N, P, K and S values courtesy International Plant Nutrition Institute (IPNI) and AgPhD. These are estimations where the actual fertility removal may vary based on many factors. Grain is the amount of nutrients removed with the harvested grain and Stover is the amount of nutrients included in the stalk. If the residue is removed, these nutrients will also leave the field.. If the residue is left behind in the field, these nutrients will eventually return back to the soil as the residue breaks down.