Water-Regime Effects on Greenhouse Gas Emissions from Plant-Less, Silt-Loam Mesocosms in the Greenhouse

Evaluation and understanding of processes affecting atmospheric greenhouse gas (GHG) concentrations from the soil surface are critical to mitigating global climate change, particularly from the agricultural sector and the impact of soil-water regimes. The objectives of this study were to assess GHG [i.e., carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)] emissions, evaluate soil oxidation-reduction (redox) potential (Eh), and track water-soluble (WS) nutrient changes under differing water regimes [i.e., flooded (FL), intermittent wet and dry (IWD), seasonally flooded (SFL)] in silt-loam-textured mesocosms in the greenhouse. Soil Eh was measured hourly via redox sensor, GHG concentrations were collected weekly using vented, closed-chamber sampling with gas chromatography analysis, and soil samples were collected five times during the study period from January to April 2025. Greater fluctuations of GHGs and Eh were observed in IWD and SFL mesocosms. Carbon dioxide was the only gas with statistical differences among GHG emissions and was greatest (P −1) and the lowest from FL (0.30 Mg∙ha−1) mesocosms. Water soluble phosphorus was the greatest (4.1 mg∙kg−1) from IWD, and the lowest from SFL (3.5 mg∙kg−1) and FL (3.2 mg∙kg−1). Water soluble magnesium and redox-active elements (i.e., manganese, iron, sulfur) differed (P < 0.05) between water regime and time. Results determined water management practices can impact biogeochemical processes in multiple ways. The investigation of soil resource properties under various water regimes could better inform future management practices to improve nutrient and water efficiency, reduce greenhouse gas emissions, and enhance soil health.