The Lowdown on Drip and Low-Volume Irrigation
In an article about weight training I recently read, the writer made the startling observation that when it comes to building muscle mass, slower is better. Doing a whole bunch of reps with a barbell really fast isn’t as efficient as doing a few good ones, deliberately. So I tried it, even though I was reluctant to add more stolen minutes to my exercise routine. Darned if it didn’t work, though.
As it turns out, going slowly pays off in other arenas as well. One of those is landscape irrigation. Low-volume and drip irrigation components deliver water at slower rates, but targeted to the right places. They use less water, and are much better for plant material than conventional irrigation.
There’s some uncertainty, even among irrigation professionals, about exactly what is meant by the term ‘low-volume irrigation.’ That’s because there are many variations on that theme: micro sprinklers, macro jets, micro bubblers and drip emitters.
Sometimes, they’re staked above grade, and sometimes laid on the ground or buried just below. Depending upon whom you talk to, rotary nozzles and high-efficiency spray heads are occasionally thrown into the low-volume mix as well. And then there’s drip.
Drip is the lowest volume system of all. Adding to the confusion is the fact that ‘drip irrigation’ and ‘ low-volume irrigation’ are terms that are often used interchangeably. That’s not quite correct. Drip irrigation is a form of low-volume irrigation, but not all low-volume irrigation is drip.
We also have to change our measurement scale. The low-volume universe talks in terms of gallons per hour (gph) instead of gallons per minute (gpm).
So, what exactly is low-volume irrigation? Technically, any tubingbased point-source irrigation component or system putting out 0.4 to 30 gph can be labeled low-volume. By that definition, rotary and highefficiency nozzles with flows as low as 20 gph would also qualify.
What about micro irrigation? The standard used by the American Society of Agricultural and Biological Engineers (ASABE) and the International Code Council (ICC) defines micro spray as a “micro irrigation emission device with one or more orifices…with a flow rate not to exceed 30 gph at the largest area of coverage available for the nozzle series, when operated at 30 psi.” (Micro bubblers, micro spinners and micro jets are considered micro sprays under this definition.)
“It’s one of the few standards I’ve seen that actually puts numbers to the definition,” said Janet Reilly, director of landscape drip at Rain Bird in Azusa, California.
The bottom line is this: low-volume, micro and drip irrigation systems are all specifically designed to apply small amounts of water slowly at or near the root zones of plants. That’s the most important thing to remember.
Matched precipitation rates, meaning that all the zones in a system are putting out the same amount of water, are easier to achieve with low-volume systems.
Why might one choose to employ micro spray in a planting bed rather than installing drip? According to Reilly, that decision depends on the soil conditions and type of roots involved, as well as other considerations, including the likelihood of vandalism to the visible micro components.
For instance, if an area is frequently buffeted by winds, it’s probably not a great spot for a micro sprinkler’s smaller, lighter droplets. Much of the water will simply blow away or evaporate. Drip would be a better choice for that location.
Drip irrigation—the choice of a new generation?
The demand for drip irrigation is growing. According to one contractor, a new group of homeowners is leading the charge.
“Over the past five years or so, a new, very savvy bunch of clients has popped up,” said Mike Garcia, owner and founder of Enviroscape L.A. in Redondo Beach, California. “I call them ‘The Internet Generation.’” “These people are very educated about sustainability and saving our planet. They come to me already understanding the benefits of dripirrigation, but they’re also full of questions, such as, ‘Do these systems use recycled or recyclable materials?’” This group doesn’t want anything installed in their yards that could potentially harm their children or pets. Garcia says that one of the most frequent questions these clients ask is, “What about root intrusion?” They already know that some drip components are pre-impregnated with root-killing herbicides.
“And they don’t want that. They want to know their kids can roll around on the grass without being exposed to chemicals, having read all this stuff about chemicals possibly causing autism and ADD.” Accurate or not, that’s their perception, and it’s one that motivates sales.
Garcia explains to these clients that the drip systems he will install have pure copper in their emitters, because roots won’t grow next to the copper. Once they hear that, they’re practically sold. He’s also seen a lot of business come through his door be cause of the state’s five-year drought, and the big water bills and fines that follow.
Drip systems—either subsurface or above ground—are usually confined to shrubbery beds and planters. Garcia, however, installs a lot of subsurface drip in lawns, oftentimes under existing turf, a prospect many landscape profession als shy away from.
He says that as long as you follow the manufacturer’s guidelines and do a bit of math, it can be done, and done efficiently. “You have to read the directions; you can’t just ‘wing it,’” he says. “I guarantee that’s a recipe for disaster.”
He goes on to say that, oftentimes, installers go astray installing drip systems by trying to get too many linear feet out of a certain manifold, zone or valve. Put too much line on a valve, and it won’t push out enough water. Don’t put enough line on a valve, and your installation may not be cost-effective.
“If it’s an existing lawn and short grass, then we’ll use a little trencher machine that only digs down about two inches. We lay the tubing in and staple it to the ground. We’ve become so fast at installing drip systems that we can put them in as quickly as we used to put in PVC pipes and spray heads.”
Does it pay off in the long run?
What’s the return on investment (ROI) for property owners who install drip systems? Garcia says they’ll make back what they paid for it in just one to two years.
“Most of my customers, though, aren’t motivated by money,” he insists. “They’re going for it because they’ve seen hard-core scientific evidence that we need to start implementing changes in how we use water. Even if there was no ROI, it’s still a feel-good thing for them.”
While money may not be as much of a motivator for Garcia’s generally well-off clients, for most people around the country, it’s a big one. Reilly says that drip customers have a combination of desires: to cut bills, yes, but also to help Mother Nature. In areas with watering restrictions, they also want to keep their landscapes alive.
“I see people installing drip in my area a lot more for the water savings. It’s probably also a little more cost-driven. They’re saying, ‘I want to abide by the regulations, because I know water is scarce and I want to do my part, but I still want a green lawn. Installing drip and low-flow systems is a way to do both.’”
Commercial clients Garcia has done quite a few drip conversions for commercial clients as well. But in general, they’ve been slower to jump in.
Reilly agrees, saying that on the commercial side, acceptance of drip and low-volume irrigation has taken a bit longer. Getting in on the ground floor is the key, and to do that, you need to be there when the blueprints are being drawn up.
Her company has been successful in getting the specifiers of new commercial construction projects to understand just how much water these systems can save. When they see how installing these more efficient systems can be of benefit to themselves and their clients, they’re more likely to bite.
It doesn’t hurt, either, that developers of large commercial and residential projects are often looking for LEED points. Putting in drip and low-volume systems certainly qualifies.
Although a lot of movements start in the Golden State and then move elsewhere, the trend toward drip and low-flow irrigation isn’t just a western states thing. Reilly says the drought-driven awareness of these water delivery systems is “trickling down” elsewhere.
“California is the biggest market, that shouldn’t be a surprise,” said Reilly. “But we see it growing everywhere in the U.S.—Texas is the second biggest market, with a huge installation base, especially since their drought happened. But we’realso seeing a lot of growth in the Southeast and in Florida.”
An executive for another irrigation manufacturer recently said that “the western drought did more to sell drip irrigation than all of the company’s marketing efforts over the past ten years.” Reilly won’t go that far, but concedes that the drought definitely helped put it into the forefront of people’s thinking, where it hadn’t been before.
One of the problems with a drip setup, particularly a buried one, is that you can’t see it working. Homeowners, maintenance people and others may assume that the system has been turned off, or isn’t watering enough. So, off to the controller they trot, to crank up the volume.
Suddenly, the whole purpose of installing drip in the first place— to save water—has been defeated.
Some manufacturers have gotten around this problem by creat- ing pop-up indicators; roughly analogous to the little golf-teelike thingees that tell you your holiday turkey is done. When the system is on, these signposts rise up out of the ground to signal, “I’m working here!”
A greater need for maintenance is another objection to drip that’s often raised. Garcia says that concern is exaggerated. Maintenance isn’t hard, he contends; it’s simply a matter of cleaning out the filter once a year.
Changing one’s landscape service provider could prove problematic. pany comes in, and the first thing it Say a new lawn maintenance com- does is aerate the lawn, not realizing that there’s drip tubing two to four inches below the grass. Garcia claims that aeration isn’t even necessary with subsurface drip systems.
“Every time you turn the water off, the lines fill with air. As soon as you turn it back on, the air flows out of the lines. That lawn’s getting aerated every time you turn on the system.”
Getting the word out
Reilly thinks that the market for drip irrigation could be huge, if not for the fact that many people still don’t know about it. “I can’t tell you the number of people I talk with who say, ‘Wow that sounds great!’ How come I never heard about this before?’ We need to do more as an industry to get the message out that this alternative exists.”
A contractor may assume, incorrectly, that his customers just aren’t interested. Or, he may feel that he doesn’t have enough experience to do the job properly. Reilly says that one way to close the gap is to offer training, so installers can feel more confident. To that end, her company has begun offering a new course on subsurface drip installations through its training academy.
Obviously, there’s some educating to be done, for both clients and contractors. Find out about drip and low-volume systems, and then offer them to your customers. If you’re armed with the right kind of information, it could open up a whole new revenue stream for your business. And the planet will benefit, too.