Relationship between substrate initial reactivity and residues ageing speed in carbon mineralization

A desk study was conducted on the general relationship between substrate initial reactivity and the speed of ageing of residues in carbon mineralization. Totally 306 sets of experimental data were collected from 36 studies, covering a wide range of substrates and soil and environmental conditions. A model was used as a framework, which treats a substrate and subsequent residues as a whole, and describes the carbon mineralization with two parameters: the initial average rate coefficient (R) and the speed of ageing of residues (S). While both R and S were affected by substrate properties as well as by soil and environmental conditions, they were positively related to each other. In other words, the more quickly mineralization goes in the beginning, the more quickly the residues age. As a result, the initial differences in substrate reactivity would disappear over time, but the differences in residues quantity and carbon loss rate could last much longer, with substrates initially less reactive having higher carbon loss rates. The implications of the relationship between R and S was discussed with respect to dynamics of residues reactivity, quantity and carbon loss rate in relation to effects of substrate differences and impacts of external conditions