With hundreds of prairie plant species native to Iowa, choosing which prairie species might be good candidates for biomass production was a large task. The selection process was based on two premises. First, a combination of 16 species of prairie grasses and wildflowers are needed to maximize biomass production (Tilman 2006). Second, native prairie species that we choose for our biomass seed mix be seeded at a rate that is comparable to the recommended seeding rate for switchgrass biomass production. In Iowa, the recommended seeding rate for switchgrass biomass production is 10 pounds per acre or 52 seeds per square foot (Prairie Lands Biomass Project 2011).
The next step was to determine which species should be considered for biomass production. To do this we developed a list of “biomass production criteria” for tallgrass prairie species. A rubric, developed from our criteria list, was used to determine the final 16 species selected for the biomass mix (Table 1, click here for PDF).
The final step was to determine the seeding rate of each species included in the biomass seed mix. This was accomplished through pre-biomass investigations of production plots established on the campus of the University of Northern Iowa (click here for PDF). Seeding rates for each species in the biomass mix was a result of these pre-biomass investigations (Table 2, click here for PDF).
The Biomass Mix - 16 species
|Side-Oats Grama |
|Canada Wild Rye|
|Virginia Wild Rye|
|Milk Vetch |
|Showy Tick Trefoil|
|Saw-Tooth Sunflower |
|Ox-Eye Sunflower |
|Round-Headed Bush Clover |
|Compass Plant |
Tilman, D., Hill J., and C. Lehman (2006). Carbon-negative biofuels from low-input high-diversity grassland biomass. Science, 314, 1598-1600.
Prairie Lands Biomass Project. (2011). http://www.iowaswitchgrass.com/. Accessed 3/2/2011