Mechanisms controlling soil carbon turnover and their potential application for enhancing carbon sequestration |
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| Authors: | Julie D Jastrow James E Amonette Vanessa L Bailey |
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| Institution: | (1) Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA;(2) Chemical Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99354, USA;(3) Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99354, USA |
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| Abstract: | In addition to increasing plant C inputs, strategies for enhancing soil C sequestration include reducing C turnover and increasing
its residence time in soils. Two major mechanisms, (bio)chemical alteration and physicochemical protection, stabilize soil organic C (SOC) and thereby control its turnover. With (bio)chemical alteration, SOC is transformed by biotic
and abiotic processes to chemical forms that are more resistant to decomposition and, in some cases, more easily retained
by sorption to soil solids. With physicochemical protection, biochemical attack of SOC is inhibited by organomineral interactions
at molecular to millimeter scales. Stabilization of otherwise decomposable SOC can occur via sorption to mineral and organic
soil surfaces, occlusion within aggregates, and deposition in pores or other locations inaccessible to decomposers and extracellular
enzymes. Soil structure is a master integrating variable that both controls and indicates the SOC stabilization status of
a soil. One potential option for reducing SOC turnover and enhancing sequestration, is to modify the soil physicochemical
environment to favor the activities of fungi. Specific practices that could accomplish this include manipulating the quality
of plant C inputs, planting perennial species, minimizing tillage and other disturbances, maintaining a near-neutral soil
pH and adequate amounts of exchangeable base cations (particularly calcium), ensuring adequate drainage, and minimizing erosion.
In some soils, amendment with micro- and mesoporous sorbents that have a high specific surface – such as fly ash or charcoal
– can be beneficial.
All authors contributed equally to this article. |
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