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Title: Molecular and Microscopic Insights into the Formation of Soil Organic Matter in a Red Pine Rhizosphere

Microbially-derived carbon inputs to soils play an important role in forming soil organic matter (SOM), but detailed knowledge of basic mechanisms of carbon (C) cycling, such as stabilization of organic C compounds originating from rhizodeposition, is scarce. This study aimed to investigate the stability of rhizosphere-produced carbon components in a model laboratory mesocosm of Pinus resinosa grown in a designed mineral soil mix with limited nutrients. We utilized a suite of advanced imaging and molecular techniques to obtain a molecular-level identification of newly-formed SOM compounds, and considered implications regarding their degree of long-term persistence. The microbes in this controlled, nutrient-limited system, without pre-existing organic matter, produced extracellular polymeric substances that formed associations with nutrient-bearing minerals and contributed to the microbial mineral weathering process. Electron microscopy revealed unique ultrastructural residual signatures of biogenic C compounds, and the increased presence of an amorphous organic phase associated with the mineral phase was evidenced by X-ray diffraction. Here, these findings provide insight into the formation of SOM products in ecosystems, and show that the plant- and microbially-derived material associated with mineral matrices may be important components in current soil carbon models.
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  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  2. Univ. of Idaho, Moscow, ID (United States)
  3. South China Univ. of Technology, Guangdong (China)
  4. Washington State Univ., Pullman, WA (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 2411-5126; 49147; KP1704020
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Additional Journal Information:
Journal Volume: 1; Journal Issue: 1; Journal ID: ISSN 2411-5126
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Org:
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES; rhizosphere; soil organic matter; soil microbiome; 16S sequencing; mineral weathering; Fourier-transform ion cyclotron resonance mass spectrometry; electron microscopy; mineral-organic associations; Environmental Molecular Sciences Laboratory
OSTI Identifier: