Soil heterogeneity—spanning physical, chemical, and biological variations—strongly shapes root growth, redox conditions, microbial activity, and biogeochemical cycling. These interactions influence carbon and nutrient dynamics, greenhouse gas emissions, groundwater quality, and broader ecosystem processes. This session explores how soil heterogeneity governs biogeochemical processes across spatial and temporal scales, from nano to macro. We welcome studies on nutrient and contaminant behavior, greenhouse gas fluxes, carbon storage, mineral transformations, and related topics, using laboratory, field, modeling, or novel methodological approaches that advance our understanding of soils and sediments in biogeochemical cycles.