Nitrogen Cycling in Biofuel Feedstock Crops of Central Illinois During Establishment.

As interest in biofuel feedstock production 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, yet greenhouse gas emissions (GHG) for these crops have not been well documented. 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. Our objective was to determine the biogeochemistry of nitrogen in each feedstock crop.  The leaching of nitrate was elevated in corn plots throughout the year.  Nitrate leaching was lower in all three perennial crops, although during this establishment phase leaching and tile loss was still an important 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 potent greenhouse gas.  Results from this study highlight the 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.