Taxonomic identity was determined with the RDP classifier at 80% sequence match criteria. OTU table was trimmed by abundant OTUs (>0.001%). Difference between time points within each plot for: a Clay-loam switchgrass (CL-SG) plot; b Clay-loam fallow (CL-FL) plot; c Sandy-loam switchgrass (SL-SG) plot; d Sandy-loam fallow (SL-FL) plot. Significant differences between the previous time point for each group denoted by asterisk (*) symbols within each phyla bar.