Investigating tradeoffs in nitrogen loss pathways using an environmental damage cost framework

Few studies have addressed whether in-field practices to reduce nitrate-nitrogen (NO3-N) leaching might increase nitrous oxide (N2O) emissions, which could undermine attempts to mitigate agricultural N pollution. Over a 3-year period, we assessed the impacts of N application timing and cereal rye (Secale cereale L.) cover crop on subsurface drainage NO3-N leaching and N2O emissions to quantify changes in total N loss and corresponding social and environmental damage costs under continuous corn (Zea mays L.). While NO3-N losses were reduced by 37% with the combination of in-season split N application and cereal rye cover crop relative to pre-season N application, soil N2O emissions increased by 26%, highlighting a tradeoff between N loss pathways. As a result, total N losses and social and environmental damage costs from each system were not different. These results demonstrate the importance of addressing agricultural N pollution using a holistic framework accounting for the environmental and social risks of both NO3-N losses and N2O emissions.