Marginal Lands: A Valuable Resource for Sustainable Bioenergy Production

The Science

Growing plants on marginal lands, or lands unsuitable for conventional agricultural crops, is a promising route towards attaining sufficient cellulosic biomass for the production of biofuels without compromising food crops. However, both the availability of such lands as well as the potential environmental impacts (e.g., greenhouse gas emissions) resulting from widespread biofuel crop production remain uncertain. Researchers at the U.S. Department of Energy’s Great Lakes Bioenergy Research Center (GLBRC) report results from the first assessment of the total biomass potential of these lands, including an estimate of greenhouse gas benefits and the productivity potential of unmanaged lands. Using 20 years of data from 10 Midwest states, the researchers compared both productivity and greenhouse gas impacts of several potential biofuel feedstocks, including corn, poplar, alfalfa, and old field vegetation, and then used supercomputers to model the biomass production required to support local biorefineries. The assessment shows that if properly managed, marginal lands could provide sufficient biomass to support a viable cellulosic biofuel production industry while benefiting conservation efforts and the environment.

Summary

Marginal lands are those poorly suited to field crops because of low crop productivity due to inherent edaphic or climatic limitations or because they are located in areas that are vulnerable to erosion or other environmental risks when cultivated. Often such lands are suitable for grasses, short-rotation tree crops or other perennial vegetation with persistent roots that are better adapted to low-nutrient, erodible or droughty soils.

Researchers compared greenhouse gas emissions and the productivity of established successional vegetation with those of both annual and perennial crops at a single, moderate-fertility location, without consideration of indirect carbon costs. Researchers can then project the potential for early successional vegetation to produce biofuel on marginal lands across a ten-state region of the US Midwest using a well-established quantitative crop productivity model calibrated at KBS for successional vegetation and tested elsewhere. Twenty-year patterns of GHG balances for the annual cropping systems show that without fossil fuel offsets, the conventionally managed system had a net release of GHG equivalents, whereas the no-till system accumulated enough soil carbon to offset the GHG costs of farming inputs and N₂O losses.

BER Program Manager

U.S. Department of Energy, Biological and Environmental Research (SC-33)
Biological Systems Science Division
[email protected]

References

Gelfand, I., R. Sahajpal, X. Zhang, R. C. Izaurralde, K. L. Gross, and G. P. Robertson. 2013. “Sustainable Bioenergy Production from Marginal Lands in the U. S. Midwest,” Nature. DOI: 10.1038/nature11811.