Can Sweet Sorghum and Sweetpotato Ethanol Contribute to Self-Sufficiency of Small Farms?

Sweet potato (Ipomoea batatas L.) and sweet sorghum (Sorghum bicolor L.) are promising crops for advanced biofuel production because they are better suited than corn (Zea mays L.) to low input production on small farms in the south. They can be considered advanced feedstocks only if lifecycle greenhouse gas emissions are less than 50% of basoline baseline emissions. Both sweet potato and sweet sorghum are multifunctional crops, with potential to simultaneously produce human food, animal feed, and biofuel feedstock. Kentucky State University is exploring the potential for organic production techniques and decentralized processing systems to reduce lifecycle greenhouse gas emissions of energy produced from these crops at a range of small farm scales. In 2009 biointensive production - a garden-scale strategy relying entirely on human labor - gave the greatest return to energy investment among the farm scales tested. Tractor-based small farm systems gave an inferior energy return in 2009, but a superior return to human labor in 2008 and 2009. A farmer’s decision to dedicate a portion of small-scale organic crop yield to on-farm ethanol production might be justified as a means of promoting self-sufficiency, resource cycling, or use of waste products, but ethanol feedstock production would be a poor economic choice as a principal means of income for the small organic farmer.