Use of low productivity land to grow biofuel crops in the U.S

Background/Question/Methods

Using agricultural land to grow biofuel crops can result in a reduction in the amount of land used to grow food crops. One alternative is to use low productivity land to grow biofuel crops. This paper will evaluate the potential to use low productivity land within the U.S. to grow perennial biofuel crops. We quantify potential plant production from the biofuel crop and net greenhouse gas fluxes using the DayCent ecosystem model, evaluate the ecosystem (plant production and net greenhouse gas fluxes) impacts of growing energy cane on pasture land and low productivity crop land in the Southeastern U.S., and growing Miscanthus and switchgrass on low productivity agricultural soils and grasslands in the U.S. Corn Belt and the Great Plains.

Results/Conclusions

The DayCent model has been used to simulate the impacts of growing perennial biofuel crops on grassland and cropland in the U.S. Simulations indicate that the use of low-productivity land in the Corn Belt to grow switchgrass and Miscanthus instead of the corn currently used to produce ethanol would result in an increase in grain for food (+4%), more ethanol production (+82%), while at the same time greatly reduce NO₃ leaching (-15 to 22%) and greenhouse gas emissions (> 29 %). DayCent model results also suggest that growth of energy cane on low productivity grasslands and cropland in the southeastern U.S. could result in a large potential increase in the amount of plant biomass available for production of ethanol, minimal reduction in the corn production, and a net decrease in greenhouse gas emissions. Simulated growth of perennial biofuel crops on grasslands and cropland of the U.S. Great Plains results in a reduction in net greenhouse gas emissions and the potential to produce substantial amount of biomass in the eastern part of the Great Plains. Plant production is not high enough to justify the growth of perennial biofuels in the western Great Plains. These DayCent model results are currently being incorporated into an economic model (BEPAM) to evaluate economic viability of growing perennial biofuel crops on grassland and cropland in the U.S.