Analysis on Spatial Variation of Soil Nutrients and Its Affecting Factors in Slope Land of Karst Area

By the methods of geo-statistics,the spatial variability of soil nutrients in a slope land of karst area in Zhongliang Mountain of Beipei District in Chongqing City was studied.A sampling plot sized 100 m ×100 m was installed and 7 kinds of soil nutrients,including organic matter,total nitrogen,total phosphorus,total potassium,available nitrogen,available phosphorus and available potassium,etc,were determined.The results showed that the spatial variability degrees of organic matter,total phosphorus,total potassium and available potassium were relatively higher,while that of available phosphorus was medium,and that of total nitrogen and available nitrogen were lower.The results also indicated that the spatial distribution of soil nutrients varied from the slope position.The contents of organic matter,available nitrogen,total phosphorus and available phosphorus were higher at the upper and top of the slope,while the contents of total nitrogen,total potassium and available potassium were higher at the bottom and base of the slope.Correlation analysis on soil nutrients and environmental factors showed that the spatial variabilities of total nitrogen,total phosphorus,total potassium,available nitrogen,available phosphorus and available potassium were mainly affected by structural factors,such as geology,geomorphology,soil thickness,etc.The spatial variability of organic matter was mainly affected by random factors,such as vegetation type,cropping degree,etc.