Characteristics of spatial variability of nutrients in slopeland of purple soil at plot-scale.

With the aid of geostatistics and GIS interface,the spatial distribution of soil properties in sloping land of purple soil in the central Sichuan basin was described and illustrated and the rational points in sampling of soil in the sloping land were further ascertained.The results indicated that the spatial correlation of organic matter,total-N,and available P at plot scale was high,so their variabilities were mainly affected by structural factors.The spatial correlation of available N and pH was moderate,so their variabilities were affected by structural and random factors.Moreover,the spatial correlation of available K was low.Based on the semi-variance and Kriging interpolation method,the isolines of soil nutrients were mapped.The spatial distributions of soil organic matter,total-N and available phosphorus were similar,while the available N,available K and pH were clearly different.The analysis of spatial variability was necessary for planning of rational sample points at field and catchment scales.