The unexplored role of preferential flow in soil carbon dynamics

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Author(s)Franklin, Shane M.
Author(s)Kravchenko, Alexandra N.
Author(s)Vargas, Rodrigo
Author(s)Vasilas, Bruce
Author(s)Fuhrmann, Jeffry J.
Author(s)Jin, Yan
Date Accessioned2024-03-29T17:17:01Z
Date Available2024-03-29T17:17:01Z
Publication Date2021-08-28
DescriptionThis article was originally published in Soil Biology and Biochemistry. The version of record is available at: https://doi.org/10.1016/j.soilbio.2021.108398. © 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
AbstractWater is a crucial factor controlling the fate and processing of soil organics. Water commonly flows through the vadose zone via preferential flow pathways, resulting in nonuniform and rapid infiltration. Hence, a large portion of the soil matrix is bypassed. Preferential flow paths, often associated with well-connected macropore networks (>300 μm Ø), offer a unique balance between water availability, nutrient delivery, and re-oxygenation upon drainage. The heightened concentrations of moisture, nutrients, and oxygen make these locations optimal for high rates of microbial activity. Flow paths often display temporal stability. This stability results in repeated wetting and biogeochemical reactivation through time creating a lasting impact on micro-environmental conditions relevant to microbial functioning and carbon cycling in soil. Despite decades of research on preferential flow, there is still a need to link flow paths and the resultant heterogeneous moisture distributions to soil function. In this review, we discuss how preferential flow can serve as a framework of reference for the spatially and temporally heterogeneous biogeochemical cycling of soil carbon. We highlight the importance of combining current knowledge of pore-scale carbon dynamics with an appreciation of connected networks of hydraulically active pores/paths within the soil profile. Such combination opens new possibilities for upscaling pore-scale processes with the inclusion of resource heterogeneity at the macroscale. Working within this hydraulically connected framework can provide insight for the mechanistic representation of hot moments, which are temporally isolated large pulses of CO2 after rewetting or thawing events. We conclude with suggestions on knowledge gaps and stress the critical need of linking soil physics with biology to mechanistically understand soil functions. Highlights • Preferential flow paths play a key role in soil carbon dynamics. • Pore-scale carbon dynamics could be upscaled using hydraulic connectivity. • A conceptual model is presented that considers how soil pores function from hydrological and microbial perspectives.
SponsorWe would like to acknowledge the career and contributions of Hangsheng “Henry” Lin and Peter Germann. Many of their contributions inspired this review. We would also like to thank Chelsea Mamott for making Fig. 1. Fig. 2, Fig. 3 were made on biorender.com. Funding for this work was provided in part by the Delaware Agricultural Experiment Station and the Hatch Program of the National Institute of Food and Agriculture, U.S. Department of Agriculture.
CitationFranklin, Shane M., Alexandra N. Kravchenko, Rodrigo Vargas, Bruce Vasilas, Jeffry J. Fuhrmann, and Yan Jin. “The Unexplored Role of Preferential Flow in Soil Carbon Dynamics.” Soil Biology and Biochemistry 161 (October 2021): 108398. https://doi.org/10.1016/j.soilbio.2021.108398.
ISSN1879-3428
URLhttps://udspace.udel.edu/handle/19716/34241
Languageen_US
PublisherSoil Biology and Biochemistry
dc.rightsAttribution 4.0 Internationalen
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/
Keywordspreferential flow
Keywordscarbon cycling
Keywordsconnectivity
Keywordshotspots
Keywordshot moments
Keywordsupscaling
Keywordsclimate action
Keywordslife on land
TitleThe unexplored role of preferential flow in soil carbon dynamics
TypeArticle
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