University of Kentucky research shows little relationship between forage quality of native warm-season grasses, including switchgrass, and potential cellulosic ethanol production.
But, with improved ethanol extraction procedures, forage quality may be found to affect biofuel yield, say Ray Smith, forage extension specialist, and Tom Keene, hay marketing specialist, who led the study.
Switchgrass, big bluestem, In- diangrass and eastern gamagrass were harvested at early heading stage in late June and July 2008. Dormant switchgrass was cut in November 2007 and March 2008.
Subsamples from each harvest were analyzed for forage quality and potential ethanol production.
Crude protein ranged from 3 to 3.6%; ADF, 46.5 to 59.7%; and NDF, 71.9 and 78.1% for November- and March-harvested switchgrass. For summer-harvested grasses, crude protein ranged from 3.7 to 10.4%; ADF, 31.9 to 39.4%; and NDF, 63 to 71.9%.
Generally, forage quality didn't correlate with potential ethanol production using an extraction method involving grinding to 1- and 4-mm particle sizes, a sodium hydroxide pretreatment, enzyme hydrolysis and fermentation to convert cellulose to ethanol.