Mapping Soil Test Phosphorus and Potassium for Variable‐Rate Fertilizer Application

Variable-rate fertilizer (VRF) application requires knowledge of the spatial variability of soil test P and K within a field. The objectives of the study were to: (i) evaluate cell (area) vs. point soil rumpling, both on a grid basis, and (ii) compare methods for mapping location specific soil test data. Soils in two central Wisconsin fields were rumpled with two methods; study site soils included two alfisols and one entisol. The grid-cell method involved dividing fields into 318-ft square cells and compositing soil cores to give one sample per cell. The grid-point method involved soil sampling at grid intersection points spaced on a 106-ft square grid