Grazed Pasture Effects on Greenhouse Gas Emissions and Global Warming Potential Estimates in the Ozark Highlands, USA

Grazing lands are foundational for the United States (US) livestock industry. In Arkansas, pastures are essential for rotational grazing and dairy operations. Climate change is an increasing concern in agriculture due to anthropogenic activities promoting greenhouse gas (GHG) emissions, partly due to nutrient recycling that occurs from animal manure additions. The objective of this study was to quantify and evaluate the potential effects of grazing method (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) over two consecutive growing seasons (i.e., 2024 and 2025) 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 (p ≤ 0.05) than from the MG (687 mg m−2 h−1) treatment. Averaged across grazing treatment, season-long CO2 emissions and GWP were at least 1.8 times greater (p ≤ 0.05) in 2025 than 2024, while season-long CH4 emissions were 4.6 times greater (p ≤ 0.05) in 2024 than 2025. Averaged across year, season-long N2O emissions were greater (p ≤ 0.05) 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 grazing lands.