Farm Progress is part of the Informa Markets Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them. Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

Phosphorus, potassium nutrient recommendations revised

Phosphorus, potassium nutrient recommendations revised

Advances in soil-testing research have led Iowa State University Extension and Outreach agronomists to revise recommendations for phosphorus, potassium and lime. “Field research is conducted continuously to assure that nutrient management suggestions are up to date,” says Antonio Mallarino, an extension agronomist and professor of agronomy. “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.”

He and John Sawyer, agronomy professor and extension agronomist, have updated the extension publication "A General Guide for Crop Nutrient and Limestone Recommendations in Iowa" (PM 1688). It is available online for free.

Mallarino said the most significant changes include:

  • Interpretations for the new moist- and slurry-based test for potassium
  • Changes to soil-test interpretations categories for potassium using dried soil samples
  • Adjustments to both crop nutrient concentrations and default crop yields needed to estimate nutrient removal for maintaining soil-test levels in the optimum category
  • Discontinued use of the P and K subsoil categories for interpretations

Read more about the changed and updated nutrient recommendations from Iowa State University.


You might also like:

2014 corn, soybean acreage estimates

Will the farmland bubble burst?

Green stem disorder showing up in soybeans

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.