In the US corn belt, corn yields are increasing, but so are environmental nitrogen (n) lossesdespite significant improvements in nitrogen use efficiency (NUE)

The Department of Agriculture National Institute of Food and Agriculture awarded Iowa State University of Science and Technology $649,996 under the Agriculture and Food Research Initiative (AFRI) on February 1, 2026, for research on nitrogen use efficiency and environmental nitrogen losses in corn production across the US Corn Belt.

The project will conduct three-way factorial experiments with 50 corn hybrids, five nitrogen-fertilizer rates, and two plant densities across 26 site-years to measure critical interactions among genetics, environment, and management that control agricultural inputs, outputs, and efficiencies. The research will determine whether optimum nitrogen rates for corn are increasing due to maize breeding, estimate determinants of nitrogen-use efficiency to clarify historical trends and physiological limits, and quantify environmental nitrogen loss potential of historical, present, and future hybrids using APSIM process-based modeling. Outputs will inform farmers, agronomists, breeders, and policymakers on optimum nitrogen fertilizer inputs to maximize productivity and environmental performance.

Performance occurs at Iowa State University in Ames, Iowa, with a period of performance from February 1, 2026, through January 31, 2029.

This is a major concern forthe corn belt and croplands across the globe. IT is numerically and biophysically possible forboth NUE and n losses to increase because of the interactions among genetics, environment, andmanagement (gxexm) that control agricultural inputs, outputs, and efficiencies.there is a significant opportunity to manage these interactions to increase yield and reduce nlosses; however, the many potential combinations of these factors have remained a barrier to thisgoal. Here, we will address this barrier by using coupled multi-factor experiments and croppingsystems models. We propose to measure critical components of this interaction at scale by performing three-wayfactorial experiments with 50 different hybrids, five n-fertilizer rates and two plant densitiesacross 26 environments (site-years) in the US corn belt. This project will 1) determine whether and to what extent the optimum n rate for corn isincreasing due to maize breeding, 2) estimate the determinants of NUE (n-fertilizer recoveryefficiency and plant internal efficiency) to better understand historical trends and possible physiological limits to NUE, and 3) quantify the environmental n loss potential of historical, present, and future hybrids using apsim process-based modeling.outputs from this project will advance n science and will inform farmers, agronomists, breedersand policymakers, on optimum n fertilizer input to maximize productivity and environmentalperformance.