Greenhouse gas (GHG) emissions from rice (Oryza sativa) systems have been correlated to water management practice, but to date, no study has directly evaluated three main GHGs (i.e., methane [CH₄], nitrous oxide [N₂O], and carbon dioxide [CO₂]) under flood‐ and furrow‐irrigated conditions at the same time as affected by various fertilizer‐phosphorus (P) sources, in particular the reportedly slow‐release struvite‐P source. Therefore, the objective of this study was to evaluate the effect of water regime (flooded and furrow‐irrigated) and fertilizer‐P source (diammonium phosphate, chemically precipitated struvite, electrochemically precipitated struvite [ECST], triple superphosphate, and an unamended control) on GHG emissions and two‐ and three‐gas global warming potentials (GWP* and GWP, respectively) in the greenhouse. Methane emissions were 10 times greater (p < 0.05) under flooded (29.4 kg CH₄ ha⁻¹ season⁻¹) than under furrow‐irrigated conditions (2.9 kg CH₄ ha⁻¹ season⁻¹), and four times lower (p < 0.05) with ECST (3.4 kg CH₄ ha⁻¹ season⁻¹) than other fertilizer‐P sources, while CO₂ emissions were three times greater (p < 0.05) under furrow‐irrigated (23,428 kg CO₂ ha⁻¹ season⁻¹) than under flooded (8290 kg CO₂ ha⁻¹ season⁻¹) conditions. The GWP* under furrow‐irrigated conditions was almost 40% lower (p < 0.05) than under flooded conditions. Although N₂O emissions were unaffected by fertilizer‐P source, the N₂O contribution to GWP* was more than 80% under furrow‐irrigated conditions. Flood‐ and furrow‐irrigated water regimes require diversified approaches in GHG mitigation, where the best management for ECST needs to be more fully evaluated.

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.

Biochar is a relatively new, potential climate‐mitigation strategy, but biochar still requires investigation regarding biochar's ability to reduce greenhouse gas (GHG) emissions. Little research has been conducted to quantify the impacts of biochar on GHG production from upland (i.e., furrow‐irrigated) rice ( Oryza sativa ) production systems. The objective of this study was to evaluate the effects of wood biochar type (powder and coarse particle size) and application rate (0, 2.5, and 5 Mg ha ⁻¹ ) on GHG emissions in greenhouse‐grown, simulated furrow‐irrigated rice grown in a silt‐loam soil. Carbon dioxide (CO ₂ ), methane (CH ₄ ), and nitrous oxide (N ₂ O) fluxes were measured weekly throughout a 5‐month growing season during summer 2023, and season‐long emissions and reduced global warming potential (GWP, excluding CO ₂ ) were estimated. Among the coarse‐sized biochar treatments, season‐long N ₂ O emissions (41.7 kg N ₂ O ha ⁻¹ season ⁻¹ ) were largest ( p < 0.05) from the unamended control (0 Mg ha ⁻¹ ), followed by the 2.5 (17.1 kg N ₂ O ha ⁻¹ season ⁻¹ ) and 5 Mg ha ⁻¹ rate (4.9 kg N ₂ O ha ⁻¹ season ⁻¹ ), while season‐long N ₂ O emissions did not differ ( p > 0.05) among powder‐sized biochar treatments. Reduced GWP was greatest ( p < 0.05; 11.2 Mg CO ₂ eq. ha ⁻¹ season ⁻¹ ) from the unamended control, followed by the 2.5 Mg ha ⁻¹ rate (4.7 Mg CO ₂ eq. ha ⁻¹ season ⁻¹ ), and least ( p < 0.05; 1.4 Mg CO ₂ eq. ha ⁻¹ season ⁻¹ ) from the 5 Mg ha ⁻¹ rate of coarse biochar. Results showed that coarse‐sized, wood‐chip biochar has the potential to mitigate N ₂ O emissions from furrow‐irrigated rice in a silt‐loam soil.

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.

Reduced tillage (RT) is a common conservation agriculture practice, generally regarded to be a valuable greenhouse gas (GHG) mitigation approach through increasing soil carbon (C) stocks. However, direct GHG measurements from RT compared to conventional tillage (CT) treatments can vary greatly depending on site‐specific soil properties and management practices. The objective of this study was to evaluate the short‐term effects of RT on soil‐to‐atmosphere carbon dioxide (CO ₂ ), methane (CH ₄ ), and nitrous oxide (N ₂ O) fluxes and emissions, global warming potential (GWP), yield, and emissions intensity (EI) throughout the 2024 soybean ( Glycine max ) growing season in a southeast Arkansas production field. Bulk density was lower ( p < 0.05) in the CT (1.29 g cm ⁻³ ) than in the RT (1.44 g cm ⁻³ ) treatment at the beginning of the growing season, but the greater bulk density in the RT treatment did not result in a change in yield compared to CT. There was no difference in CO ₂ fluxes between tillage treatments on any measurement date. Methane fluxes from CT were greater ( p < 0.05) than from RT on four out of seven measurement dates. Nitrous oxide fluxes were greater ( p < 0.05) from CT than RT and greater from RT than CT on four out of eight measurement dates each. Season‐long CO ₂ , CH ₄ , and N ₂ O emissions and EI, as well as GWP, did not differ ( p > 0.05) between RT and CT. Results showed that more continuous RT practices are needed to develop a residue layer capable of affecting GHG emissions.