Friday, August 7, 2009
Exhibit Hall NE & SE, Albuquerque Convention Center
Background/Question/Methods As the production of biofuel feedstock crops grows, it is important to consider the environmental consequences of cultivating individual feedstock crops. Biofuel crops have been widely promoted as a sustainable energy source by reducing carbon emissions through photosynthesis. However, greenhouse gas emissions (GHG) for these crops have not been well documented. Emissions of nitrous oxide, a greenhouse gas approximately 298 times more potent than carbon dioxide, from fertilized crops may diminish the environmental benefits of biofuel feedstocks. Additionally, the leaching of nitrate from traditionally fertilized agricultural systems has been shown to contribute to the eutrophication of receiving waters and ultimately the Gulf of Mexico hypoxia. A side-by side comparison of four biofuel feedstock crops (corn, Miscanthus x giganteus, switchgrass and restored prairie) was established in 2008 in Urbana, Illinois and will continue for at least 10 years to examine the establishment and long term biogeochemical effects of the perennial crops (Miscanthus, switchgrass, and restored prairie) compared to continuous corn. Our objective was to determine the biogeochemistry of nitrogen in each feedstock crop.
Results/Conclusions The leaching of nitrate was significantly elevated in corn plots, especially following fertilization. Nitrate leaching was lower in all three perennial crops, although during this establishment phase (the first growing season) leaching and tile loss was still an important nitrogen loss. Likewise, nitrous oxide emissions (using static vented chambers) were significantly elevated in the corn treatment following spring fertilization while the perennial crops produced minimal amounts of this powerful greenhouse gas. Results from this study highlight the effects of traditional nitrogen fertilization and need for direct comparisons of biofuel crop biogeochemical cycling. Due to perennial growth, extended growing season and low requirement for nutrients, Miscanthus, switchgrass, and restored prairie should outperform corn as a biofuel feedstock, although during establishment periods environmental impacts will still be present. Nitrogen cycling in these crops may be more influential for affecting global climate change than carbon cycling.
Results/Conclusions The leaching of nitrate was significantly elevated in corn plots, especially following fertilization. Nitrate leaching was lower in all three perennial crops, although during this establishment phase (the first growing season) leaching and tile loss was still an important nitrogen loss. Likewise, nitrous oxide emissions (using static vented chambers) were significantly elevated in the corn treatment following spring fertilization while the perennial crops produced minimal amounts of this powerful greenhouse gas. Results from this study highlight the effects of traditional nitrogen fertilization and need for direct comparisons of biofuel crop biogeochemical cycling. Due to perennial growth, extended growing season and low requirement for nutrients, Miscanthus, switchgrass, and restored prairie should outperform corn as a biofuel feedstock, although during establishment periods environmental impacts will still be present. Nitrogen cycling in these crops may be more influential for affecting global climate change than carbon cycling.
