Research results from long-term and short-term experimentation in Iowa have been consistent in the response or lack of response of Iowa field crops to applications of fertilizer phosphorus (P) and potassium (K) at various soil test levels for P and K. As a consequence of the research, recommendations for P and K based on soil test results and the interpretation of soil test values are being revised. The time frame for implementation is tentatively set to be prior to the 1996 spring planting season.