A Comparison of Corn- and Prairie-Based Biofuel Cropping Systems.

The best biofuel production systems will be those most consistent with the original purposes of biofuels by having a high net energy yield, being environmentally resilient, and decreasing greenhouse gases in the atmosphere. Tilman et al. (2006) found evidence that low-input, high-diversity prairie systems may fit this description by producing more usable energy and greater greenhouse gas reductions than corn grain ethanol or soybean based biodiesel. However, prairie data in that study was site-specific, whereas corn and soybean data were drawn from national databases. A direct comparison of energy yield and greenhouse gas reduction in prairie and corn cropping systems is needed and has been established at the Iowa State University South Reynoldson Farm, Boone Co., IA. An important component of this experiment is the determination of how much biomass is produced aboveground for biofuel use and belowground for carbon (C) sequestration. In the establishment year of the study, corn-based systems were found to produce 5 times more aboveground biomass and 6 times less belowground biomass than prairie-based systems.  In addition to differences in the harvested aboveground biomass between corn and prairie systems, the phenology of aboveground biomass accumulation differed between corn and prairie systems with prairie systems having longer durations of growth and earlier maximum growth rates and corn systems having shorter durations of growth with very high growth rates. The implications of differences in C allocation patterns and phenology for biofuel production and environmental services will be discussed.