Cornelia Rumpel and
Year : 2011
Title : Deep soil organic matter - a key but poorly understood component of terrestrial C cycle
Journal : Plant Soil
The aim of this paper is to synthesize literature concerning the sources, composition, mechanisms of stabilisation
and destabilization of soil organic matter stored in subsoil horizons.
Despite their low carbon content, most subsoil horizons contribute to more than half of the total soil carbon stocks, and therefore need to be considered in the global carbon cycle.
Organic C input into sub-soils occurs in dissolved form (DOC) following preferential flow pathways, as above-ground or root litter and exudates along root channels and/or through bioturbation.
With few exceptions, the carbon-to-nitrogen (C/N) ratio is decreasing with soil depth, while the stable C and N isotope ratios of SOM are increasing, indicating that organic matter (OM) in deep soil horizons is highly processed.