Abstract:Soil biotechnology, as a result of combination of soil science with molecular biology and genetical engineering, is one of the new research areas and growth points of soil science. Based on the research fruits of soil science, this cross discipline uses the theories of molecular biology and the techniques of genetical engineiering to study molecular mechanisms and genetical control of plant mineral nutrition, plant resistance to adverse soil conditions and soil microbiological processes, with the aim of creating genetically manipulated plants to solve such problems as low efficiency of plant nutrition and poor productivities of soils due to infertility, salinity, acidity, the pollution and toxicity of alumium and other heavy metals, etc. Also, some achievements in these fields are briefly introduced and the future development is discussed in this paper.

Abstract:The field simulation column method was employed to study quantitatively the dynamic law of soil moisture availability to plant in the southern Loess Plateau, by using a methematical modle on the relation between crop yield and soil moisture and a mathematical modle of soil moisture absorption by plant roots. The same results were achieved by the above-mentioned mathematical modles, i. e., when the soil moisture changes from 95% to 55% of the field capacity, with the soil moisture decresing gradually, the soil moisture availability to plant decreased parabolically, dropping faster and faster. Meanwhile, the reasons resulting in different viewpoints on the soil moisture availability and the condition in which the soil moisture availability is in agreement with the soil muisture easy-absorbability are discussed briefly.

Abstract:In this paper, by means of the minimum gradients theory for unsaturated flow in capillary porous media, the equations governing the moisture saturation, energy and total pressure of moist air in unsaturated wet porous media are developed. Therefore, a general theory of heat and moisture transfer in unsaturated wet porous media considering the effect of capillary hysteresis is established.

Abstract:A humic acid extracted from dark brown soil was fractionated by the fractional precipitation technique into 12 fractions which were characterized by various methods. Results showed that with the increase of alcohol concentration, the degree of humification and molecular weight of humic acid fractions thus obtained showed a tendency to decrease gradually, total N, the relative contents of total hydrolyzable N and amino acid N increased progressively but the amino sugar N and NH₄⁺-N decreased. The possible reason for causing the difference between the results got by this method and the gel filtration method is discussed.

Abstract:In this work, assaying of minerals and pot experiments with the graminaceous crop-ryegrass, rice and barley as the indicator crops were carried out by using chemical methods and Electro-Ultrofiltration technique to study the varieties of soil K forms as well as their distribution invarious particle fractions of soils (yellow chao soil, yellow brown earth, grey chao soil and red soil) and their relations to the K-supplying power of the soils.

Abstract:The effects of some physical and chemical properties of soil on the electrode potential of aluminium in soils were studied. Results demonstrate that the soil pH, soil salts, soil moisture and soil compactness affect the electrode potential of aluminium in soils apparently. Three regions can be divided according to the effect of pH. The electrode potential of aluminium is negatively correlated with the soil pH in acid and alkaline regions. And there is a voltage-plateau under nearneutral pH, indicating that in this region the effect of the soil pH on the electrode potential of aluminium can be neglected. Different soils have special pH ranges of voltage-plateau, own to their different characteris.ics. Increasing soil salt content causes a shift of electrode potential to negative direction, especially in variable charge soils. Three regions are also found concerning the influence of soil moisture on the electrode potential of aluminium, which went down to the negative direction as soil moisture increased and showed little change after saturation. However, in a narrow range of moisture near saturation point of soil, a large voltage-drop appzared. At the samc level of soil moisture, a negative correlation was observed between the electrode potentials and bulk density which is an index of soil compactness.

Abstract:¹⁵N-labelled green manure mixed with nitrogen-free starch was used to feed pigs in the study. The results showed that the amount of ¹⁵N transformed into the bodies of the two slaughtered pigs accounted for 23.51% on average, of the total amount of ¹⁵N deposition in the experimental diet taken by each pig. The ¹⁵N excreted through the feces and urine of the two pigs accounted for 23.85% and 28.76%,respectively, of the total amount of ¹⁵N deposition in the feed (green manure) of pigs. The average recovery of total ¹⁵N for the two pigs was 76.12%.At the same time, the mean digestibilities of carbohydrates for two pigs was 75.63%.The results of rice micro-plot experiment showed that the amount of ¹⁵N transformed from pig feces and urine into whole rice plant accounted for 3.75% and 7.25% of the total amount of ¹⁵N deposition of the feed-green manure respectively, of which 2.51% and 4.82% of the total ¹⁵N were transformed into rice grain, respectively. The pig bodies and rice grain recovered altogether 30.84% of the feed-green manure N, being 15.7% relativly higher than that in the plot of combined application of green manure and urea where rice grain recovered 26.65% of the ¹⁵N-labelled green manure N.

Abstract:Pot experiments were carried out to study the effect of combining application of organic manure (silkworm manure) and inorganic fertilizer (urea and ammonium bicarbonate) on the biomass-N and N-supplying characteristics of coastal slightly saline soil. The results obtained showed that(1)application of both organic and inorganic fertilizers could significantly increase the soil biomass-C and biomass-N and the combining application of silkworm manure and inorganic fertilizer might cause a more increase of biomass-N than single application of silkworm manure or inorganic fertilizer; (2) soil biomass-N was an important link in soil nitrogen transformation and a major part of available N in soil; (3) there was a significantly close relationship between the changes of soil biomass-N and soil N-supplying characteristics, thus a strong immobilization of N fertilizer by microorganisms was always followed by a net N mineralization, which was most favourable for the growth and development of barley plant; and (4) silkworm manure was helpful in raising fertilizer utilization efficiency, especially for ammonium bicarbonate which can volatilize violently in coastal saline soil because of its higher pH, and it would be an efficient way to raise N utilization efficiency by combining application of various organic manures and inorganic fertilizers.

Abstract:Our predecessors thought that heilu soils in our country were formed under modern biological and climatic conditions. The author's researches on the heilu soils in the middle and east of Gansu Province show that heilu soils are not merely the outcomes of modern prairie environment, also historical natural products. There had been some very long periods of soil forming processes under prairie environment in the early and middle Holocene and as early as in the late Pleistocene, ancient soils formed and the profile had complete humus horizons and calcic horizons. In the late Holocene up to present, the covering strata formed on the ancient soils under modern soil forming environment, the soil elements were recomposed, translocated and illu viated again in the covering strata and ancient soil horizons of the whole profile. The continued loess accumulation at a rate of 0.1-0.2mm per year is of great significance to the formation of thick heilu soil peofiles, especially in the north and northwest of Loess Plateau. The most striling characteristic of heilu soil profiles is that they possess the covering strata and buried ancient soil hirizons.

Abstract:A seven-step sequential extraction procedure was used to investigate the disribution and fractions of Fe, Cu, Zn, Co and Ni in Luochuan loess-paleosol sequence. Seven fractions i.e., exchangeable(EX), carbonates-bound(CARB), Mn-oxidebound (MnOX), amorphous Fe-oxide-bound(AFeOX), crystalline Fe-oxide-bound (CFeOX), organically bound (OM), and residual (RES) fractions were found through fractionation.

Abstract:Based upon the Limestone soil survey, spectral measurement and analysis, the Paper elucidates the spectral charavteristics of Limestone soil in Zhejiang Province. The total spectral reflectivity increased in the order of Black Limestone soil

Abstract:Algorithm of terrain factors of GIS pixel is the key technique in monitoring soil loss by remote sensing. The principle, the applied process and the applied results of this algolithm are introduced and its applied accuracy is discuced in this article. Although the algorithm of terrain factors of GIS pixel is more complicated, and its calculation is more complicated than that of contour terrain factors, it is more dependable, automatic and of a higher accuracy than the latter algorithm. Neglecting the slope-length factor of pixel or regarding it as the same constant value due to similar slope lengths of pixels would lead to bad mistakes in the soil loss monitortng.

Abstract:The national soil survey and mapping project has been carried out since 1979 by detailed soil survey and mapping in each villeage. Then these of materials were comailed into counties, prefectures and provinces simultaneously, and the soil reports- and maps were published. The national compilation of the materials into 1:1 million scaled national soil map of China in 64 sheets and also the soil basic categories classrfication units of China were compiled into 6 volumes. The atlas of soils were also compiled including 16 sheets in 1:4 million in scale. A big volume of book entitled 《Soils and Their Resources of China》 will be published, which not only shows the genesis, classification and properties of whole China but alsu shows the soil resources covering different soil regions. Furthermore, the managing and reclamation of various soil types of arable lands and soil types under forests and pasture conditions were also discussed.

Abstract:肥料效应函数的研究,我市是从1985年开始,通过5年多的研究,已经获得了大量的原始数据资料,为我市优化配方施肥工作的进一步发展奠定了良好基础。本文是笔者5年多来在板页岩发育的漪育性黄泥田中的试验结果的整理,现简报如下。