Soil organic matter and mineral surface interactions are governed by the anchoring pathway

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Abstract
Soil organic carbon (SOC) is the largest terrestrial carbon reservoir and acknowledged to play an important role in climate mitigation. It has been advocated to store additional SOC in stable forms to provide efficient climate change mitigation. For this, mineral associated organic matter (MAOM) is considered to be relatively stable and has longer residence times than faster cycling particulate organic matter. However, we require a better mechanistic understanding of microscale interactions and the controlling factors of MAOM formation. Here we used arable soils across Germany representing three texture classes (sandy, loamy and clayey), two levels of SOC contents (low and high; 7-73 mg OC g-1 soil) and consequently a range of SOC loading in the MAOM fraction (2-122 mg OC g-1 fraction). The soils were incubated for two years after an addition of highly 13C labelled (8 atom%) barley-litter and fractionated by particle size to extract the MAOM (