The priming effect, i.e. the increase in soil organic matter (SOM) decomposition rate after fresh organic matter input to soil, is often supposed to result from a global increase in microbial activity and competition due to the higher availability of energy released from the decomposition of fresh organic matter.
However a new study suggests that:
The chemical structure of added compounds on the priming effect is much larger than the effect of energy-content.
Different substrates resulted in different priming effect but appeared to stimulate the growth of similar bacterial groups. This suggests that the added compounds stimulate different enzyme systems within similar bacterial taxa.