TY - JOUR

T1 - The role of clay content and mineral surface area for soil organic carbon storage in an arable toposequence

AU - Schweizer, Steffen A.

AU - Mueller, Carsten W.

AU - Höschen, Carmen

AU - Ivanov, Pavel

AU - Kögel-Knabner, Ingrid

N1 - Funding Information: We acknowledge the financial support by the Deutsche Forschungsgemeinschaft within the framework of the research unit “MAD Soil—Microaggregates: Formation and turnover of the structural building blocks of soils” (DFG RU 2179) through project KO 1035/48–1 and the NanoSIMS instrument (KO 1035/38–1). Open Access funding enabled and organized by Projekt DEAL. Publisher Copyright: © 2021, The Author(s).

PY - 2021

Y1 - 2021

N2 - Correlations between organic carbon (OC) and fine mineral particles corroborate the important role of the abundance of soil minerals with reactive surfaces to bind and increase the persistence of organic matter (OM). The storage of OM broadly consists of particulate and mineral-associated forms. Correlative studies on the impact of fine mineral soil particles on OM storage mostly combined data from differing sites potentially confounded by other environmental factors. Here, we analyzed OM storage in a soil clay content gradient of 5–37% with similar farm management and mineral composition. Throughout the clay gradient, soils contained 14 mg OC g−1 on average in the bulk soil without showing any systematic increase. Density fractionation revealed that a greater proportion of OC was stored as occluded particulate OM in the high clay soils (18–37% clay). In low clay soils (5–18% clay), the fine mineral-associated fractions had up to two times higher OC contents than high clay soils. Specific surface area measurements revealed that more mineral-associated OM was related to higher OC loading. This suggests that there is a potentially thicker accrual of more OM at the same mineral surface area within fine fractions of the low clay soils. With increasing clay content, OM storage forms contained more particulate OC and mineral-associated OC with a lower surface loading. This implies that fine mineral-associated OC storage in the studied agricultural soils was driven by thicker accrual of OM and decoupled from clay content limitations.

AB - Correlations between organic carbon (OC) and fine mineral particles corroborate the important role of the abundance of soil minerals with reactive surfaces to bind and increase the persistence of organic matter (OM). The storage of OM broadly consists of particulate and mineral-associated forms. Correlative studies on the impact of fine mineral soil particles on OM storage mostly combined data from differing sites potentially confounded by other environmental factors. Here, we analyzed OM storage in a soil clay content gradient of 5–37% with similar farm management and mineral composition. Throughout the clay gradient, soils contained 14 mg OC g−1 on average in the bulk soil without showing any systematic increase. Density fractionation revealed that a greater proportion of OC was stored as occluded particulate OM in the high clay soils (18–37% clay). In low clay soils (5–18% clay), the fine mineral-associated fractions had up to two times higher OC contents than high clay soils. Specific surface area measurements revealed that more mineral-associated OM was related to higher OC loading. This suggests that there is a potentially thicker accrual of more OM at the same mineral surface area within fine fractions of the low clay soils. With increasing clay content, OM storage forms contained more particulate OC and mineral-associated OC with a lower surface loading. This implies that fine mineral-associated OC storage in the studied agricultural soils was driven by thicker accrual of OM and decoupled from clay content limitations.

KW - Clay content

KW - Fine mineral particles

KW - Nanoscale secondary ion mass spectrometry

KW - Organic carbon loading

KW - Organic carbon storage

KW - Soil organic matter

U2 - 10.1007/s10533-021-00850-3

DO - 10.1007/s10533-021-00850-3

M3 - Journal article

AN - SCOPUS:85116219493

VL - 156

SP - 401

EP - 420

JO - Biogeochemistry

JF - Biogeochemistry

SN - 0168-2563

ER -