Phosphorus (P) fertilization is needed for profitable crop production in most Iowa soils. Extensive research has been conducted for decades on crop yield response to P and calibration of soil-test P methods. Frequent changes in crop genotypes and increasing yield levels necessitates continuous research to revise and update management guidelines as needed. This report summarizes results of a multi-year experiment conducted to evaluate corn and soybean grain yield response to different P fertilization rates and soil-test P levels.