Greenhouse gas (GHG) emissions evaluations from agroecosystems are critical, particularly as technology improves. Consistent GHG measurement methods are essential to the evaluation of GHG emissions. The objective of the study was to evaluate potential differences in gas-flux-determination (GFD) options and carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) fluxes and growing-season-long emissions estimates from furrow-irrigated cotton (Gossypium hirsutum) in southeast Arkansas. Four GFD methods were evaluated [i.e., linear (L) or exponential (E) regression models, with negative fluxes (WNF) included in the dataset or replacing negative fluxes (RNF)] over the 2024 growing season using a LI-COR field-portable chamber and gas analyzers. Exponential regression models were influenced by abnormal CO₂ and N₂O gas concentration data points, indicating the use of caution with E models. Season-long CH₄ emissions differed (p < 0.05) between the WNF (−0.51 kg ha⁻¹ season⁻¹ for L and−0.54 kg ha⁻¹ season⁻¹ for E) and RNF (0.01 kg ha⁻¹ season⁻¹ for L and E) GFD methods, concluding that RNF options over-estimate CH₄ emissions. Gas concentration measurements following chamber closure should remain under 300 s, with one concentration measurement obtained per second. The choice of GFD method needs careful consideration to result in accurate GHG fluxes and season-long emission estimates.

Corn (Zea mays) production systems are described as high risk for emissions of greenhouse gases (GHG) due to large fertilizer inputs. Conservation practices, such as cover crop (CC), can limit the effects of agricultural activities on GHGs while increasing carbon and nitrogen storage. The objective of the study was to assess the effects of cover crops, i.e., with CC and no-CC, on GHG (i.e., CO₂, CH₄, and N₂O) emissions and global warming potential (GWP) in furrow-irrigated corn in the Lower Mississippi River Valley. Gas sampling was conducted with an automated system that measured GHGs four times daily during the 2024 growing season in furrow-irrigated corn on a loam soil in Mississippi. Only CO₂ emissions differed (p < 0.05) by CC treatment, with soil respiration ~30% greater from CC than no-CC. Season-long emissions ranged from −0.22 to 0.30 kg CH₄ ha⁻¹ season⁻¹, 5.53 to 7.28 kg N₂O ha⁻¹ season⁻¹, with a GWP between 12,888 and 15,053 kg CO₂ eq. ha⁻¹ season⁻¹ from no-CC and CC, respectively. The role of CC as a conservation practice needs to be evaluated with soil and plant parameters. The beneficial effects of CC on soil physical and chemical properties likely outweigh a predictable increase in GHG emissions.

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.

Agricultural greenhouse gas (GHG) fluxes are often measured using chamber-based methods. However, comparisons among chamber-based methods are limited. This study compared the effects of chamber type and GHG concentration measurement method on GHG fluxes, emissions, global warming potential (GWP), and reduced two-gas GWP (GWP*) in conventionally tilled soybean (Glycine max L. [Merr]) on a silt-loam soil (Aeric Epiaqualfs) in southeast Arkansas. Carbon dioxide (CO₂) fluxes measured by optical feedback-cavity enhanced absorption spectroscopy (OF-CEAS, FT-LICOR) were greater (p < 0.01) than from the non-steady-state, non-flow-through, static, closed-chamber method analyzed by gas chromatography (NFT-GC), while methane (CH₄) and nitrous oxide (N₂O) fluxes were greater (p < 0.01) from the NFT-GC than the FT-LICOR method. Cumulative season-long CO₂ emissions were 36.2, 31.6, and 13.7 times greater (p < 0.01) from the FT-LICOR than the NFT-GC method for 0–15, 0–30, and 0–60 min gas sampling intervals, respectively. Methane N₂O emissions and GWP* did not differ (p > 0.05) between FT-LICOR and NFT-GC methods for the 0–15, 0–30, and 0–60 min intervals. Results suggest that differences in GHG flux, emissions, and GWP estimates reflect the combined influence of measurement methods rather than individual system components (i.e., chamber design, analyzer type, or closure time), which should be considered when designing and executing field studies.

Temporal resolution of carbon dioxide (CO₂) release from the soil at the field scale is not completely understood. The objectives of this study were to identify trends, repetitive cycles, and residual patterns and structures with a time-series analysis from a furrow-irrigated corn (Zea mays L.) field with and without cover crops (i.e., CC and No-CC, respectively) over the course of one growing season in the Lower Mississippi River Basin. Carbon dioxide fluxes were measured from 5 May to 18 August 2024, four times a day (i.e., 0300, 0900, 1500, and 2100 h) from each of the two CC treatments. Linear trends were significant, but they were only able to explain 3 and 10% of the CO₂-flux variability for CC and No-CC, respectively. Spectral density analyses indicated the significant presence of repetitive patterns every four lags, the amplitude of which was numerically 25% greater for CC than for No-CC. The structure of the residual was best described by separate autoregressive-moving-average (ARMA) models for the CC and No-CC treatments. The current study provides preliminary yet fundamental information to improve the understanding of the dynamics of soil respiration processes from a row-crop production system.