The Functional Diversity of Soil Microbial Communities Vary with Plant Cultivar

With the threat of climate change there is a growing incentive to reduce atmospheric carbon dioxide (CO ₂ ) levels. Soil is the largest sink of terrestrial carbon (C), and the natural processes of soil C sequestration could be harnessed to reduce atmospheric CO ₂ . Grasses like switchgrass ( Panicum virgatum ) and big bluestem ( Andropogon gerardi ) have the potential to sequester C since they have extensive root systems, and their cultivation involves little disturbance to the soil. Research in our lab has shown that soil C accumulation differs among cultivars of switchgrass and big bluestem. Additionally, studies have indicated that the microbial community functioning can affect soil C accumulation. However, whether variation among the microbial communities of big bluestem and switchgrass cultivars could be responsible for the observed differences in soil C accumulation is still unknown. This study seeks to understand how cultivars of switchgrass and big bluestem affect microbial functional diversity across a soil depth profile. We collected 30 cm soil cores split into 3 increments from a long-term field experiment in the Fermilab National Environmental Research Park, IL. Microbial functional diversity was analyzed for samples from cultivar monocultures by exposing them to different C substrates, incubating, and determining respired CO ₂ .