Abstract:The type and devepment of soil are related nonexchangeable potassium in soils of the loess regzon. The present paper deals with the regime of nonexchangeable potassium in major soil types of the loess region. The results obtained are summarized as follows: (1) The primary factors affacting nonexchangeable potassium content and potassium release were the soil texture and the organic matter. The nonexchangeable potassium content were positively correlated with the contents of silt, clay and organic matter, but negative correlated. with content of sand in soil. (2) The content of nonexchangeable potassium and accumulative amount of potassium released were getting increased from north to south in loess region. The. distribution of nonexchangeable potassium and fhe accumul are amount of potassium released in young soils (sandy yellow cultivated Loessial soil and light dark loessi.al soil and yellow cultivated loessial soil), sandy dark loessial comparatively uniform in profile. However, in argillic horizous of clayey dark loessial soil and dark loessial soil, the content of nonexchangeable potassmm and released potassium was higher than in cultivated horizon and parent materia horizon, and it changed with topographic conditions of the soils.

Abstract:China has a very small area of volcanic ash soils which are roughly distributed in three regions, i.e. Inner Mongolia region, Xizang Plateau region and Pacific region. This paper-deals with the preliminary study on the genetic, characteristics and classification of volcanicash soils in the four locations, Leihu of Hainan Island, Tengchorig of Yunnan, Dedu of Heilongiiang and the Changbai Mts. of Liaoning in China. (1)Volcanic ash soils derived from volcanic ash and generally developed on tableland have shallow solum and brownish black color, glassy fragments in, the solum and weatherable minerals like plagioclase and pyroxene in the silt fraction. The soils are low in bulk density and high in porosity and water-holding capability, with a capillary moisture capacity close to the saturated water content, and slightly acid to neutral in reaction and very high in content of exclmneeable Ca⁺⁺, total P and total K.

Abstract:This paper deals with the Al-substitution of goethite in paddy soils and their original soils. The change of Al-substitution of goethire during the develoment of paddy soils was stutdied and its significance in soil classification is discttssnd. Cinder the artificial waterlogged condition, the Al-substitution of goethite in soils was weakened. the Al-substitution of goethite in paddy soils was much less than that of their original sails, and it decreased with soil developing. The change of Al-substitution of goethite in the diagnostic horizons not only reflected the special pedogenic condition of paddy soil, but also the characterized pedogenic process, So, it can be used as one of the major indices for dividing the subgroup of paddy soil. The Al-substitution of goethite was 9-18 mol% in the percogenic horizon of percogenic paddy soil,.but it was lower than 9 mol% in the periodically,waterlogged horizon of periiodically watterloged paddy soil.

Abstract:In this paper, soil cartography is considered to study and express the forms of structure of soil mantle distribution in space. The principle that soil mapping should be based on the genesis of soil combination and the miethod-that attention should be paid on both simple de lineation and compound delineation that can promote the quantified degree have been sugge sted. It also deals with the components of soil mapping units, the bases of their determination, the corresponding categories of soil classification, and the grades and arrangement o soil mapping unit system, as well as the relationship and differeces between soil mapping unit and soil classfication unit. Having generalized the structural forms of both simple and compound delineations and their forming. factors, ideas of classification and examples are formu fated first on division of the compound delineations into forming fartor suquences such a those of relief, parent material, historical evolution,, and cultivation, and then on subdivision into numerous types under each of the above forming factor sequences according to the genetic relations amoung the components of soil combination as shown by the combination of delineatians, the regularity of geographic distribution of the soils in China has been discussed.in addition, the significance of mapping generalization in the soil mapping on small scales, the ways of generalization, points for attention, and the prospects for the small scale sail mapping have also been discussed.

Abstract:By the main component and cluster analysis of the properties, the relative contents, crystallinity ete of clay minerals in beach soils and their parent materials, the parent materials of the soils were divided into three types, i.e., the deposits of Yellow River, Yanshu River and Yishu River. The results obtained well consisted with the geographical locations of the soil samples, which indicates that under the premises of correct analytic figures, proper selected properties and right grouping statistics, cluster analysis of the contents and characters of clay minerals is practicable for classification of clay minerals in soil.

Abstract:This paper deals with the natural-conditions of Dayuzhang irrigation area in Shandong Province, the experiment of undlergrownd drainagre for improving saline soils in these area's, the observations and analysis of its effect and. the suitable condition of underground drainage. The experiment was eanductrd from 1978 to 1984. The results obtained indicated that the underground drainage could davain off the water and salt from soil, lower ground water table, increase the ratio of drainage to exaporation of the soil, speed up desatination of soil and ground water, intrease the yeeid of crops.and coon, avoid, the sliding of slopes of open ditch on silty soil. It is considered that undergroutad drainage hs an effectuie way to improve saline soil in coastal regions.

Abstract:Generally, heavy metal hays a tendency to 1.e enriched in the clay of soil, but from the preliminary study on the relationships between some heavy metals and the mechanical composition of soil, together with the composition of minerals in the soils of Hainan Fsland, it was found that the clay fraction of latosol was not enrich by heavy metals, whereas with decreasing particle size of paddy soil that was situated on the same tropical landscape as the latosol was, concentrations of the heavy metals increased and it was highest in the clay fraction(<0.001mm). In order to reveal the cause of the distribution of heavy metals, the different fractions of particle-sizes of the soils were identified by x-ray diffration. The silt group and sand group of the latosol contained large amount of iron oxides, Lut its clay group mainly consisted of kaolinite and gibbsite. Therefore, the distribution characteristic of heavy metals in the latosol is closely relative to iron oxides adsorbing a.u containing heavy metal. However, X-ray diffration analyses showed that with the incerase of particle size of paddy sail, its heavy metal content decreased, which is reaafed to quartz and feldspar increasing and clay minerals decreasing with the increasing of particle size of the soil. The distribution of heavy metals in the paddy soil conforms to that of other soils.

Abstract:The present paper deals with preliminary study on the influence of clay mineyals and organic matter on specific surfacL area of colloids of some soils collected from northeast northwest. south and central China. The results obtained are summarized as follows: 1. A significant eorrelation between specific surface area of soil colloids and its clay mineralogical composition, the magnitude for specific surface area of the colloids of the soils was in the order: Black soil > Yellow brown earth > Loessal soil > Red earth > Latosol. The removal of free ion oxides from the latosol caused a considerable reduction in, specific surface area of its colloid while the removal of free iron oxide from the yellow brown earth resulted in the increase in specific surface of the soil.

Abstract:Potassium fixation was studied with < minerals and 10 soil samples under 5 potassium concentrations at room temperature and 60℃. After equilibrium of samples with different K levels in solution, the K fixed that was not extracted by 1 N neutral NH₄OAc is considered as fixed K of slowly available form, and the K fixed that was not extracted by 1 N boiling HNO₃ is considered as fixed K of mare slowly available form. The results obtained are summerized as follows: 1 Rate of potassium fixation for all samples was significantly correlated with the increase of K concentrations; the fixed K of slowly available form was much more than the fixed K of more slowly available form. 2. The lowest rate of fixed h of slowly available form was found in kaolinite, next in montmorillotaite, the highest in vermiculite, then in illite. Biotite and muscovite were between montmorillonite and illite.

Abstract:Present paper deals with the correlation between crystal properties of apatite which include the substitution of PO₄^3- by CO₃^2-, a₀、c₀、Da₀、Dc₀ and the CO₂ index, and the availabiliey of powdered rock phosphate. Phosphate ores taken from 99 main mines in China were studied. Besides, two phosphate ores taken from Ivlotocco and Kora in Soviet Union were used for reference. And 21 phosphate ores were: used irr pat culture experiments to verify the relationship between their crystal structure and the availability to plant growth, and the amount of soluble phosphorus extracted successively for three times by 2% citric acid from raw and purified rack phosphate were determined, another series of purified powdered roc's phosphate were prepared for the determination of the absolute citrate soluble phosphate. The results obtained showed that in the lattice of 101 apatites, CO₂ ranged from 3.62 to 0.04%; a_o from 9.331 to 9.380Å the range of c₀ was very small; Ca_o was 391-2242Å Dc_o, 424-2000Å the range of the CO₂ index was 0.000-0.493. The correlation matrix between the availability of powdered rock phosphate and the crytal parameters of apatite showed that the correlation between the amount of CO₂ and the crystal parameters was most signicant (r=0.999). It gives the illustration of the formation of carbonate-fluorapatite on the basis of the P0₄^3- in fluorapatite being substituted by CO₃^2-,And there was significant negative relationship between CO₂ and a_o, Da₀ and Dc_o. The progressively regression analysis indicates that among all the above-mentinned parameters, Da₀, Dc_o p. X-ray the most important role in the availabitily of powdered rock phosphate to platat growth, i.e. the size of its specific surface area is an appropriate index to evaluate the availability of powdered rock phosphate. When raw rock phosphate was extracted dvrectly by 2% citric acid, the obtained resultes were interfered by accompanied carbonate ingredients, and the impact of calcite was obviously greater than that of dolomite. While the purified rock phosphate were used, the impact of carbonates had been eliminated, and the reliability of correlative coefficient between this parameter and the availability of powdered rock phosphate was raised about to 2 times.

Abstract:Some isothermal phosphate sorption curves were determined on typical soils in Zhejiang province of China. Most of the soil samples are paddy soils derived from different parent materials, The isothermal phosphate sorption data obtained all fitted very aveli with Freundlich, Temkiza, Langmuir's conventional as well as its two-site-adsorption equations, and the conventional Langmuir equatzon seemed to be the best fitted model. The parameters in the canventional Langmuir equation, namely the adsorption maximum (q_m) and the constant(k)related to the bonding energy as well as their product,k×q_m can be used as a comprehensive index to characterize the potential posphate sorptivity of the soil. In the present study the k×q_m values of the soil samples tested were found to be 2100 for gaethite, 425-990 for paddy soils developed on red earth, and 4219 for upland red earth. With regard to the textural variation of the paddy soils k×q_m value for sandy loam was 297, for silt loam, 658 and clayey soil with stagnanting water regime, up to 800.

Abstract:轮作复种能减少作物病虫害,改善土壤理化性质,增加土壤微生物数量,是调节和改善土壤肥力状况的重要措施。研究不同连作和轮作复种下土壤腐殖质含量、组成以及与土壤无机部分复合的状况,可为寻找合理的轮作措施,以提高和保持土壤肥力提供一定依据。

Abstract:自从陆地卫星发射以来,已经提出了不少关于陆地卫星数据信息提取的方法^[3-6],其中最重要的为Karhunen-Loeve变换和Kauth-Thomas变换。这些变换基本上都是先用已有的数学统计方法(主成分分析等)对图象数据进行运算而不管其结果如何,仅仅在通过运算得到新变量之后,将新变量与实际地物对照,才能大致地确定这些新变量的意义。