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Title: Biofuels on the landscape: Modeling to balance the environmental footprint of feedstock production on marginal lands

Author
item FIELD, JOHN - Colorad0 State University
item DINH, THAI - University Of Oklahoma
item EASTER, MARK - Colorad0 State University
item MARX, ERNIE - Colorad0 State University
item TRYNER, JESSICA - Colorad0 State University
item Adler, Paul
item PAUSTIAN, KEITH - Colorad0 State University

Submitted to: National Symposium - New Crops
Publication Type: Proceedings
Publication Acceptance Date: 6/6/2014
Publication Date: 9/14/2015
Citation: Field, J., Dinh, T., Easter, M., Marx, E., Tryner, J., Adler, P.R., Paustian, K. 2015. Biofuels on the landscape: Modeling to balance the environmental footprint of feedstock production on marginal lands. In: Proceedings of the Joint Annual Meeting of the Association for the Advancement of Industrial Crops and the USDA National Institute of Food and Agriculture (eds. Janick J, Whipkey A, Cruz VM), pp. 142–151. Washington D.C., October 12-16, 2013. Available: https://hort.purdue.edu/newcrop/proceedings2015/142-fields.pdf p 142-151.

Interpretive Summary: An interpretive summary is not required.

Technical Abstract: The sustainable production of large quantities of biomass from dedicated energy crops will be necessary to meet renewable fuel and power mandates being implemented in the United States at the federal and state level. However, fundamental questions about the relative merits of intensification versus extensification (or land-sharing versus land-sparing) strategies remain unsettled. Production on marginal lands is an attractive prospect, though some recent field trials suggest that inherently low yields of perennial grass crops in these areas may be problematic. Our objective was to apply a well-validated biogeochemical process model at fine scale across a representative bioenergy feedstock production landscape to predict switchgrass yields and soil greenhouse gas (GHG) balances, compute associated biomass transport burdens, and use multi-criteria optimization techniques to identify practical cultivation strategies and landscape designs that maximize total system GHG mitigation within certain economic constraints. The DayCent soil biogeochemistry model was parameterized to reflect the productivity of upland and lowland switchgrass cultivars across a variety of climates and soil types, incorporating results from recent field trials on marginal lands. The model was then applied to a case study representing the production of second-generation biofuels in a heterogeneous landscape in the Great Plains. Productivity and soil GHG balance (CO2, N2O, and CH4) were simulated spatially across the landscape and in a third dimension representing management intensity. These data were integrated into a lifecycle assessment framework and a crop production budget tool to estimate total supply chain environmental impacts and economic viability, and algorithms were used to identify optimal landscape designs. Preliminary results suggest that a) variations in land productivity and emissions balance driven by soil type, climate, and land use history result in large variations in biomass cost and GHG footprint, b) such variations are greater than biomass transport costs and GHGs at many scales, and c) optimal landscape designs will likely draw heavily on lands currently uncultivated. We suggest that the coupling of biogeochemical simulations, LCA frameworks, and enterprise budget tools can start to address fundamental questions of sustainable bioenergy landscape design, including a) what is the maximum GHG mitigation capacity of a landscape?, b) how does the concept of economies of scale change with feedstock production and collection over a heterogeneous landscale and what are the associated implications for GHG emissions?, and c) in what instances do the goals of maximizing profits and minimizing environmental impacts diverge? Development of these tools can also help support LCA and GHG analyses for other research projects within the AFRI biofuel program.