Spatial Distribution Feature of Soil Nutrient Contents from a Small Watershed and Their Relations to Land Use

Based on the application of GIS and traditional statistical methods, this paper studied the spatial distribution feature of soil nutrient contents and their relations to land use in a small watershed, which located in the Ziyang County, Sichuan Province. The results showed that soil total nitrogen and organic matter for the upland,orchard and bare land in interested area were widely deficient, especially for the bare land on the top and steep slope of hill. We should pay more attention to this kind of land use in the future. Moreover, the high value distribution areas for the soluble nutrients in the upland and orchard should also be more cared. And remarkable spatial distributions with the feature of stripe and patch were also found for all nutrients. The spatial heterogeneity of most soil nutrients except for total potassium and nitrate was significantly influenced by the land use. The rank of the influenced nutrients was as follows: organic mattertotal nitrogentotal phosphorus soluble phosphorus. Generally speaking, the total potassium with lesser coefficient of variability mainly inherited the quality of material rock. However, more important factors (e.g. fertilizer,rainfall and runoff) may control the content of nitrate, as a result, there no existed significant relationship between land use and nitrate.