Spatial Variability of Soil Organic Matter and Total Nitrogen at Different Scales

Under the GIS technical support,classical statistics and geostatistics were used for the analysis of the spatial variability of soil organic matter(OM) and total nitrogen(TN)in Yucheng city with two sampling scales.The results showed that the coefficients of variation(CV)for both OM and TN variables at two scales were in the range of 0.278～0.376,which demonstrated a moderate variation among.With the decreasing of scale,the CV for the soil OM content was increased,while the CV for the TN content was reduced slightly.Semivariance analysis showed that both OM and TN variables of the two different scales were spatially correlation at different lag distances.At the county scale,soil OM and TN content had a large spatial correlation distance,which were 11.5 km and 24.5 km,respectively.However,the soil OM and TN content at the town scale had the smaller spatial correlation distance,which were close to 3.0 km.Moran′s I coefficient analysis showed that with the research-scale reduction,the self-correlation of soil OM and TN are weakened,and weakened structural factors,random factors increased.The unobserved points were estimated and the map of spatial distribution were obtained using the kriging interpolation.The results indicated that the spatial distribution of soil OM and TN content at two different scales was obviously different.The mainly affected factors were the topology,soil type soil improvement etc.