Is soil carbon mostly root carbon? Mechanisms for a specific stabilisation

SOC is mainly derived from root C, root exudates, and fine root turnover.

“Rasse et al. (2005) assert that SOC is mainly derived from root C, from root exudates and fine root turnover.”

Soil carbon storage is linked to root inputs including root exudation, which is known to change the activity and composition of the microbial community.

“Second, soil carbon storage is linked to root inputs 31,32 including root exudation, which is known to change the activity and composition of the microbial community 33 .”

Fine root carbon is a measure of carbon input and basal respiration is a measure of microbial metabolic activity, and both were included as variables potentially mediating plant community effects.

“As variables potentially mediating plant community effects we included fine root carbon as measure of carbon input 31,32 and basal respiration as measure of microbial metabolic activity 20,34,37 .”

Rhizodeposition and root exudates can cause a priming effect on the turnover of stored soil carbon, which could increase soil carbon emission and lower the sequestration rate.

“Rhizodeposition and root exudates can cause a priming effect on the turnover of C stored in the soil [100], which could increase soil C emission [101, 102] and lower the sequestration rate.”

The view that roots contribute more to soil organic carbon than aboveground sources seems reflected in the figures, and recent data showed a tight relationship between root and Miscanthus-derived soil organic carbon.

“The view that roots contribute more to SOC than aboveground sources [100] seems to be reflected in Figs. 3b and 4, and recent data showed a tight relationship between root and Miscanthus-derived SOC [80].”