Meeting Irrigation Mandates
With water restrictions increasing, growers are looking to conserve water.
April 16, 2008
Every year, Carroll Brothers Nursery, Clearwater Fla., uses 18 million gallons of water to irrigate its 10 acres using overhead irrigation. The pricetag on that much water per year has jumped from $4,500 to $18,000 between 1991 and 2007, so owner Richard Carroll has been looking for ways to reduce cost. The goal when the gardenia grower first started searching for water alternatives was a second water source - one that would pump and clean water or one that would collect rainwater.
"Either way, it was too expensive for a nurseryman to handle," Carroll says. "Knowing I couldn't touch either of those, I was looking for a way to save water."
Drought and water restrictions can cause a grower to rethink irrigation, but so can research. Looking for an irrigation method that would follow BMP practices, as well as provide consistent irrigation, Carroll Brothers did research comparing drip and overhead irrigation and Aquamats, a capillary mat system for pot and nursery crops. The findings on overhead watering showed that pots at the end of the nursery's 150 foot rows were being overwatered as much as three times what was required because of an irregular water pattern. Drip tube tests showed crops were getting double the water required at the beginning of each row. Both methods also resulted in excessive leaching.
Aquamats, manufactured by Soleno Textiles, have provided uniform watering for all areas with no leaching. And if Carroll Brothers switched the whole facility to Aquamats (currently, one acre is grown on Aquamats), the lessened runoff would reduce water use to 1.7 million gallons per year. The Aquamat beds also hold 2 ¼ pounds of water per square yard, so some rainwater capture is possible. A good rain helps the grower turn off the water, as ¼ inch of rain gives four or five days worth of water to the crops.
Improving Plant Quality, Too
Aquamats have not only helped Carroll Brothers save money and water, they have improved production time.
"It's actually sped us up 30 percent as far as growing," Carroll says. Six-inch pots are finishing in six weeks, compared to two to two and a half months with other irrigation methods. Aquamats also reduce the amount of water pressure needed for irrigation. Drip irrigation requires 40 psi of pressure, while the Aquamats only require 11 psi. This is a pressure that Pinellas County can provide and it's also a pressure reading that reduces the energy costs for pumping from $15,500 to $3,000 per year. Carroll is looking at solar pumps now that would save the company even that $3,000. The next step for Carroll Brothers is to cut back on the amount of fertilizer used. Carroll says he hopes to cut back fertilizer use by up to 50 percent.
The big dream Carroll has is an underground reservoir beneath greenhouses to store captured rainwater. He figures that a tank could be built that would hold 1.2 million gallons of captured rainwater, but hasn't figured out a way to make it happen yet. "It's too expensive, but I haven't lost that dream yet," Carroll says.
Success Through Best Management Practices
Like Carroll Brothers, Delray Plants, Delray, Fla., is looking for new irrigation solutions. There has been a crackdown on permits for watering and the mandate has been to cut water use over a number of years by 30 to 50 percent, and now guidelines ask that water use be cut back by 10 percent more, according to Delray Plants' Randy Gilde. "We're doing everything we can to save water," Gilde says. Blanket mandates for water consumption cuts are a frustration to companies like Delray that already have made efforts toward conservation.
"We've already cut our water consumption over the years by 30, 40 or 50 percent," Gilde says. "We already realized water is precious years ago and have always had Best Management Practices on our water use and conservation." The company still holds a goal of cutting water use by 10 percent.
"We could see already that water is going to get more scarce," says Gilde. "What brought it to our attention was common sense. When you get lots of hurricanes and record rainfall, it's usually followed by a lack of hurricanes and lack of rainfall. We just felt it was going to get really dry. As you see in Georgia and other places, it's pretty severe."
Meeting The Mandate
The grower has combated these restrictions by following Best Management Practices, as it always has, Gilde says, but the greenhouses' irrigation structure has also helped save water.
While it may be cheaper and easier to have a main irrigation line that waters all greenhouse or nursery yard area at once, Delray divides its greenhouse area into bays, 40 bays per acre on average, each on its own solenoid and watering schedule. Using this method, irrigation to individual bays can be turned off and there's no watering of empty space.
The grower also uses the heaviest soil it can to hold the most water and just recently started adding drip tubes, which the grower has found more efficient. "Over the next few years, we're going to continue to add drip tubes at a more aggressive rate," Gilde says.
Delray Plants retains all its runoff into lakes and ponds on the property, and water for production is drawn from aquifers. Gilde predicts that the future of the greenhouse industry includes moving towards ebb-and-flow irrigation models and drip systems. "They're 10 times more efficient than overhead watering," he says. "These types of irrigation are costly, but they're the future of the industry. It's a big investment, but in the nursery industry, you either have to invest in that or find another line of work."