Potential for Biofuel and Animal Feed Production From Native Prairie Grasslands

Most of the research focusing on the use of native prairie grasses for lignocellulosic ethanol production has been in terms of developing individual species for monoculture, analogous to modern agricultural methods. However, it may be desirable, in certain scenarios, to harvest native mixed-species grasslands for biofuel production. When using minimal agronomic inputs and maintenance, these fields have the potential to provide greater yields than monoculture grasslands, in addition to providing higher value as a wildlife habitat. Additionally, it might be possible to use pretreated biomass produced from these fields as a higher value animal feed.

In order to investigate the feasibility of using native prairie grasses as a biofuel feedstock and animal feed, samples from six fields, five early-successional and one late-successional, of differing plant composition were harvested in August 2009. Ammonia fiber expansion (AFEX) pretreatment followed by either enzymatic hydrolysis or in vitro rumen digestibility were performed on these samples in order to determine their value as both a biofuel feedstock and an animal feed compared to untreated material. Because the high diversity in plant species, while environmentally beneficial, may result in widely different optimal pretreatment conditions from one field to the next, each sample was optimized via a Box-Behnken response surface optimization and the effect on both hydrolysis and digestibility was investigated for each field and compared.