Increase of CH₄ emission in No-tillage Paddy Soil during Rice Cultivation

Sang Yoon Kim¹⁾, Jessie Gutierrez¹⁾ and Pil Joo Kim^1,2)*

¹⁾ Division of Applied Life Science (BK 21 Program), Gyeongsang National University, Jinju, 660-701, South Korea

²⁾ Institute of Agriculture and Life Science, Gyeongsang National University, Jinju, 660-701, South Korea

Abstract

Concerns for the reduction of greenhouse gases emissions like methane (CH₄) from agricultural activities led to the recommendation of various best management practices to control CH₄ emission from paddy rice cultivation such as conservation tillage or no tillage. We report a new finding, which showed higher CH₄ emission with long-term no-tillage system during rice (Oryza sativa L., cultivar Dongjinbyeo) cultivation under identical water and fertilizer management by comparison with conventionally tilled cultivation. Closed chamber measurements were used to monitor daily CH₄ fluxes, to describe the seasonal pattern of CH₄ emissions and estimate total CH₄ fluxes on a field-trial during rice growing season. Soil Eh, temperature and plant growth and yield were also monitored. Daily CH₄ emissions followed typical CH₄ emission patterns but were higher in the no-tillage field. Total CH₄ emission under no-tillage was 2.5-fold higher at 45.25 g CH₄ m^-2 than by tillage at 17.97 g CH₄ m^-2. As previously reported, CH₄ production could be potentially related to organic carbon (C) content in soil. In our study, higher amount of labile C as hot water extractable C (C_HWE) were detected in the no-till treatments, especially at its upper surface layers (0-5 cm depth) than conventional tillage. As a result, this higher accumulation of soil organic matter in no tillage system might have activated more methanogenic Archaea and then influence higher CH₄ emissions during rice cultivation.

Keywords:  No-tillage, Conventional tillage, CH₄ emission, Rice paddy soil, Hot water extractable carbon