Shallow water habitat management influences soil CO ₂ efflux from agricultural fields in the Lower Mississippi River Basin (LMRB), USA

Abstract Temporary winter flooding is a common practice for enhancing wildlife habitat in the Lower Mississippi River Basin (LMRB) and other migratory waterfowl flyways in North America. This practice also facilitates nutrient retention and reuse of rainwater‐ or drainage‐water. This study examines the consequence of five different water management approaches on soil carbon dioxide (CO 2 ) efflux and corn ( Zea mays L.) residue decomposition, from October 11, 2021, through January 31, 2022. Management treatments included (i) control (CT) or no flooding; (ii) passive (P) rainfall capture; (iii) fall (F) pumping of leftover irrigation water; (iv) winter (W) flooding with leftover irrigation water; and (v) fall–winter (FW) flooding. The fall–winter flood field (FW) had reduced daily soil CO 2 efflux for 4 out of 12 observations and increased soil pH and residue decomposition compared to the control field. The winter flood field (W) had reduced CO 2 efflux on December 8 and January 21, and FW had lower efflux on December 8, December 14, December 21, and January 13, than the control field (CT). Soil temperature was positively associated with soil CO 2 efflux in all fields except control. Results are consistent with the hypothesis that flood‐timing and ‐duration had strong connections with soil carbon dynamics in LMRB row croplands during fallow periods.