Growing on plastic produces higher yields of sweet corn

Kent Hamilton is a major participant in the fruit and vegetable industry, growing about 1,100 acres of vegetables with two crops annually in south-central Georgia. Southern Valley Fruit & Vegetable, Inc. (, a family operation, is located in Norman Park, Ga. In addition, Southern Valley grows vegetables in Dayton, Tenn., and on the Yucatan Peninsula in Mexico to provide customers with vegetables year-round. Careful attention to management and growing crops entirely on plastic with drip irrigation helps ensure a profitable operation.

Sweet corn grows on plastic, allowing high seeding rates with a higher concentration of water and nutrients.
Photo courtesy of Glenn Beard, UGA Extension.

Southern Valley grows cabbage, zucchini, bell peppers, yellow squash, eggplant, okra, and fresh-market and pickling cucumbers, along with 250 acres of sweet corn. Sweet corn production is relatively new to this part of Georgia, with less than 10 percent grown on plastic.

“Plastic and drip irrigation were getting so expensive, we were trying to have [produce] we could get six crops [out of]. We get two crops annually here in south Georgia, and we decided to add sweet corn in 2010,” Hamilton explained.

While Southern Valley manages the usual farming challenges, Hamilton cited labor issues and increasing regulations as significant challenges to operating efficiently, not just for Southern Valley, but for the entire industry.

Hamilton’s mother’s family started farming in Georgia six generations ago, and in 1987, at the age of 22, Hamilton and his brother, Kirk Hamilton, then 25, launched a major vegetable production business. “Our parents were silent partners, helping us with financing,” Hamilton said. Kirk was accidentally electrocuted at the farm and died a few months after the brothers launched their operation. Hamilton’s father has also passed away, but his mother, Wanda Hamilton-Tyler, continues as a partner in the business. Two of Hamilton’s four children – daughter, Courtney, 24, and son, Austin, 22 – currently work in the business.

Just-harvested bell peppers await shipment.

Benefits of plasticulture

“Growing sweet corn on plastic allows us to produce higher yields, and to keep moisture and fertility better controlled,” Hamilton said. The higher yields are due to the combination of the higher rate of seeding that is done when growing on plastic and the increased control of nutrients that are added to the drip irrigation.

“We have about 16 inches of sandy soil on top of a clay base,” Hamilton said. “It’s better to spoon-feed the nutrients to prevent leaching.”

Dr. David Langston, plant pathologist with the University of Georgia, noted that growing on plastic is more efficient. In addition to the higher seeding rate and moisture control, Langston cited another benefit of plasticulture: “The black color helps with heating the soil.”

“We get four to six crops with our plastic, replacing every two to three years,” Hamilton said. About one-third of the plastic, approximately 300 to 400 acres, is replaced each year.

Deep wells on the property provide water for the drip irrigation system. Hamilton said, “We had some diesel pumps that we converted to electricity, which is so much cheaper than diesel.”

Replacing plastic and drip irrigation tape is expensive in terms of product cost, and also in the labor-intensive work required. Southern Valley uses Pliant Plastic from Bell Irrigation, Cairo, Ga., and Jain drip tape. Irvin Singletary, Bell Irrigation vice president, noted that 91.95 percent uniformity in fertilization is achieved in drip irrigation, thereby increasing efficiency. “The biggest deterrent to [implementing] drip irrigation is the initial cost,” Singletary said.

Southern Valley uses Seminis seed ( for corn, growing about 40 percent bicolor, 40 percent yellow, and 20 percent white. “We grow to our customers’ requests,” Hamilton said. Southern Valley grows its own vegetable transplants for all other crops.

Innovation is important to the operation, and Hamilton noted that most of the equipment used is built at Southern Valley. “We build our own sprayers, bedders and plastic laying equipment,” he said. “We use John Deere and Kubota tractors. The John Deere tractors are from Lasseter [Tractor Co.] in Moultrie, Ga., and we own a Kubota dealership [Southern Tractor & Outdoors], also in Moultrie.”

With the addition of sweet corn, a hydro-cooler is used to cool the corn before it is iced for transportation. “We had wanted to add hydro-cooling,” Hamilton said. “Adding it for sweet corn production has allowed us to use it for other vegetables as well.”

From left, Austin, Courtney and Kent Hamilton discuss Southern Valley crop production.
Photos courtesy of Southern Valley Fruit & Vegetable unless otherwise noted.

Challenges to growers

Hamilton is a past president of the Georgia Fruit & Vegetable Growers Association and currently serves on the organization’s board of directors. “Collectively, our association is actively involved in legislation affecting vegetable and fruit production and sales,” Hamilton said. He is also a member of the Southeast Produce Council.

Expressing concern about labor costs and availability, Hamilton said, “The American public needs to realize we’re going to have to do one of two things: We will have to import our labor to grow and harvest here, which will allow us to provide fresher and safer produce, or [we will have to] import our food.”

Southern Valley uses about 4,500 federal H-2A workers for 10 months of the year. In addition to planting and harvesting, removing the plastic requires extensive labor. “Labor costs keep us constantly looking for mechanization to cut [the] hours required,” Hamilton said.

Glenn Beard, University of Georgia Colquitt County Extension agent, said that limited sweet corn production is done in the area where Southern Valley is located.

“Corn is very perishable and has to be harvested and cooled down within a very short time,” he explained. He noted that while plasticulture allows a concentration of fertilizer and water that can substantially increase yield, limited crops are grown on plastic. “We have limited use due to expensive outlays of cost for production and labor,” he said.

While Southern Valley is large enough to offer work to crews for most of the year, many smaller growers cannot offer work for extended time frames, and obtaining labor is almost impossible. “In our area, 99 percent of our crops are harvested by hand, mostly with Hispanic labor,” Beard said. “Georgia passed stricter local immigration enforcement policies, and we had some vegetable crops that weren’t harvested in the spring of 2011 because the Hispanic labor just disappeared.”

Beard noted that food safety regulations and traceability are increasing concerns to growers. “Third-party certification is demanded by the marketplace, which is getting more and more stringent. This certification process involves mounds of paperwork, training and inspections,” Beard said. “The growers must bear these costs.”

He cited the efforts of growers to be in compliance and noted that in addition to increasing regulations and labor issues, growers must contend with insects, diseases and weather conditions. “Growers want to send the highest-quality products to the market, but once in the supply chain, they have no control on how those products are maintained.” He emphasized the importance of the appearance of vegetables, noting that perfect-appearing vegetables are expected, and marketability of the produce depends on that appearance.

Controlled management of water and nutrients on plastic with drip irrigation increases yields.
Photo courtesy of Glenn Beard, UGA Extension.

The Southern Valley organization

“We’re organized with people who have different areas of responsibilities, and my son Austin and I oversee them. We have very little turnover. I try to keep good help, pay them well, and make them feel they are part of the business, not just employees,” Hamilton said.

He stated, “We have a sales staff of six that handles sales and transportation.” That’s not a lot for a customer base that encompasses the area east of the Mississippi River and north from Georgia to Canada.

Hamilton noted all the things that must come together in order for his business to be successful – crop selection, weather, labor and markets – but he added, “It’s rewarding to see the crops grow.”

Nancy Riggs is a freelance writer. She resides in Mount Zion, Ill.