Highly diverse soil biotic communities are central drivers of biogeochemical processes, and soil biodiversity as a “hot topic” has been raising political interest. We now increasingly understand the diversity, composition and even functional profiles of many soil taxa, still, the integration of physiological functions, community interactions and functional group composition into biogeochemical processes in heterogeneous soil systems remains limited due to methodological challenges. Developing fields of –omics, micro-/spectroscopy, isotope labelling and improved biomarker interpretations allow direct analyses of the activity of microorganisms and fauna in soil, contributing important novel perspectives in soil science. These emergent approaches are critical to predict how environmental changes modifies biogeochemical processes, as climate change, agricultural practices and pollutants threatens soil biodiversity. Our session presents research exploring soil biotic dynamics from individuals to complex communities with a focus on their impact on soil carbon and nitrogen cycling. The impact of environmental change on the functions of diverse biotic groups is explored with an exciting range of novel techniques. Beside a focus on soil microbial dynamics, understudied groups including protists, soil fauna and diverse trophic interactions are highlighted.