From Litter Decomposition to SOM Formation: What Are We Missing?.

Accurate modeling of the flow of C from decomposing above- and below-ground plant litter to the atmosphere (e.g., as CO₂ and VOC) and soil, and its distribution among functionally distinct soil organic matter pools, remains a challenge. While we have precise knowledge and modeling capability of the controls of plant litter decomposition rates, we largely ignore transfer amounts, temporal dynamics and C-chemistry of litter-C fluxes to the soil (e.g., DOC and light fragments), as well as the environmental and litter quality factors controlling litter-C fate. In the mineral soil, litter-derived C will most likely persist if it is used with high efficiency by microbes and allocated to microbial products that will stabilize through interaction with the soil matrix. These concepts will be discussed on the basis of experimental evidences, using laboratory incubations and field studies with ¹³C enriched plant material, and conceptual models.