Influence of different aeration regimes in rice cultivation : alternate wetting and drying versus direct oxygen-enriched irrigation on methane flux dynamics | |
| Author | Shrestha, Urja |
| Call Number | AIT Thesis no.EV-26-25 |
| Subject(s) | Methane Greenhouse gases Agriculture--Environmental aspects |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Abstract | Methane (CH₄) emissions from irrigated rice systems remain a significant contributor to agricultural greenhouse gas outputs, largely driven by anaerobic soil conditions that favor methanogenic activity. This study evaluates the influence of different water management regimes, including Continuous Flooding (CF) and Alternate Wetting and Drying (AWD), along with an additional Venturi pump–based aeration treatment (AE), on methane emissions and rice plant performance. The experiment was conducted under semi-controlled greenhouse conditions using a box based setup, where methane fluxes were measured over the crop growth period alongside key soil physicochemical parameters. Gas sampling was carried out using an acrylic closed chamber setup, enabling the assessment of temporal variations in emissions under different treatments. This approach allowed for a direct comparison of CF, AWD, and AE conditions. Under CF, methane emissions reached the highest recorded peak of 346.63 ± 43.49 mg m⁻² d⁻¹ at 90 days after transplanting (DAT), driven by sustained anaerobic conditions that favored methanogenic activity. The AWD regime demonstrated a consistent reduction in methane emissions compared to CF, with an overall reduction of approximately 24%, reflecting the role of intermittent soil aeration in suppressing methanogenesis and promoting methane oxidation. The AE condition provided further insight into the role of oxygen availability, as it appeared to enhance methane oxidation and reduce methane emissions by approximately 12% compared to CF; however, its effects were less consistent, likely due to variations in aeration efficiency and oxygen distribution within the soil system. Overall, the findings highlight that methane emissions in rice systems are governed by complex interactions between water regime, oxygen availability, and soil processes. While AWD emerges as a more reliable approach for reducing methane emissions, the AE treatment offers a promising but less stable pathway that requires further refinement. These results emphasize the need for integrated management strategies that consider both environmental and agronomic outcomes. |
| Year | 2026 |
| Type | Thesis |
| School | Faculty of Civil and Environmental Engineering (2026) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Environmental Engineering and Management (EEM) |
| Chairperson(s) | Cruz, Simon Guerrero |
| Examination Committee(s) | Ghimire, Anish;Ekbordin Winijkul |
| Scholarship Donor(s) | AIT Scholarship |
| Degree | Thesis (M. Sc.) - Asian Institute of Technology, 2026 |
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