Abstract:The present paper deals with the influence of different physical conditions of three typical red earths in China on the phosphorus self-diffusion.Experiment was made under three moisture levels including about 17,22 and 28% for the latosol;15,20 and 25% for the lateritic red earth;15,20 and 25% for the red earth with low fertility;23,27 and 30% for the uncultivated red earth and four grades of soil bulk densities being 1.20,1.35,1.50 and 1.65 g/cm³ except those of uncultivated red soil.

Abstract:This paper deals with the influence of application of rice straw,milk vetch,weathered coal and polyvinyl alcohol on the properties of organo-mineral complexes of yellow-brown earth (collected from Jiangning) and red earth (collected from Jinxian,Jiangxi).The results obtained are summarized as follows:In the yellow-brown earth,the polyvinyl alcohol and the nce straw were conduave to the formation of aggregates and thus increased the percentage of effective pore spaces of 0.1-0.01 mm.The polyvinyl alcohol treatment could promote the stability of aggregates.In the red earth,the rice straw and the milk vetch might cause dispersion of the aggregates.In above two soils,the treatment of ammonical weathered coal caused highly dispersion of aggregates.

Abstract:In this paper,Langmuir isotherm was used for the interpretation of the phosphate adsorption in soils.The soil samples tested were collected from the representative soils in north-eastern China.Meanwhile,the fractionation of inorganic phosphates were conducted.Results showed that the maximum adsorption was conrrelated negatively with soil pH,and positively with CEC.Moreover,the product of parameters in Langmuir equations (K₁×K₂ was conrrelated negatively with desorption %:Besides,the acid soils were rich in occluded Fe-P,but low in desorption %.While the calcareous soils generally possessed higher desorption %,even though the Ca-P and Fe-P in soils were extremely high.The Al-P was increased after the soil samples treated with KH₂PO₄solution.The Al-P was increaced with the increase of phosphate adsorption.

Abstract:1.An experiment of air-dried soil incubated under sealed-waterlogged condition at 3℃ for 2 weeks showed that the soil N mineralized was correlated positively with the total N and amorphous iron oxides contents in soil,and negatively with the soil pH.In field experiments,however,the correiation between the N supply to the mentioned above was insignificant.

Abstract:Field experiments conducted recently in provinces of North China showed that in calcareous soil of loess parent material and fluvisol in the region of the Yellow and Huai rivers,Mn deficiency was becoming a problem in crop production.It seems that further study on Mn in calcareous soils and crops,effect of Mn-application and applicability of soil testing procedures for prediction of requirement of Mn by plant in the soil are of not only theoretical significance in micronutrient researches,but also of practical importance for improving yields.In order to achieve the objectives mentioned above,this study involves the following three harts:Ⅰ.Mn absorbtion of plants from applied Mn and crop response In pot experiments,MnSO₄ was applied at 5 rates to three calcareous soils which were collected from different provinces of North China.

Abstract:The geochemical characteristics of zinc in soils of Hengyang basin in the middle south of Huxian Province is closely related to rice growth.The content of available zinc extracted by DTPA solution in the calcarcous and neutral soil is correlated significantly with the content of zinc in rice ulants (r=0.83;p<0.05).The availability of zinc is affected by the factors such as soil pH,content of organic matter,parent material and soil type.The content of phosphorus in paddy soils derived from purple soils is rather high,and the soil available zinc is <0.5ppm.

Abstract:Limestone soils are widespread in southern China.This paper ceals with the contents of trace elements in limestone soils,i.e.rendzina,brown rendzina,terra rossa and yellow rendzina.The trace elements in soil investigated include boron,molybdenum,manganese,zinc,copper,cobalt,nickel,vanadium,chromium,lead and gallium,some of which are importent to the normal plant growth and others are essential to animal health.The trace elements in limestone soils are rather rich.

Abstract:Three-River-Plain is a typical dry farming agricultural region.Investigation shows that solum structure pattern is:internal factor of drought and waterlogging resistance of soils.The difference in drough and waterlogging resistibility of the solum patterns depends on presence or absence of block soil layer in the soil profile of 0-100 cm.In the soil without block soil layer,the capacity of water storage and supply is higher,the drought and waterlogging resistibility of the soil and crop yield are generally high and stable.In the soil with block soil layer,the drought and waterlogging resistibility varies with the depth of block soil layer in profile and its properties.With well development of block soil layer,the soils of Three-River-Plain belong to those of the pooz solum pattern which are unfavorable for resistance of drought and waterlogging of the soil.It is of practical significance to improve these soils with proper measures in combination with reasonable management of water for the control and regulation of soil water and the alleviation of disaster of drought and waterlogging and the ncrease of cmp yield.

Abstract:The present paper deals with soil secondary alkalization due to irrigation with alkaline groundwater of low salinity.It was showed by modelling experiment of soil column in laboratory that the accumutation of soda,pH and ESP of soil increased due to irrigation of the soil with alkaline groundwater of low salinity.The degree of soil alkalization depended on the content of residual sodium carbonate in alkaline groundwater of low salinity and the time of irrigation.henerally speaking,the higher content of residual sodium carbonate in groundwater,the more soil alkalization is.At the same time,the thickness of soil alkalized horizon was increased with the increase of irrigation time.

Abstract:The patterns of solum structure for distinguishing taxa at soil species level consist of basic horizons including surface (ploughing) horizon,and other special horizons,which are naturally differentiated and arranged within the soil profile.For comparative study,the thickness and positron of the basic horizons and speaal horizons in the profile of a depth or 1m.are delimited and defined according to the criteria designed especially for delimitation of the pattern of solum structure.Within a soil genus,the pattern of solum structure is the basis for distinguishing soil species.Under the conditions of soil formation including the integrated influence of natural factors and human activity,the development degree of the diagnostic horizons combined with the differences of soil fertility in surface (ploughing) horizons may serve as the criteria for distinguishing soil species.In this paper,the procedure for classification of soil at the soil species level is discussed.

Abstract:1.Under the condition of pure culture,Trifluralin,Linuron and Lasso(10-50 ppm) showed sensitive inhibitory effect on the growth of bacteria,while Amiben had no this effect.Azotobacters and Saccharomycetes had high resistibility to herbicides.Nodule bacteria of soybean and green manure crops could be grow well on Trifluralin agar plate in which the concentration was 5-20 times as high as that in the fields.The growth of actinomycetes and majority of fungi was inhibited strongly by Lasso and Linuron.Trifluralin and Amiben had inhibitory effect only on a few actinomycetes and fungi.The formation of actinomycete conidiospores was inhibited by most of herbicides under the condition of low concentration.

Abstract:珠江是我国南方最大的河流,主要由东江、西江和北江组成,流域面积45.3万平方公里,年总迳流量3412亿立方米,年输沙量达8336万吨,其中80%的泥沙在珠江八大口门外沉积下来形成大片海涂.这些海涂地处南亚热带南缘,水热条件优越,地势平坦,土壤肥沃,生产潜力大,是今后围海造田,扩大耕地面积的对象,也是三角洲发展农业生产的潜在基地.