Continuous no-till decreased soil nitrous oxide emissions during corn years after 48 and 50 years in a poorly-drained Alfisol

The soil quality benefits from switching from chisel-disk (CD) operations to continuous no-till (NT) in corn (Zea mays L.) and soybean (Glycine max L.) rotations have been proven over time; but to mitigate climate change, effects of continuous NT on nitrous oxide (N₂O) emissions must be evaluated. The objectives of this study were to determine the influence of contrasting tillage practices (CD vs. NT) on soil N₂O emissions, soil nitrogen (N) dynamics, corn grain yields, N removals and partial N balances, soil volumetric water content (VWC) and soil temperature following 48 and 50 years of tillage implementation in a long-term corn-soybean rotation experiment in a poorly-drained Alfisol. A four-time replicated randomized complete block design was conducted with tillage treatments [CD (grower's current practice) and NT] as main plots and fertility [a no-fertilizer control (CTR) and fertilizing corn N, P, and K (NPK)] as subplots. Corn grain yield, N removal, and partial N balances were greater in CD than NT in 2018 but not in 2020. Soil N₂O-N was similar among tillage treatments in 2018 (3.2 kg N₂O-N ha⁻¹) but higher in CD (8.5 kg N₂O-N ha⁻¹) than in NT (6.2 kg N₂O-N ha⁻¹) in 2020. The CD treatment had higher two-yr cumulative N₂O-N emissions (11.9 kg N₂O-N ha⁻¹) than NT (9.1 kg N₂O-N ha⁻¹), indicating that NT has a potential for reducing N₂O-N in poorly-drained Alfisols. Grain yield-scaled N₂O-N was lower in NT than CD in 2020 but not in 2018. Soil N₂O emissions were positively associated with soil NO₃-N, partial N balances, and corn grain yield and negatively associated with soil bulk density and temperature. We concluded that after 48 and 50 years, continuous NT can maintain corn grain yield and mitigate N₂O-N emissions indicating to mitigate climate change and increase multi-sphere benefits, continuous NT practices should be implemented.