ARS | Publication request: Fermentability of Eastern Gamagrass, Big Bluestem and Sand Bluestem Grown Across a Wide Variety of Environments

Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 10, 2006
Publication Date: January 26, 2007
Citation: Weimer, P.J., Springer, T.L. 2007. Fermentability of eastern gamagrass, big bluestem and sand bluestem grown across a wide variety of environments. Bioresource Technology. 98:1615-1621.

Interpretive Summary: Developing a bio-based fuels and chemical industry will require an abundant supply of plant material that has consistently high fermentability. We examined the microbial fermentability of three perennial grass species grown at various locations in the U.S. over a three year period. Two related species, big bluestem and sand bluestem, displayed high fermentability (slightly greater for big bluestem) that showed relatively little variation among plant growth environments. A third species, Eastern gamagrass, displayed lower and more variable fermentability, although this was due in part to the wider geographic range over which Eastern gamagrass was grown. This study shows that bluestems, particularly big bluestem, may be a useful biomass feedstock for direct microbial fermentation into products such as ethanol.

Technical Abstract: Three species of warm-season perennial grasses grown at multiple locations in the eastern and central US and harvested over a three year period were examined for fermentability via in vitro ruminal gas production and dry matter digestibility assays, and near-infrared reflectance calibrations were developed for these fermentation parameters. Big bluestem (Andropogon gerardii) displayed greater fermentability than did sand bluestem (A. hallii) or Eastern gamagrass (Tripsacum dactyloides). The bluestems also displayed less variation in fermentability over different growth environments (geographic locations and harvest years), suggesting a more consistent biomass quality than for Eastern gamagrass. Thus, in addition to their use as forage for ruminant animals, bluestems may be of particular interest as feedstocks for bioconversion to ethanol and other products via direct microbial fermentation (consolidated bioprocessing) schemes.