Abstract: It is significant to explore the spatial variation of soil biochem istry characteristic by densely soil sampling，to construct the mathematical models for revealing the relation between crop yield and its environment for precision agriculture, to raise the resolution of soil maps through indirect methods and evaluate its reliability． Based on the evaluation of interpolation methods， this paper adopts Kriging interpolator to produce soil map of organic matter in Shanghai Base，using 280 soil samples of systematic sampling of 3 samples per hectare．The comparison between Kriging and inverse distance function interpolating is carried out by using the same data set，showing that the Kriging interpolator is better than the latter in this situation．This study also analyzes the scenario of producing soil maps by reducing the amount of samples and gives the relevant evaluations． Based on these analyses， the authors present the procedure of optimal design of soil sampling for precision agriculture of rice growing．