Evaluating Corn N Use Efficiency with Replicated On-farm Trials

Matt Wiebers: Joe Hopkins, Dusty Zander, Chad Hoese

The University of MN publication 08560 and related regional publications provide guidance on N rate choices for corn farmers in Minnesota. In addition, the MRTN calculator developed by Iowa State University ( is a tool that is more dynamic and responsive as a decision support tool that utilizes state or regional data. This tool recommends fertilizer rates that are adjusted by economic factors including corn and fertilizer price ratios. The MRTN database at version 1.8 for Minnesota has 87 sites of corn-soybean data and 58 sites of continuous corn. This project will add site years of data to the MRTN and help develop a list of BMPs for other farmers to use. The MRTN database does not account for any weather input characterization as of 2017. By collecting site-specific weather data at each site, the intent is to classify the weather which may be a future component in N recommendations tools used by growers.

Minnesota corn farmers have the ability to generate on farm research data from their fields that can supply databases with site years of data that university extension, local agronomists, and other farmers across Minnesota can use to make data-based decisions. This project works to achieve three goals aligned with generating usable data:

  • Demonstrate the capabilities of farmers to conduct high-quality replicated on-farm trials as BMP examples for other MCGA growers.
  • Generate site years of yield response data from N rate trials that are compatible with the MRTN calculator used by farmers to select N rates for corn production in Minnesota.
  • Generate yield response data from trials that provide a replicated comparison of current MRTN N recommendations versus a weather-adjusted nitrogen recommendation system such as Climate, Adapt-N, or Encirca