| The grid-sampling method was used to study spatial variability of available soil nutrients. The results showed that the sampling intervals did not significantly affect the contents and variance coefficients of available soil nutrients; they affected the proper sample number to some extent and the proper number should be 71 for alkali-hydrolysable nitrogen, 36 for available phosphorous, and 18 for available potassium. The spatial variability of available soil nutrients were mainly affected by structural factors but chance factors affected alkali-hydrolysable nitrogen and available phosphorous more than available potassium. The contour map of the available soil nutrients at different sampling intervals were depicted with Kriging interpolation method. |