Mechanism and development for a sustainable rice cultivation system with extreme low level of input

2021 Fiscal Year Final Research Report

• Project/Area Number: 17H03951
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Environmental agriculture(including landscape science)
• Research Institution: Ehime University
• Principal Investigator: UENO HIDETO 愛媛大学, 農学研究科, 教授 (90301324)
• Co-Investigator(Kenkyū-buntansha): 当真 要 北海道大学, 農学研究院, 教授 (10514359)
• Project Period (FY): 2017-04-01 – 2022-03-31
• Keywords: 水稲 / 持続的農業 / 水田土壌 / 養分動態 / 微生物相解析 / 土壌酵素 / 生物多様性 / マメ科緑肥

Outline of Final Research Achievements

A paddy rice cultivation experiment was conducted continuously for five years in the Ultra-low Input Sustainable Paddy Rice System which no fertilizers or pesticides were applied. The rice growth was vigorous and yields were comparable to those of conventional cultivation, although there was some variation from field to field. As the cultivation continued for longer periods, the amount of available phosphate decreased, which significantly affected the growth and yield of paddy rice. Application of leguminous green manure increased soil microbial activity, as well as soil enzyme activities related to carbon, nitrogen, and phosphorus, resulting in higher metabolic turnover. Bacterial community structure analysis of the soil showed no significant differences from the conventional plot, but there was a trend toward an increase in specific bacterial groups during water drainage. Nitrogen fixation by weed endophytes was newly discovered.

Free Research Field

土壌肥料学

Academic Significance and Societal Importance of the Research Achievements

①養分・元素動態測定手法を確立することで、フィールド研究遂行の高効率化が行えた。②水田生態系における生物群集の土壌肥沃度に関する能力の新規評価に貢献できた。③資材調達が難しい途上国等の農業に対する技術応用が期待できる。④低投入持続型水稲栽培システムにおける農耕地生態系機能の知られざる一端が明らかとなった。
以上のことから、土壌学、作物栽培学、環境学、アグロエコロジー分野へ貢献できる。これにより、水稲栽培の省エネ、省資源、低コスト栽培の道が開け、我が国のフードセキュリティの問題解決に資することができる。