Soil organic carbon is critical for climate regulation and ecosystem stability. Its decomposition can be significantly influenced by plant root exudates via the priming effect. However, the understanding of how specific compounds of root exudates influence soil C decomposition via the priming effect is still lacking.

In a recent study, researchers led by WANG Peng from the Institute of Applied Ecology of the Chinese Academy of Sciences investigated general patterns and drivers of the priming effects caused by root exudates by conducting a meta-analysis.

They found that amino acids induced the highest priming effect followed by simple sugars, low-molecular-weight organic acids and phenolics. The priming effect caused by simple sugars increased but then decreased with soil C to N ratio increasing, and the threshold was at a soil C to N ratio of ~14. The incubation temperature also plays an important role. The low-molecular-weight organic acid-induced priming effect was positively correlated with the addition rate.

“Our new findings emphasize that more attention should be paid to the importance of the specificity of root exudate types when evaluating its influence on the priming effect, especially considering that root exudates vary largely in response to environmental changes”, said Prof. Wang.

This study, funded by the Strategic Priority Research Program (A) of the Chinese Academy of Sciences, National Natural Science Foundation of China, and Major Program of Institute of Applied Ecology, Chinese Academy of Sciences, has been published in Soil Biology and Biochemistry entitled " Priming effect on soil carbon decomposition by root exudate surrogates: A meta-analysis."