Drip irrigation is economical and effective

By Angela O'Callaghan

Wednesday, Jan. 28, 2009 | 1:31 p.m.

Checking an irrigation system can seem like a daunting task. It can be especially so for those who came to the Mojave Desert from other regions where irrigation is generally provided by precipitation.

In the desert Southwest, having water drop down freely from the sky is a somewhat rare event. Even when it happens, our soils are often so dry that water bounces off, rather than seeps into the soil. For this reason, Mojave gardeners need to provide that essential nutrient, water, usually through built-in irrigation systems. Even desert plants need a certain amount of water, and it is only through these artificial means that we can keep our arid landscapes alive.

Drip irrigation is a wonderfully water-thrifty method that was originally designed for growing vegetables in the Negev desert in Israel. We have adapted it, more or less successfully, to all manner of perennials, shrubs and trees.

Unfortunately, some people treat landscape plants as if they did not need to be provided with adequate water on a regular basis; as if the skies were going to take care of their plants' water needs. These people will often rely on occasional hand watering with a hose if they notice plants are failing. The problem with that method is that it generally results in only the top couple of inches of ground becoming moist, with the deeper root system remaining parched.

Others simply ignore the irrigation system that came with their house and do not attempt to delve into the mysteries of clocks, valves and emitters, as if it would be better to ignore it all, like ignoring the scary, possibly crazy neighbor across the street. They instead will permit the irrigation to come on and off as it was originally programmed. This method may seem simple, but, in addition to being against Southern Nevada Water Authority rules, it can result in too much water applied during the winter, or not enough during spring and summer.

It can also mean that problems go undetected, leading to the death of valuable landscape plants.

Examining the irrigation system does not require a degree in hydraulic engineering by any means. As in so much else, to paraphrase the great Yogi Berra, "You can see a lot just by looking."

Drippers are all marked with the amount of water they will emit over an hour — rarely is it less than one-half gallon per hour; most emit fewer than five gallons per hour. This is how one determines how much water a plant should be receiving when the system is working at full capacity. With such a low amount of flow, it is possible for emitters to become clogged with clay and salt. Do not wait until a plant begins to wilt or lose leaves before becoming taking steps. Before temperatures rise to our summer averages, turn on the drip system and see if all the emitters are actually releasing water. If not, simply replace the faulty dripper; this is easy.

At the Cooperative Extension office, we have information on drip and other forms of irrigation available by calling the Master Gardener help line at 257-5555.

Angela O’Callaghan is the area specialist in social horticulture for the University of Nevada Cooperative Extension. She can be reached c/o the Home News, 2360 Corporate Circle, Third Floor, Henderson, NV 89074, or [email protected].