Elucidation of various stabilization mechanismsof soil organic carbon

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H04890
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Plant nutrition/Soil science
• Research Institution: Nagoya University
• Principal Investigator: Watanabe Akira 名古屋大学, 生命農学研究科, 教授 (50231098)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 土壌学 / 土壌圏現象 / 炭素循環 / 環境 / 地球温暖化

Outline of Final Research Achievements

To elucidate the stabilization mechanisms of soil organic C (SOC) in paddy soils and those for cattle manure (CM) and biochar in upland fields as well as to confirm the formation of black humic acids (HAs) owing to volcanic ash were aimed. Progression of simultaneous accumulation of SOC with enhanced stability in terms of C structure and adsorption to clay minerals and labile SOC were found in macro aggregates in paddy soils. Analyses of the archib soil samples from CM applied soils did not indicate an enhancement in the stability of SOC in terms of chemical structure and accumulation form. Biochar equivalent to 33-89% of the initial amount was maintained 5-7 years after application(s) and up to 20% was stabilized by binding to clay minerals. Incubation of Type Rp HAs with volcanic ash at 40-60oC, respectively, increased degree of humification with a larger extent at a higher temperature. The increase in condensed aromatic structures was also suggested for those incubated at 60oC.

Free Research Field

土壌圏物質循環学

Academic Significance and Societal Importance of the Research Achievements

土壌の長期水田利用は、マクロ団粒に安定な形態でCを蓄積し、微生物のエネルギー源になりうるC量も増えることを示唆した。畑土壌に厩肥を連用しても長期的に安定なCは形成されないことを明らかにし、C量を維持するには施用し続けるしかないことを示唆した。土壌施用後のバイオ炭Cの残留性には、バイオ炭の生分解性の違いよりも、鉱物への吸着や気候条件の方が重要である可能性を示した。火山灰存在下でのフミン酸の腐植化度の増大が、縮合芳香環含量の増大を伴うことを示した。また、常温においてもポリフェノールから縮合芳香環を含むフミン酸が形成することを示唆した。