Estimation of Methane Emission from Rice Cultivation in Korea

Abstract

This study focused on estimating a methane (CH₄) inventory and developing mitigation options in South Korea, and was performed jointly in an integrated national research program on CH₄ from rice fields conducted by three National Agricultural Research Institutes, under the Rural Development Administration during 1993–1997. Methane emissions were measured by a closed chamber method, in rice plots at three locations (Suwon, Iksan, and Milyang) with the single rice cropping system. All experimental data from 5 years of study were summarized and used for calculating nation-wide CH₄ emissions. Temperature, soil type, cultural practices, water management, organic matter management, and cultivar selection significantly affected the fluctuations of CH₄ emissions. The two most promising mitigation options for reducing emissions were altered water management, in particular mid-season aeration by short-term drainage, and improved organic matter management, by promotion of aerobic degradation through composing or soil incorporation. Annual total CH₄ emission in Korea changed from 410 Gg in 1990 to 339 Gg in 2000, due mainly to a decrease in the cultivated area of paddy rice. If we convert annual CH₄ emission to Global Warming Potential as CO₂ equivalent, it amounts to 7.1 M CO₂ t yr⁻¹ of greenhouse gas emitted to the atmosphere in 2000 from the rice fields in Korea, which is just 5.3% of the annual CO₂ emission from the industry and energy sector. More importantly, the balance between CO₂ uptake by photosynthesis and CO₂ emission is positive (a net sink), so that rice culture actually has net benefits for the global atmospheric carbon issue. Further reductions in emission amounts, by following recommendations in this article, could make these benefits even greater.

Keywords:

• Global warming potential
• Methane emission
• Methane inventory
• Mitigation options