Soil flooding increases greenhouse gas fluxes

Soil flooding poses significant challenges to livelihoods, agriculture, and the environment by adversly affecting soil health. This study investigated the effects of flooding, flooding duration, and water source (seawater and freshwater) on greenhouse gas fluxes from two predominant soil types in South Florida—Krome and Biscayne. Experiments were conducted by flooding Krome and Biscayne soils with fresh and seawater, and greenhouse gas samples were collected using PVC chambers on the 1^st, 7^th, 14^th, and 28^th days of flooding. Samples were analyzed for soil carbon dioxide (CO₂), nitrous oxide (N₂O), and methane (CH₄) fluxes using a gas chromatograph. Results confirmed that CO₂ and N₂O fluxes exhibited a distinct pattern, peaking one day after flooding and sharply decreasing with the progression of flooding. Soil type, flooding duration, and water source were critical factors modulating CO₂ and N₂O fluxes, but CH₄ fluxes were consistently below the detection limit. Biscayne soil had the highest CO₂ and N₂O fluxes under seawater and freshwater flooding compared to Krome. These findings underscore the critical role of the initial flooding phase in driving greenhouse gas emissions, emphasizing the need for targeted mitigation strategies.