The scramble to find sufficient land for biofuel production has experts eyeing marginal croplands that have been placed in the Conservation Reserve Program (CRP). Now a study by Agricultural Research Service (ARS) scientists indicates that plant species diversity and composition are key factors in potential energy yield per acre from biomass harvested from land.
The team studied plant species composition, species diversity, aboveground biomass, plant chemical composition and potential ethanol yield at 34 warm-season grassland sites across the major ecological regions of the northeastern United States. The sites were a mix of holdings, wildlife refuges, state parks and other public and private lands. The researchers identified 285 plant species, most of them native, on the study sites. Switchgrass, big bluestem and indiangrass, which are all tall native prairie grasses, dominated the vegetation mix. There was an average of 34 different plant species per quarter-acre.
CRP grasslands with the highest number of species had the lowest potential ethanol yields per acre. But sites dominated by a small number of native tall prairie grass species, such as switchgrass, big bluestem, and indiangrass, had the highest yields.