Abstract:Base on the determination of soil age, spore-pollen in soil, composition of humus, soil micromorphology, X-ray diffraction, soil profile morphological character, soil physical and chemical properties, the genetic environment of dark loessial soil are discussed. The results show that dark loessial soil is a palesol. Many characteristics of dark loessial soil are the result of paleontology,climatic conditions. ¹⁴C soil age. The genesis of dark loessial soil includes three year ranges: 8100-8500 4600-7400, and 2000-3000 years B.P., which were cold in the climate. Spore-pollen appraisal. According to the appraisal of spore-pollen in Xian Luo-chuan, Ansai, Longxi and Xifeng,a conclusion can be drawn that the herb is predominant and the environment is cold and damp in the geneticperiod of dark loessial soil.

Abstract:Based on the radio-carbon dating, spore-pollen analysis, and physical and chemical data of some heilusol profiles in the loess plains of the eastern Gansu Province, this paper deals with the pedogenesis and evolution process as well as the laws of time-space variation of soil-forming intensity of heilusol. Heilusol profile is composed of some overlapping soil genetic horizons formed in different soil-forming stages with diversified properties. The formation of overlapping profile of heilusol successively underwent paleosol developing stage, Holocene loess accumussting and covering stage, and artificial cultivating, manuring and maturing stage. The overlapping feature in the appearance of heilusol profile and some compound genetic phenomena in the buried argillic paleosol horizon reflects an overlapping function of different soil-forming processes which occurred before and after the paleosol was buried.

Abstract:Quantity and intensity(Q/I)relationship of potassium (K) in three soils, a gray desert soil from Xinjiang, a dark brown earth from Jiling and a brown earth from Shandong, were determined at 5, 25 and 4090 to investigate the effect of temperature on K supplying power of the soils. With the increase of temperature, the AR° and △K° values increased, while the PBC value decreased. When temperature increased from 5℃ to 40℃, the AR° avlues of the gray desert soil, the dark brown earth and the brown earth increased from 0.0167,0.00074 and 0.0010 to 0.0348,0.0015 and 0.0014√mol·L^-1,respectively.

Abstract:The present paper deals with the characreristics of isothermal phosphate adsorption and desorption of warped irrigated soil collected from Yinchuan Plain in Ningxia. The data of isochermal phosphate adsorption of the twelve soil samples tested in a wide range of phosphorus concentration (up to 3097 ug P/g) were all found to be in close agreement with the Freundlich, Langmuir and Temkin equations. Their correlation coefficients (r) ranged from 0.931 to 0.999, with a very significant level (P<0.01). Among these equations the Langmuir adsorption isotherm seems to be the best fitting model.The P adsorption maxima of the soil samples tested as estimated by the Langmuir equation varied from 172 to 460 ug P/g. Their average was approximately 347±28 ug P/g. The relationships between the P adsorption maxima and some soil properties have been examined by simple linear regression analyses. Results have showed that P adsorption maxima were in fairly significant direct correlations (P<0.01) to the contents of physical clay and CaCO₃ in warped irrigated soil. According to the experimental data in the paper, the isothermal phosphate adsorption curves of soils could be used for predicting the requirement of phosphorus fertilizer for soils.

Abstract:Total 67 rock phosphate samples collected from 36 phosphate deposits and 30 phosphate fertilizer samples from main phosphate plants of China were studied.The content of Cd in rock phosphates from different deposits varied from 0.1 to 571 mg/kg, with an average value of 15.3±74 mg/kg. The highist value was found in the rock phosphates from Guangxi Province, varying from 12.2 to 571 mg/kg; while the lowest Cd content of the rock phosphates from Hubei Province varied from less than 1 to 2.10 mg/kg. Fortunarely. all the phosphate deposits of high Cd content are of less importance in the phosphate fertilizer production of China. If not counting these minor important but high Cd content phophase rocks the average Cd content of phosphate rocks of China should be 0.98 mg/kg.

Abstract:The toxicity of yellow-brown earth added with Cu, Cd, or Pb was researched using the MICROTOX method in the process of successively growing of paddy and wheat in a pot experinvent. It was confirmed that when three metal elements in yellowbrown earth were extracted by water, their concentrations were too low to display toxicity as contrasted with red soil; but when extracted by 0.1 mol L^-1 HCl, their concentrations rose obviously and toxicity appeared. The optimum quasi-conjunction equarion between metal's concentration in soil and its remanent luminosty (toxicity index) was founded on the basis of correlation significance at p=0.01 level. The critical remanent luminosity of soils containing metals was defind as 90% (EC₁₀). Accordingly, the critical concentrations of Pb, Cu and Cd in yellowbrown earth (grown with preceeding crop) were estimated to be 488-587, 17.8-25.3 and 1.11-2.12 mg/Kg soil, respectively.

Abstract:Good soil physical environment is a fundamental for gaining stable and high yields of crops. The return way of organic materials was controlled artificially in the present study. Recults from the nine-year filed location study show that in the case of continuous application of inorganic fertilizers, especially mono-application of inorganic fertilizers, in paddy soil from red soil, the soil structure was damaged, soil became more compact, the filth of soil became worse, the plowpan rose, and the land productivity declined as a result of decrease in the inorganic and organic colloids.

Abstract:In this paper, the experimental data of soil water in artificial swards are used to diteuss the annual variation regularities of soil water in sward. The dynamics of soil water in award is mainly affected by precipitation and the water consumption of grass. Precipitation in the raing season plays on important role in the supplement of soil water in arid sward.

Abstract:Soil surface acidity, as one of the most important characteristics of soil solids, is very Closely related with adsorption, floculation and other interface phenomena, and acid-base titration curve technique is widely used to describe the acidity. A model to describe the acidbase titration curves of variable charge soils was established on the assumption that all the H⁺ or OH^- added into soils were buffered by soil surface groups M-OH₂^+1/2, M-OH^-1/2, and M-o^-3/2 and equations concerning the relationship between equalibrium suspension pH and amount of acid or base added were derived according to the principle of mass balance and charge balance. The acid and base rirrarion curves and buffering curves were modelled using the model on computer and the results showed that Ka₁ has great effect on both acid and base titration curves, but Ka₂ inflenced the base migration curves only wuh no effect on acid titration curves. The model could well describe the acid titration curves of 3 variable charge soils. The model could provide soil acid intensity (Ka₁ and Ka₂), soil acid capacity (St), buffering capacity pH of soil acid and base at different pH, and greatest buffring capacity pH of soil. The acid capacity (St) was mainly determined by the content of soil clays and soil special surface, the acid intensity was mainly determined by the content of iron oxide. Buffering capacity of soils to acid and base was correspondance with K₁ and K₂. The experimental results of acid titration of 3 variable charge soils, red soil, lateritic red soil and latosol, could fitted well with the model. The model will be helpful in understanding the acidification mechanism, adsorption process and other surface processes.

Abstract:Sia paddy soils derived from three different parent materials were sampled from the Chengdu Plain which was one of the most important rice-growing regions in China to study the characteristics of the differentiation of iron oxides in various forms and its relation to the formation of the specific genetic horizon. Tlte results showed that the extent of the variation of iron oxides in various forms in the paddy profiles studied decreased in the following order: amor. iron oxide > free iron oxide > total iron. It was revealed that the content of total iron was closely related to the parent material from which the paddy soil was derived, and the content of free iron was positively linearly related to the content of total iron in the paddy soil, which suggested that it was also related to the parent materials to some extent, but the content of amor iron oxide was greatly influenced by the environmental conditions.

Abstract:This paper deals with the effect of organic material application on the chemical and thermal properties of HAs from brown soil, meadow soil and paddy soil in the field and incubation experiments. The results obtained are summarized as follows: In the field experiment, the number-average molecular weight(Mn) of HAs were markedly decreased by applying organic materials. For example, the Mn of HAs of CK, 18.7 (O₁) and 37.4 T/ha (O₂) of pig manure (PM) in brown soil were 1332, 835 and 578 zespectively. The same changes were found in other soils. PM was more effective than corn stalk (CS) in decreasing Mn of HAs in the incubation experiment. With the increase of the rate of organic materials applied. Mn of HAs decreased greatly. The Mn of HA in the incubated soil without application of organic material went up to 1768.

Abstract:1097 soil samples of 219 typical soil profiles, 114 ground water samples and 16 offshore sea water samples were collected from the sea beach of Jiangsu. The salt content and ionic composition of the samples were analyzed and the saline geochemical characteristics of sea beach soil and their regularities of variations were summarized se follows.

Abstract:Current situation and prospect of the studies on the loading capacity of soil for pollutants (LCSP) are briefly introduced in this paper. The values of LCSP which are based at present on the "black box" theoretics or take the "total amount" and "availability" as starting points are reviewed. The main problems existing in tLe present studies are described as follows. (1) there is a lack of long-term experimental results. Tests with wetland rice as an index for four years in succession showed that the significant difference of the LCSP value among the years appeared in the same soil. The coefficient of variability reached 51-66% and the highest value was 3.2-4.6 times as much as the lowest one. Thrr}fore the reliable values of LCSP should be acquired from the long-term experiment in a fixed region, and the lowest value is the appropriate one. (2) There is certain limitation in the choosing of chemical compounds. For instance, the marked differences were found in the yield decrement and the amount of As absorbed by rice plant at the same concentration of As added with various compounds.

Abstract:福建南亚热带的地带性土壤为砖红壤性红壤。在本地带沿海漳浦、龙海等县的低丘、台地玄武岩风化物上发育的一种暗色粘质土壤,历史上归属于砖红壤性红壤,经研究其性状明显区别于砖红壤性红壤,我们确定它为典型艳色湿润变性土。这种变性土与砖红壤性红壤呈复区分布。

Abstract:红外光谱这一近代的物理研究方法,近20年来在土壤有机质研究、土壤矿物鉴定等方面已得到广泛应用。此外近年来,我国主要土壤的粘粒部分和土壤中新生体等已获得了一些红外鉴定资料。为应用红外光谱进行土壤发育和特性的研究起了促进作用。