Update to Iowa phosphorus, potassium, and lime recommendations
This article highlights revisions to Iowa State University (ISU) soil-test interpretations and application guidelines for phosphorus (P), potassium (K) and lime in the updated ISU extension publication PM 1688 “A General Guide for Crop Nutrient and Limestone Recommendations in Iowa”. The previous update to this publication was in 2002. Field research is conducted as issues or questions arise to assure that nutrient management suggestions are up to date. This research has indicated that some recommendations should not be changed, but that others needed significant changes to optimize nutrient management to improve the profitability and sustainability of crop production.