Expanding areas and markets

Although the specialized harvesting plow simplifies the harvesting process, vegetables still must be gathered by hand.
Photos Courtesy Of Aimee D. Nielson, University Of Kentucky.

While no area is poised to topple North Carolina, the nation’s top producer of sweet potatoes, in the near future, there is good news for growers.

Trials are showing promise in colder climates, offering a possible new crop that is relatively simple and inexpensive to grow, suitable for lengthy storage and gaining popularity with consumers.

Facts and fallacies about the sweet potato

The confusion about sweet potatoes seems only to be topped by the tomato as fruit or vegetable debate. Although products labeled “yams” are marketed here, yams are African vegetables rarely available in the United States; thus, the U.S. Department of Agriculture requires that so-called yams also be labeled as sweet potatoes. Those Thanksgiving yams are actually sweet potatoes that aren’t closely related to the white potato at all. Members of the morning glory family, most of the U.S. crop, valued at $370 million annually, is grown in California, Louisiana and Mississippi, with close to 40 percent originating in North Carolina.

Highly nutritious and packed with beta-carotene, sweet potatoes are earning year-round popularity in baked, fried and value-added forms. Newer products include diced sweet potatoes, purees, flakes, flour and fresh cuts.

Adapting to differing climates

Native to South America, the sweet potato prefers a sandy soil and a long growing season, but can be adapted to other conditions. Scientists and extension agents in eastern Kentucky began looking into alternative crops when the tobacco buyout wiped out the region’s traditional cash cow. Because sweet potatoes are a popular food in their area and University of Kentucky (UKY) Extension Agricultural Agent Sarah Fannin had observed their production as far north as Canada, she and UKY’s Dr. Ken Coolong investigated the possibilities of introducing them to area growers.

“[It seemed a natural choice because] some tobacco equipment [could be repurposed] as setters,” Fannin says. “Sorghum production is big here and there’s a tie between the two; we have an annual sorghum festival well-established.”

Coolong and Fannin knew that sweet potatoes would not replace the tobacco income and wanted to avoid misleading hungry growers. Their plan included up-front research and establishing a basis for success.

“We were awarded a Southern Region Sustainable Agriculture Research and Education (SARE) grant, which enabled us to supply some resources up front to reduce the risk for growers,” Fannin adds.

The $15,000 grant, which ran during 2008 and 2009, funded a study tour in North Carolina, which growers say was crucial to their success. In addition, a sweet potato school was offered, providing a comprehensive nine-hour course in production. The grant has provided sweet potato slips to the growers testing the crop. Slip production strategies by certified North Carolina growers were modified to meet the conditions presented in eastern Kentucky. Most slips were produced in a semicontrolled environment such as a high tunnel to guard against the low temperatures that would cause injury and are prevalent in early spring in the trial areas. Additionally, planting was delayed until late May.

Further support was provided through the newly formed East Kentucky Sweet Potato Growers’ Association, which pools information and resources such as equipment and labor.

“If you’re going to take a risk, if others will sink or swim with you, it is less scary,” Fannin says of her decision to form the group. Current membership stands at 15.

Kentucky growers have produced varieties such as Beauregard, Covington and O’Henry.

Growing sweet potatoes in eastern Kentucky

In North Carolina, the Kentuckians saw seemingly endless flat, sandy land where sweet potatoes thrive, but their terrain is quite different. The mountainous region puts level growing plots at a premium. Countless acres of the crop were not in their futures. Still, the other factors in their favor convinced the group to give the crop a chance.

The scarcity of land meant that certain equipment wouldn’t be appropriate. For instance, North Carolina’s harvesting plows are designed to tackle six rows at once, a capacity not possible in eastern Kentucky. Knowing that harvesting would be the most labor-intensive process, Fannin worked with agricultural fabricator Strickland Brothers (www.stricklandbros.com/) to create a one-row plow, which the extension service purchased for about $4,000. Association members share the equipment.

Association President Keith Hall was one of the initial four growers to take the plunge. A clear example of the challenges area farmers face, his 100-acre farm only boasts 10 acres suitable for cultivation. He began with 1 acre in 2008 using UKY’s recommendations for spacing, inputs and other production techniques.

Hall says the land preparation was identical to the process he’d once completed for tobacco, plowing in late winter and testing and amending the soil. He cultivates several times using a tractor set with a two-row tobacco setter modified to 1-foot spacing with the rows on a 36-inch setter. Unlike his mentoring growers in the Tarheel state, he doesn’t form hills in which to set the plants, but finds the cultivation forms a small rise.

Hall experienced no weed problems, but did spray for wireworms and cultivated by hand. Despite a rainy harvest time, he yielded about 500 bushels. He has tested Beauregard, Covington and the white-fleshed O’Henry varieties, and finds Covington to be the best bet for growers as it is uniform in size and has a longer storage life. O’Henry has been a strong seller in his region.

Hall and his fellow growers direct-market 80 percent of their crop and got about 75 cents per pound of ungraded vegetables. Fannin says that 2009 demand exceeded supply. Both see a bright future for the crop, which requires little investment for inputs. Hall would like to see the cost of slips reduced to help ensure the viability.

Looking to the future

Both Fannin and Hall hope the association and production will expand. Next steps include a greater emphasis on marketing. Fannin is planning a workshop to educate growers about liability, branding, communication and sales techniques. The group is evaluating the notion of growing its own slips and establishing a curing and storage facility. Some growers are considering drip or overhead irrigation.

“We were pretty successful this year; I’d give us a B+!” Hall says.

Monica and Keith Hall harvest sweet potatoes with a one-row harvesting plow custom-made for the Eastern Kentucky Sweet Potato Association.

Sweet potato research

As Coolong, Fannin and growers such as Hall pinpoint the optimal production methods for their region, Agricultural Research Service (ARS) scientists are helping to find sweet potatoes for all producers. For the first time, the plant’s DNA structure will be mapped, which will aid in developing new varieties. Researchers are learning that caffeoylquinic acids directly beneath the skin help protect the vegetable from rhizopus soft rot, a fungus that infects sweet potatoes after harvest by invading through breaks in the skin. The same compounds are found in the plant’s roots and have been shown to fend off bacteria and fungi. New cultivars with higher concentrations of the caffeoylquinic acids are expected to better protect the roots and benefit human diets, as the substances also act as antioxidants. A project that concluded late last year was aimed at helping perfect value-added products, such as fried sweet potato chips.

Based in Greensboro, N.C., the author writes articles about horticulture, landscaping, agriculture and travel. She has been a contributor to Moose River Media publications for three years.