Geological Society of America

T286 Rock Transforming to Soil—The Weathering Engine Intersects with the Carbon Cycle (Posters)

Tuesday, 24 October 2017
9:00 AM - 6:30 PM
Halls 4EF

MOLECULAR AND MICROSCOPIC INSIGHTS INTO THE FORMATION OF SOIL ORGANIC MATTER IN A RED PINE RHIZOSPHERE

Paper number: T286-3
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

A. Dohnalkova
Pacific Northwest National Laboratory, Richland, WA
James B. Harsh
Department of Crop and Soil Sciences, Pullman, WA
Zsuzsanna Balogh-Brunstad
Hartwick College, Oneonta, NY
C. Kent Keller Presenting Author
Washington State University, Pullman, WA
Malak M. Tfaily
Pacific Northwest National Lab, Richland, WA
A. Peyton Smith
Pacific Northwest National Laboratory, Richland, WA
Rosalie Chu
Pacific Northwest National Laboratory, Richland, WA
Alex R. Crump
University of Idaho, Moscow, ID
Colin J. Brislawn
Pacific Northwest National Laboratory, Richland, WA
Tamas Varga
Pacific Northwest National Laboratory, Richland, WA
Zhenqing Shi
South China University of Technology, Guangzhou
Linda Thomashow
Wheat Health, Genetics and Quality Research Unit, Pullman, WA

Abstract

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. These findings provide insight into the formation of SOM products in ecosystems, and show that the residual plant- and microbial-derived material associated with mineral matrices may be important components in current soil carbon models.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-307345

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