ABSTRACT
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.
