1. Effects of Soil Phosphorus and Potassium Levels on Corn Yield Response to Nitrogen Fertilization, Nitrogen Use Efficiency, and Profitability

Annual investment in nitrogen (N) fertilizer for corn production represents a significant portion of annual input costs. Yield response to N fertilization is affected by soil N supply, crop N demand, and interacting factors that affect crop N use, such as phosphorus (P) and potassium (K) supply. To investigate the effects of soil-test P and K levels on corn yield response to N fertilizer, a four-year study was conducted at two southern Wisconsin sites. Soil-test P and K were maintained at low,... J.D. Jones, C.A. Laboksi, F.J. Arriaga