2023 Fiscal Year Final Research Report
Microbial processes regulating carbon/nitrogen cycling and methane release in unfertilized paddies
| Project/Area Number |
20H04382
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Basic Section 64050:Sound material-cycle social systems-related
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| Research Institution | Hirosaki University |
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Principal Investigator |
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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Keywords | 温室効果ガス排出抑制 / 水田 / メタン生成菌 / 窒素固定菌 / 生物地球化学 |
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| Outline of Final Research Achievements |
In order to clarify the actual state of methane emission from rice fields and the factors involved, we measured the methane flux of many paddies across Japan and investigated the influence of soil microorganisms. As a result, methane emission peaks at the heading stage, and then decreases. There were large differences between regions in the amount of methane emitted during the heading stage, with rice fields in Miyagi prefecture emitting more than 10 times as much methane as those in Akita, Niigata, and Okayama prefectures. This difference was largely due to water management in the rice fields, especially soil drying due to intermittent irrigation before heading, rather than the effects of microorganisms involved in methane production and decomposition. Although bacteria involved in iron reduction and sulfate reduction involved in anaerobic respiration also contributed to nitrogen fixation in rice fields, the contribution of bacteria involved in methane decomposition was the largest.
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| Free Research Field |
応用生態学
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| Academic Significance and Societal Importance of the Research Achievements |
水田から放出されるメタンは，我が国の農林水産セクターの温室効果ガス排出量の37.2％を占め，水田からのメタン放出を抑制する技術の開発は大きな社会的意義を持つ。水田からのメタン発生は，酸素のない嫌気条件下で特定の微生物の働きにより起こる。本研究では，出穂期前の間断灌漑がメタン放出抑制に最も効果があること，メタンをエネルギー源として窒素固定を行う（窒素肥料をつくる）微生物を水田で活性化することで水田のメタン発生を大幅に抑制できる可能性を示した。本研究の結果は，我が国の温暖化対策に大きな意義を持つ。
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