논토양 종류가 메탄배출에 미치는 영향

Abstract

논토양 종류가 메탄배출에 미치는 영향을 구명하기 위하여 적황색토인 화동통과 회색토인 신흥통을 공시하여 벼 재배기간중 메탄배출량, 산화환원전위 및 토양중 산화물 함량을 분석하였다. 적황색토에서 메탄배출이 회색토에 비해 유의하게 낮았으며, 산화환원전위는 상대적으로 높았다. 적황색토는 회색토에 비해 쉽게 환원될 수 있는 Active oxide 함량은 낮은 반면, 상대적으로 안정성이 높은 Free oxide의 함량이 높았다. 따라서 논토양 종류별 메탄배출은 벼 재배기간중 산화환원전위와 토양중 Geothite, Hematite 등과 같은 메탄산화제의 함량에 영향을 받는 것으로 나타났다. Anaerobic decomposition of organic materials in flooded rice fields produces methane (<TEX>$CH_4$</TEX>) gas, which escapes to the atmosphere primarily by transport through organs of the rice plants such as arenchyma etc., Although the annual amount of methane emitted from a given area is influenced by cultivation periods of rice and organic/inorganic amendments etc., soil type also affects methane emission from paddy soil during a rice cultivation. A field experiment was conducted to evaluate effects of soil type on <TEX>$CH_4$</TEX> emission in two paddy soils. One is a red-yellow soil classified as a Hwadong series (fine, mixed, mesic family of Aquic Hapludalfs), and the other is a gley soil classified as a Shinheung series (fine loamy, mixed, nonacid, mesic family of Aeric Fluvaquentic Endoaquepts). During a flooded periods, redox potentials of red-yellow soil were significantly higher than gley soil. <TEX>$CH_4$</TEX> emission in red-yellow soil (<TEX>$0.21kg\;ha^{-1}\;day^{-1}$</TEX>) was lower than that in gley soil (<TEX>$5.25kg\;ha^{-1}\;day^{-1}$</TEX>). In the condition of different soil types, <TEX>$CH_4$</TEX> emissions were mainly influenced by the content of total free metal oxides in paddy soil. The results strongly imply that iron- or manganese-oxides of well ordered crystalline forms in soil such as goethite and hematite influenced on a <TEX>$CH_4$</TEX> emission, which is crucial role as a <TEX>$CH_4$</TEX> oxidizers in paddy soil during a rice cultivation.