Bridging 20 Years of Soil Organic Matter Frameworks: Empirical Support, Model Representation, and Next Steps

Journal Article · 02 June 2024 · Journal of Geophysical Research. Biogeosciences

DOI: https://doi.org/10.1029/2023JG007964 · OSTI ID:2369834

Rocci, Katherine S.  ^[1]; Cotrufo, M. Francesca  ^[2]; Ernakovich, Jessica ^[3]; Foster, Erika ^[4]; Frey, Serita ^[3]; Georgiou, Katerina ^[5]; Grandy, A. Stuart ^[3]; Malhotra, Avni ^[6]; Reich, Peter B. ^[7]; Schlerman, Else P. ^[3]; Wieder, William R.  ^[8]

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1. Institute of Arctic and Alpine Research University of Colorado Boulder CO USA, Institute for Global Change Biology University of Michigan Ann Arbor MI USA
2. Department of Soil and Crop Sciences Colorado State University Fort Collins CO USA
3. Department of Natural Resources and the Environment Center of Soil Biogeochemistry and Microbial Ecology University of New Hampshire Durham NH USA
4. Point Blue Conservation Science Petaluma CA USA
5. Physical and Life Sciences Directorate Lawrence Livermore National Laboratory Livermore CA USA
6. Pacific Northwest National Laboratory Richland WA USA
7. Institute for Global Change Biology University of Michigan Ann Arbor MI USA, Department of Forest Resources University of Minnesota St. Paul MN USA
8. Institute of Arctic and Alpine Research University of Colorado Boulder CO USA, Climate and Global Dynamics Laboratory National Center for Atmospheric Research Boulder CO USA

Abstract In the past few decades, there has been an evolution in our understanding of soil organic matter (SOM) dynamics from one of inherent biochemical recalcitrance to one deriving from plant‐microbe‐mineral interactions. This shift in understanding has been driven, in part, by influential conceptual frameworks which put forth hypotheses about SOM dynamics. Here, we summarize several focal conceptual frameworks and derive from them six controls related to SOM formation, (de)stabilization, and loss. These include: (a) physical inaccessibility; (b) organo‐mineral and ‐metal stabilization; (c) biodegradability of plant inputs; (d) abiotic environmental factors; (e) biochemical reactivity and diversity; and (f) microbial physiology and morphology. We then review the empirical evidence for these controls, their model representation, and outstanding knowledge gaps. We find relatively strong empirical support and model representation of abiotic environmental factors but disparities between data and models for biochemical reactivity and diversity, organo‐mineral and ‐metal stabilization, and biodegradability of plant inputs, particularly with respect to SOM destabilization for the latter two controls. More empirical research on physical inaccessibility and microbial physiology and morphology is needed to deepen our understanding of these critical SOM controls and improve their model representation. The SOM controls are highly interactive and also present some inconsistencies which may be reconciled by considering methodological limitations or temporal and spatial variation. Future conceptual frameworks must simultaneously refine our understanding of these six SOM controls at various spatial and temporal scales and within a hierarchical structure, while incorporating emerging insights. This will advance our ability to accurately predict SOM dynamics.

• Sponsoring Organization: USDOE
• Grant/Contract Number: NONE; AC52-07NA27344; AC05-76RL01830
• OSTI ID: 2369834
• Alternate ID(s): OSTI ID: 2375436; OSTI ID: 2377815; OSTI ID: 2473222
• Journal Information: Journal of Geophysical Research. Biogeosciences, Journal Name: Journal of Geophysical Research. Biogeosciences Journal Issue: 6 Vol. 129; ISSN 2169-8953
• Publisher: American Geophysical Union (AGU)Copyright Statement
• Country of Publication: United States
• Language: English