Abstract:In China the paddy yield per unit area varies from 4-5 times between the lowest and the highest.In order to low-yield paddy soils,protinote their fertility and increase the rice yield,it is primarily necessary to work out a proper drainage project in paddy Field.end to lower,the ground water table so as to fundamentally improve the aeration condition in the root-layer of paddy soil.The higher rnntrnt of organic matter in paddy soil is related to the poor water regiame,hawing nothing to do avith the fertility level.The effect of soil organic matter on the iinprovetrient of physical properties of paddy soil is conditional.For the clayey soils of,low-yield and those located in lowland,only by ameliorating their poor water regime can the organic matter be brought into full play.For the well-drained paddy soils,the effect of organic matter on physical properties of the soil is remarkable.

Abstract:Fujian is one of the mountainous provinces in China.The plains are formed as narrow strips along the southeastern coast with mountains behind facing the sea.The high mounrains of central Fujian predominated by the Daiyunshan mountains are stretched and distributed in the northwest part of the province which is under middle subtropical climate;while in the south-east part,it belongs to south subtropical climate.In this region,from hilly land in Quanzhou plain up to the summit of Mt.Daiyunspan,the vegetations change from the subtropical rain forest,the evergreen broad-leaved forest,the mixed deciduous and evergreen broad-leaved forests,the coniferous forests dourinated by Pirtus taiwanensis to mountain shurbs,and finally to meadow grasses with sealtered dwarf Pinus taiwanensis.Correspondingly,the soils change from lateritic red earth,red earth,mountain red earth,mountain yellow-red earth to mountain yellow earth,and finally to the mountain meadow soil.

Abstract:Present paper deals with the comparative study of three soils which are derived from loessal material,tuff and granite respectively on the hills in the northwest of Beijing.The results obtained are as follows:1.Under semi-arid continental climatic conditions,the soils are mote or less developed and characterized by such features es lack of watetr soluble salts in the soil due to leaching,apparent movement of carbonates in soils,more clays in subsoil due to physical weathering in situ,base saturated,Neutral to slightly alkaline in reaction,comparatively uniform SiO₂/Al₂O₃ ratios throught profile,and hydromica and montmorillonite as the main clay minerals in soils.

Abstract:Studies were conducted on the effects of application methods on the recovery of fertilizer N by rice plant (Oryza sativa L.) using ¹⁵N labeled urea in microplots at the International Rice Research Institute (IRRI) in 1981.Uniform placement with prilled urea and point placement with urea supergranule (SGU) gave the highest yields(6.4t/ha) with the efficiency of 51Kg rough rice/Kg N in dry season.IN wet season,Point placement with SGU produced the highest yield (4.4t/ha) with the efficiency of 40 Kg rough rice/kg N.

Abstract:The study was carried out to verify the empirical equation Y=K[(T-T₀)D]^π for predicting the amount of nitrogen,mineralization in soil by submerged incubation method;and in tre equation,the amount of NH₄-N released from the soil is tre function of soil effective accumulated temperature.The soil used for experiment was a gleyed paddy soil in the suburbs of Shanghai.Incubation experiment and chemical analysis in laboratory as well as field and micro-plot experiments were conducted.

Abstract:The effect of rice growth on the mineralization of soil nitrogen was investigated by pot experiment and sealed anaerobic incubation.The results obtained are summarized as follows.Except in the initial stage of mineralization,the nitrogen mineralized from soil organic matter calculated from the sum of nitrogen in whole plant (including roots) and ammonium-N in soil under rice growing condition was 29-62% higher than that in sealed anaerobic incubation being carried out under the same conditions with pot experiment,which showes that the growth of rice plant can considerably promote the mineralization of soil nitrogen.

Abstract:Paddy soils and vegetable soils (pH 5.10-6.95,organic matter 1.21-2.95 % and total phosphorus (P) 0.021-0.067%) in granite area of South China were used in pot experiments applied phosphatic fertilizer,and the "A" values for available phos-phorus according to Fried were determined.The soil samples were fractionated for their soil inorganic P-fractions by the procedure of Chang and Jackson.Equilibrium phosogate potentials (1/2pCa+pH₂PO₄),aluminum phosphate potentials (1/3pAl+pH₂PO₄),manganese phosphate potentials (1/2pMn+pH₂PO₄) and RTlna_H2PO4^- were determined according to White and Beckett's method.

Abstract:A new method was used for the determination of lime potential of soils in the field.A flat-type glass pH electrode and a calcium-selective electrode were inserted into the thick soil paste,and the pH-0.5pCa value was found by measuring the potential difference directly with a portable mV-meter.It was found that the ranges of lime potential of various soils were:1.4-3.0 in yellow soils under natural forest;1.6-2.5 in laterites under monsoon forest;1.7-4.0 in laterites under rubber tree;1.8-2.5 in upland soils with shifting cultivation,3.2-5.5 in paddy soils.The lime potential in paddy soils was highest at the middle part of the soil profile,and that in other types of soil was lowest at a certain depth in the middle part of the soil profile.For a terra rossa.the lime potential was as high as 6.3-6.7.

Abstract:The present article deals with thp study of K⁺ status in rhizosphere soil of cotton,barley and vetch by means of the potassium selective microelectrode and frozen slice methods.It was found that there were some factors affecting the either accumulation or depletion of K⁺ in rhizosphere soil of plants.The moisture content of soil was the main factor to induce the change of K⁺ status.When the moisture content was lower than the field moisture capacity,there appeared a depletion gradient in thizosphere.On the contrary,while it was hieher than the field moisture canacitv,an accumulation zone occured.

Abstract:Present paper deals with the total contents of trace in forest soils (great groups or sub-eroups) developed from different parent materials in Western Sichuan and Northern Yunnan.This regions,including the Hengduan mountains,is one of the most famous regions of high mountains and deep gorges in the world.The total mateats of Sr,Ba,Mo,Cu,Mn,B,Co,Zn,Ti,Cr,V,Ni,Pb and Sn in parent materials were determined.Such trace elements as B,Mo,Mn,Zn and Co in parent materials of the majority of forest soils in this region are more abundant.In general,the contents in the parent materials are higher than the average contents in lithosphere (or earth's crust) with the exception of Si and Ti.

Abstract:The paper deals mainly with the Zn status in rubber growing soils and rubber leaves,and its distribution and effect on the growth,yield and resistence to Oidium disease rubber trees in China.The available Zn in rubber growing soils amounts to 2.07 ppm on average,while the total Zn comes to 250 ppm and 242 ppm in the layers of 0-20 cm and 20-40 cm of the soil in rubber plantation respectively,which is higher than that of all other soils in China.The Zn content of rubber leaves amounts to 32.4 ppm on average,which is higher than that in other rubber growing contries.The Zn level of soils vanes greatly,the maximum total Zn being 33 times the minimum total Zn.

Abstract:Biennial sweet clover (Melilotus.albus Dear) is the main green manure crop in Jilin Province.The nodulation and nitrogen fixation activity of nodules of biennial sweet clover in different soils were investgeted during 1979-1980.Nodulation arrd nitrogen fixation activity (A.R.A) were found in all plants and nodules of the sweet clover in field,but their differences were greater between different soils.The fresh weight of nodule was highest in meadow black soil (about 3g per soil core),and it was getting decreased from warped soil,podzolic soil,black soil,to salt-affected soil in which it is lowest (less than 0.1g per soil mre).