A Historical Perspective on Nitrogen Fertilizer Rate Recommendations for Corn in Indiana (1953-2011)

For many years, N recommendations in the Midwest were based on achieving a specific corn yield goal (if you want so many bushels per acre, apply so much N). This began to change in 2006 when several universities in the Corn Belt adopted a substantially different N recommendation system. That system was developed from recent N trial results and took into account the relative costs of grain and N. Researchers from several universities detailed the new approach in Concepts and Rationale for Regional Nitrogen Rate Guidelines for Corn (Iowa State University Extension publication PM 2015, www.extension.iastate.edu/ Publications/PM2015.pdf).