Characteristics of spatial variability of total soil nitrogen in the typical subtropical red soil hilly areas

A geostatistics method combined with GIS was applied to analyze and map the spatial variability of total soil N in topsoil. The results showed that total soil N had strong spatial relativity at 60 m lag interval and its range of autocorrelation extended to 208 m. The variogram of total soil N was characterized by geometric anisotropy in NE30° and NE120° directions and zonal anisotropy in NE60° and NE150° directions. The spatial distribution map of total soil N interpolated by Kriging interpolation showed apparently strip and block. The "hot spots" of high soil N content were consistent with the low locations of the field. The spatial distribution of total soil N was controlled by topology.