[Soil nutrient distribution and its relations with topography in Huangshui River drainage basin].

By using GIS and geostatistic techniques, this paper studied the spatial distribution patterns of soil nutrients and their relationships with topographic factors in Huangshui River drainage basin, a water source of Danjiangkou Reservoir. In the study area, the soil total nitrogen, total phosphorus, and organic matter varied spatially at medium level, with the variation coefficients being 51%, 66%, and 85%, respectively, whereas the soil available phosphorus displayed a strong spatial variation, with the variation coefficient reached 161%. The soil total nitrogen and organic matter exhibited a spatially positive autocorrelation, while the soil total and available phosphorus presented a spatially weak autocorrelation.