Pedosphere (2): 460--473, 2026
ISSN 1002-0160/CN 32-1315/P
©2026 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Mechanism of biochar decomposition mediated by bacteria shifts the molecular structure of soil organic matter to high-molecular-mass aromatic components |
Xu CHEN, Xiaozeng HAN, Wenxiu ZOU, Jun YAN, Xinchun LU |
| Key Laboratory of Mollisols Agroecology, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin 150081 (China) |
| ABSTRACT |
| The interaction between biochar amendments and soil dissolved organic matter (DOM) is crucial for soil health and carbon (C) sequestration, yet the molecular mechanisms underlying these effects are not fully understood. This study employed ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry to comprehensively assess the influence of biochar on the chemodiversity of DOM at a molecular level, with a particular focus on the interactions between bacterial species and DOM molecules. A five-year field experiment was conducted, involving four treatments, no fertilization (NF), conventional fertilization (CF), conventional fertilization with low-rate biochar at 15 000 kg ha-1 (LB), and conventional fertilization with high-rate biochar at 60 000 kg ha-1 (HB). Biochar amendment, while increasing soil pH and nutrient contents, stimulated bacterial diversity and abundance, particularly at the higher application rate. Specifically, bacterial abundance increased by 58.0%, 130.9%, and 272.8% in CF, LB, and HB treatments, respectively, compared to NF, while bacterial diversity was also notably lower in both NF and CF than in HB. Furthermore, biochar amendment lowered the chemodiversity and thermodynamic stability of DOM by shifting its composition toward more aromatic molecules that contain more C, less C saturation, and higher molecular mass, ultimately increasing the retention of DOM. Further analysis of the molecular composition of DOM indicated that the overall increase in molecular mass was primarily due to increases in high-molecular-mass C-hydrogen (H)-oxygen (O)-nitrogen (N) and CHO compounds. Keystone bacterial taxa in the biochar-amended co-occurrence networks were also the most closely connected with the CHO and CHON compounds. These compounds exhibited similar, narrow O/C and H/C ratios within the high-molecular-mass range, and their positive correlations were approximately twice as strong as the negative correlations. These results together suggest that biochar amendment leads to the homogenization of the DOM pool, with its molecular characteristics being shaped more by bacterial contributions than by their consumption. |
| Key Words: bacterial community,biodiversity,chemodiversity,dissolved organic matter,soil amendment,soil microbiome |
| Citation: Chen X, Han X Z, Zou W X, Yan J, Lu X C. 2026. Mechanism of biochar decomposition mediated by bacteria shifts the molecular structure of soil organic matter to high-molecular-mass aromatic components. Pedosphere. 36(2): 460-473. |
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