As some Florida growers try to find new crops and the demand for biofuel feedstocks increases globally, University of Florida Institute of Food & Agricultural Sciences (IFAS) researchers have found that sweet potato vines, which usually are thrown out during harvest, can serve well as livestock feed while the roots are an ideal source for biofuel.

This could be a key finding for the agriculture industry in Florida and for meeting biofuel needs worldwide, post-doctoral researcher Wendy Mussoline said.

“The agriculture industry in Florida is looking to find new, viable crops to replace the citrus groves that have been diminished by the greening disease,” Mussoline said. “Potato farmers are also trying to find new crops that offer both biofuel alternatives as well as food and/or animal feed opportunities. They are conducting field trials on several varieties of sweet potatoes to determine if they are an economically viable crop that they can market.”

According to a newly published study by professor Ann Wilkie and Mussoline, an industrial sweet potato variety (CX-1) may do the trick.

Currently, 99% of the ethanol produced in the U.S. comes from corn or sorghum, the study found. However, scientists and business interests are considering highly productive alternatives — such as sweet potatoes — for biofuel. Although China produces 81% of the world’s sweet potatoes, U.S. sweet potato production reached a record high of 3.2 billion lb. in 2014, according to the U.S. Department of Agriculture.

Wilkie and Mussoline, both researchers in the IFAS soil and water sciences department, found that CX-1 is a superior choice as a dual-purpose crop compared to Beauregard and Hernandez, the so-called “table” varieties that people would normally eat. They determined this by putting CX-1, Beauregard and Hernandez through multiple tests in the field and laboratory in Gainesville, Fla.

“The CX-1 roots have higher starch content and, thus, higher potential for fuel ethanol yields than the table varieties,” Mussoline said.

The study demonstrated the value of CX-1 as an animal feed and recommended the industrial sweet potato as a dual-purpose crop that could be used for both fuel ethanol — made from the starchy roots — and nutritious animal feed — made from the vines.

“Although this would be a ‘new’ feedstock for biofuels in the U.S., sweet potato is currently used in other countries; for example, China and Brazil use it as a biofuel feedstock,” Mussoline said.

“The sweet potato is a high-yielding crop suited to tropical and subtropical climates that requires minimal fertilization and irrigation, and the CX-1 industrial cultivar offers superior potential for feed and fuel,” Wilkie said.

The new study was published online in the Journal of the Science of Food & Agriculture.