Greenhouse Gas Fluxes from the Furrow and the Bed in Furrow-irrigated Soybean on a Silt loam Soil in Southeast Arkansas

Furrow irrigation in cropping systems creates distinct environments within fields, with raised beds remaining relatively aerobic, while furrows experience wetter, flood-like conditions during irrigation. The distinct adjacent environmental conditions can differentially affect production and release of greenhouse gases (GHGs). While the aerobic raised beds can enhance soil respiration, the wet to saturated furrow can intensify methanogenic activity during irrigation and nitrification–denitrification during drying periods. To date, no study has simultaneously compared carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) fluxes from adjacent raised beds and furrows in a soybean [Glycine max (L.) Merr.] production system. This study evaluated the effect of measurement position (i.e., raised bed or furrow) on GHG (i.e., CO₂, CH₄, and N₂O) fluxes and season-long emissions in a conventionally tilled soybean field on a silt loam soil (Aeric Epiaqualfs) in southeast Arkansas. Gas fluxes were measured weekly from May to August 2024 using a field-portable measurement system. A linear mixed model was used to assess the effects of measurement position (i.e., raised bed and furrow), time (weekly measurements), and their interaction on CO₂, CH₄, and N₂O fluxes. Carbon dioxide fluxes were consistently greater (P ≤ 0.05) in the raised bed than in the furrow across the growing season. Methane fluxes were generally greater in the furrow (P ≤ 0.05), while N₂O fluxes were typically greater in the raised bed (P ≤ 0.05). The results demonstrated substantial variation in CO₂, CH₄, and N₂O fluxes between raised beds and furrows, emphasizing the need for field position-specific GHG flux measurements to accurately scale emissions to the whole-field level.