Using On-farm Precision Experimentation Data to Analyse Maximum Return to Nitrogen (MRTN) Recommendations

Alternative derivatives of the original yield-goal based recommendations have been employed by researchers, outreach personnel, and private-sector crop management consultants to direct farmers. Current research indicates, however, that the original yield-goal-based method used scant data, questionable data omissions, and flawed statistical analysis. Maximum Return to Nitrogen (MRTN) recommendation is the first publicly available nitrogen recommendation tool to consider economic outcome when recommending nitrogen application rate. However, MRTN adoption is low; farmers may still be following retailer recommendations or prior experience, in part because the nitrogen application rate suggested by the MRTN system is relatively low. This study aims to determine the efficiency of the MRTN recommendations in directing nitrogen application rates in the corn belt. Between 2016 and 2021, forty-two on-farm precision experiments were conducted in Illinois and Ohio to determine the ex-post economically optimal nitrogen rate (EONR), which are used here to evaluate MRTN rates. MRTN rates are compared to the current rates of farmers to determine which achieves relatively high profit margins. Findings suggest that MRTN recommendations can be excessively high or inadequately low across fields in the same region and during the same year. Additionally, grower chosen rates performed better than MRTN on some fields in some regions. Thus, adopting the MRTN recommendation appears riskier than developers claimed.