Soil heterogeneity and potato fertilizer recommendations

Each of 24 field experiments ranging from. 23 to 3.1 acres in size was divided into small rectangles. Each rectangle was soil sampled and each sample was analyzed separately for phosphorus and potassium. In some experiments separate samples were taken from both the top and the second foot of soil. The means, standard deviations, coefficients of variation and the percentage of the experimental area which fell into one of five nutrient level classifications were calculated.