Saturday, April 19, 2008
Simple Drip Emitter Tubing
It’s irrigation season on my friend Chester’s garlic farm. The garlic has been growing all winter but now needs irrigation until July or so. That's him to the left, 85 and still growing and eatin' garlic.
About 18-years ago, I helped put in a simple drip irrigation system for each of his 4-foot by 10-foot planter boxes. I insisted on in-line emitter tubing.
In-line emitters are still probably the least well-known drip irrigation technology, but afford the best mix of efficiency, ease of installation, and resistance to clogging. The tubing is 1/2-inch in diameter with an emitter pre-installed inside the tubing at regular intervals.
These internal emitters seldom clog because they utilize what is known as a "tortuous path,” which forms a continuous vortex, a kind of horizontal tornado that keeps any sediment, sand or silt in suspension until it passes out of the emitter. (See the illustration above or in my books Drip Irrigation for Every Landscape and All Climates or in Roots Demystified - Change Your Gardening Habits to Help Roots Thrive. Click on the illustration for a bigger image) In-line emitters even work with well water high in soluble iron-oxide or other minerals. In-line emitter tubing moistens the soil the entire length of the line, but slightly below the surface where the bulbous-shaped wet spots come together to form one nearly continuous moist zone.
The emitters come pre-installed in the tubing, which is most commonly sold in pre-spaced, 12-inch intervals—but also comes in intervals of 24- and 36-inches. The emitters inside the hose are rated to dispense either ½ or 1 gallon-per-hour (gph) and the hose is available in both non-compensating and pressure-compensating versions.
We used ½ gph pressure-compensating emitters on 12-inch spaces along the tubing. We placed three equally-spaced lines running down the length of every box. (See upper-left photo. Taken before the straw is added.) Each box has the three lines connected to the water supply and the other ends connected to a drain-down manifold to flush the system at the beginning of each irrigation season. That’s what Chester is doing in the right-hand photo above. The garlic has grown considerably during the rainy winter months.
The benefits of pressure-compensated in-line emitters are: it's easy to install, simple to snake around your existing plantings, it is easy to put together a simple array of tubing which can be readily removed from the vegetable beds for seasonal cultivation, suffers less clogging than porous tubing and most punched-in emitters Chester stopped using the filter several years back and still only a handful of plugged emitters. Even with iron-based irrigation water only a few emitters in the thousands of feet of tubing have clogged over the past 18 years, and not cracked or leaking. Warranty says 10 years, but this tubing is always under six inches of mulch, works at the greatest range of pressures (9-25 psi), provides consistent rates of irrigation without regard to slope or length, has no external parts to snap off (a premier advantage over all punched-in emitters), and the compression fittings don't leak and seal better than the hose clamps used with porous hose.
The regular interval of the emitter makes it easy to irrigate the entire root system of all vegetables—in this case, garlic—and ornamentals by simply running parallel line of tubing throughout these raised beds or any garden. This will insure the greatest yields when compared to any other irrigation method—even sprinklers.
The drawbacks are few: it requires extra planning for plants placed very far apart and at very odd intervals, it can't turn a sharp radius, and it’s not carried by very many retail outlets.
You can get by mail from Harmony Farm Supply & Nursery, Peaceful Valley Farm & Garden Supply, and DripWorks (one word). Google them for what’s sold on their web site. You may have to order from one of their printed catalogs.
Let me know if you’ve tried in-line emitter tubing. How did it work for your garden?
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Labels: Chester Aaron, drip irrigation, emitters, gardening, garlic, in-line emitter tubing, irrigation, raised beds