Spatial Variability And Quality Evaluation Of Soil Nutrient In The Small Watershed Of Red Eroded Soil Area

Soil was formed by the combined action both natural factors (parent material, climate, biological, terrain and time) and human factors, it was uneven change continuum. Soil characteristics was different between different regions, even in the same plots of different locations, this attribute was called soil characteristics of spatial variation. The red soil area of Southern China hills was rich in heat and water resources, and the potential production was tremendous. But due to the long-term illogical use of land resources and natural condition interaction, the ecology and environment were damaged in the whole area. Soil degradation and soil erosion were in serious trouble, which led soil quality and productivity decline. The small watershed of Zhuxi, which is one of the thirty typical monitoring watersheds in China, it is a typical representative of red eroded soil in Southern China for its complexity and diversity erosion present. A lot of foundation data were gotten by field sampling and experiment test. The spatial distribution of soil nutrient was analyzed in the small watershed supported by geostatistics method and the GIS technology. The research objective is to provide reference for the implementation of sustainable agriculture and the rehabilitation of soil erosion in the small watershed.The results were as follows:1) According to the soil testing data, soil organic matter(OM), alkali-hydro nitrogen(AN), available phosphorus(AP) were at the medium level, and total nitrogen(TN), total phosphorus(TP), total potassium(TK), available potassium(AK) were at the low level. The general situation of the soil nutrient was poorer contrast with the classification standard of the second national census of soil.2) Through the semi-variance analysis, the majority of soil nutrient factors are all medium spatial relativity except that AP which has a weak spatial relativity. The soil nutrient spatial distribution in the small watershed was generated by Kriging interpolation.3) Soil fertility grade was division in the small watershed, and the relationship between soil fertility and the site conditions were analyzed.4) The soil fertility effect of different soil erosion control measures were analysed, and the close hillsides to facilitate afforestation was better than the others on soil fertility improvement.