Abstract:In brown earth, the microaggregates<10 μm and, in particular,<5 μm have a greater reserve of C, N and P, and greater ability for adsorbing N, P and exchangeable cations and more intensive enzyme activity, but a less total content <30%, while the microaggregates >10 μm contain less amount of C, N and P, have a greater ability for desorbing N, P and exchangeable cations, and considerable strong enzyme activity, capecially with a large total content being more than 70%, this fraction of the microaggregates, which in fertile soils is higher than in infertile soils,is one of the important factors influencing the fertility of brown earth. Soil microaggregates can influence the aril physical, chemical and biological properties and may be used as an overall index for evaluating the fertility level of soil. As for soil enzyme activity, it may be used as a supplementary index.

Abstract:Charge characteristics of a typic Gibbsihumoa (Halii soil) and a hydric Dystrandept (Maile soil)were investigated. The specific surface of Maile soil is about two times greater than that of Halii soil. The pH₀ of Maile soil equal to 5.90 and pH₀ of Halii soil equal to 4.55 specifically, adsorbed calcium ions shift the pH₀ to lower values and specifically adsorbed sulfate anions shift bhe pH₀ to higher values, when CaCl₂ or Na₂SO₄ and CaSO₄ are used as the supporting electrolytes. It was found that a positive permanent charge existed for the Halii soil and a negative permanent charge existed for the Maile soil by using the surface charge model developed by Uehara and Gillmsn.

Abstract:The data for phosphate retention of the eighteen surface soil samples in a wide range of phosphate concentration (up to 100 μm P/g soil) were all found to be in close agreemeat with Langmuir, Freundlich and Temkin equations. Their correlation coefficients (r) were mostly over 0.97. Among these equations the Langmuir adsorption isotherm seemed to be the best fitting model. The great differences of their phosphate retention capacity were evidenced by the variations both in their adsorption maxima (M) and their bonding energy parameters (R).Thus, M varied from around 300 μg P/g Foil (Psa.mmaquent, 504 and Loessial soil 498) to 1500 μg P/g (Lateritic soil, 497). For the soil of volcanic ash orgin, it even ran up as high as 5000 μg P/g. In terms of percentage of phosphate added(100 μm P/g soil),the adsorption rates by these soils correspond to about 10%, 47% and 95% of the added phosphate respectively. Among various physical and chemical properties of the soils studied, the contents of clay, as well as the amorphous and crystalline free iron and aluminum oxides were found to be all correlated with the phosphate retention capacity. In spite of the diversity of the soil samples, the specific surface area of the soil was found to be the most relevant single attribute which shows the best correlation with the phosphate retention capacity. Cultivation practices, fertilizer applications and use of organic refuses exerted some influences on soil phosphatic retention properties. Seasonal flooding of soil by converting upland red earth into irrigated rice field is particularly effective in lowering the M and K values of their phosphate adsorption isotherms.

Abstract:Materials used in the experiment were Azolla imbricdtcc, Azolla japonica, Azolla filiculoidcs (E.G.) and Azolla filiculoides (Ph.),and they were cultured with nutrient solution in green house for 25 days after the samples being washed by and cultured in distilled water through ioneachange resins for 48 hours, and then their contents of nutrient elements including N, P, Si, Ca, Mo, Mn, Fe, Cu, Zn, Co and B were determined. Results obtained from the experiment showed that nutrient contents in the plants of Azolla were rather high as compared with the contents of their cultural solution, which indicates Azolla has a very high absorbability of nutrients. Meanwhile, the activity of nitrogenase was also determined by acetylene reduction method. The activities of nitrogenase in the plants were in the following order:Azolla japonica>Azolla filiculoides (E. G.) >Azolla filiculoides (Ph.)>Azolla mixican >Azolla imbricata. The results by statistical analysis showed that the activity of nitrogenase (x) was very significantly positively correlated with the content of molybdenum(Y₁) (r=0.991),and it was significantly positively correlated with the content of copper (Y₂) (r=0.958) in AzoLla sampies. Under the experimental conditions the respective regression equations are as follows:Y₁=-2.71+2.43X;Y₂=0.529+0.294X.

Abstract:The influences of different NH₄⁺-N Ievpls on the nitrogenase activity in rhizosphere of rice under the ecological condition of Hangzhou were observed. The results obtained are as follows:(1) NH₄⁺-N significantly inhibites nitrogen-fixing activity in rhizosphere of rice within a certain time. There was a highly (or medium) negative currelation between the concentration of NH₄⁺-N in soil and the nitrogen-fixing activity in rhizosph ere of rice. During different grnwing stages, values of correlation coefficient ranged from -0.4428 to -0.9945. (2) The initial concentration of NH₄⁺-N in soil which began to inhibite the nitrogen-fixing activity in cores of paddy soils was 20 ppm. (3) The time duration of the inhibiting effect of NH₄⁺-N varied with the rate of NH₄⁺-N applied. The inhibiting effect lasted about 20 days in low nitrogen plots, and about 25-30 days in medium and high nitrogen plots. Since then, the application of NH₄⁺-N showed favorable effect on the nitrugen-fixing activity in rhizosphere of rice.

Abstract:Contents of mica in 46 soil samples, total K in particles of different sizes in 51 soil sarriples and K weathering coefficients of 14 soil samples collected from the main zonal soils of China were determined by chemical methods, and the K-supplying potentials of these soils were also calculated. Content of mica in laterite was very low, that in red earth was more than that in laterite, but it. varied greatly with the parent materials. Content of mica in yellow-brown earth was slightly higher than that in red earth. The purple soils and soils derived from loess generally contained more than 20% of mica. Contents of mica in paddy soils derived from alluvium, lacustrine deposits and marine sedimenx ranged widely.From the relationship between contents of mica and content of total K in various fractions, it was found that the content of feldspar in the fraction<2μm was very low, therefore the total K in the fraction <2μm can be wholly calculated as Lhe content of mica, but half of total K in the fraction >10μm was the K contained in mica. In laterite, red earth, yellowbrown earth and purple soil, fine particles of mica amounted to 80-90% of total mica. While in fluvo-aquic soil, drab soil chernozem, castanozem and sierozem, the fine mica content decreased, and the coarse mica content increased, amounting to 36-47% of total mica.

Abstract:The main soil types in Sichuan Basin are paddy soil, purplish soil, yellow earth, yellow brown earth and brown earth. The soil samples of more than 620 sites were analyzed. The main results are summarized as follows:1. The range and mean value of the total contents of Zn, B, Cu and Mn in the soils of Siehuan Basin are 37-400 ppm with an average of 112.8 ppm, 17-370 ppm with an average of 80.7 ppm, 9-125 ppm with an average of 33.0 ppm, and 41-1750 ppm with an average of 641 ppm respectively. It is obvious that the total contents of B, Zn Cu in the soils of this region are higher than those in the soils of other regiuns in China. However, total content of Mn is lower than that in the soils of other regions in China. 2. The content of available trace elements varied greatly. The range and mean value of available B, Zn, Cu, Mn and Fe in the soils of Sichuan Basin are 0.01-1.61 ppm with an average of 0.23 ppm, 0.08-9.60 ppm with an average of 1.45 ppm, 0.1-9.44 ppm with an average of 2.53 ppm, 0.18-262.4 ppm with an average of 27.8 ppm, and 0.86-401.4 ppm with an average of 61.1 ppm respectively. The content of available B in the soils of Sichuan Basin is very low (0.16-0.29 ppm),being much more below the critical value (0.5 ppm).Although the average contents of available Zn and Mn are slightly higher, but in the most of soils, especially the calcareous purplish soil, they are lower than the critical values. The contents of available Cu and Fe in the soils of Siehuan Basin are higher. The availability of trace elements in soils are influenced by many factors. The avaiTable trace element contents in the soils of Sichuan Basin are often varied with the soil types, increased with the lowing of soil pH and increasing of organic materials. At same time, the content of available trace elements (except B) in the paddy soil are higher than that in the upland soil derived from the same parent material.

Abstract:Study on numerical classification for 34 soil profiles in Chenggian County of Gansu Province was carried out by means of a cluster analysis method of standardized variateoblique distance-sum of square error. Indexes used in numerical classification include soil pH, organic matter (O. M.),total N, totoal P, total K, available P, available R, cation exchange capacity(CEC) SiO₂, Al₂O₃, Fe₂O₃, CaCO₃ and physical clay(<0.01 mm). Ii,esults obtained from this study showed that 34 soil profiles used in the egperi.ment may be divided into five soil groups. From variance analysis for eight main indexes (i.e.pH,O.M., CEC, SiO₂, Al₂O₃,Fe₂O₃, CaCO₃ and clay) of the five soil groups shows that the differences of indexes between soil groups are all significant (F_0.05) or very significant(F_0.05)respectively except pH, CEC and SiO₂ content. In addition, there are also significant differences between soil groups in geographical distribution, vegetation types and calcareous reaction in fields etc.. Each soil group has its marked genetic characters. Compared with genetic classification system, the five soil groups belong to brown earth, leached drab soil, ortho-drab soil, carbonate drab soil and cultivated fluvioaquic soil respectively.

Abstract:The present paper deals with the micromorphological features of the fine mass of some drab soils developed on different parent materials in West Liaoning used by a combination method of polarized microscope and SEM. The most important micromorphological features of the soils have been described and enmmarized in table 1. The function of physical and ehemioal characters of fine mass on the soils stability and erodibility are discussed.

Abstract:The contents of organic matter and humus increase in order of the profile₁-profile₂-profile, of the three paddy soils derived from red earth. The carbon/nitrogen and humic acid/fulvic acid ratios increase in the same order. The composition of clay minerals of three paddy soils shows no obvious difference and is similar to their parent soil-red earth. These paddy soils are rich in iron and manganese oxides, especially in the illuvial horizon. Because of intense redoxing and eluviation-illuviation processes in soil, the distinct segregation of iron and manganese occurs in profile, and there is the most distinct segregation in profile, and the segregation of amorphous iron is most evident in the profiles, the iron in form of crystal segregates regularly also in the three profiles;the ratio of crystalline iron/amorphous iron in the dignostic horizon (w) of profile₂ is much higher than that in other horizons, this is rather important for distinction of the genetic types of paddy soil developed under different water regimes. The content of the iron in form of complex compound is related to that of the organic matter. As compared with iron oxide, manganese is more sensitive to the change of redoxing conditions, the segregation of manganese in soil profile tends to be more distinct than that of iron, although the content of manganese in soil is rather low.

Abstract:作物植株营养诊断研究所要解决的问题,正如李庆逵教授所指出的:第一是分析方法;第二是采样问题;第三是分析数据和作物生长或产量之间的相关性;第四是把分析结果应用于施肥指导^[1]。近年来,我们在解决上述四个问题上进行了一系列的试验研究,现将试验结果报告于后。

Abstract:土壤有机质不仅能直接提供作物生长所需的养分,而且还能改善土壤理化性质,使影响土壤肥力发挥的诸因素效能得到提高,这就是人们常把土壤有机质作为衡量土壤肥力指标之一的原因所在。了解某一地区的土壤有机质含量、分布规律,寻找其培肥改土措施,提高或保持某一地区的土壤有机质含量和品质,必将对农业生产产生良好的作用。

Abstract:成土因素学说是发生土壤学的重要组成部分。历来一些学者虽然指出了学说的某些不足,但作者认为最重要的是对影响较大的新构造运动未有考虑,笔者拟就有关问题阐明如下。

Abstract:我国著名土壤学家、中国科学院南京土壤研究所名誉所长、研究员、中国科学院学部委员、中国科学院环境科学委员会副主任委员、全国人大代表、中国共产党党员熊毅同志于一九八五年一月二十四日六时二十分不幸与世长辞。