Abstract:After a review of the study on soil fertility at home and abroad and of our recent it is clearly reeongnized that in studying soil fertility,both the basic materials affecting the fertility and the patterns of pedon structure of soils should be investigated in a comprehensive way.In black soil,the organo-mineral eompLeaes with different binding status are the basic substances influencing soil fertility.The quantitative variation of various groups of organo-mineral complexes induces a series of changes of nutrients and moisture in soil.In fertile black soil,the total amount of the microaggregates <10μm is above 50%.They are the main parts influencing fertility.The humification and transformation of organic matter are regulated by the soil enzymes.Their activity can reflect the nutrient status and physico-chemical praperties of soil to a great extent.In fertile black soil,humus,humin and humie acid combined with calcium are distributed uniformly in the whole soil mass.It helps improve the formation and uniform distribution of stable structure in soil.

Abstract:The variation of fertilizer-N in rice rhizosphere was studiedied means of the dense root plane in contact with soil blocks labelled by 15N and fresh frozen sections.Meanwhile some conditions of research method were determined.Results revealed that there existed a depletion zone of nitrogen in rice rhizosphere which was induced mainly by the decrease of fertiliter-N.The extension of depletion zone in soil was consistent with the rate of depletion.There was a exponential correlation between the rate of depletion (y) and the distance from root plane (x) in accordance with the equation y=a+bx^1/2,The content and depletion rate of fertilizer-N in soil varied with the cultivated time of rice.The amount of depletion in the rhizosphere soil of upper part of roots (below root node 4-6 cm) was greater than that of the lower part of roots (below root node 8-10 cm) due to the upper part of roots with more vigorous branches and higher ability of nitrogen absorption.In addition,raising temperefute during the growing period of rice promoted the rate of nitrogen uptake by root system and expanded the extension of depletion zone of fertilizer-N in soil.Therefore increased supplying capacity of nitrogen in soil to a certain extent may reduce the rate and extension of depletion of fertilizer-N in rhizosphere soil.Experiment showed that nylon cloth (pore radius<25 μ)and cellulose micropore membrance (pore radius<2 μc)were ideal materials for separation between the soil and root interface.These materials can allow water and nutrients to pass the membrance freely,but prevent the roots penetrating into soil.

Abstract:Selenium is one of essential trace elements for human and animal.In order to study some endemic diseases in relation to environmental selenium,the distribution of Se in soils of Shaanzi Province was investigated.The quaternary loess and granite with low-Se content are predominant in parent materials of the soils in Shaangi.The average total Se content of soils developed on these parent materials is 0.118 ppm,and the average content of water-soluble Se is 1.9 ppb.Most of them belong to the.soils defecient in Se.Seleniferous rocks and soils are only distributed in limited areas of the eaatern Bashan Mountains of Southern Shaangi.According to the geographical distribution of Se in soils of Shaangi Province,five regions are divided as follows:(1) the region of very low content of Se,including Maowusu desert region and Loess Plateau in Northern Shaangi;(2) the region of lower content of Se,including Guanzhong Plain and "Sanbian" closed flow depression;(3) the region of medium content of Se,including Hanzhong-Ankang Basin;(4) the region of variable content of Se,including Qinling and Bashan Mountains;(5) the region of medium-high content of Se,including the eastern Bashan Mountain.The Se content of topsoil is the highest,and it decreases with the increasing of depth gradually in soil profile.There is a better correlation of exponential function between the percentage of water-soluble Se and soil pH,the regression equation is y=0.027e^0.53x,r=0.763.The content of soil water-soluble Se is dependent on the total Se content,organic matter content and pH of soil.The regression equation of three variables is as follows:y=-7.148+0.014x₁+0.128x₂+0.93x₃,r=0.785.Among the three factors mentioned above,the total Se and pH are the primary and the organic matter is the secondary.

Abstract:Some chemical and eletrochemical kinetics and the equilibria of CdCO₃ and CdS in soil solution were investigated under the condition of additional Cd,P and Zn compounds.Suhmergence brought about a series of physicochemical and chemical changes that markedly influenced the pH,Eh,EC,Es,chemical kinetics and mineral equilibrium in paddy soils.The pH of soil solution gradually increased while Eh decreased with the time of soil flooding.Some of Cd treatments decreased Eh.The maximum EC value reached at 4th week after flooding and then declined gradually.The concentrations of NH₄⁺-N,K,Ca,Mg,Fe and Mn in soil solution increased markedly during first 2 to 4 weeks after flooding,while those of Zn and P were getting decreased.A study of CdCO₃ and CdS equilibria by means of IAP method showed that there might be CdS present in the soil after 5 weeks of submergence.But results gave no thermodynamic evidence fur CdCO₃ existence.

Abstract:Studies were made for eight methods of extracting available Mn from three calcareons soils which received MnSO₄ at 5 rates to evaluate their correlations with Mn uptake of plants,their abilities to eztract amounts of applied Mn,and their applieabilities to atomic absorgtion spectrography.The influences of the duration of plant growth and air drvine of soil samples on soil tests were also srtudied.Of the eight methods investigated,the extraction of soil Mn with 1 N NH₄Ac+0.2% hydroquinone at pH 7.0 can well indicate plant available Mn status of the soil.All the other methods,i.e.DTPA+CaCl₂+TEA at pH 7.3,DTPA+CaCl₂+TEA at pH 8.5,EDTA at pH 7.0,EDTA+(NH₄)₂CO₃ at pH 8.5,EDTA+(NH₄)₂CO₃ at pH 9.3,1M NH₄H₂PO₄ and 1N NH₄ Ac at pH 7.0 are unsuitable for estimating plant available Mn in calcareous soils.Multiple regression analysis which involves eatraction of soil Mn with NH₄ Ac+hydroquinone and several soil factors demonstrated that in given cultural conditions,inclusion of soil CaCO₃ of organic matter in the equation can improve Mn uptake predietability.

Abstract:This paper deals with evaluation of the practical significance of soil available Mn (DTPA-Mn) and the discussion of critical level.Pot and field experiments for the response of crops to manganese fertilizer on 18 loessial soils in which DTPA-Mn ranged from 1.6-25 ppm were conducted.Results of experiments showed that the content of soil available Mn (DTPA-Mn) was signifieantly positively correlated with dose of manganese fertilizer,Mn concentration of crops,amount of Mn absorbed by crops and the content of easily reducible Mn in soil.Among soil chemical properties the content of available Mn extracted by DTPA solution was the most important factor that influeneed the effect of manganese fertilizer.The lower the amount of available Mn in soil,the better the response of the crop to manganese fertilizer.For this reason it is considered that the level of soil available Mn extracted by DTPA solution may indicate the supplying capacity of manganese in soil,and consequently it may be used as the index of available Mn in soils of loess region.The soil DTPA-Mn has been divided into four levels in accordance with the response of craps to manganese fertilizer,i.e.the very low level df 4.8 ppm,the low level of 4.8-7.0 ppm,the medium level of 7.0-9.2 ppm and the high level of 9.2 ppm.The critical level of sail DTPA-Mn varied with different crops and soils.It ranged from 5.5-7.5 ppm for different craps anti 5.8-8.6 ppm for different soils.It is suggested that 7 ppm and 7-9 ppm might be used as the critical level and the range of critical levels for the soils under general condition,and 5 ppm and 5-9 ppm for the soils with lower fertility.

Abstract:This article deals with the saprophytic colonization of F.oxysporum on plant residues in relation to its survival in soil.Most of the plant residues,such as the straws of wheat,rice,bean,cotton,milk vetch,etc.,are easily colonized by F.oxysporum in soil under dry farming,even if those have been colonized previously by Chaetomium,Mucor,dsPergillus,Rhieoctonia,Sordatia and other soil fungi.The temperature and soil moisture adapted to saprophytic colonization ranged from 15°-30℃ and 20-80% of moisture holding capacity respectively.Fungal growth was suppressed in submerged soil due to lack of oxygen,while colonization still occurred on residues floated above the water.Propagule density of the pathogen in heavily infested soil decreased sharply under flooding condition,but it could not be entirely eliminated from flooded rice growing soil.It existed in the oxidation layer and propagated gradully as saprophytes or parasites after 1 or 2 successive cotton croppings.When fresh organic matter was added into the soil under flooding condition,the pathogen diminished with the decline of soil Eh.

Abstract:With plenty of peat resources,Shanjiang Plain has a reserve amounting to 1.2-1.5 billion cubic meters.Most of them belong to the eutrophic low moor peat.Peat is 1.5 billion cubic meters.Most of them belong to the eutrophic low moor peat.Peat is an escelle}nt resource of organic matter which can be used for reclamation of soils and preparation of organic fertilizers.Peat is rich in organic matter (about 60% of dry matter weight),humie acids (more than 30%) and nitrogen (1.8%).Its water-holoing capacity is np to 500-900% and its adsorption capacity of ammonia can be up to 1%.Experiments showed that peat could be used for the improvement of soil physical and eh}emicsl conditions such as inereasing the content of soil organic matter by 1-1.5%,the total nitrogen content by 0.02-0.06%,the total porosity by 7-10%,the water content by 5-6% and decreasing the volume weight of soil by 0.1-0.2 g/cm2 and consequently increasing crop yields by 10-30%.Its residual effect could be maintained for more than three years.The optimum dose of peat applied directly to the field was 10-15 m³/mu.Peat application mixed with adequate amounts of water-soluble nitrogenous and phosphoric fertilizers,especially with the latter,could raise its effect on early ripeness and high yield of crops.A series of methods for application of peat and preparation of organic fertilizer were studied in the past four years.The results showed that in addition to direct application to the soils,peat can be also mixed with animal excreta and night soil,and it can be aced for bedding and composting,and preparation of hnmicfertilizers.

Abstract:With the introduction and using of the System 101,some satisfactory results on the mapping of soil erosion by using of LANDSAT MSS CCT's images were obtained.The results include the method of registering regional boundaries on CCT's images,and the selection of optimal process available for the mapping of soil erosion.Is praetice,the map of soil erosion in Xinggu County of Jiangzi Province was compiled and the area of eroded soils and agricultural fields in the region were ealculated.The conclusions of this paper are summarized as follows:1.Unsupervised classification is not suitable for image classification,at least in the mapping of soil erosion,but B classification is suitable for it.2.The key to image classification is the selection of training fields,of which the key iis the analysis of the image.3.Before image classification the regional boundary must be registered.4.The mapping of soil erosion by means of LANDSAT CCT's images is a more rapid,accurate method with low cost.

Abstract:There are varieties of pests and peaty soils in the uplands of mountain area in northern England which were developed mainly on sedimentary rocks and glacial drift under the condition of wet and cold climate.The air photo interpretation has been eatentively used in the national small-scale soil mapping programme.It was showed that medium-scale panchromatic prints were used better than colour prints and satellite image for interpretation.In this paper the methodology for soil and land use capacity survey with air photos is described and evaluated.

Abstract:The correlation between elements in soils of Tianjin area was studied based on the analytical data of soil samples collected from this area including fluvo-aquic soil,salinized fluvo-aquic soil,boggy fluvo-aquic soil derived from alluvial deposits,lacustrine deposits and diluvial deposits,and cinnamon soils derived from granite,limestone,sandstone ete.The contents of Co,Ni,Li,Cd,Cu Cr and Pb were determined by AAS,those of Fe,Zn,Sr,Zr,Ti and Ca by XRF;that of As by Ag-DDTC speetrophotometry and that of Hg by cold vapour atomic absorption method.Correlation coefficients were calculated by the aid of statistical method with natural logarithm of analytical.data.Critical value of correlation coefficient was 0.254,which was calculated by the correlation detection method (α=0.01,n=103).According to the data obtained,the correlation coefficients are divided into four levels i,e,significantly correlated(|R|>0.75),better correlated (0.75>|R|>0.50),correlated (0.50>|R|>0.25),and incorrelated(|R|>0.25).The degree of correlation of elements is related to their geochemical characteristics.It is found that there is a positive correlation between the elements,if their geochemical characteristics are similar;while there is a negative correlation between them,if they are different in geochemical characteristics with different directions of their translocation and accumulation.In addition,in the soil forming process the organic matter,chemical and physical conditions,etc.can offeet the translocation,accumulation and degree of correlation of elements in soil.

Abstract:近年来不少地区土壤中有机质减少,土壤结构状态变劣,成为生产上极需解决的问题。改良土壤结构,除多施有机肥料^[3,4],种植牧草等措施外,施用以天然的有机物及无机物制备的,或人工合成的高分子有机化合物,也是很有效的办法^[1]。本文介绍了几种土壤结构改良剂的研制及其效应,初步证明施用土壤结构改良剂能有效地增加土壤中团粒结构,改善作物生长条件,有利于提高产量。

Abstract:1840年—1920年间,老一辈的土壤科学工作者,做出了四个巨大的贡献,也奠定了现代土壤科学的基础。1.十九世纪中期,李比希(Liebig)以他杰出的分析化学知识,测定了植物组成,说明植物从土壤中吸取灰分元素。并且通过最低因子律,指出各个营养元素对于植物生长的不可代替性。他所提出的土壤矿质营养理论,影响了近一百年的土壤肥料工作^[40],李比希的学说推动了十九世纪末期欧洲化肥工业的发展,特别是过磷酸钙工业。尽管李比希的矿质营养学说存在着缺点,但本世纪初期欧美作物产量成倍的增加,这个学说是起了很大的作用。

Abstract:中国土壤学会第五次代表大会暨学术年会于1983年11月27日至12月3日在西安举行。出席会议总人数为504人,提交大会的论文和摘要共700多篇。大会印发了题为《中国土壤的合理利用和培肥》的论文集三册。会议检阅1979年以来我国土壤学界所进行的大量工作,交流了经验,共议如何进一步发展土壤科学,更好地为国民经济建设服务。除进行大会学术报告外,会议还按八个学科或专题组分别宣读论文和开展热烈的讨论。