Formation of mineral-associated organic matter in temperate soils is primarily controlled by mineral type and modified by land use and management intensity

authored by

De Shorn E. Bramble, Susanne Ulrich, Ingo Schöning, Robert Mikutta, Luise Brandt, Christian Poll, Ellen Kandeler, Christian Mikutta, Alexander Konrad, Jan Siemens, Yang Yang, Andrea Polle, Peter Schall, Christian Ammer, Klaus Kaiser, Marion Schrumpf

Abstract

Formation of mineral-associated organic matter (MAOM) supports the accumulation and stabilization of carbon (C) in soil, and thus, is a key factor in the global C cycle. Little is known about the interplay of mineral type, land use and management intensity in MAOM formation, especially on subdecadal time scales. We exposed mineral containers with goethite or illite, the most abundant iron oxide and phyllosilicate clay in temperate soils, for 5 years in topsoils of 150 forest and 150 grassland sites in three regions across Germany. Results show that irrespective of land use and management intensity, more C accumulated on goethite than illite (on average 0.23 ± 0.10 and 0.06 ± 0.03 mg m⁻² mineral surface respectively). Carbon accumulation across regions was consistently higher in coniferous forests than in deciduous forests and grasslands. Structural equation models further showed that thinning and harvesting reduced MAOM formation in forests. Formation of MAOM in grasslands was not affected by grazing. Fertilization had opposite effects on MAOM formation, with the positive effect being mediated by enhanced plant productivity and the negative effect by reduced plant species richness. This highlights the caveat of applying fertilizers as a strategy to increase soil C stocks in temperate grasslands. Overall, we demonstrate that the rate and amount of MAOM formation in soil is primarily driven by mineral type, and can be modulated by land use and management intensity even on subdecadal time scales. Our results suggest that temperate soils dominated by oxides have a higher capacity to accumulate and store C than those dominated by phyllosilicate clays, even under circumneutral pH conditions. Therefore, adopting land use and management practices that increase C inputs into oxide-rich soils that are under their capacity to store C may offer great potential to enhance near-term soil C sequestration.

Organisation(s)

Soil Mineralogy

External Organisation(s)

Max Planck Institute of Biogeochemistry (MPI-BGC)
Friedrich Schiller University Jena
Martin Luther University Halle-Wittenberg
University of Hohenheim
Justus Liebig University Giessen
University of Göttingen

Type

Article

Journal

Global change biology

Volume

30

No. of pages

19

ISSN

1354-1013

Publication date

08.12.2023

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Global and Planetary Change, Environmental Chemistry, Ecology, Environmental Science(all)

Sustainable Development Goals

SDG 15 - Life on Land

Electronic version(s)

https://doi.org/10.1111/gcb.17024 (Access: Open)