A data frame made from a soil `phyloseq` object with only taxonomy data.
References
Whitman, T., Pepe-Ranney, C., Enders, A., Koechli, C., Campbell, A., Buckley, D. H., Lehmann, J. (2016). Dynamics of microbial community composi-tion and soil organic carbon mineralization in soil following addition of pyrogenic andfresh organic matter. The ISME journal, 10(12):2918. <doi: 10.1038/ismej.2016.68>.