The Effects of Nitrogen Fertilizers and Cultural Patterns on Methane Emission From Rice Paddy Fields

논토양에서 질소비종 및 벼 재배양식이 메탄가스 발생에 미치는 영향

To mitigate the methane emission from rice paddy fields, effects of nitrogen fertilizers source and cultural patterns were evaluated on silty loam soils. And a pot experiment was carried out to find out the effects of nitrogen fertilizers on soil pH, Eh, sulfate concentration of soil water in flooded soil. In transplanting cultivation, the total methane emission depending on fertilizers was $32.9gm^{-2}$ for urea ; $30.3gm^{-2}$ for ammonium sulfate ; $26.4gm^{-2}$ for coated urea. Methane emitted in direct seeding on dry soil was $24.7gm^{-2}$ for urea ; $16.7gm^{-2}$ for ammonium sulfate : and $22.8gm^{-2}$ for coated urea. Thus, the methane emission rate of direct seeding on dry soil was 29.7% lower than transplanting. According to the nitrogen fertilizers, the methane emission rate by ammonium sulfate and coated urea were reduced 18.4 and 15.9% in comparison with urea, respectively. In pot experiments, pH in flooded soils depending on nitrogen fertilizers dereased in order of urea > coated $urea{\fallingdotseq}no$ fertilizer > ammonium sulfate and the order was coincided with that of total $CH_4$ emission from flooded soil. Soil Eh was highest in ammonium sulfate application followed by coated urea, no fertilizer, urea. And sulfate concentrations of soil water were in order of ammonium sulfate > coated urea > urea > no fertilizer.

논토양에서 질소비종 및 재배양식에 따른 메탄배출양상과 질소비종이 담수토양의 pH와 Eh에 미치는 영향을 조사한 결과는 아래와 같다. 1. 중묘이앙재배에서 질소비종에 따른 메탄배출총량은 요소 32.9g $m^{-2}$ > 유안 30.3 > 완효성비료 26.4g $m^{-2}$의 순이었으며, 건답직파재배에서는 요소 24.7g $m^{-2}$ > 유안 16.7g $m^{-2}$ > 완효성비료 22.8g $m^{-2}$의 순이었다. 2. 질소비종에 따른 메탄배출량은 요소시비구보다 유안은 18.4%, 안효성비료는 15.9% 저감되었다. 3. 재배양식별로는 건답직파재배는 중묘이앙재배보다 29.7%의 메탄발생량이 저감되었다. 4. 질소비종에 따른 담수토양의 pH는 요소>완효성비료${\fallingdotseq}$무비>유안의 순으로 높았는데 이는 질소비종별 메탄배출량의 순서와 일치하였다. 토양 Eh는 유안>완효성비료>무비>요 소의 순으로 높아 pH 및 메탄배출량과 반대경향이었으며, 토양용액내 $SO_{4}$ 농도는 유안>완효성비료>요소>무비의 순으로 높았다.