Extension agronomists at Iowa State University have revised their nutrient management recommendations. The recommendations are part of the extension publication "A General Guide for Crop Nutrient and Limestone Recommendations in Iowa" which is free to the public (click here).
Antonio Mallarino, an extension agronomist and professor of agronomy said, “This research has indicated some recommendations should not be changed, but other recommendations needed significant change to optimize nutrient management in order to improve the profitability and sustainability of crop production.”
The most notable revisions include interpretations for the new moist-and-slurry-test for K, changes in interpretations of K with dry samples, adjustments to crop nutrient concentrations and the discontinuation of P&K subsoil categories for interpretation. This field research proved the moist-and slurry-test to be more reliable at assessing potassium levels in the soil than the former, dry test method.
Interpretation categories that have not changed are the general P&K recommendations for long-term profitability, soil pH, interpretations for the Bray-P1, the Mehlich-3 test and the inductively-coupled plasma test, and interpretations for micronutirnets, which is currently limited to zinc in corn and sorghum as research is ongoing.
The updated nutrient management recommendations are part of ISU's commitment to research and improving nutrient management on the farm. Mallarino notes, “Field research is conducted continuously to assure that nutrient management suggestions are up to date.”
See the full release from Iowa State University Extension here...
View a PDF copy of "A General Guide for Crop Nutrient and Limestone Recommendations in Iowa" here...