Nitrogen dynamics and microbial activities in aerobic and anaerobic coexistence soils with soil water flow

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K06286
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 41030:Rural environmental engineering and planning-related
• Research Institution: Iwate University
• Principal Investigator: Muto Yoshiko 岩手大学, 農学部, 准教授 (30422512)
• Co-Investigator(Kenkyū-buntansha): 渡辺 晋生 三重大学, 生物資源学研究科, 教授 (10335151)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 窒素動態 / 水分移動 / 嫌気・好気状態 / 土壌微生物

Outline of Final Research Achievements

Understanding nitrogen dynamics in soil, which variously changes the water content, is important to promote sustainable agriculture. In this study 7.5cm soil columns were settled in a constant temperature room and the distributions of water content, Eh, and concentrations of ammonium- and nitrate-nitrogen in the soil, as well as soil ATP, were monitored during evaporation. Assuming the nitrification in soil is the first-order reaction, when Eh was greater than 440 mV, the rate constant was proportional to the soil water content, and the ATP. Numerical calculation using the rate constant as a function of water content well-reproduced the column experiment when Eh was greater than 440 mV. And the rate constant seemed to be able to estimate by the ATP, which is relatively easy to measure.

Free Research Field

土壌物理学

Academic Significance and Societal Importance of the Research Achievements

水分移動過程での土壌中の窒素動態の解明は，食料生産や環境保全などの見地から重要視されており，これまでに，土壌物理学・土壌学の各分野で現象に関わる土壌の諸条件が一定条件下にあるときの影響が調べられてきた．しかし，土壌中における窒素動態は微生物活動の結果であることから，現象の更なる理解には，関連する土壌物理条件・その変化速度と微生物反応速度との関係が重要である．本研究の特色は，「速度」という新たな視点に，さらに「土壌微生物活動の評価」という新しい切り口をプラスして窒素動態を考えた点である．この新たな発想により，窒素炭素動態が関わる未解明な現象の理解に突破口を開くことが期待される．