I chose to write my paper about corn-based ethanol and its contributions to soil erosion. I also analyzed some of the impacts of soil erosion on surface water resources that are used for drinking water.
Currently, soil erosion from corn production for ethanol totals an estimated 65 million tons each year. As ethanol production increases in response to the Energy Independence and Security Act of 2007, this erosion is projected to increase.
Additionally, corn stover (the stalks, leaves, and cobs left over after grain harvest) is under consideration for use as a feedstock for cellulosic ethanol. While this increases ethanol production by utilizing crop wastes, this negatively affects soil quality and productivity while also contributing to increased soil erosion. Harvesting corn stover for cellulosic ethanol production removes crop residue that would normally be left in the field to decay, returning nutrients and organic matter to the topsoil. Harvesting stover also removes the soil protective cover, leaving topsoil highly susceptible to soil erosion.
In order to preserve soil quality, researchers at the University of Nebraska-Lincoln suggest no more than 28% of corn stover should be removed for cellulosic ethanol production. Based on current corn production, this results in potential production of 8 billion gallons of cellulosic ethanol annually.
In addition to negative impacts on topsoil, soil erosion also degrades surface water resources from additional sediment and pollutant loading. Topsoil carries many of the nutrients necessary for crop growth, as well as many farm chemicals (fertilizers and pesticides). When this topsoil washes into surface water, these contaminants travel with the sediment. Utilizing these surface water resources for drinking water presents additional challenges in delivering safe drinking water. Potentially costly modifications or additions to water treatment plant equipment may be necessary to handle the additional sediment loading.
This analysis emphasizes the tradeoffs associated with energy production, specifically biofuels. As a nation, we must weigh the impacts on all our resources - soil, water, and energy - when making energy decisions.