Soil Nitrous Oxide Emissions Following Crop Residues Management in Corn-Wheat Rotation Under Conventional and No-Tillage Systems

Abstract

Agricultural activity is the major anthropogenic source of nitrous oxide (N 2 O) emissions from terrestrial ecosystems. Conservation agriculture including crop residue management can play a key role in enhancing soil resilience to climate change and mitigating N 2 O emissions. We investigated the effects of crop residue rates, including 100 % (R 100 ), 50 % (R 50 ), and residue removal (R 0 ), on N 2 O emissions in corn-wheat rotation under conventional (CT) and no-tillage (NT) systems. The key factors evaluated affecting N 2 O emissions included soil temperature, soil moisture, soil ammonium, and soil nitrate concentrations. Results showed that the N 2 O emissions increased with the increasing rate of residue under both CT and NT systems. Both R 100 and R 50 significantly ( p < .05) increased the N 2 O emissions compared to R 0 during the annual rotation cycle. Soil moisture and mineral nitrogen (ammonium and nitrate) were the main driving factors that stimulated N 2 O emission in both CT and NT systems. In the NT and CT systems, cumulative N 2 O emissions showed a significant increase with R 50 (+75.5 % in NT, +36.5 % in CT) and R 100 (+134 % in NT, +40 % in CT) as compared to R 0 . Furthermore, no significant differences were found between R 100 and R 50 in the CT system, while in the NT system significant increases were observed for R 100 compared to R 50 . Overall, our study justified as a first approach only during the first year that crop residue removal led to decreased N 2 O emissions under semi-arid conditions. However, due to the deteriorating impact of crop residue removal on crop productivity and soil C sequestration, this management method cannot be considered a sustainable agronomic practice. We suggest long-term studies to determine the appropriate rate of postharvest crop residue to achieve less N 2 O emissions and climate-friendly agricultural practices.