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The Root of the Matter: Soil Carbon Mobilization in the Rhizosphere


EMSL Project ID
50268

Abstract

The exploratory work we propose aims to improve mechanistic understanding of links among rhizodeposition of organic compounds by plant roots, microbial growth and activity, and the strength of organic matter - mineral associations in soil. These mineral associations serve to protect organic matter (OM) from microbial attack and thus preserve very large terrestrial soil carbon pools. However, model compounds common in rhizodeposits can destabilize mineral-associated OM and cause soil carbon loss. OM-mineral associations are featured in DOE's newly developed ELM model, but the potential vulnerability of OM-mineral associations to the effects of rhizodeposition has not yet been considered. Our long term interest thus lies in characterizing the quality and dynamics of rhizodeposition and quantifying their effects on the fate of otherwise stable mineral-associated OM. Here we aim to identify the biogeochemical mechanisms by which rhizodeposition can trigger the release of organic matter (OM) from protective mineral associations. We propose combined fine-scale measurements of the molecular composition of solutes in the rhizosphere along single roots, using EMSL's mass spectrometry resources, with in situ monitoring of their effects on rhizosphere biogeochemistry using a novel suite of microsensors developed by our team. Specficially, we relate shifts in overall solute composition (FTICRMS), presence of specific low-molecular weight compounds (Orbitrap GC-MS and 1H-13C NMR), and phytosiderophores (LC-ICP coupled with 21T FTICRMS) around actively growing roots to effects on OM-mineral associations. Process-level understanding derived from these data will inform future development and application of portions of the ELM code.

Project Details

Project type
Large-Scale EMSL Research
Start Date
2018-10-01
End Date
2021-03-31
Status
Closed

Team

Principal Investigator

Marco Keiluweit
Institution
University of Massachusetts Amherst

Co-Investigator(s)

Zoe Cardon
Institution
Marine Biological Laboratory

Team Members

Carolyn Malmstrom
Institution
Michigan State University

Related Publications

Hui Li, Tobias Bölscher, Malak M. Tfaily, Matthew WinnickZoe G. Cardon, Marco Keiluweit, , 2021. "Simple Plant and Microbial Exudates Destabilize Mineral-Associated Organic Matter via Multiple Pathways." Environmental Science & Technology 2021, 55, 5, 3389–3398