Effects of plant host and plant community diversity on soil rhizosphere microbial community composition, diversity, structure, and function were explored in long-term experimental plots. Soil samples were collected from the rhizosphere of one of 4 target plants species (Andropogon gerardii, Schizachyrium scoparium, Lespedeza capitata, or Lupinus perennis) growing in 1, 4, 8, 16, or 32-species plots. Pathogen-suppressive activities of soil streptomycetes were determined for every sample. In addition, soil metagenomic analyses were performed targeting bacterial or streptomycete communities. Soil edaphic characteristics were determined for every sample. Analyses consider both the effects of plant host and plant community diversity on microbial community structure and function, and the relationships of diverse taxa with plant host, plant community diversity, and soil edaphic characteristics.