Abstract:This paper deals mainly with the content and distribution of chemical elements in different types of paleosol in loessial section of Luochuan, and the geochemical characteristics of elements in their translocation or accumulation process during process of soil formation from loess to paleosol. Comparing with parent material (loess), the average contents of Al, Fe³⁺ and K of the paleosol are higher than those of loess; whereas the average contents of Ca, Fe²⁺ and Na are lower than those of loess. The contents of AI, Fe³⁺, K in paleosol profile increase from bottom upward, and the highest value appears in the argillic layer, but the CaCO₃ content is lowest and caliche horizon is evident.

Abstract:Three representative types of paddy soil (well permeable, side bleached and gleyed) and three kinds of plant material(azolla, rice straw and milk vetch)were used in the experiment. The results obtained are summarized as follows: The content of 1.0-0.25 mm water-stable aggregates in the paddy soil of high-fertility ranged from 2-14% greater than that in the paddy soil of low-fertility. The destruction perecentage of structure and the degree of dispersion were higher for the infertile paddy soils. Soil organo-mineral complex is an important factor in determining soil fertility and it is closely related to the structure of paddy soils. It was found that about 80-90% of organic matter in paddy soils were associated with clay fraction, forming organo-mineral tomplexes. The quantity of comple."ted organic carbon was significantly correlated with the total content of organic carbon of the soil and aggregates (Fig. 3).the quantity and degree of additional complexing of organic matter (QAC and DAC) increased with the raising of fertility of the soil (Table 6).If the amount of organic material added to the soil less than 1% of the dry soil weight, the largest coefficient of complexing (CC) might be obtained(Fig. 7). According to the preliminary investigation of ‘QAC', ‘DAC' and ‘CC', the effect of the organic materials on the soil structure improvement is in the following order: Azolla>Rice straw>Milk vetch (Fig.4-6).

Abstract:The present paper deals with the subdivision of degree of soil alkalinization in Huang-Huai-Hai plain, the conclusions are summarized as follows:1. If the soil samples collected are typical and representative, the analytical data are reliable and variables selected (property indexes)are suitable, the application of "the analytical method of synthetic numerical value" in subdivision of degree of soil alkalinization may be realized satisfactorily. 2. Based on the major items and specific indexes suggested by the authors, the alkalized soils in Huang-Huai-Hai plain are subdivided into 4 grades, namely, tile alkali soil, strongly alkalized soils, moderately alkalized soils and weakly alkalized soils. The standards for subdivision of the alkalized soils are given in tables 2. According to the equation.

Abstract:The present paper deals with the morphological characteristics of soil structure and their relations to shringkage and swelling. Four paddy soils used in the study were collected from Taihu lake region. The content of clay in the soils ranged from 20-40%. Plough layer and plowpan of clayey paddy soil are characterized by puddling and compactness. Weathering may advance the formation of structural pores of the soil. There are internal relations between behaviors of soil shrinkage and swelling and regime of soil structure. There are three shrinkage stages of a clyey soil clod in the drying process, i. e., structural shrin-kage, normal shringkage and residual shrinkage. The ratios of tre change of soil volume to volume of water lost from soil in the three stages are <1,1 and <1 respectively. When structure of clod is destroyed, the structural shrinkage disappears and normal shrinkage develops. Therefore the characteristics of soil shrinkage can reflect the regime of soil structure.

Abstract:This paper deals with the forms and content of N, P, K, Ca, Mg, available SiO₂ and micronutrients in soils of tropical region in South China according to which fertility of the soils are evaluated. The hyrolyzable N extracted by 6 N HCl in soils under the tropical rain forest and high grass was about 60-80% of the total N, and it was only 30% of the total N in lateritic upland field. It may be because the frequent ploughing on lateritic upland field accelerates the rapid decomposition of nitrogenous compounds in soil. Results of the study are summarized as follows.

Abstract:The eroded soils are widely distributed in the Loessial hilly region of China, which is the direct result of water and wind erosion. As the result of development of the eroded soil, the surface layer of a soil became thin, infertile, and even barren finally. Therefore, it is greatly harmful to agricultural production. The eroded soils are generally classfied by the thilcness of eroded soil or that of soil layers remained. The principal components and stepwise discriminatory analysis are based on the data from the field observation and numerical coding. In this study, four important factors(erodibility, slope, intensity of land utilization and damage from unreasonable land utilization) which influenced soil erosion were used as variable for calculation.

Abstract:Results of the study on five soil profiles collected from west Liaoning showed that the soils developed on granite gneiss, red clay, loess and purple shale were rich in hydramica and smectite in their clay fraction. The smectite was mostly interstratified. In addition to detrital inherence of chlorite in loess, there had been chloritization of vermiculite in some soils. No apparent differentiation of clay minerals was found in the profiles. The composition of the clay minerals in soils was quite identical with their cation exchange capacity.

Abstract:Yellow earth is one of the main soil great group in the mountainous area of south China. Thirty four soil profiles derived from granite, Quaternary red clay, limestone, shale, schist and sandstone were analyzed. Total contents of B, Mo, Mn, Zn, Cu, Co, Ni, V, Cr, Ga, Pb and available B, Mo, Mn, Zn, Cu were determined. Conclusions are summarized as follows.

Abstract:A polarographic method for determination of molybdenum in soil was developed. In supporting electrolytic solution of sulphuric acid, sodium chlorate and amygdalic acid, a catalytic wave of molybdenum can be formed with a detection limit below 1 ppb. Since 1975, large amount of soil samples have been analyzed and it is proved satisfactory. For determination of available molybdenum in calcareous soils 5g of soil sample is extracted with 50 ml of ammonium oxalate and oxalic acid solution (pH 3.3),shake for 8 hours as conventional way. Transfer 10 ml of the extract into a small beaker (GG-17 glass) Evaporate to dryness. Ignite to destroy oxalate. Dissolve the residue with 2.5 ml of 2N sulphuric acid and 2.5 ml of 0.4M amygdalic acid, and then add 5.0 ml of 50% sodium chlorate, and mix evenly. Record the polarogtaphic wave from -0.1V. Removal of oxygen is unnecessary.

Abstract:菌根广泛存在于自然界,农作物中除十字花科和藜科外.一般都有VA菌根.豆科植物实际上是由寄主、根瘤菌和VA菌根真菌三种生物组成的共生联合体^[6].大量试验已经证明VA菌根的作用与植物的营养有关,尤其对磷素的吸收关系更为密切,豆科植物的结瘤和固氮也需要有足够的磷素供应^[7,1].

Abstract:棕色荒漠森林土(简称棕漠林土)或称“吐加依土”、“林灌草甸土”、“荒漠森林草甸土”和“胡杨林土”等,这是指发育在漠境地区胡杨林下的土壤.这种土壤在干旱地区有较广泛的分布,但研究资料较少.近年来,在塔里木盆地进行荒地资源综合考察工作中,对于这种土壤进行了初步研究,现报道如下.