Measured and simulated effects of residue removal and amelioration practices in no-till irrigated corn (Zea mays L.)

Reducing nitrous oxide (N2O) emissions to the atmosphere is expected to provide substantial climate mitigation benefits. Herein, we measured soil N2O emission and crop yield responses in a nine-year, no-till continuous corn system under contrasting management practices including irrigation (full; deficit), corn stover retention (100 % retention; maximum mechanical removal), and cover crop use (winter cereal rye, Secale cereale L.; no cover crop). Field-measured data were used to construct a structural equation model (SEMobs) to explore the causal effects of management on soil N2O emissions. We also used the Root Zone Water Quality Model 2 (RZWQM2) to simulate management effects on soil N2O emission. Structural equation modeling was used for the field-measured data (SEMobs) and the RZWQM2 simulated data (SEMsim) to quantify management relationships with soil and determine whether relationships observed in field data were captured by RZWQM2 simulations. Our experimental field results showed that stover removal decreased annual N2O emissions compared to stover retention, only for deficit irrigated soil (2.83 ± 1.31 vs. 4.49 ± 3.65 kg N ha−1 y−1) and that deficit irrigation decreased annual N2O emissions compared to full irrigation, only for soil with cover crops (3.31 ± 3.19 vs. 4.11 ± 3.80 kg N ha−1 y−1). The SEMobs and SEMsim results showed similar direction and magnitude of relationships between daily soil N2O emissions and various management and environmental drivers. Our study improved the mechanistic understanding for the effects of agricultural management on soil N2O emissions and can help reduce N2O emissions from agricultural systems.