Grazed Pasture Effects on Greenhouse Gas Emissions in the Ozark Highlands

In the United States (US), grazinglands serve as the main foundation for the livestock industry, and, in Arkansas specifically, pastures are essential for rotational grazing and dairy operations. Climate change is increasingly becoming a concern in the agriculture industry, largely caused by anthropogenic activities increasing greenhouse gas (GHG) concentrations in the atmosphere, at least partly due to the nutrient recycling that occurs from animal manure additions in grazinglands. Therefore, quantifying GHG emissions from pastures is essential to better understanding the impacts of grazing on the environment. The objective of this study was to quantify and evaluate the potential effects of grazing methods [i.e., enhanced grazed (EG) and minimally grazed (MG)] on carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) fluxes, season-long emissions, and global warming potential (GWP) on a silt-loam soil in the Ozark Highlands region of northwest Arkansas. In 2024, averaged over time, the CO2 flux from the EG (880 mg m-2 h -1 ) was greater than from the MG (687 mg m-2 h -1 ) treatment and, averaged between treatments, CO2 flux differed over time. In 2025, CO2 fluxes were unaffected by treatment, but differed over time. In 2024 and 2025, both CH4 and N2O fluxes differed between treatments over time. Averaged across grazing treatment, season-long CO2 emissions and GWP were at least 1.8 times greater (P ≤ 0.05) in 2025 compared to 2024, while season-long CH4 emissions were 4.6 times greater in 2024 than in 2025. Averaged across years, season-long CH4 emissions were greater from the EG (1.0 kg ha-1 ) than the MG (0.12 kg ha-1 ) treatment and, averaged over treatments, was greater in 2024 (0.93 kg ha-1 ) than in 2025 (0.20 kg ha-1 ). Averaged across year, season-long N2O emissions was greater from the EG (1.6 kg ha-1 ) than from the MG (0.38 kg ha-1 ) treatment. Two-year-cumulative, season-long CH4 and N2O emissions and GWP from only CH4 and N2O were greater (P ≤ 0.05) in the EG compared to the MG treatment. Considering the large land area devoted to various agricultural grazing operations throughout the US, understanding the magnitude of GHG emissions from different grazing strategies will contribute to improving GHG mitigation efforts in managed grazinglands.