Title: What do we know about soil carbon destabilization?

Abstract

Most empirical and modeling research on soil carbon (C) dynamics has focused on those processes that control and promote C stabilization. However, we lack a strong, generalizable understanding of the mechanisms through which soil organic carbon (SOC) is destabilized in soils. Destabilization includes processes that occur along a spectrum through which SOC shifts from a “protected” state to an “available” state to microbial cells where it can be mineralized to gaseous forms or to soluble forms that are then lost from the soil system. These processes fall into three general categories: (1) Release from physical occlusion through processes such as tillage, bioturbation, or freeze-thaw and wetting-drying cycles; (2) C desorption from soil solids and colloids; and (3) Increased C metabolism. Many processes that stabilize soil C can also destabilize C, and C gain or loss depends on the balance between competing reactions. For example, earthworms may both stabilize C through aggregate destruction, but may also create new aggregates and redistribute C into mineral horizon. Similarly, mycorrhizae and roots form new soil C but may also destabilize old soil C through priming and promoting microbial mining; labile C inputs cause C stabilization through increased carbon use efficiency or may fuel priming.more » Changes to the soil environment that affect the solubility of minerals or change the relative surfaces charges of minerals can destabilize SOC, including increased pH or in the reductive dissolution of Fe-bearing minerals. By considering these different physical, chemical, and biological controls as processes that contribute to soil C destabilization, we can develop thoughtful new hypotheses about the persistence and vulnerability of C in soils and make more accurate and robust predictions of soil C cycling in a changing environment.« less

Authors:

Bailey, Vanessa L.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-2248-8890"
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Pries, Caitlin Hicks  ^[2];

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• Search DOE PAGES for ORCID "0000-0003-0813-2211"
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Lajtha, Kate  ^[3]

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• Search DOE PAGES for ORCID "0000-0002-6430-4818"
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+ Show Author Affiliations

1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
2. Dartmouth College, Hanover, NH (United States)
3. Oregon State Univ., Corvallis, OR (United States)

Publication Date:

2019-07-29

Research Org.:

Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1545407

Alternate Identifier(s):

OSTI ID: 1572469

Report Number(s):

PNNL-SA-143015
Journal ID: ISSN 1748-9326

Grant/Contract Number:  

AC05-76RL01830

Resource Type:

Published Article

Journal Name:

Environmental Research Letters

Additional Journal Information:

Journal Volume: 14; Journal Issue: 8; Journal ID: ISSN 1748-9326

Publisher:

IOP Publishing

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; soil organic carbon; destabilization; physical occlusion; metabolism; bioavailability; priming; Birch effect