Producers in Southeast Iowa are interested in managing available soil phosphorus (P) and potassium (K) to achieve optimum grain yields. This study was established in 1989 to examine P and K management in a corn-soybean crop rotation. In 2001 and 2006, nitrogen (N) treatments were added to supply this nutrient to corn at low and moderate rates to determine if corn yields were affected by P and K levels in the soil.