Report Says Corn Stover Has Other Uses
Building an ethanol industry that relies on corn stover will require increased investments in research of a variety of farming practices.
"Corn stover is sometimes thought of as agricultural waste, but it serves an important function when left on the field. Increasing harvest of stover has the potential to exacerbate soil erosion, reduce surface-water quality, and increase agriculture-related greenhouse gas emissions that cause global warming," said Liz Marshall, lead author of a report released Jan. 27 by the World Resources Institute.
"Corn Stover for Ethanol Production: Potential and Pitfalls" analyzes the potential impact on both soil erosion and greenhouse gas emissions from the agricultural sector when corn stover is removed and used to produce biofuels. Corn stover removal results in increased greenhouse gas (GHG) emissions through both the loss of agricultural carbon sequestration capacity and increased use of fertilizer necessary to replace nutrients removed from the field with stover.
"It is becoming increasingly difficult to justify support of the biofuels industry without assurances that the biofuels produced achieve policy objectives without unacceptable soil, water, and air side effects," Marshall added. "Environmental safeguards should be required for participation in any government programs that provide incentives for ethanol industry growth."
Federal policies already exist that should be revisited and revised, including the Volumetric Ethanol Excise Tax Credit (VEETC) and the revised Renewable Fuel Standard, passed as part of the Energy Independence and Security Act of 2007. Any new and proposed policies should also include such safeguards.
Corn stover's use as a feedstock for biofuels production is promising because of the existing corn production infrastructure. The fact that it is a residue of an existing use of the land means there is less competition between land allocated to food versus fuel crops, and it places less pressure on agriculture to expand its use of acreage to produce fuel crops. However, its use has environmental drawbacks because leaving corn stover on the field helps replenish soil carbon and control erosion. The report notes that further research is needed to determine the feasibility and costs of replacing the ecosystem services that could be threatened by large-scale removal of corn stover for biofuels production.