The technique of Precision Agriculture (PA) has widely been extended at present. Soil sampling by grids is a very important way for nutrient management in PA. The methods of computer-based interpolation was used for analysis of soil nutrients and performanced at five randomly selected soil sampling points. Results were compared between interpolation and actual measurement by grids difference in scales. The interpolation errors of total nitrogen, plant available nitrogen, and plant available phosphorus increased with the size of sampling grids. But those of potassium and other micronutrients showed a reserve trend. The distribution of soil sampling points had a direct effect on interpolation results.