Elucidating microbial utilization of mineral associated organic nitrogen in soils

2022 Fiscal Year Final Research Report

• Project/Area Number: 20KK0261
• Research Category: Fund for the Promotion of Joint International Research (Fostering Joint International Research (A))
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 63010:Environmental dynamic analysis-related
• Research Institution: Kyoto University
• Principal Investigator: Watanabe Tetsuhiro 京都大学, 地球環境学堂, 准教授 (60456902)
• Project Period (FY): 2021 – 2022
• Keywords: 窒素循環 / 粘土鉱物 / 土壌 / 生物地球科学

Outline of Final Research Achievements

In this project, mineral associated organic nitrogen, which is the largest terrestrial nitrogen pool, was investigated in terms of its accumulation form and microbial utilization. First, the influence of major soil forming factors on the distribution of active Al/Fe, which stabilize organic nitrogen, was clarified. Also, decreases in plant-derived organic compounds (e.g., lignin and polysaccharides) and increases in microbial-derived compounds (e.g., nitrogen containing organic compounds) were observed with increasing soil depth. The utilization of organic nitrogen was inhibited by the adsorption of organic nitrogen on active Al/Fe, but the effect was weakened by the organic matter coverage on active Al/Fe.

Free Research Field

土壌学

Academic Significance and Societal Importance of the Research Achievements

窒素は植物の生産量を制限する極めて重要な元素である。現在、その循環量が農業を主とする人間活動によってかつてないレベルまで増大し、深刻な環境問題として顕在化している。本研究の成果は、有機窒素の蓄積と分解に大きく影響する活性Al・Feの分布について、その規定因子の影響を明らかにし、活性Al・Feの広域分布の理解への基礎を与えた。また、有機窒素の活性Al・Feへの吸着により、その分解が影響されることを示し、窒素動態の理解を進めることができた。