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Drip Irrigation Technology

GRETA ANDERSON | Drip Irrigation - Low Flow

 THE FUTURE
OF WATER
CONSERVATION
by Greta Anderson

Up and down the eastern seaboard, 1999 will be remembered as the year of the drought. At least ten states were declared drought disaster areas. Homeowners in New York, New Jersey, Maryland, Delaware, Pennsylvania, and Ohio were asked or ordered to cut their water use. The long-term effects on landscapes in this normally moist, humid region will vary. Brown lawns will green up again next spring, but many shrubs and trees will not survive. According to John Noelle, the city arborist of Alexandria, Virginia, "We're already seeing a lot of losses in commercial areas, where trees and shrubs are pretty much left to their own devices. I think there will be problems with larger trees that we won't see until next year."

emitter low flowTrees and shrubs commonly use drip irrigation, a water-conservation irrigation technology. Small, regular doses of water improve the health and productivity of plants, and the installation and operating costs are often less than conventional irrigation systems. In places like the Southwest, drip is commonly used and landscape professionals have more experience with it.

After this torrid year, Easterners who may not have thought much of irrigation in the past, let alone drip irrigation, may be looking to drip for new plantings. "I can see there would be a role for drip in high visibility areas and especially in new developments," says Noelle. "This summer, we've had a terrible drought ever since April, but the two previous years we had major droughts in the middle of summer, as well." This, in a region known for muggy weather.

If drip technology does break new ground in the East in the ensuing years, care must be taken for the systems to be installed correctly Emitrs3and for personnel to be properly trained to maintain them. Failures can give drip a bad name.

"Every time there is a drought, landscape contractors and irrigation consultants flock to buy drip irrigation systems to install in their new and existing projects," remarked Mike Baron of Rain Bird's Landscape Drip Division. "Those who do become sold on it come back in non-drought years. Installing drip irrigation then becomes a part of the designers repertoire."

Not all contractors, however, take the time to learn how to design, install and maintain drip irrigation systems properly. Although the drip system does not require unusual maintenance, it does periodically need to be checked.

The main benefits of drip irrigation are that it reduces water use and improves the health of the plant. "Drip irrigation systems are designed to deliver the water to the plant's root zone," Kurt Maloney of Netafim explains. "When you're talking efficiency, conventional spray heads deliver only 55 to 65 Emitrs3percent of the water to the ground; the rest is blown away or evaporates, depending on weather conditions. In contrast, drip irrigation is up to 95 percent efficient." The difference in efficiency increases when you consider widely-spaced plantings, or areas adjacent to fences or sidewalks. There's not much sense in watering mulch and hardscape, especially when water is scarce.

While drip irrigation has been used in landscapes for thirty years, it is only in the last decade that a number of companies have refined their products specifically for landscaping needs. Several years of experimentation by manufacturers and designers have finally worked out most of the bugs for landscape applications. The use of drip for landscaping is picking up pace in water-conscious states. First commercialized for use Emitrs3in agriculture on a kibbutz in Israel, drip irrigation technology matured into a company called Netafim. When Netafim expanded its market into the United States, it was soon joined by a host of American manufacturers similarly geared toward agricultural markets.

During the early 1960s, drip irrigation caught the eye of growers, farmers, etc., because of the economic value. Many crops produced higher yields with less water and at relatively low cost. However, drip irrigation in a landscaped environment is developing very slowly, with the exception of certain areas in the West and Southwest. With the recurrence of drought, drip has become a mainstay for horticultural pro duction on the U.S. west coast.

With only a few exceptions, drip manufacturers remained focused on the agriculture markets until the late '80s and early '90s, when they began to look seriously at the landscape market, as well. According to Mike Baron, the first approach of many companies was simply to sell agricultural products to landscape projects. The results were understandably "mixed." Eventually, firms developed separate product lines for landscape applications.

Salco Products, Inc., is one exception to this rule. The firm started out like the others in agriculture, but has focused its sales on the landscape market for most of its 31 years. Salco Products has also remained focused on point-source systems, eschewing the newer dripper line technology. Median-ShrubStreetscaping, or narrow road side plantings, was discovered early on where the use of drip technology is ideal. "Whenever you have pavement, and that pavement gets wet, there's an increased risk of accidents, and no one wants that," remarked Sam Tobey, president of Salco Products, Inc.

Counter to its name, Agrifim, a fifteen-year-old firm with sales of drip products, has also focused specifically on drip in landscape settings. According to president Rael Sacks, Agrifim's strength lies in the diversity of its drip products. "I believe that drip irrigation has applications in every situation in every part of the country. But every area has to be custom-designed."

The irrigation designers we spoke with were split on their attitude toward drip, they had useful tips for planning and troubleshooting drip irrigation zones. Steve Smith, vice president of Aqua Engineering, in Ft. Collins, CO, uses drip in about 40 percent of his projects, "especially in shrub beds." Here, drip tends to have a lower-unit cost for installation. Savings can also come in labor costs. It takes less hired labor to install drip systems, a factor that could make drip more profitable for a contractor.

Dave Pagano, a noted irrigation consultant/designer based in Southern California, uses drip less frequently Aerial of Gardenand has a somewhat more cautious view of it. A major deterrent for him is the potential for vandalism at public plantings. "You'd be amazed what a kid on a bike can do." Fertilizing is another issue to consider. "Since you can't simply broadcast granular fertilizer, you have to plan on injecting it or spraying it on." We believe more common use of fertigation will play an important role in expanding the use of drip irrigation.

According to both Smith and Pagano, getting maintenance people to understand and accept the technology may be the biggest challenge. It's one thing to master the technology in order to make an appropriate installation; it's entirely another to train maintenance crews.

One problem is that the watering is often done out of sight. "Sometimes you have stressed plant material before you know there's a problem," says Smith. Pagano also describes scenarios where a worker has cut a dripper line while digging in a planting bed. "That's the landscaping business," says Pagano. "Things get broken, things get fixed. But should you get some dirt in the line, it's very difficult to get it out."Salco1Drip has an excellent role to play in situations where spray is a nuisance. Pagano specified subsurface dripper line for several displays in the Legoland theme park in Southern California, because it was essential that the models stay dry.

At Aqua Engineering, the use of drip in dense groundcover always provokes "a little debate" among the engineers. "How it's settled comes down to a multitude of factors, including the client's interest and local attitudes toward drip," says Smith.

Drip irrigation is based on narrow, flexible PVC or polyethylene tubing. There are two basic approaches to drip: dripper line and point-source systems.

"We have one
of the highest rates
of water use per person
of any country in the world."

RainbirdEmitrs3Dripper line is a flexible hose with in-line emitters spaced one foot to 18-inches apart for landscape applications (further for agricultural uses). These emitters are designed not to clog, and are "pressure-compensating," meaning that the emission flow is constant throughout the line. Using simple "T"s that require no bonding material, a continuous grid can be laid out for irrigation of ground cover or annual planting beds. Or, the tubing can be snaked around the area, much as a leaky soaker hose would, except with the option to "T" off and add loops as needed. In point-source systems, water is delivered to large plants through a solid hose and individually installed emitters. The small, plastic emitters come in a variety of sizes and flow rates. Typically, these low-volume emission devices are attached to a spaghetti hose that snaps into the main hose with a barb connection. Emission devices can be added or "capped" as needed. Some manufacturers recommend installing the hose at grade, or ground level, with two to three inches of mulch covering it. Point-source systems are generally buried underground, with the option of either keeping emitters buried or bringing them to the surface. Salco is one of the companies that specializes in this type of system, and recommends at-surface emission for reduced risk of contamination and easier maintenance, reserving subsurface emissions for turf-related application.

multioutletTop: Emitters show
three different
new emitter low flowvolumes per hour.
Left: Multiple emitter.
Right: Single emitter.
Photos courtesy of Rain Bird Landscape Drip Division


 Steve Smith, of Aqua Engineering, has found that keeping emitters under mulch is one way to significantly reduce vandalism in public places.

Recently, several manufacturers have developed dripper line hosing to be used underground, especially beneath turf. Their products repel root intrusion using low-level emission of a chemical that is poisonous to plant roots. Netafim's product was impressively utilized at the Sonora Clubhouse in Scottsdale AZ, where subsurface drip tubing was installed to create a championship lawn tennis court. The turf is actually watered while members play. It never gets soggy and, with the help of a subsurface heating system, stays in great shape year round.

"Silent, slow, invisible delivery of water
by drip methods is an important option for landscapers to consider."

CALCULATING FLOW
So how does one design a drip system? Mike Baron has several useful "rules of thumb" for estimating drip requirements. First of all, worries about line or zone capacity can, for the most part, be put out of mind. A drip system can support about 240 times as many emitters as the number of spray heads on a conventional line! So, if an area can be irrigated with a spray system, it can definitely be irrigated with drip.

According to Baron, a contractor's product purchases will fall into four categories: the control zone components, where the line flow is regulated and water is filtered; delivery systems, or tubing; emission devices; and tools.

Baron encourages landscape contractors installing drip systems to try to get away from the "so many inches a week" formula of turf irrigation. Instead, the landscaper should simply imagine how much water he or she would use on a plant each day if it were in a pot above ground. About a gallon? Then use a gallon per hour emitter on a system designed to run for an hour, or a two gallon per hour emitter on a system designed to run for thirty minutes. Drip systems should be designed to run on a regular, daily basis.

Baron also cautions users to be careful with hose end timing devices. They may not work at the low flow rates used with drip irrigation. "Say you have 50 emitters delivering one gallon per hour each, that's less than one gallon per minute of flow. Most timers are geared for around five to six gallons per minute, and may not recognize the low flow of a drip system. People come back from vacation and find out their systems never switched off." One should check for minimum rate specifications on hose end timers before purchasing them: if no minimum is listed, the product is probably not geared to drip.

With El Nino and La Nina thrown in the mix these last two years, it's hard to tell how fast, or how our climate is really changing. The hardiness zones seem to be marching north at a steady pace. What is certain is that water is becoming an increasingly scarce-and expensive-resource. Even where rainfall is moderate or heavy, municipal water systems are being expanded to serve new suburban developments, adding significantly to the cost of treated water. Public attitudes toward water are changing, as well. Watering lawns is, in some places, frowned upon as an indulgent extravagance.

All of these factors make the silent, slow, invisible delivery of water by drip methods an important option for landscapers to consider, even in areas not considered arid or semi-arid. Drip irrigation may be attractive to potential new customers with the memory of droughtSalco3 fresh in their minds. If you can steer clear of the pitfalls, it will be just the thing to keep them satisfied. Many of the firms offer seminars and complete training kits with videos, booklets, and product samples, to help the contractor getting started with drip. So, study up during the slow season and make drip part of your repertoire.

 


 
Camp Snoopy
is an indoor amusement park
where all trees and plant material
are watered by drip irrigation.
Photo courtesy of Salco Products Inc.

 
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