Estimates of rhizosphere priming effects are affected by soil disturbance

There was no difference in SOM decomposition rates between the trenched and the rooted plots estimated using our non-disruptive technique. In contrast, laboratory incubations of sieved soils highlighted a two-fold increase in SOM decomposition rates in the rooted plots compared with rates from the trenched plots. Our results suggest that rhizosphere priming may not actively influence soil carbon turnover in the undisturbed soil environment and question conclusions from laboratory incubation studies. We attribute the different findings from laboratory and field studies to the physical disturbance of the soil involved in laboratory incubations causing the release of previously protected substrates, making them available for decomposition.