3. Results
3.1. Cropping system effects on microbial biomass
Total microbial lipid biomass in unfertilized switchgrass and both fertilized and unfertilized prairie was significantly greater than the baseline values at both soil depths (Fig. 1). By contrast, total microbial lipid biomass in corn was reduced from baseline values at the surface (0–10 cm), but not the subsurface (10–25 cm). At both depths, microbial biomass for the corn, miscanthus, and poplar systems was lower than for unfertilized prairie and switchgrass. Fertilized plots corresponded to lower total microbial biomass in switchgrass at the surface and both switchgrass and prairie at the subsurface. Stover removal in corn had no effect on microbial biomass at either depth.