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Welcome to the Iowa State University Agronomy Extension Soil Fertility Home Page. Nutrient topics are listed on the left side. Simply click on a topic of interest and you can find information about that topic, including Extension publications, newsletter articles, conference proceedings and reports, presentations, and links to other related sites. Links also provide access to soil fertility decision aid tools, a photo gallery, and the ISU Soil and Plant Analysis Laboratory.
UPDATE TO IOWA PHOSPHORUS, POTASSIUM, AND LIME
Antonio P. Mallarino and John E. Sawyer, Professor, Department of Agronomy, Iowa State
September 20, 2013
This article highlights revisions to Iowa State University (ISU) soil-test interpretations and
application guidelines for phosphorus (P), potassium (K), and lime in an update of Extension
Publication PM 1688 "A General Guide for Crop Nutrient and Limestone Recommendations in
Iowa". The printed version of this publication will not be ready until later in the fall and the
online version should be posted here by early October at and on
the Soil Fertility web site. Field
research is conducted continuously to assure that nutrient management suggestions are up to
date. This research has indicated that some recommendations should not be changed, but other
recommendations needed significant changes in order to optimize nutrient management to
improve the profitability and sustainability of crop production. Read on.
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