Biofuels derived from fermentation of cellulose (cellulosic ethanol) have the potential to reduce carbon emission to the atmosphere, reverse some of the negative impacts of row crop agriculture in the mid western US, and provide a measure of energy independence.
Our research team recently was award a grant from the Energy Biosciences Institute to examine the ecological consequences of converting portions of the mid west from row crop agriculture to different potential biofuel feedstocks (Miscanthus x giganteus, switchgrass (Panicum virgatum), and restored prairie). The summary of our proposal is reproduced below. This research will be initiated in 2008.
Summary of EBI Proposal:
Environmental Impact and Sustainability of Feedstock Production
Evan DeLucia, Principle Investigator and Project Coordinator
Senior Personnel: May R. Berenbaum, Department of Entomology, University of Illinois; Carl J. Bernacchi, Department of Plant Biology, University of Illinois and Center for Atmospheric Sciences, Illinois State Water Survey; Mark B. David, Department of Natural Resources and Environmental Sciences, University of Illinois; Roderick I. Mackie, Department of Animal Sciences, Division of Nutritional Sciences, University of Illinois; Donald R. Ort, Department of Plant Biology, University of Illinois
The widespread deployment of biofuel feedstocks may herald a new era for US agriculture; an era in which feedstock production and ecological impacts are balanced leading to a sustainable system. Because of their high rates of biomass accumulation with minimal nutrient inputs, Miscanthus x giganteus, switchgrass (Panicum virgatum), and restored prairie hold great promise as potential feedstock crops in the US Midwest. Before the self-scouring steel plow, this region was expansive grassland with enormous stores of soil organic matter. The conversion of this vast grassland to row crop agriculture dominated by the soybean-corn rotation, depleted soil carbon and nitrogen stores, caused extensive soil erosion and contributed to pollution of surface and ground water primarily by nitrate derived from fertilizer. Because of their perennial growth habit, extended growing season, and low demand for nutrients, replacement of a portion of this corn-soybean landscape with feedstock crops has the potential to mitigate many of these environmental impacts. To date, there have been no side-by-comparisons of potential ecosystem impacts of feedstock crops with corn, also used in the production of cellulosic ethanol. The objective of the proposed research is to quantify the major pools and fluxes in the biogeochemical cycles of carbon, nitrogen and water in large plots of M. x giganteus, switchgrass, restored prairie and corn, and to determine how and on what timescale interactions with soil microbial and insect populations affect these biogeochemical cycles. By “closing” the biogeochemical cycles of C, N and water, we will develop a mechanistic understanding of how different feedstock crops affect major ecosystem services, such as the capacity to sequester atmospheric carbon, retain soil nitrogen and minimize water contamination and the production of important greenhouse gases including methane and nitrous oxide.
Large replicated plots of M x giganteus, switchgrass, restored prairie (12 species) and continuous corn will be established at the UIUC Energy Farm. Each plot will be instrumented with a micrometeorological tower for measuring surface-atmosphere exchange of CO2, water vapor, energy, N2O and methane. Patterned tile drains under each plot will allow complete collection of drainage water from each vegetation type to quantify elemental and nutrient losses to leaching. Tissue specific measurements of material exchange, in some cases using stable isotope fractionation, will facilitate closure of the major biogeochemical cycles in each feedstock type. Above- and belowground herbivore damage and changes in the diversity and activity of the soil microbial communities will enable us to determine how soil processes, particularly rates of mineralization, nitrification and denitrification, are regulated. We expect that the greatest dynamic differences in ecosystem processes between M. x giganteus, switchgrass and restored prairie with corn to occur during the three-year establishment period leading to mature perennial communities. Data will be used to inform DAYCENT, a process-based model that will enable us to extrapolate our results regionally. A later phase of this research will examine climate interactions dominated by decreasing precipitation by examining ecosystem processes in feedstock plots distributed along a longitudinal gradient from Ohio to California.
This research will inform the broader biofuel and environmental communities of the potential ecosystem consequences and benefits of the extensive deployment of perennial feedstock crops in land currently supporting row-crop agriculture, and will guide efforts to reduce unforeseen negative impacts of these feedstocks.