧化铁存在^[2]。因此,研究不同形态氧化铁对铜离子的吸持性能具有一定的理论价值和实际意义。