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 (NO) emissions must be evaluated. The objectives of this study were to determine the influence of contrasting tillage practices (CD vs. NT) on soil NO 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 NO-N was similar among tillage treatments in 2018 (3.2 kg NO-N ha) but higher in CD (8.5 kg NO-N ha) than in NT (6.2 kg NO-N ha) in 2020. The CD treatment had higher two-yr cumulative NO-N emissions (11.9 kg NO-N ha) than NT (9.1 kg NO-N ha), indicating that NT has a potential for reducing NO-N in poorly-drained Alfisols. Grain yield-scaled NO-N was lower in NT than CD in 2020 but not in 2018. Soil NO emissions were positively associated with soil NO-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 NO-N emissions indicating to mitigate climate change and increase multi-sphere benefits, continuous NT practices should be implemented.