Abstract: Field nutrient distribution maps obtained from the study on soil variation within fields are the basis of precision agriculture. The quality of these maps and value for management depends on the accuracy of the predicted values, which in true depends on the initial sampling. To produce reliable predictions efficiently the minimal sampling size and combination should be decided firstly, which avoides the misspent funds for field sampling work. A 7.9 hectare silage field close to the Agricultural Research Institute at Hillsborough, Northern Ireland, was selected for the study. Grid sampling method (25m×25 m) was adopted and there were 123 sampling points in this field. Based on all sampling data, the least required numbers of soil properties were calculated for a 95% confidence within 5% of population mean. Using the geo-statistical method of Kriging with the data in the various sampling combinations for soil available P and K were made at sampling points from which the known values had been removed. These predicted data groups were compared using Least Significant Difference (LSD) test method. The results showed that the 62 sampling size of triangle arrangement for soil available K were sufficient to fulfil the required accuracy. The triangular design to be more efficient of Kriging than a rectangular or hexagonal sampling arrangement.