Environmental Impact and Sustainability of Feedstock Production
The program quantifies 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. Researchers also determine the regulation of these fluxes by the insect and soil microbial communities. The group is developing a mechanistic understanding of how different feedstock crops affect major ecosystem processes, such as the capacity to sequester atmospheric carbon, retain soil nitrogen, minimize water contamination, and produce greenhouse gases including methane and nitrous oxide.
The objective of the program is to understand how the production of high-yield cellulosic bioenergy crops -- including switchgrass, miscanthus, and prairie -- will affect carbon, nitrogen, and water cycles. Research is conducted on the Energy Farm on the UIUC campus, where replicate plots of different energy crops are grown alongside plots of corn and soybeans in traditional row crop agriculture. During the establishment phase – the first four years – we have demonstrated that perennial bioenergy crops, particularly miscanthus and switchgrass, allocate more carbon below ground than traditional row crops. Perennials also retain more nitrogen through internal transport from root to shoot during the growing season and retranslocate to the roots for the winter. The abilities to sequester atmospheric carbon in the soil and to minimize the loss of nitrogen from the system -- either to the atmosphere as nitrous oxide, a potent greenhouse gas, or to soil water as nitrate, a problematic pollutant -- present potential environmental benefits to replacing corn ethanol with perennial feedstocks. Not only will land yield more harvestable biomass with perennial energy crops than maize or soybean, but the added environmental benefits will reduce soil nutrient losses and greenhouse gas emissions to the atmosphere, leading to a more favorable life-cycle assessment. While perennial bioenergy crops will likely supplant a portion of the row crop agriculture in North America, particularly on low-yielding or marginal land, the expansion of sugarcane for energy production in Brazil is displacing pasture. The environmental benefits of sugarcane expansion may be less intense than perennial biofuel grasses in the Midwest, as the low-yielding pasture grasses have strong capacity to store nitrogen and allocate carbon belowground. However, we have conducted preliminary modeling experiments with the replacement of pasture by sugarcane in Brazil, as well as energy cane replacing pasture in Florida, and both model runs predict that expansion of cane will enhance ecosystem services through carbon sequestration and nitrogen conservation in much the same way as the expansion of perennial grasses do in temperate regions.
The Environmental Impact Program accomplished significant progress in 2013 toward quantifying and closing the biogeochemical cycles of carbon, nitrogen and water, and advancing our knowledge of soil microbial population dynamics associated with our bioenergy feedstocks. Improvements in our understanding of soil organic carbon (SOC) through modeling are helping us to understand long-term benefits of our perennial feedstocks to carbon sequestration and soil fertility. Decomposition of plant material also plays a pivotal role in SOC development. Feedstock composition drives the rate of this process, which is contrary to the previous belief that changes in the microbial community composition were responsible for differing rates of decomposition. Previous modeling work has suggested that miscanthus may fix large amounts of N, thus increasing the sustainability of this feedstock. Our work over several growing seasons has shown very little evidence of N fixation. The total amount of N in above and below-ground biomass is much lower than previously reported, thus suggesting that soil mineralization may provide all nitrogen needed for productivity. New opportunities for understanding the environmental impacts and sustainability of our bioenergy crops arose due to the drought of 2011-2013. We now understand miscanthus to be a more drought-tolerant feedstock.
Four years after establishment, all perennial biofuel crops are approaching maturity, though peak production of perennials and annuals was limited in 2012 by region-wide drought, reducing total above-ground biomass yield below 2011 totals. Nonetheless, Miscanthus plots yielded close to 11.6 t/ha, only slightly less than the 12.7 t/ha harvested from the cornfields. We completed and published the carbon budget analysis for the Energy Farm, demonstrating that the root systems of perennial crops increase below-ground carbon, below-ground biomass, and root respiration over root systems of annual row crops. More root-associated carbon is found under perennials than the corn and soy fields they replace: a four-fold increase in the prairie, and 6- and 7-fold increases in Miscanthus and switchgrass, respectively, compared to corn. This concentration of carbon in the rhizosphere results in net carbon sequestration even after harvest of above-ground biomass. Drought conditions in 2012 allowed for exploration of the water use efficiency of Miscanthus through the use of eddy flux towers. Miscanthus is often suspected of being a heavy water user and poorly evolved for drought conditions. Alternatively, we found that under water stress, Miscanthus reduces water use and plant respiration, and increases respiration during periods of water availability.
When compared to row crop agriculture, perennial crops reduce nitrogen losses. Nitrate leaching and nitrous oxide emissions are reduced in perennial cropping, as the perennial grasses do not require the application of fertilizer that is considered standard practice in corn-corn-soy agriculture. Efficient recycling of nutrients by perennial crops yields low-nutrient biomass at harvest, as N, P, and micronutrients are returned to the root system at senescence. Measurements of nutrient removal during biomass harvest show that perennial crops remove 50-90% less N, P, K and micronutrient as plant tissue harvest than annual row crops. Nitrogen fixation was evaluated in corn, soybean, switchgrass and Miscanthus using several established techniques. Preliminary results show minimal fixation in the perennial crops; however, due to the continued drought, further measurements will be required.
Most plants reached maturity after planting three years ago. The three bioenergy feedstocks allocated considerably more biomass below ground than corn and soybeans, suggesting they have a strong potential to restore depleted carbon to the soil. The three perennial feedstocks also showed strong retention of nitrogen, thus diminishing toxic nitrate losses to ground water. Biofuel crops grown without fertilization have little nitrate leaching compared to corn and soybean, another environmental benefit.
During the transition from annual row crops, perennial feedstocks retained more nitrogen, greatly reducing nitrate leaching to streams and ground water. Model simulations indicate that replacing corn ethanol with ethanol derived from perennial grasses would transform the Midwest from a source to a sink for greenhouse gases providing significant ecological and climate benefits.
Published in 2014
The Theoretical Limit to Plant Productivity, Evan H. DeLucia, Nuria Gomez-Casanovas, Jonathan A. Greenberg, Tara W. Hudiburg, Ilsa B. Kantola, Stephen P. Long, Adam D. Miller, Donald R. Ort, and William J. Parton, Environmental Science & Technology, V. 48 (16), pp. 9471-9477, doi: 10.1021/es502348e, July 28, 2014.
Enrichment of Specific Bacterial and Eukaryotic Microbes in the Rhizosphere of Switchgrass (Panicum virgatum L.) Through Root Exudates, Y. Mao, X. Li, E. M. Smyth, A. C. Yannarell, R. I. Mackie, Environmental Microbiology Reports, V. 6, pp. 293-306, June 2014.
Bioenergy Crop Greenhouse Gas Mitigation Potential Under a Range of Management Practices, Tara W. Hudiburg, Sarah C. Davis, William Parton, and Evan H. Delucia. Global Change Biology—Bioenergy, doi: 10.1111/gcbb/12152, March 7, 2014.
Dynamics of the Bacterial Community Structure in the Rhizosphere of a Maize Cultivar, X. Li, J. Rui, Y. Mao, A. C. Yannarell, and R. I. Mackie, Soil Biology and Biochemistry, V. 68, pp. 392-401, January 2014.
Published in 2013
Altered Below-ground Carbon Cycling Following Land-Use Change to Perennial Bioenergy Crops, Kristina J. Anderson-Teixeira, Michael D. Masters, Christopher K. Black, Marcelo Zeri, Mir Zaman Hussain, Carl J. Bernacchi, Evan H. Delucia, Ecosystems, 16, pp. 508-520, doi: 10.1007/s10021-012-9628-x, January 5, 2013.
Reduced Nitrogen Losses After Conversion of Row Crop Agriculture to Perennial Biofuel Crops, Candice M. Smith, Mark B. David, Corey A. Mitchell, Michael D. Masters, Kristina J. Anderson-Teixeira, Carl J. Bernacchi, Journal of Environmental Quality, 42, pp. 219-228, doi: 10.2134/jeq2012.0210, January-February 2013
Altered Dynamics of Forest Recovery Under a Changing Climate, K. J. Anderson-Teixeira, A. D. Miller, J. E. Mohan, T. W. Hudiburg, B. D. Duval, E. H. Delucia, Global Change Biology, doi: 10.1111/gcb.12194, March 25, 2013, online.
Water Use Efficiency of Perennial and Annual Bioenergy Crops in Central Illinois, Marcelo Zeri, Mir Zaman Hussain, Kristina J. Anderson-Teixeira, Evan Delucia, Carl J. Bernacchi, Journal of Geophysical Research: Biogeosciences, 118, pp. 581-589, doi: 10.1002/jgrg.20052, April 25, 2013
Gap-Filling Strategies and Error in Estimating Annual Soil Respiration, Nuria Gomez-Casanovas, Kristina Anderson-Teixeira, Marcelo Zeri, Carl J. Bernacchi, Evan H. Delucia, Global Change Biology 19, pp. 1941-1952, doi: 10.1111/gcb.12127, June 2013.
Predicting Greenhouse Gas Emissions and Soil Carbon from Changing Pasture to an Energy Crop, Benjamin D. Duval, Kristina J. Anderson-Texeira, Sarah C. Davis, Cindy Koegh, Stephen Long, William J. Parton, Evan H. Delucia, PLoS One 8(8), E72019, doi: 10.1371/journal.pone.0072019, August 21, 2013.
Bioenergy Crop Greenhouse Gas Mitigation Potential Under a Range of Management Practices, T. W. Hudiburg, S. C. Davis, W. Parton and E.H. DeLucia, Global Change Biology-Bioenergy, doi 10.111/gcbb.12152.
Published in 2012
Published in 2011
Carbon Exchange by Establishing Biofuel Crops in Central Illinois, Marcelo Zeri, Kristina Anderson-Teixeira, George Hickman, Michael Masters, Evan Delucia, Carl Bernacchi, Agriculture, Ecosystems & Environment, 144(1), pp, 319-329, doi:10.1016/j.agee.2011.09.006, October 14, 2011.
Ethanol from Sugarcane in Brazil: A 'Midway' Strategy for Increasing Ethanol Production While Maximizing Environmental Benefits, Marcos Buckeridge, Amanda DeSouza, Rebecca Arudale, Kristina Anderson-Teixeira, Evan Delucia, Global Change Biology-Bioenergy, doi: 10.1111/j.1757-1707.2011.01122.x, September 12, 2011.
Impact of Second-Generation Biofuel Agriculture on Greenhouse-Gas Emissions in Corn-Growing Regions of the U.S., Sarah Davis, William Parton, Stephen Del Grosso, Cindy Keough, Ernest Marx, Paul Adler, Evan DeLucia, Frontiers in Ecology and the Environment, doi:10.1890/110003, July 1, 2011.
Do Biofuels Life Cycle Analyses Accurately Quantify the Climate Impacts of Biofuels-Related Land Use Change?, Kristina J. Anderson-Teixeira, Peter K. Snyder, Evan H. Delucia, Illinois Law Review 2011(2), pp. 589-622, April 2011.
The Greenhouse Gas Value of Ecosystems, Kristina Anderson-Teixeira, Evan DeLucia, Global Change Biology, 17(1), pp. 425-438, doi: 10.1111/j.1365-2486.2010.02220.x, January 2011.
Impacts of Second-Generation Biofuel Agriculture on Greenhouse-Gas Emissions in Corn-Growing Regions of the U.S. , Sarah Davis, William Parton, Stephen Del Grosso, Cindy Keough, Ernest Marx, Paul Adler, Evan DeLucia, Frontiers in Ecology and the Environment, doi:10.1890/110003, 2011.
Published in 2010
Published in 2009
Comparative Biogeochemical Cycles of Bioenergy Crops Reveal Nitrogen-Fixation and Low Greenhouse Gas Emissions in a Miscanthus x giganteus Agro-Ecosystem, Sarah Davis, William Parton, Frank Dohleman, Candice Smith, Stephen Del Grosso, Angela Kent, Evan DeLucia, Ecosystems, 13(1), Dec. 22, 2009.
Life-Cycle Analysis and the Ecology of Biofuels, Sarah Davis, Kristina Anderson-Teixeira, Evan DeLucia, Trends in Plant Science, 14(3): pp. 140-146, March 2009.
Changes in Soil Organic Carbon Under Biofuel Crops, Kristina Anderson-Teixeira, Sarah Davis, Michael Masters, Evan DeLucia, Global Change Biology-Bioenergy, 1: pp. 75-96, 2009.