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Protected Agriculture Project Boosts Crop Yields By 10 Times Over Field-Grown Production


News from
University of Florida

By Chuck Woods, UF Staff
April 20, 2006

CITRA, Fla. — With a few taps on a computer keyboard, University of Florida researchers can control just about every aspect of growing vegetables and other high-value crops in greenhouses that protect plants from pests and diseases – boosting yields by 10 times over field-grown production.

“It’s all part of the growing trend toward precision, high-tech agriculture in Florida,” said Dan Cantliffe, who leads the Protected Agriculture Project at UF’s Institute of Food and Agricultural Sciences. “The project demonstrates how vegetable and fruit crops can be produced on a year-round basis – not just when weather conditions or market windows are favorable for Florida growers.”

He said the computerized project, which covers one acre, reduces labor requirements and automates everything from plant nutrients in drip irrigation systems to temperature controls in the greenhouses. The amount of phosphorus, nitrogen and other plant nutrients needed by each crop can be precisely controlled by the computers. Greenhouse operations at the Plant Science Research and Education Center in Citra can also be monitored and controlled by UF computers in Gainesville, 20 miles from the site.

For those who say the protected agriculture system is too expensive, Cantliffe said the greenhouses can be constructed for $2 to $4 per square foot – far less than the cost of a new home.

Unlike existing hydroponic greenhouse structures that require substantial investments in heating and cooling systems, the Protected Agriculture Project relies on passively ventilated greenhouses for greater energy efficiency, Cantliffe said. The automated greenhouse production system requires no pesticides and recycles water and fertilizers – solving several major problems facing the state’s $1.6 billion fruit and vegetable industry.

“For example, it will help growers who are increasingly concerned about more state and federal regulation of water, fertilizer and pesticides,” said Cantliffe, a professor and chairman of UF’s horticultural sciences department. “It will also solve problems associated with the recent federal ban on the use of methyl bromide, a widely used soil fumigant to control soil pests.”

He said the sustainable farming system will also eliminate or minimize worries about freezes, drought and other weather problems. The greenhouses can be built almost anywhere in the state, reducing problems associated with urbanization and loss of prime farmland in South Florida.

“Growing crops in a protected greenhouse environment will make Florida producers more competitive against imports from other areas in the world,” Cantliffe said. “If the vegetable industry in Florida is going to prosper and grow, there is a clear need for these new greenhouse production technologies.”

He said Florida vegetable production now involves intensive production practices on more than 230,000 acres. Crops such as tomatoes, peppers, cucumbers, strawberries and watermelons account for 61 percent of the state’s vegetable crop value, and the new protected agriculture system could allow growers to produce more of these crops – with higher plant densities – on a year-round basis.

“Production of crops such as blueberries, eggplants and squash could also be increased, along with the production of new crops such as the Galia muskmelon, which is widely produced in Spain and Israel, Morocco, Turkey and other Middle Eastern countries and shipped to Europe where consumers pay top prices for this excellent-tasting melon,” Cantliffe said.

“Considering the fact that vegetable culture in Florida is a already a highly technological business involving several high-cost inputs such as polyethylene mulch, drip irrigation, fertilizer and pesticides, this new system will be cost efficient and sustainable over the long term,” Cantliffe said. “Almost one third of Florida vegetables, including all tomatoes, strawberries, peppers, eggplants and most melons, are produced on plastic mulch, and nearly half of all the crops grown on mulch have drip irrigation.”

While the passively ventilated greenhouse structures can protect crops from wind and rain, they also can protect crops from insects when fitted with insect-exclusion screens. Therefore, these greenhouse structures can reduce the need for pesticides, he said.
Cantliffe said the greenhouse structures – also known as plasticulture systems – could include the use of soil-less culture for crop production. One example would be bag or container production using inert media such as perlite, vermiculite, peat or coconut fiber. Pine bark, which is an inexpensive and renewable resource, can also be used as a growing medium.

”With soil-less culture in greenhouses, winter vegetable production would not depend on warm, sandy soils of southern coastal Florida,” he said. “In addition, the loss of methyl bromide would be less troublesome if a portion of the vegetables could be grown in soil-less culture under a protective structure.”

Cantliffe said the new greenhouse technology is already being used in Israel and other Middle Eastern countries as well as Canada, China, Korea, Mexico and Japan. He said producers in these countries face some of the same challenges as Florida growers.

“The Protected Agriculture Project provides much-needed information for hands-on training and demonstrations so that Florida producers can examine, work and train in this new agricultural business environment,” Cantliffe said.

The new greenhouse technology being demonstrated at Citra has already been adopted by Beli Farms in Wellborne and other several Florida vegetable growers. Emil Belibasis, owner of the farm that grows tomatoes on the vine and mini-cucumbers in four acres of greenhouses, said the new structures are naturally ventilated with overhead retractable shade.

“We use pine-bark pots and coconut-fiber slats for the growing medium, with one row of pots for two rows of crops,” Belibasis said. “Recently, we installed a computerized environment controller and a weather station to better control the greenhouse environment. It controls fans, pads, heaters, curtains, shade and irrigation.”

He said the new structures also have improved environmental controls for managing disease. Use of insect screens, soaps, specialized equipment and cultural practices for insect control has helped reduce the need for pesticides.