Phosphorus and Potassium Placement for No-Till Corn

The information presented is part of ongoing research to identify effective fertilizer placement methods and diagnostic tools for phosphorus (P) and potassium (K) in no-till and ridge-till corn and soybean. Results for no-till cornfields will be emphasized here. There is uncertainty about soil test interpretations and cost-effective methods of fertilizer application for the no-till system. Moreover, producers are uncertain about the value of soil testing in conservation tillage because of large variability and lack of knowledge concerning techniques for collection of samples. Broadcast placements are less costly than banded placements but they seem inefficient for no-till fields because fertilizers are not incorporated. Because of the reduced movement of P and K in soils, broadcast applications result in stratification of these nutrients and accumulations within the top 2 or 3 inches of the soils. Although residue cover usually improves root growth and root absorption efficiency at shallow soil layers, the stratification could result in lower P or K uptake by plants during dry periods