Priming effect (PE) is a natural process sequence induced by pulse or continuous inputs of fresh organics leading to changes of soil organic matter (SOM) turnover. The interactions between C pools with contrast availability and their effects on the C turnover are challenging for understanding and simulation. Therefore, methodological approaches for identifying apparent and real priming, evaluating statistical uncertainties of PE estimation, and consequences for C and N turnover and destabilization of SOM are particularly encouraged. Studies evaluating the sources, directions and magnitude of PEs and their dependence on microbial and enzyme activities are appreciated. Studies on relevance of priming effects to expected climate and land-use changes and to increased rhizodeposition under elevated CO2 in natural and agricultural ecosystems are welcomed. The session challenges the modelers addressing soil C and N dynamics and microbial biomass turnover that incorporate the PEs as interactions between living and dead organic matter.