Profitable corn production requires adequate amounts of plant-available phosphorus (P) and potassium (K) in the soil. Deficiencies of these nutrients are not a problem in many Iowa soils. In fact, recent soil-test summaries and surveys show that fertilization practices have increased initially low values of P and K in most soils to levels higher than needed to maximize yields. Additional studies indicate that applying P or K fertilizers to corn and soybeans grown on soils testing high in these nutrients is not profitable, Consequently, evaluating excess P and K is now more important than evaluating P and K deficiencies.
Alfred M. Blackmer
Antonio P. Mallarino
Year of Grant Completion
Blackmer, Alfred M. and Mallarino, Antonio P., "Corn tissue tests for excess phosphorus and potassium" (1993). Leopold Center Completed Grant Reports. 9.