Tuesday, November 6, 2007 - 11:00 AM
162-5

Cellulose-Based Energy: Crop Residue.

Robin L. Graham1, Richard Nelson2, John Sheehan3, Robert Perlack1, and Lynn Wright1. (1) Oak Ridge National Laboratory, Environmental Sci Div, Oak Ridge, TN 37831, (2) Kansas State University, Manhattan, KS 66506, (3) National Renewable Energy Laboratory, Golden, CO 80401

Agricultural residues such as corn (Zea mays L.) stover are a potential cellulosic feedstock for bioenergy and bio-based products that could reduce U.S. dependence on foreign oil. Yet collection of such residues must take into account concerns that residue removal could increase erosion, reduce crop productivity, and deplete soil carbon and nutrients. This paper estimates where and how much corn stover can be sustainably collected in the U.S. using existing commercial equipment. Erosion constraints to collection were considered explicitly while crop productivity and soil nutrient constraints were considered implicitly by recognizing the value of residues for maintaining soil moisture and including the cost of fertilizer to replace nutrients removed with the collection of stover. Possible soil carbon loss was not considered in the analysis.    Overall, under the current mixture of rotation and tillage practices, ~30% of the stover produced in the US could be collected while still addressing erosion and soil moisture concerns and nutrient replacement costs. However, there is considerable spatial variability in collectable stover. In many places any stover collection would cause erosion to exceed T, the tolerable soil loss. Wind erosion is a major constraint to stover collection. Changing to no-till practices increases the amount of stover that could be removed. If US farmers implemented  universal no-till production of corn, then over 50% of the stover could be collected annually without causing erosion to exceed the tolerable soil loss (T) but again there would still be spatial variability to this collection. 

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