Open Peer Review Any reports and responses or comments on the article can be found at the end of the article. RESEARCH ARTICLE Mitigation of methane gas emission in rice by drip irrigation [version 1; peer review: awaiting peer review] Theivasigamani Parthasarathi , Koothan Vanitha , Sendass Mohandass , Eli Vered 3 VIT School of Agricultural Innovations and Advanced Learning (VAIAL), Vellore Institute of Technology, Vellore, Tamil Nadu, 632014, India Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, 641003, India Netafim Irrigation Ltd, Kibbutz Mahal, Israel Abstract Rice farming faces major challenges, including water Background: limitation, drought and climate change in the current scenario of agriculture. Among the innovative water-saving techniques, drip irrigation is a forerunner, with maximized water-saving potential, increased grain yield and methane mitigation. A field experiment was conducted comprising four different drip Methods: irrigation practices: (i) sub-surface drip irrigation (SDI) with 1.0 litre per hour (lph) discharge rate emitters (DRE) (SDI+1.0 lph DRE) (ii) SDI+0.6 lph DRE, (iii) surface drip irrigation (DI) with 1.0 lph discharge rate emitters (DI+1.0 lph DRE), (iv) DI+0.6 lph DRE and were compared with (v) a conventional flood aerobic irrigation (considered conventional). The estimated grain yield of rice was found to be 23.5%, 20.3%, Results: and 15.1% higher under SDI+1.0 lph DRE, SDI+0.6 lph DRE and DI+1.0 lph DRE practices, respectively, than the conventional method. A water saving of 23.3% was also observed for all drip practices compared with conventional practices. Seasonal methane emission flux declined 78.0% in the drip methods over the conventional irrigation: better mitigation than previously reported values (alternate wetting and drying (47.5%) and system of rice intensification (29.0%) practices). Continuous soil aeration and enhanced soil methanotrophs (P<0.05) limit the peak methane emission in rice during the flowering phase in drip irrigation, which is reflected in the methane emission flux values. Consequently, the equivalent CO (CO -eq) emissions and yield-scaled CO eq-emission were found to be significantly lower in SDI (43.8% and 49.5%, respectively), and DI (25.1% and 26.7%, respectively) methods as compared with the conventional that ensures better methane mitigation and future climate-smart rice production systems. Drip irrigation could reduce the cumulative methane Conclusions: emission in aerobically grown rice. SDI + 1.0 lph DRE practice can be applied in areas with inadequate water availability and effective in reducing the CO -eq emission with better yield than conventional. 1 2 2 3 1 2 3 Reviewer Status AWAITING PEER REVIEW 28 Nov 2019, :2023 ( First published: 8 ) https://doi.org/10.12688/f1000research.20945.1 28 Nov 2019, :2023 ( Latest published: 8 ) https://doi.org/10.12688/f1000research.20945.1 v1 2 2 2 2 Page 1 of 12 F1000Research 2019, 8:2023 Last updated: 04 DEC 2019