Abstract:The present paper deals with the conception, character and evolution of tilth of paddy soil in China. According to physical, chemical and micromorphologieal stndiea, ten tilth types of paddy soil was divided. It is considered that the tilth of paddy soil may be used as the basis on which the soil species are classified.

Abstract:1. A comparison of the solubility diagram of the phosphate compounds in soils with the measured curves showing the actual relationships between phosphate potentials and lime potentials and between phosphate potentials and aluminum (or ferric) hydroxide potentials reveals that there may exist two mechanisms of phosphate fixation.

Abstract:The present paper deals with the formation and classification of podzolic soils developed under cool-temperate zone with coniferous forest in northern part of Da Xinganling. Evidence from field survey and laboratory investigation indicated that the podzolization is the principal soil forming process in this region. The salient genetical characteristics are as follows:(1) By the study of soil humus, it has been shown that the organic matter of soil almostly keeps in partly decomposed form, the composition of humus is mainly fulvic acid and the ratio of A/F remains 0.08-0.61. In addition, in comparison with humic acid in strongly podzolized soils in some other regions, the nature of light density of humus acid in this soil is just about the same. The value of E₄:E₅ is near 5. The degree of structure condensation of humic said is decreased, whereas the fatty branched chain and the degree of ionization are increased. Under such condition, the ability of chelation with R₂O₃ by soil humus is accelerated and thereby promoted the development of podzolization of the soil.

Abstract:1. The regularities of the transformation of the ferrous sulphate in the soils and organic manure, and the mechanisms of the effect of ferrous sulphate on controlling chlorosis of apple tree were studied. 2. The chlorosis of apple tree was cured rapidly by the application of 2% ferrous sulphate solution to the roots in hole, at a rate of 60 liters per tree. The curative effect lasted a month.3. By application of a mixture of ferrous sulphate and organic manure in the ratio 1:20 (or 1:10;1:5) to the roots in hole, at the rate of 22.5 kilograms per tree, the chlorosis of large apple tree was cured after a month. The curative effect lasted about a year. Injuries occured by watering after the treatment with the mixture in the ratio 1:5. 4. Favorable effect was acquired in hole application of mixture of ferrous sulphate and organic manure in the ratio 1:20 (or 1:10) at the rate of 22.5 kilograms per tree after the application of 2% ferrous sulphate solution 60 liters per tree. The curative effect of this method lasted about a year. 5. The application of manure alone to the root zone was ineffective under our experimental conditions.

Abstract:A soil sample submerged in water previously was saturated with Cu⁺⁺ by 1 N CuCl₂, and its cation exchange capacity was then determined by leaching with 1 N NH₄Cl. However, the eation exchange capacity obtained was always lower than untreated samples. This indicated that certain amounts of Cu⁺⁺ were attracted by exchange site. The △ valve of CEC showed a well positive correlation with dithionite-citrate soluble Fe₂O₃ and clay content of the soil samples used in present experiment. (r²=0.51 for Fe and r²=0.64 for clay; n=25).The total amount of fined Cu⁺⁺, including a part of complexed form was determined eolorimetrically in the same extracting solution used for CEC measurement of soils treated with Cu⁺⁺. It was showed that there is not any correlation between the total amount of fixed Cu⁺⁺ and the organic matter or clay content of the samples. However, the difference between the amount of fixed Cu⁺⁺ and △ value of CEC was correlated with the organic matter content and C/N ratio of soils.

Abstract:In order to study the adsorption of rations and anions by red soils in relation to the electric charge of the soil, electrolyte solutions of KCl, NH₄Cl and K₂SO₄ in concentrations of 0.001, 0.01 and 0.1 N were equilibrated with soil samples at different pH. Two soil samples were used for the study, one was red earth with a permanent negative charge of 7.4 m.e. per 100 gms. and a positive charge of 2.8 m.e. per 100 gms. at pH 2 and the other was a lateritic soil with a permanent negative charge of 3.3 m.e. per 100 gms. and a positive charge of 5.8 m.e. per 100 gms. (iso-electric point at about pH 4.7).

Abstract:Investigations on the mineralogical properties of the important soils developed on sediments in Northern Honan made by X-ray diffraction, polarizing microscopic egaurination and chemical analysis showed that the mineralogical composition of the soil was closely related to the origin of the sediment materials, but not related to the soil types and the mechanical composition. The main constituent of the clay fraction(<1 micron) of the soils was hydrated micas, at the same time kaolinite, montmorillonite and a few vermiculite were also present. The content of montmorillonite was highest in the soils developed on the sediments of Yellow river, and it was lower in the soils developed on the primary and secondary loess and on the sediments of Zhang river, whereas the least content of montmorillonite was found in the soils developed on the sediments of Xin river.In the coarse soil particles, ranging from 10 to 100 microns, the light minerals were mainily composed of quartz, feldspars and micas. The heavy minerals in this fraction, however, varied with the origin of the soil. Hornblende was predominate in the soils developed on the sedimients of Yellow river, and magnetite in the soils developed on the sediments of Xin river and Zhang river.The paper suggested the possibility of tracing the origin of the soil parent materials, as illustrated in the said areas,by their mineral composition.

Abstract:In this paper the application of destruction neutron activation analysis technique to soil samples of complex matrix is described. The chemical group separation based on a combination of distillation and anion-exchange was used. Five-fractions of As-Se, Hg-Sb, Cr-La-Sc, Co-Fe and Zn-Cd-Mo were measured by both the Ge(Li) detector connected to the computer and the NaI(Tl) well-type detector. The combined use of the two systems gives full scope to the high resolution of the Ge(Li) detector in the analysis of samples of complex matrix and the highest sensitivity and the high efficiency of NaI(Tl) detector in the analysis of trace elements at very low concentration. The results of 12 trace elements of the soil samples from Beijing and Nanjing determined with the method mentioned above were obtained.

Abstract:This artical deals with the application of the mathematical method of principal component analysis in soil research. No correlation is found among these principal components reflected the different and unique processes of their weathering and soil forming process respectively. Using paddy so11 as an example, the application of the principal component analysis on the identification of its soil forming process, the type of index and soil type was disenssed.

Abstract:A colorimetric method of new mixed indicator with a wide range and clear changes of colour for soil pH values has been studied. This method was compared with electrometric method using more than eighty soil samples from different parts of China. The results obtained from the two mothods were well agreed and their maximum variation was about 0.3 pH unit. Twenty-two soil samples of various main soil types were examined for pH by different workers, the average deviation was also less than 0.3 pH unit.

Abstract:要正确判断土壤中有效养料的供应状况,需要有三方面的指标。第一,供应的强度;第二,养料的数量;第三,补给的速率。所谓供应强度即是指土壤中所存在养料的能量水平。