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Low-Volume Irrigation: Do Be A Drip

ROBIN WESTMILLER | Drip Irrigation - Low Flow

How blessed we are to be living in the United States. We are also blessed that our country has always had an abundance of water. So why is it that we are now experiencing water shortages in most parts of our land?

It’s not that we lack water; the problem is that we are spoiled. In the past, we never had to monitor the amount of water we were using. We had more water than we needed and it was never an issue. So, we used as needed without really thinking. However, with our population greater than ever before— 310 million plus and growing—our situation has changed. Since there doesn’t seem to be any way around a growing population, we must learn to conserve this most precious resource, and that is by implementing efficient water use so we can sustain not only ourselves, but the landscape environment as well.

There are several effective strategies for making landscapes more water-efficient. Replacing older sprinkler heads with low precipitation sprays and adding smart controllers with weather sensors are some techniques. However, another important strategy for water conservation that has seen an increase in popularity recently is the use of low-volume, or drip irrigation systems.

“For a long time, drip irrigation was simply promoted as the “right thing to do” by those who were looking to specialize in the field of sustainable landscapes,” says Diane Noecker, director, landscape sales and marketing, Netafim USA, Fresno, California. “But as more municipalities began to mandate low-volume usage of water, drip irrigation methods started to become the technology of choice. Today, with improved materials, ease of installation and the increased availability of components, drip irrigation is now a viable option for all parts of the country.”

A low-volume irrigation system typically applies water slowly, at low pressure, at or near the root zones of plant material. Low-volume systems also reduce or eliminate runoff on walkways and paved areas, and overspray onto windows, pavement and walls.

“Whether referred to as drip, micro-irrigation, or low-volume, these systems can greatly reduce or eliminate water waste while promoting healthier plant growth, because you can match the amount of water applied to the specific needs of each plant,” says Kendall Smith, product manager, landscape drip, with Rain Bird Corporation, Azusa, California. “By applying water directly to the root zone, a properly designed and installed low-volume irrigation system can be more than 90 percent water-efficient,” Smith said.

A drip irrigation system consists of a ” ‘spaghetti’ drip line and a selection of emission devices. Tra ditionally, the tubing was placed in plant beds and then covered with stone or mulch. Water then flows through the tubing to emitters, bubblers or micro-sprays placed in or along the drip line that directs the flow of water in a slow, precise manner, under low pressure, directly to where it will do the most good, at the root of the plant. With this type of irrigation system, the optimum moisture level can be regulated and maintained with greater accuracy, which is essential for water conservation.

“When selecting drip system components, there are several features to look for. First, the emitter should be pressure-compensating. Pressure compensation will make certain that  the emitter at the beginning of the system will flow at the same rate as the emitter at the end of the system, guaranteeing an even, uniform precipitation rate throughout the area being watered,” said Noecker.

“Second, make certain the emitter has a self-flushing feature. This feature will flush any accumulation of dirt and debris which may have passed by the filter out of the emitter. Finally, some emitters have a check valve built into each emitter. With a check valve, all the emitters come on at the same time and shut off at the same time. The check valve prevents low head drainage and back-siphonage.”

With water conservation spearheading the eco-friendly movement, many water districts are offering rebate programs and lower utility bills to their customers who convert part of their property to water-wise landscaping zones. And with a renewed interest in eco-friendly sustainable landscapes, you only need to follow the water to see that it leads directly to greener pastures for your clients and your company.

Additionally, low-volume irrigation installation is now a vital part of the application process when it comes to awarding major construction contracts.

“With Leadership in Energy & Environmental Design (LEED) being more and more influential in the marketplace, and the new International Green Construction Code, irrigation systems need to be more efficient or we’re not going to be able to install them,” says Carl Dowse, irrigation department manager at The Bruce Company, Middleton, Wisconsin. “Contractors know that there’s a huge difference between a conventional system that applies water in gallons per minute and a low-volume system that applies water at a rate of gallons per hour, and if you’re not installing the right system, you could very easily lose that job to your competitor who is.”

While it may be true that you can’t teach an old dog new tricks, learning the proper installation technique of a low-volume system isn’t all that difficult. Rain Bird’s downloadable XF Series and Hunter’s online traini ng program are two examples of what is available from irrigation manufacturers to help you add low-volume to your business, or improve on what you may already have.

Like conventional installations, the most important factor to consider first is the type of plant material you’ll be watering. Then you can match your precipitation rate— in the case of drip, the application rate—to make sure it gets just the right amount of water it needs; not too much and not too little. Where the plants are located, and even the type of soil they’re planted in, needs to be taken into consideration as well.

“You definitely want to consider the site conditions as well as the plant material before you select what type of lowvolume irrigation system you’re going to install,” says Todd Polderman, CIC, CID, CLIA, product manager, Hunter Industries, San Marcos, California. “This will help you determine what device you’ll want to use along the drip line.”

Dowse says he uses drip lines with built-in emitters, but also likes the versatility of the ‘point source’ method where he can choose where to plug the emitter into the drip line for better placement of the water. He also installs micro-sprays, especially on residential sites, because the homeowners don’t see the tubing. “We try to keep the tubing up against the house, on the edges, so when any modifications are done to the landscape like weeding or re-mulching, it’s out of harm’s way,” Dowse added.

Some of his clients have garden pots installed on their decks and he says bubblers are ideal for that. “Normally, the drip line is on the plant bed adjacent to the deck or down below it, so all we need to do is run the spaghetti line up the sides and install a micro-bubbler into the pot,” Dowse said. “Drip also works well around shrubs and hedges. If you have a three- or fourfoot high hedge, there really isn’t any way to irrigate it from overhead, so you would want to use a drip product to go underneath.”

Because low-volume systems are typically designed to run at low pressures, it is necessary to install a special controller valve with a regulator that will bring the water pressure down to between 20 and 50 psi, depending on what type of emitter, or micro-spray you’re going to use. Some manufacturers suggest using an air-release valve to help prevent blowback.

With a drip system, you will also need some type of filter to protect the emitters, bubblers or microsprayers in the line. The holes are much smaller than a conventional system and can become clogged unless there is a filter to clean out the dirt and debris that comes from the water source. Most manufacturers of low-volume irrigation components sell kits specially designed to be used with their system.

Low-volume irrigation filters come in three different types: manual, semi-automatic and fully automatic, or self-cleaning. With a manual filter, the operator manually unscrews it from the valve, pulls the screen out, cleans it, and manually puts it back. With the semiautomatic filter, the operator opens the valve, turns the handle and it cleans itself, and the fully automatic filters are pretty much left alone to clean themselves.

“The nice thing about self-cleaning filters is that there are no cartridges to throw away and you never have to purchase new ones,” says Matt Aguilar, national sales manager, irrigation, for Amiad in Oxnard, California. “The selfcleaning aspect also minimizes the amount of time you’ll need to service the system, because there are no filters to replace. You’re also reducing your labor cost in the fact that you don’t have to send your crew out to the jobsite several times a week to change or clean a filter in the drip system,” Aguilar added.

One of the biggest challenges with drip irrigation systems is that emitters could not be installed underground because the plant roots would grow into the holes, cutting off the water. Traditionally, herbicides like trifluralin were used on the emitters to stop root intrusion, but with the advocacy of eco-friendly landscapes, alternatives to chemicals were being sought out and tested. After nearly a decade of trial and error, Samir Shah, business development manager for Rain Bird, found that a small copper strip placed inside the emitter was sufficient to keep roots from growing into the device.

“All roots, by their biology are slightly acidic in nature,” said Shah, “and they don’t react well to copper. So, when the root tries to enter the emitter, it gets a bad taste of copper instead. The copper ions eventually stunt the growth of the intruding root. The nice thing about this method is that the copper won’t harm any of the other roots growing along the drip line, or harm animals who might come in contact with the emitter.”

With the root intrusion problem solved, drip irrigation systems can now be installed below ground, like conventional irrigation systems. But unlike conventional systems, they can also be installed way, way above ground, on rooftops and walls. For the fast growing eco-friendly building industry, low-volume irrigation methods are ideal.

“We’ve been very successful using drip to establish the green roofs,” says Dowse. “The plants are native, dry-loving plants, so once they’re established, you’ll have a beautiful green roof with no weeds that can pretty much take care of itself. After the initial installation, we might turn the drip on only two or three times a year at the most,” Dowse explained.

Another perk of drip irrigation is your ability to be really creative with the design of the plant materials. One of the advantages of a low-volume irrigation system is that it can be configured around odd-shaped areas, and follow the path of the plants, in rose beds and around trees. With drip lines, you’re not confined to ground level, or horizontal installation.

In the past several years, Dowse has seen an increase in the demand for green walls, and says there is no way he could have created vertical displays without the use of low-volume irrigation techniques.

“I’m working on a wall that is very steep, so installing conventional irrigation would be very costly, should it need to be repaired. We installed a drip line throughout the living wall, and spaced the micro-sprays on stakes,” Dowse said. “This living wall has shrubs and native plants, and we covered it with hydromulch that contained native grass seeds. We’ll use the micro-spray heads to help establish the wall, and then we’ll remove the hardware once it’s no longer needed.”

Up, down, over, under, around or through, low-volume irrigation systems can be an effective solution to many irrigation situations facing today’s landscape professional. From government regulations, to cost-saving incentives—whatever the motivation, low-volume irrigation is simply another way for you to do what’s best for your clients, their landscapes, and your business.

 
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08.02.2011 at 10:59 Reply

I agrree Low Volume Irrigation is the wave of the future.  I am pleased to see the industry has improved the products and their installation to make installation fast and easy.  I can't stress strongly enough that a pressure regulator and filtering system are essential to an excellent system.  Many who install drip are misinformed in regard to pressure compensating heads.  Often times you will se a system installed on a system with pressure at or above 70 PSi with the expectation that the compesating factor built into the head will allow it to work correctly.  From past experience I can tell you it doesnt work, and the agravation factor involved to keep a client happy isn't worth the savings of not installing a pressure regulator.

 

02.11.2012 at 03:49 Reply

There are many other aspects to consider in a localized irrigation system, for example its very important to consider soil type,because a sandy soil daoes not have the same characteristics of a clay one. You have also to consider field capacity, wilting point, that are such important aspects to consider. If we want to have a more sophisticated system we can start talking about tensiometers. This artifact allow us to see exactly when the plant needs water, and when not. 

Also we have to consider that self- compensated irrigation tapes can have a flow rate difference approximate at 20%, so its not that true talk about "uniform irrigation" a great advantage of localized irrigation is what you have mentioned, high efficiency of application, and low pressure requirement (10 psi to 20psi).

 

 

 

 
 
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