Why do subsoil sampling?
Crops feed on nutrients through the rooting zone. Factoring results from deep samples helps refine fertilizer application maps by considering what will be available to the crop during key yield building growth stages. While the top 6 2/3 inches of the soil are where most of fertilizers are applied, that is not where much of the nitrogen is taken up. It is important to look at more of the soil profile when determining what nutrient will be available for plants. This is also true for soil nutrients other than nitrogen.
