ASSESSMET ON INFLUENCE OF AGRICULTURAL LAND USE ON SOIL NUTRIENT FERTILITY IN RED SOIL HILLS REGION

In this paper ,system theory and quantitative analysis method are applied to the approach of soil nutrient fertility changes caused by different land utilization in South China. Nanning municipality located in red soil region was taken as a study case,the time from 1980 to 1994 was for study period,general soil survey in 1980 and detailed investigation data of land use in 1992 were considered as basic data to analysis. Then according to the statistics methods,analysis of soil samples collected in 1994 and investigation of changes of land use input/output and land use were also carried out. In addition,the input and output in land uses were investigated in detail. With the index of soil nutrient fertility level compared with the input and output in land uses were investigated in detail. With the index of soil nutrient fertility level compared with the soil nutrient fertility of 1980,it decreasedby 10% in 1994 generally,in which the available K in the most one that decreased up to 14.17%. Almost all of soil nutrient fertility indexes of cultivated land especially upland decreased,but the decreases of soil fertility in forest and fruits garden land aren′t remarkable. According to this characteristics and conditions of red soil,current land utilization patterns must be regulated and improved. It is necessary to adopt high_efficient sustainable land use techniques such as agroforest to maintain and increase soil fertility,and the sustainability of agricultural ecosystem.