The structure of plant communities (i.e., the plants’ identities and abundances) can have large effects on soil biogeochemical cycles. These effects can stem from the plant's use of soil resources (water and nutrients), their contribution of detritus and SOM (through the quality and quantity of their leaf litter, fine roots, and root exudates), and their associations with soil microbial communities (beneficial associations with mutualists or antagonistic associations with pathogens). Of these, how plant-microbial associations affect soil biogeochemistry is arguably the least explored. In this session, we welcome all presentations that link plant communities to soil biogeochemical cycling, especially those considering plant interactions with symbiotic organisms (mycorrhizal fungi, N-fixing bacteria) and non-symbiotic free-living microbes.