Drip is Hip
16 Jun, 2008 By: Ken Krizner Get Growing|
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Drip irrigation is a system where the water runs through pipes or tubes to a small device, called an emitter, which dispenses water onto the soil surface at a low rate. The water is almost immediately absorbed into the soil.
Since the water sits 1 to 2 inches below the soil surface there isn’t as much evaporation while the water is waiting to soak in, compared with an overhead sprinkler system. In overhead systems, a percentage of that water vaporizes while it is airborne and additional droplets are blown away by the wind.
Once the water is in the soil, capillary action will move it sideways so it will wet an area usually about 24 to 36 inches in diameter around the emitter.
Drip irrigation is a more targeted system, applying water in proximity to the plant’s root zone.
While a good sprinkler system is about 75% to 85% efficient, a correctly installed drip system typically exceeds a 90% efficiency rate, meaning there is a 5% to 15% savings in water usage, says Jess Stryker of Ventura, CA, who has written a tutorial on drip irrigation (irrigationtutorial.com).
Like any irrigation system, landscape contractors can take a drip system, install it incorrectly and it will perform poorly.
“Some people think you can just throw it together and have a great system operating efficiently,” says Ed Martin, associate director of programs and irrigation specialist at the University of Arizona. “If the emitter isn’t just right, it could put out too much or too little water. The margin for error is much less.”
In a drip irrigation system, tubing distributes water from the source to various parts of the landscape. The drippers are small emitters installed on the tubing, and they deliver water to each plant.
Tubing is laid out across the yard to connect a landscape, and one length of tubing, known as a circuit, can serve many plants.
One common mistake in installing a drip irrigation system is placing emitters too close together, Stryker says. They should be kept at least 12 inches apart in sandy soil and between 18 and 24 inches apart in clay soil.
On larger plants, multiple emitters are recommended. A large tree, for example, might need up to six emitters spaced 24 inches apart around the drip line.
Components of a drip irrigation system are small — the tubing, for example, can be one-quarter inch in diameter — meaning they could break easily.
It is also easy to install a drip irrigation system and forget about it, which could be a problem. As plants grow, the amount of water applied needs to be adjusted to ensure they are getting proper amount. And as the seasons change, the amount of water applied must also be altered so plants aren’t getting as much in the winter as they do in the summer.
It’s also important to know the type of water going through the system. Since drip irrigation is a low-pressure system, silt can settle in the tubes and impede its efficiency. Water high in calcium or bicarbonates can also clog the tubes.
“Small tubes are by far the biggest maintenance headache of a drip system,” Stryker says. “It is a good idea to flush out the tubes once a year.”
This article was excerpted. See the July issue of Livescapes for the full article.
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