Each year from September and into October, Plant City strawberry grower Joel Connell follows a simple routine: lay out plastic for plants, bed them and, once they’re ready for nourishment, make sure that the drip tape is in place with lines clean for irrigation.
For Connell, a Florida Southern graduate with a citrus business degree, handling 400 acres of strawberries for owner Charlie Grimes is a complex and large task – but one made simpler by drip irrigation as specific amounts of water and fertilizer are directed to the root zone of thirsty budding plants.
Connell says he uses overhead irrigation while establishing plants and to avoid frost freezes, but drip irrigation is his method of choice for several reasons.
“You’re not wasting water by spreading it all over the field, it’s just in the bed,” Connell says. “You can be very precise with it and know where your fertilizer is going, directly to the root system of your plants. Then you can tweak your blends to meet your needs and your soil types.”
Resource Management is Crucial
Connell’s reliance on drip irrigation, a production technique that reduces labor and production costs while improving productivity, is mirrored by more and more growers, both in Florida and nationally.
At a recent Toro symposium on drip irrigation and new technology in Riverside, Calif., senior marketing manager for micro-irrigation Claude Corcos addressed the role micro-irrigation plays as it is adopted for many crops as part of water management initiatives.
Farmers must find better ways to make use of existing resources, Corcos says, because by 2025 farms will need to provide an estimated 8 billion people with food, fiber and fuel.
“The rate of adoption of drip irrigation technology in Florida leads much of the U.S.,” he says. “However, there’s still a long way to go. Many growers in Florida have adopted drip, particularly tomato and citrus (but) there are many crops within Florida that could benefit through both yield and quality and water conservation.”
Drip or trickle irrigation is estimated to cost between $500 and $1,200 per acre, broken down into an initial capital investment and the annual cost of maintenance. Despite that, growers of melons, peaches and green leafy vegetables as well as sweet corn are realizing what strawberry, tomato and citrus growers have known—over time drip irrigation pays off.
Saltwater intrusion in coastal areas and the abandonment of wells because of it have led to more drip irrigation advocates, he says.
“All three of those (strawberry, citrus and tomato growers) have recognized the agronomic benefits of using drip irrigation,” he says. “In reality, water conservation is a secondary benefit to these growers. The increase in yield and quality justifies the investment alone.”
Growers also embrace drip irrigation’s ability to deliver fertilizers and other chemicals at exact times, permitting more control over conditions in sandy soils that don’t retain water or nutrients, Corcos says. It’s all part of an adoption of new technology that is constantly being refined by scientists and researchers.
Among them is Dorota Z. Haman, the chairman of the agricultural and biological engineering department at the University of Florida and a co-author of several papers, including “Design Tips for Drip Irrigation.” Investing in soil moisture sensors is critical, she says, to assure the right amount of water is delivered to the root zone and not below it.
“It’s better to do it more frequently in smaller amounts. If you don’t manage the system, it will be extremely wasteful,” she says.
Simplifying the process is the use of 9-volt batteries that run belts to automate the system, she adds. Even with automation, such systems are high maintenance as growers test their water—often through a local Extension office—for iron. Iron and calcium levels can lead to clogs from iron bacteria and slime.
“You want to have a very good filtration system,” she says, mentioning self flushing emitters as an alternative. “You want to have an injection for fertilizers or if you’re having a problem with clogging, inject chlorine or some cleaning agent.”
Some Growers Remain Wary
Not being able to see the clogs and their resolution in systems that are traditionally under plastic mulch makes older growers wary of drip irrigation, according to Ron Cohen, a senior professional engineer with the Southwest Florida Water Management District, West Palm Beach. Cohen, who earned a degree in agriculture and irrigation engineering from Utah State, Logan, has been passionate about drip irrigation since he wrote a 1987 article for Florida Farmer and Rancher.
“Especially the older generation, they’re so used to the way their fathers had done it, if they didn’t get runoff at the end of a field, something was wrong,” Cohen says. “It’s almost a cultural change to get people to use drip irrigation.”
Other issues that come into play include proper design and installation of systems, Cohen says. Accounting for surface elevation is important, he says, so that when an uphill gradient comes into play, proper pressure is employed so water is dispersed evenly along the line.
Products Keep Systems Unclogged
Addressing concerns about pressure and clogging is a host of companies whose products are specifically designed to ease the passage of water in drip irrigation. At Fresno, Calif.-based Netafim, district sales manager Mike Gris oversees products for growers in his region of Florida and southern Georgia. Netafim sprinklers need only 120 mesh filtration or 130 microns, as opposed to 50 to 60 for a regular lawn sprinkler, he says.
“You can do lots more acreage for the same amount of flow and a lot more acreage for the same cost because you’re using the water exactly where you need it,” Gris says. “As opposed to everywhere or as opposed to overhead irrigation that needs 45-50 psi or better.”
Another product, the Neptune Filter Feeder, is used primarily in greenhouses in New Jersey and the Northeast. Although it isn’t in use in Florida, its metering pumps are represented by Largo-based Flo-Tec and used extensively in its water treatment systems. Flo-Tec, a 32-year-old company that previously distributed such metering pumps, has focused solely on chemicals that maintain cleanliness in drip irrigation systems. Owner John Thomas oversees 22 dealers in the eastern half of the United States. They are certified through a program developed and presented by Kevin Watts, Flo-Tec’s director of marketing and business development. As part of his presentation on low volume systems prone to plugging, he explains how Flo-Tec chemicals are introduced at 3 to 5 parts per million in both drip tape and drip tubing.
“This tubing you’ll find in blueberry and blackberry crops,” among others, he says. “Tubing stays down a period of years. To get our chemicals into these systems there are a number of different ways chemicals are put in.”
An Anderson ratio feed injector and an electronic piston solenoid pump are common devices used to inject chemicals, according to Watts, to address both biological and mineral contamination.
Watts checked off the sources of irrigation water common in Florida, from shallow wells to ponds and reclaimed water, and the contaminants that cause problems. Systems get plugged from turbidity or grit as well as biological sources like bacteria and algae and minerals such as calcium and iron.
“To prevent biological plugging, we remove the food source from the offending organism and create an inhospitable environment,” Watts says. “Mineral plugging and precipitation will be calcium and iron for the most part.”
When a grower senses a plugging problem, he can send a sample to Flo-Tec’s laboratory to identify the problem and recommend solutions. Levels of pH, conductance or dissolved solids are measured and biological analyses include algae and iron bacteria counts. Flo-Tec products recommended include Matrix for biological growth, Nic to control mineral growth and Nic 6 for combination problems. Di-oxy Flush may be applied first to open the line.
“Acid or chlorine was the old approach to break up plugging,” Watts says. “We came up with a better way to do that. We have three products to control plugging and they are environmentally friendly.”
Plant City’s Connell has been impressed.
“They’ll help you find your problem areas and then attack your problems,’ he says. “That makes things simpler and puts your mind at ease, knowing you’re doing everything you can to keep your lines clean.”
Continued Acceptance is Expected
Refining management practices for irrigation has been the bailiwick for the past 29 years of Craig Stanley at the University of Florida’s Gulf Coast Research and Education Center in Wimauma. Stanley, the associate director of the center and a professor in the soil and water department at the University, has conducted extensive research on tomato production with drip irrigation. It has shown that growers could double their crop by using this method.
“Because of the tightening of water restrictions, tomato and other commodity growers are having to consider using drip irrigation,” Stanley says. “The primary crops are of such high value, it justifies using drip irrigation. I see it continuing to grow and catch on.”
That enthusiasm is shared by Eric Simonne, an associate professor at the UF and an Extension specialist working in integrated water and nutrient management. Simonne, who co-authored a UF/IFAS paper on water movement in strawberry beds, pointed to reduced pest problems and easy automation as reasons why drip irrigation is preferable to overhead and seepage systems.
He compared it to intravenous feeding for plants and cycles of wetness and dryness with nutrients applied when most needed. As Florida continues to grow, he sees it as the best option.
“The resources of the state are finite in terms of water,” he says. “As we have more and more people, the section of the pie that’s going to have to be reduced is agricultural water. If water is your main limitation, which it is in Florida, then drip is the way to go.”