벼 논에서 양수분 복합관리에 따른 온실가스 (CH4, N2O) 배출 특성 및 수량 변동에 미치는 영향

Abstract

Intermittent drainage can be used to reduce methane (CH₄) emission from paddy soils. However, there is a significant increase in nitrous oxide (N₂O) emission when this water is drained, a significant amount of which originates from N fertilizer. Therefore, to mitigate the side effects of drainage, the source of N fertilizer should be considered. However, water and nutrient management effects during rice cultivation are not well examined in Korea. In this study, effects of water and nutrient management on reducing greenhouse gas (GHG) emissions were investigated in a rice paddy. Three types of water management were conducted: Continuous flooding (CF), intermittent drainage (ID), and low level water management (LL). At 30 days after rice transplant, drainage was carried out for 20 days in the ID treatment, and a low level of water (2~5cm) was maintained in LL treatment. The same amount of fertilizer (N‐ P₂OSUB5/SUB‐K2O:110‐45‐57 kg ha‐1) was applied in each treatment group, but different types of N sources were used: Urea (NPK), hairy vetch with urea (HV), and slow release fertilizer in the form of latex‐coated urea (SRF). To prevent N deficiency in HV treatment, 50% of the N fertilizer was replaced with urea as additional fertilizer. Methane and N₂O emissions were monitored during rice cultivation, as were growth properties and rice yield. Compared with CF treatment, ID and LL showed significantly decreased CH₄ emission. Despite organic matter application, CH₄ emission was lower in the LL+HV and ID+HV treatments than in the CF+NPK treatment. On the contrary, N₂O emission was increased in ID and LL treatments. However, due to the CH₄ reduction effect, global warming potential (GWP) was decreased in ID and LL treatments. Rice yield was slightly higher in the SRF than NPK treatment. As a result, yield‐scaled greenhouse gas intensity (GHGI) was decreased in water and nutrient managed fields due to the low GWP and high yield. Conclusively, a combination of water and nutrient management might reduce GHG emissions in rice paddies without loss of yield. In particular, low level water management and slow release fertilizer application were effective to reduce CH₄ and N₂O emissions and increase rice yield.