Effect of intermittent drainage on the emission of two greenhouse gases (CO2 and CH4) from three paddies in South Korea

In this field pot study, effect of irrigation practice (continuous flooding (CF) and intermittent drainage (ID) treatment) on greenhouse gas (GHGs, CO₂ and CH₄) emission was determined from three Korean paddies (BG, MG, and JS series), varying soil properties such as soil texture, labile carbon, and mineral types.  Emission of GHGs was evidently influenced by irrigation practices, to a different extent, depending on paddy’s redox response to flooding events.  The Eh decline upon flooding was slower in JS pot, where pore-water concentration of ferric and sulfate ions is the highest (~ up to 3-fold) among three paddies.  MG pot was 2- to 3-fold percolative than others and the Eh drop during flooding period was the smallest (remaining above -50 mV) among three pots.  By adopting ID, CH₄ emission (t CO₂-eq ha-1 yr-1) was reduced in a wide range by 5.6 for JS pot, 2.08 for BG pot, and 0.29 for MG pot relative to CF, whereas CO₂ emissions (t CO₂-eq ha-1 yr-1) was increased by 1.25 for JS pot, 1.07 for BG pot, and 0.48 for MG pot due to the enhanced carbon oxidation upon drainage.  Grain yield and aboveground biomass production from ID were no less than those from CF (p < 0.05).  Consequently, benefit of global warming potential (S GWP) by ID varied as in order of JS (37%) > BG (14%) > MG (~0 %) pots, and negligible effect observed for MG pot was due to the equivalent trade-off between CO₂ and CH₄. Our findings imply that that the efficacy of drainage on GHG mitigation depends on the redox response of paddies.

Keyword

Climate Change, Greenhouse gas, Paddy, Intermittent drainage

 

Acknowledgement

This research was in part supported by the Korea Environment Industry & Technology Institute (KEITI), funded by Korea Ministry of Environment (MOE) (No. 2022002450002 (RS-2022-KE002074)) and in part supported by Korea University Grant.