Nicholas Institute for Environmental Policy Solutions
Effective management of nitrogen (N) in agricultural landscapes must account for how nitrate (NO3) leaching and nitrous oxide (N2O) emissions respond to local field-scale management and to broader environmental drivers such as climate and soil. This article in the Soil Science Society of America Journal reflects assemblage of a comprehensive database of fertilizer management studies with data on N2O (417 observations, 27 studies) and NO3 (388 observations, 25 studies) losses associated with 4R fertilizer N management in North American corn-cropping systems. Only one study measured both losses, and studies of N2O and NO3 differed by location, time period, and management practices. Meta-analysis of side-by-side comparisons found significant yield-scaled N2O emission reductions when SUPERU replaced urea or UAN, and when urea replaced anhydrous ammonia. The large effects of climate and soil, and the potential for opposite reactions to some management changes, indicate that more simultaneous measurements of N2O and NO3 losses are needed to understand their joint responses to management and environmental factors, and how these shape tradeoffs or synergies in pathways of N loss.