Spatial Variation of Soil Total Nitrogen and Their Nested Simulation

In this paper, effect of scale on soil total nitrogen(TN) variation is analyzed, and spatial distribution of TN is simulated by nested model in Houhu farm in centre China. It is sampled at 144 locations under nested scenario, which is constituted by scale of 400, 100 and 50 meters. Data of TN are agree with normal distribution and vary in median level in three scales. Using geostatistics, variation of TN is simulated in each scale. It seems that the coefficients of spatial character are distinctive obviously in different scale, and spherical model fit best for semi-variogram in three scales. By nested simulating method under multi-scale data, the spatial distribution of TN is described in this region. Result shows that, in different scale, TN varies under different driving factors, which leads to the appearance of scale effect; TN content is the highest in South-West of the area, and decrease gradually to east and north part as strip-shaped. Through multi-scale simulation, is more accurate than traditional method, which isn't limited by nested distance(100m, 50m in this research); furthermore, the standard error is only 1/3-1/2 of the original method in local area; and the degree that the precision improved relates to the setting of scale distance. In additional, both of nested model and traditional method, there is boundary effect of precision during kriging interpolation. So, several samples should be added outside of study area.