Technologies and techniques for lowering irrigation water use

With many areas of the Southeast currently experiencing severe drought conditions, and more and more local municipalities enacting water conservation measures, those working in the green industry might be concerned about how they’ll be able to keep their customers’ lawns looking green.

Fortunately, new research at the University of Florida has identified a combination of approaches, both new technologies and proven techniques, which can protect turfgrass quality while cutting water consumption during irrigation.

Michael Dukes, an assistant professor with the University of Florida’s Institute of Food and Agricultural Sciences in Gainesville, works with equipment that measures soil moisture in a turfgrass research plot.

Michael Dukes, an associate professor of agricultural and biological engineering at the University of Florida, and an irrigation specialist with the state’s extension agency, says that the drought conditions being experienced in Florida have helped bring the issue of irrigation efficiency to the forefront. “It’s made an ongoing problem—there’s just a lot of people in this state and tremendous construction growth, nearly all of which includes irrigated landscaping—and exacerbated it,” he explains.

Dukes has been leading several ongoing research projects examining the effectiveness and proper use of new technologies, perhaps most notably soil moisture sensor controls. He has been working with soil moisture sensor-controlled irrigation since he arrived at UFL in 2001. “Initially, it was in agricultural settings on high-value vegetable crops,” he says. Now, with more attention being turned toward water use in residential landscape settings, the technology has moved in that direction, as well.

“Some vendors came into the state and wanted the water management districts to rebate the cost of soil moisture sensor controls. The districts were a little nervous because they had done this 20 years ago, when the technology wasn’t very well defined.” UFL was asked to test these sensors, as well as ET controllers, which can detect when days get shorter and there’s less sunlight, and irrigate less in response. “We’re pretty much testing the spectrum of controllers now,” says Dukes.

Thus far, research results show that technologies such as soil moisture sensor controls hold a great deal of promise. In a recent project, three of four rain sensors tested produced an irrigation water savings of 69 percent to 92 percent, compared to systems operating without the sensors (which are typically installed in a dry part of the lawn and determine when the turf needs water based on soil moisture levels). ET controllers have also shown promise in reducing water use while preserving plant health.

The challenge now, says Dukes, is to convince homeowners to invest in these technologies. “Although many utilities are increasing their rates, water is still pretty inexpensive,” he says. “We know from various studies in this state that those irrigating do respond to increases in prices. In other words, they will become more efficient if the price goes up, but generally speaking, prices are still pretty low. I think if prices increase further, there is the potential for driving more water conservation measures.”

There is also potential, he observes, for those in the green industry to learn more about new irrigation technologies and position themselves to provide expertise as interest in irrigation efficiency and water conservation grows. There are resources available to lawn and landscape professionals who see a potential to sell their services in helping homeowners and other customers to reduce water consumption and increase irrigation efficiency. “We’ve done three pilot soil moisture sensor training workshops here in Florida, and our goal is to produce a training module where we can train people across the state who can then provide additional training in their area,” Dukes explains. In addition to extension personnel, he says that the trainings offered thus far have attracted a number of irrigation contractors and a handful of landscape contractors.

Dukes says working with irrigation technologies does involve a learning curve. “There are technological hurdles, and with any of these technologies, I constantly caution people that while they do work—and many work very well in achieving water conservation—they’re not foolproof. There is a temptation to say, ‘Ah ha, we have a fix. Let’s unleash these technologies on developers and contractors and homeowners all around the state,’ but I think we need to be cautious, because implementation is the key to success. For example, water conservation in irrigated landscapes is not like water conservation with high-efficiency toilets. Once you buy that toilet and put it in, it’s going to save water, there’s no questions about it, but even if you put in a moisture sensor and ET controller, you can still over-irrigate if they’re not set up right. Or, even if the contractor sets them up right and the homeowner comes through and adjusts them, they can achieve ‘negative savings,’ which is not a good thing. I really strongly believe that we need to be cautious in implementing these technologies.”

Additionally, Dukes stresses, in order for new technologies to achieve their water conservation potential, the irrigation itself must be functioning properly—there can’t be broken heads, incorrect types of heads, improper coverage, etc. “If there isn’t good coverage, for example, when you start dialing the amount of water back, those areas will quickly show problems.”

Dukes says that because many irrigation efficiency technologies are still in their infancy, research is just now looking into how best to implement them. “We’re currently trying to fine-tune the process. For example, we’re trying to determine if just one training event is adequate for contractors, or is it better to have a follow-up training. Once all the systems are up to speed, and the contractors understand the technology, it won’t be a problem, but we’re still at the beginning of this. If the learning curve looks like a hockey stick, we’re still down there where you hit the puck.”

New irrigation technologies will save water only if the entire system is in proper working order and adjusted properly.

It doesn’t take new irrigation technologies to achieve water conservation. “If everyone would follow our basic recommendations, if they went to their time clock and set it every other month or every season according to our recommendations, the average person will see a water savings,” says Dukes. That goes for any system with a clock that’s in good repair, without broken heads, etc., and doesn’t apply just to newer systems.

One common problem regarding irrigation is the tendency to apply too much water, even more than the plants need. Dukes says, “That’s the perception, but it’s hard to generalize. When you think about the population that are irrigating, you have people who are very conservative and run the system manually and they’re fine with not irrigating very much; then you have the people who end up in the newspapers because they’re putting out something like 200,000 gallons a month on a .25-acre lot.”

Duke says that the irrigation system is often the one area of the lawn/landscape that homeowners end up managing by themselves, with little professional advice. “The other parts of the landscape, the biological parts of the lawn, there are many, many services for. There are companies to plant shrubs, mow the grass, fertilize, but in terms of irrigation, there really aren’t as many people. Sometimes the landscaper will help the homeowner set their system clock, but it’s not usually marketed as a stand-alone service.”

While there are contractors that homeowners can turn to in the event a broken component in their irrigation system needs to be repaired or for general maintenance, “those contractors typically don’t offer service plan options where they’ll come by four or five times a year, adjust the clock and just make sure everything is working properly. By and large, that doesn’t happen.”

This, again, signals that there might be an opportunity for those working in the green industry to educate themselves to offer irrigation system expertise to their customers. It makes good sense for those who are caring for the lawn and landscape—those with expertise in plant health—to be involved in determining when, where and how often irrigation water should be applied.

To help simplify the process when working with systems that don’t include new sensor technologies, the University of Florida has created an Urban Irrigation Scheduler (http://www.fawn.ifas.ufl.edu/tools/urban_irrigation) as part of the Florida Automated Weather Network. “We developed some recommendations based on long-term historical ET and rainfall to tell those with irrigation systems how many inches they need in any given month, but we realized that homeowners couldn’t make the leap between how many inches to put down and how to set their clock,” Dukes explains. “So, we created a table conversion to tell those operating the system how many minutes they need to apply for. Someone with basic information about their system can get a ballpark run time to shoot for.”

Those recommendations are then divided into three regions for the state of Florida, and also three levels depending on how conservative the operator wants to be. He says that a graduate student study using these recommendations produced a 30 percent savings in water use.

The key, says Dukes, is to get homeowners and contractors to actually follow these recommendations, or to explore the new irrigation technologies such as ET controllers and soil moisture sensors. If water prices continue to rise, there may be further opportunities for those lawn/landscape companies providing irrigation system expertise to explain to homeowners that such services will pay for themselves in the form of lower water bills.

Dukes says that right now there may not be enough financial incentive (in terms of high water prices) to spur adoption of new sensor technologies. “People love the idea,” he says. “When I give talks and tell homeowners and contractors what we’re doing, they love it. The contractors tell us, ‘That’s great, that’s what we should be doing,’ but when I ask them, ‘Do you think you can sell these technologies to your clients,’ they say, ‘I don’t think so, it’s a little pricey.’ So, we’ve got a bit of a hurdle to overcome. I think utilities are interested and there is the potential for rebate programs, but right now I don’t know if that’s enough to get the technology more widely adopted. The technology is good, and it’s getting better rapidly. What we need to do is educate people.”

Patrick White is a freelance writer and editor who is always on the lookout for interesting and unusual stories.