Plant-soil interactions play an important role in regulating CO2 emissions and storage of carbon (C) as soil organic matter (SOM) creating the potential for crop selection to be a tool for sustainable agriculture. This is of particular importance in grassland soils which are known to be important stores of C. However, there is still a need to understand whether the selection of different grass species and varieties can control the rates and products of C cycling and if this is driven by the interaction with below ground microbial communities.