08/16/2011
Assessing Carbon Impacts of Land-Use Choices for Bioenergy Crops
Summary
The Conservation Reserve Program (CRP) contains over 13 million hectares of former croplands now in grasslands, providing a reservoir of biodiversity, water quality, and carbon sequestration benefits. However, these benefits could be lost if the land is converted back to agricultural use for biofuel production. Scientists from the DOE Great Lakes Bioenergy Research Center analyzed the effects that converting CRP lands to annual crops for biofuel production (continuous corn and corn-soybean rotation, each either tilled or permanent no-till) would have on greenhouse gas (GHG) emissions as compared with directly harvesting perennial grasses on these lands for cellulosic ethanol. They report that although a no-till management regime of an annual bioenergy crop would reduce the carbon debt significantly compared with tilling, harvesting perennial grasses would result in virtually no GHGs lost, because the disruption required when converting to annual crops would be avoided. This is the first time field trials have been used instead of model predictions. The trials show that carbon debt can be avoided and climate change mitigated by directly using unconverted CRP grasslands for cellulosic feedstock production. The results will be helpful in developing strategies for producing bioenergy crop systems.
References
Gelfand, I., T. Zenone, P. Jasrotia, J. Chen, S. K. Hamilton, and G. P. Robertson. 2011. “Carbon Debt of Conservation Reserve Program (CRP) Grasslands Converted to Bioenergy Production,” Proceedings of the National Academy of Sciences of the United States of America 108(33), 13864-69. (DOI: 10.1073/pnas.1017277108)