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Research article - Peer-reviewed, 2021

Oxalate-extractable aluminum alongside carbon inputs may be a major determinant for organic carbon content in agricultural topsoils in humid continental climate

Fukumasu, Jumpei; Poeplau, Christopher; Coucheney, Elsa; Jarvis, Nick; Kloffel, Tobias; Koestel, John; Katterer, Thomas; Svensson, David Nimblad; Wetterlind, Johanna; Larsbo, Mats

Abstract

The relative importance of various soil mineral constituents (e.g. clay-sized particles, aluminum- and iron-bearing mineral reactive phases) in protecting soil organic carbon (SOC) from decomposition is not yet fully understood in arable soils formed from quaternary deposits in humid continental climates. In this study, we investigated the relationships between soil physico-chemical properties (i.e. contents of oxalate-extractable aluminum (Alox) and iron (Feox) and clay size particle < 2 mu m), grain yield (as a proxy for carbon input) and total SOC as well as SOC in different soil fractions for samples taken from the topsoil of an arable field at Bjertorp in south-west Sweden. We found a positive correlation between Alox and total SOC content, where Alox explained ca. 48% of the spatial variation in SOC. We also found that ca. 80% of SOC was stored in silt- and claysized (SC) fractions, where Al-bearing reactive mineral phases (estimated by Alox) may be important for organicmineral associations and clay aggregation. Our results were supported by data collated from the literature for arable topsoil in similar climates, which also showed positive correlations between SOC and Alox contents (R-2 = 23.1 - 74.5%). Multiple linear regression showed that including spatially-variable crop yields as a proxy for carbon inputs improved the prediction of SOC variation across the Bjertorp field. Other unquantified soil properties such as exchangeable calcium may account for the remaining unexplained variation in topsoil SOC. We conclude that Al-bearing reactive mineral phases are more important than clay content and Fe-bearing reactive mineral phases for SOC stabilization in arable topsoil in humid continental climates.

Keywords

Soil organic carbon; Oxalate-extractable aluminum; Clay; Arable soil; Fractionation; Carbon input

Published in

Geoderma
2021, volume: 402, article number: 115345
Publisher: ELSEVIER

Authors' information

Swedish University of Agricultural Sciences, Department of Soil and Environment
Poeplau, Christopher
Johann Heinrich von Thunen Institute
Swedish University of Agricultural Sciences, Department of Soil and Environment
Swedish University of Agricultural Sciences, Department of Soil and Environment
Klöffel, Tobias (Klöffel, Tobias)
Swedish University of Agricultural Sciences, Department of Soil and Environment
Koestel, John (Koestel, Johannes)
Swedish University of Agricultural Sciences, Department of Soil and Environment
Koestel, John (Koestel, Johannes)
Agroscope
Swedish University of Agricultural Sciences, Department of Ecology
Swedish University of Agricultural Sciences, Department of Soil and Environment
Swedish University of Agricultural Sciences, Department of Soil and Environment
Swedish University of Agricultural Sciences, Department of Soil and Environment

Sustainable Development Goals

SDG15 Life on land

UKÄ Subject classification

Soil Science

Publication Identifiers

DOI: https://doi.org/10.1016/j.geoderma.2021.115345

URI (permanent link to this page)

https://res.slu.se/id/publ/113466