Basic study on the suppression of soil reductive conditions in a flooded rice paddy by the irrigation with water containing nanobubbles

Research Project

Project/Area Number	16K18829
Research Category	Grant-in-Aid for Young Scientists (B)
Allocation Type	Multi-year Fund
Research Field	Environmental agriculture(including landscape science)
Research Institution	Japan International Research Center for Agricultural Sciences (2018) National Agriculture and Food Research Organization (2016-2017)
Principal Investigator	Minamikawa Kazunori 国立研究開発法人国際農林水産業研究センター, 生産環境・畜産領域, 主任研究員 (60601151)
Research Collaborator	MAKINO Tomoyuki TAKAHASHI Masayoshi
Project Period (FY)	2016-04-01 – 2019-03-31
Project Status	Completed (Fiscal Year 2018)
Budget Amount *help	¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000) Fiscal Year 2018: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000) Fiscal Year 2017: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000) Fiscal Year 2016: ¥2,730,000 (Direct Cost: ¥2,100,000、Indirect Cost: ¥630,000)
Keywords	ナノバブル / 水田 / ウルトラファインバブル / マイクロセンサー / 重金属汚染 / 地球温暖化 / メタン / カドミウム / 気候変動緩和策 / 気候変動 / 溶存酸素 / 温室効果ガス / メタン排出削減 / レドックス化学
Outline of Final Research Achievements	This study carried out a series of basic soil experiments to elucidate the ability of the irrigation with water containing bulk nanobubbles made of pure oxygen (hereafter, oxygen NB water) for suppressing the development of the reductive conditions in a flooded paddy soil. The results of soil column experiments indicate that oxygen NB water can reduce the production and emission of methane, a potent greenhouse gas, in a flooded soil under rice unplanted conditions. The result of measuring soil oxygen profile shows that oxygen NB water shift oxidatively the redox conditions in a shallow soil layer under flooded conditions. The results of pot rice cultivation with a soil containing relatively high heavy metals suggest that the effect of oxygen NB water is remarkable during and around rice heading stage.
Academic Significance and Societal Importance of the Research Achievements	本研究は、バルク酸素ナノバブルが持つ還元環境に対する改善効果を、水田土壌を事例として定量的に示したものである。このような還元改善の研究事例は農学分野にとどまらず、多分野で試行錯誤が続けられており、本研究成果はそこに科学的エビデンスを提供した。バルク酸素ナノバブルは、全球的には絶対嫌気性の古細菌によるメタン生成・排出（地球温暖化）、地域的には水田土壌からのヒ素の溶出・イネへの移行（重金属汚染）という環境問題に対して、農作物の生産性を維持しつつ、水田還元環境の改善による緩和策を提供する。