title: Direct evidence for microbial-derived soil organic matter formation and its ecophysiological controls.
abstract: Soil organic matter (SOM) and the carbon and nutrients therein drive fundamental submicron- to global-scale biogeochemical processes and influence carbon-climate feedbacks. Consensus is emerging that microbial materials are an important constituent of stable SOM, and new conceptual and quantitative SOM models are rapidly incorporating this view. However, direct evidence demonstrating that microbial residues account for the chemistry, stability and abundance of SOM is still lacking. Further, emerging models emphasize the stabilization of microbial-derived SOM by abiotic mechanisms, while the effects of microbial physiology on microbial residue production remain unclear. Here we provide the first direct evidence that soil microbes produce chemically diverse, stable SOM. We show that SOM accumulation is driven by distinct microbial communities more so than clay mineralogy, where microbial-derived SOM accumulation is greatest in soils with higher fungal abundances and more efficient microbial biomass production.
authors.affiliation: Department of Natural Resources and the Environment, University of New Hampshire, Durham, New Hampshire 03824, USA.|Soil and Crop Sciences Department, Colorado State University, Fort Collins, Colorado 80523, USA.
authors.forename: Cynthia M
authors.initials: CM
authors.lastname: Kallenbach
authors.affiliation: Department of Natural Resources and the Environment, University of New Hampshire, Durham, New Hampshire 03824, USA.
authors.forename: Serita D
authors.initials: SD
authors.lastname: Frey
authors.affiliation: Department of Natural Resources and the Environment, University of New Hampshire, Durham, New Hampshire 03824, USA.
authors.forename: A Stuart
authors.initials: AS
authors.lastname: Grandy
mesh_terms: D000538:Aluminum Silicates; D001419:Bacteria / Q000378:metabolism*; D000077215:Clay; D017753:Ecosystem; D008962:Models, Theoretical; D009930:Organic Chemicals / Q000378:metabolism*; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology
chemical_list: D000538:Aluminum Silicates; D009930:Organic Chemicals; D012987:Soil; D000077215:Clay