Enhanced efficiency nitrogen fertilizers (EENFs) can reduce nitrous oxide emissions and maintain high grain yields in a rain-fed spring maize cropping system.

Enhanced efficiency nitrogen fertilizers (EENFs) have provided opportunities for the simultaneous mitigation of nitrous oxide (N 2 O) emissions and increases in crop productions. However, the practice of combining EENFs with optimal fertilization under conditions of misaligned water and fertilizer inputs in rain-fed spring maize systems remains inadequately understood. This study aims to determine the factors controlling N 2 O emissions under the soil climatic conditions in rain-fed plastic mulching cropping systems treated with different nitrogen (N) fertilization rates and EENFs, and to determine the most effective N fertilization measure to reduce N 2 O emissions while maintaining crop yields. A 3-year field experiment was conducted in a spring maize system located in the semiarid rain-fed region of the Loess Plateau, applying two types of EENFs: a nitrification inhibitor dicyandiamide (DCD) and a slow-release fertilizer (SRF). It comprised five fertilization treatments: unfertilized (CK), conventional N rate (CON, 200 kg N ha−1), optimal N rate (OPT, 160 kg N ha−1), OPT with the addition of DCD (OPT+DCD), and OPT using SRF (OPT-SRF). The average annual cumulative N 2 O emissions over the 3-year experimental period ranged from 0.74 to 1.87 kg N 2 O-N ha–1. Fertilizer N contributed 26−60% to annual N 2 O emissions. The highest N 2 O fluxes (50–161 μg N 2 O-N m–2 h–1) typically occurred within the initial 10 days following fertilization, likely induced by strong nitrification processes, constituting 12–19% of the annual N 2 O emissions during this brief period. In comparison to the CON treatment, the OPT, OPT+DCD, and OPT-SRF treatments resulted in significant reductions in annual N 2 O emissions of 24%, 46%, and 34%, respectively, without causing any significant decrease in maize grain yields. The application of DCD led to increased ammonium (NH 4 +-N) concentrations while reducing nitrate (NO 3 –-N). Conversely, using SRF resulted in a decrease in both NH 4 +-N and NO 3 –-N concentrations. Using EENFs at the ideal fertilization rate significantly curtailed yearly N 2 O emissions without adversely affecting maize yields in a rain-fed plastic mulching spring maize system prevalent in the Loess Plateau. Most N 2 O emissions occurred post-fertilization, with rainfall events further influencing these emissions. Our findings recommend the incorporation of nitrification inhibitors, such as DCD, as the most effective fertilizer measure for reducing N 2 O emissions in the rain-fed region of the Loess Plateau. [ABSTRACT FROM AUTHOR]