Assessing Cellulosic Biofuel Feedstock Production Across a Gradient of Agricultural Management Systems in the U.S. Midwest
Hurtt, George C
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While biofuels are widely considered to be a part of the solution to high oil prices, a comprehensive assessment of the environmental sustainability of existing and future biofuel systems is needed to assess their utility in meeting U.S. energy and food needs without exacerbating environmental harm. The following questions guide this research: 1. What is the spatial extent and composition of agricultural management systems that exist in the U.S. Midwest? 2. How does sub-grid scale edaphic variation impact our estimation of poplar biomass productivity across a gradient of spatial scales in the U.S. Midwest? 3. How do location and management interactions impact yield gap analysis of cellulosic ethanol production in U.S. Midwest? In the first chapter, I developed an algorithm to identify representative crop rotations in the U.S. Midwest, using remotely sensed data; and used this information to detect pronounced shifts from grassland to monoculture cultivation in the U.S. Midwest. In the second chapter, a new algorithm is developed to reduce the computational burden of high resolution ecosystem modeling of poplar plantations in U.S. Midwest, with the results from the high resolution modeling being used to estimate the impact of averaging and discretization of soil properties on poplar yield estimates. In the third chapter, a novel yield gap analysis of cellulosic feedstocks on marginal lands in the U.S. Midwest is conducted to determine the management inputs needed to reach their yield potential in a sustainable manner. The significance of this research lies in providing a spatially explicit regional scale analysis of the tradeoffs between food and fuel production and providing an understanding of which biofuel crops should be grown where to maximize production while mitigating environmental damage.