Aims: To assess 1) the effect of the combination of flooding (winter flooding vs. non-winter flooding; WFL vs NWF) and timing of straw incorporation (early vs late straw incorporation; ESI vs LSI) in the post-harvest of paddy agrosystem, on a year-round global balance of greenhouse gases (GHG) exchanges, i.e. methane (CH₄), carbon dioxide (CO₂) and nitrous oxide (N₂O); 2) the impact on the net ecosystem carbon balance (NECB) and 3) the resulting net global warming potential (GWP). Methods: A field experiment was conducted with fortnightly samplings of main GHG emissions. Effect of the studied factors on GHG emissions was seasonally assessed. The net GWP is estimated from the balance between GHG (CH₄ and N₂O) and NECB. Results: NWF-LSI reduced net GWP by 206% compared to conventional post-harvest management (WFL-ESI). NECB was similar in all treatments. Avoiding winter flooding reduced CH₄ emissions significantly in the post-harvest and next growing seasons, while delay straw incorporation prevented CH₄ and CO₂ emissions during post-harvest. None of the treatments increased N₂O emission. Environmental implications of post-harvest management options are discussed. Conclusions: Post-harvest management affects net GWP of the paddy rice cultivation by modifying GHG emissions in post-harvest and next growing season without compromise sequestration C budget. The combination of non-winter flooding and late straw incorporation strategies were more effective in reducing both CH₄ and CO₂ emissions, due to avoiding higher temperatures at the time of the straw incorporation during post-harvest and increasing soil Eh conditions at the following growing season.

The effluents from conventional wastewater treatment plants (WWTP), even if accomplishing quality regulations, substantially differ in their characteristics with those of waters in natural environments. Constructed wetlands (CWs) serve as transitional ecosystems within WWTPs, mitigating these differences and restoring natural features before water is poured into the natural environment. Our study focused on an experimental surface-flow CW naturalizing the WWTP effluent in a semiarid area in Eastern Spain. Despite relatively low pollutant concentrations entering the CW, it effectively further reduced settled organic matter and nitrogen. Dissolved organic matter (DOM) reaching the CW was mainly protein-like, yet optical property changes in the DOM indicated increased humification, aromaticity, and stabilization as it flowed through the CW. Flow cytometry analysis revealed that the CW released less abundant but more active bacterial populations than those received. MiSeq Illumina sequencing highlighted changes in the prokaryotic community composition, with phyla Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria dominating the CW outflow. Functional prediction tools (FaproTax and PICRUSt2) demonstrated a shift towards microbial guilds aligned with those of the natural aquatic environments, increased aerobic chemoheterotrophs, photoautotrophs, and metabolic reactions at higher redox potentials. Enhanced capabilities for degrading plant material correlated well with changes in the DOM pool. Our findings emphasize the role of CWs in releasing biochemically stable DOM and functionally suited microbial populations for natural receiving environments. Consequently, we propose CWs as a naturalization nature-based solution (NBS) in water-scarce regions like the Mediterranean, where reclaimed discharged water can significantly contribute to ecosystem's water resources compared to natural flows.