Effects of Nitrogen Rate on Corn Yield Potential - Iowa

Trial Objective

  • This trial was designed to help determine optimum nitrogen rates for new corn products and to demonstrate the interaction of crop inputs with specific corn products. The summary contains two years of results for some products and also results from some products grown only in 2018.

Research Site Details

  • Nitrogen (N) was applied at rates of 110, 140, and 170 total lb N/acre as anhydrous ammonia (NH3) in the spring 5-9 days before planting.
  • Corn products were planted into each NH3 zone consisting of six 30-inch rows, approximately 370 feet long.

Understanding the Results


  • The two-year average yield for seven products in a corn-soybean rotation was greatest with 140 lb total N/acre.

What Does This Mean For Your Farm?

  • The crop response to nitrogen is dependent on several variables such as corn product, soil, and environment.
  • Low nitrogen rates can limit yield potential, while excess rates are not beneficial for additional crop response and reduce the return on investment.
  • The economic return to each additional unit of nitrogen will depend upon grain price and nitrogen price.