Optimizing Nitrogen Use Efficiency and Minimizing Nitrification-Induced N Leaching and Gaseous Losses with PostPlant Fertilizer Applications: Field and Lab Studies

University of Minnesota/Rodney Venterea

The aim of the project is to overcome some of the limitations of post-plant nitrogen (N) applications through the use of post-plant inhibitor applications, and to document the environmental and agronomic benefits of the practice. In a two-year field study, we will measure soil nitrate and nitrite concentrations, nitrous oxide (N2O) emissions, soil temperature and moisture, grain yield and N fertilizer recovery efficiency.

In addition to testing these management practices under field conditions subject to highly variable weather effects, the lab component of the study will be used to better understand N loss processes at the molecular level. In the lab study, we will measure short-term biochemical responses to N addition including changes in pH, mineralization and nitrification rates, nitrite and nitrate concentration and N2O production under different moisture, temperature, and carbon conditions expected for a range of field conditions representative of different periods of the growing season.

This study will compare novel combined approaches for increasing N use efficiency that, if shown to be successful, will provide Minnesota corn farmers with management options that have both agronomic and environmental benefits. A truly beneficial N management strategy is one that can reliably increase yields at the same level of N input or maintain yields at a lower rate of N input compared to a typical practice, while reducing N losses in both cases. The research also aims to improve the fundamental understanding of the short-term biochemical processes driving N losses following addition of N fertilizers that will have broader benefits over time.