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United States Department of Agriculture

Agricultural Research Service

Research Project: CROP AND WEED RESPONSES TO INCREASING ATMOSPHERIC CARBON DIOXIDE Title: An evaluation of cassava, sweet potato and field corn as potential carbohydrate sources for bioethanol production in Alabama and Maryland

Authors
item Ziska, Lewis
item Runion, George
item Tomecek, Martha
item Prior, Stephen
item Torbert, Henry
item Sicher, Richard

Submitted to: Biomass and Bioenergy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 15, 2009
Publication Date: August 6, 2009
Repository URL: http://hdl.handle.net/10113/38543
Citation: Ziska, L.H., Runion, G.B., Tomecek, M.B., Prior, S.A., Torbert III, H.A., Sicher Jr., R.C. 2009. An evaluation of cassava, sweet potato and field corn as potential carbohydrate sources for bioethanol production in Alabama and Maryland. Biomass and Bioenergy. 33:1503-1508.

Interpretive Summary: The recent emphasis on corn production to meet the increasing demand for bioethanol has resulted in fears regarding the sustainability of the global food supply. To assess the potential of alternative crops as sources of bioethanol production, we grew sweet potato and cassava at locations near Auburn, Alabama and Beltsville, Maryland in order to measure root carbohydrate (starch, sucrose, and glucose) and root biomass. Averaged for both locations, sweet potato yielded the highest concentration of root carbohydrate (ca 80%), primarily in the form of starch (ca 50%) and sucrose (ca 30%); whereas cassava had root carbohydrate concentrations of (55%), almost entirely as starch. Relative to carbohydrate production from corn in each location, sweet potato and cassava yielded approximately 2.8x and 2.9x as much bioethanol as corn in Alabama; 2.3x and 0.5x for the Maryland site. If economical harvesting and processing techniques could be developed, these data suggest that sweet potato in Maryland, and sweet potato and cassava in Alabama, have greater potential as ethanol sources than existing corn systems, and as such, could be used to replace or offset corn as a source of biofuels. This data and its inference for ethanol based biofuels will be of interest for policy makers, scientists, agronomists, and plant breeders.

Technical Abstract: The recent emphasis on corn production to meet the increasing demand for bioethanol has resulted in trepidation regarding the sustainability of the global food supply. To assess the potential of alternative crops as sources of bioethanol production, we grew sweet potato (Ipomoea batatas) and cassava (Manihot esculentum) at locations near Auburn, Alabama and Beltsville, Maryland in order to measure root carbohydrate (starch, sucrose, glucose) and root biomass. Averaged for both locations, sweet potato yielded the highest concentration of root carbohydrate (ca 80%), primarily in the form of starch (ca 50%) and sucrose (ca 30%); whereas cassava had root carbohydrate concentrations of (ca55%), almost entirely as starch. For sweet potato, overall carbohydrate production was 9.4 and 12.7 Mt Ha-1 for the Alabama and Maryland sites, respectively. For cassava, carbohydrate production in Maryland was poor, yielding only 2.9 Mt Ha-1. However, in Alabama, carbohydrate production from cassava averaged ~10 Mt Ha-1. Relative to carbohydrate production from corn in each location, sweet potato and cassava yielded approximately 2.8x and 2.9x as much carbohydrate as corn in Alabama; 2.3x and 0.5x for the Maryland site. If economical harvesting and processing techniques could be developed, these data suggest that sweet potato in Maryland, and sweet potato and cassava in Alabama, have greater potential as ethanol sources than existing corn systems, and as such, could be used to replace or offset corn as a source of biofuels.

Last Modified: 7/24/2014
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