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Irrigation

As a rule, irrigation systems are not utilized to their full potential and are operated inefficiently. Research has shown that on the average, irrigation systems have inefficiencies running in the 50% range. This means that one out of two gallons of water applied during the irrigation is wasted.

When we irrigate, we replace the water used by plants and soil since the last irrigation or rainfall. This water loss is measured at the rate of evapotranspiration (ET). Evapotranspiration rates increases by changes in temperature, humidity, wind velocity and sunlight. During hot summer months, evapotranspiration is greater than during the cool winter months.

Since hot temperatures and highwinds evaporate water very quickly, never irrigate at noon or when the wind is blowing, wait until the wind is calm and when the temperature cools down before applying water. This way, the plants can take advantage of the irrigation. In our region, the best time to irrigate is after 6:00 P.M. or early in the morning before 10:00 A.M.

Generally, people do not know how long they should have their sprinkler systems. Experts agree that we need to apply one inch of water every time we irrigate.

Infrequent, deep irrigation builds strong, deep, drought tolerant root systems. Frequent, shallow watering invites disease and the development of a shallow root system that is more susceptible to heat and drought.

To determine how long it takes to apply one inch of water, you need to do a can-test. Collect several empty cans, such as tuna or cat food cans. Distribute the cans in the area receiving the irrigation. Turn the system on and measure the time it takes to fill most of the cans with one inch of water. This will be the amount of time needed to run your sprinkler system the next time you water. Although, the El Paso Water Utilities and Las Cruces allow homeowners to water three days a week, you might only need to water twice a week during the summer months and less frequent during the spring, fall and winter.

If the cans have different volumes of water, your system is applying more water, unevenly over the same amount of time. This causes dry spots and wet areas in the grass. This condition is called poor uniformity. Call a professional licensed irrigator to modify your system to improve distribution uniformity.

Additional measures to improve irrigation system efficiency

The following information is included to provide you with suggestions and information on irrigation systems technology. For a well maintained and designed system, contact a professional irrigator to evaluate your system.

Controlling excess irrigation

A very simple method of conserving water is to control controlling water runoff. Runoff occurs when the water applied is not absorbed quickly by the soil. At the beginning of the irrigation, soils tend to absorb water more rapidly. As the soil gets saturated, the infiltration rate decreases. If water continues to be applied, runoff will occur. This translates into water waste. Sometimes it is necessary to apply irrigation water in short cycles to allow for water penetration.

Use low volume irrigation systems for those special areas

New irrigation technology allows us to apply precise amounts of water needed by plants in order to thrive. Low-volume irrigation, or drip systems, are creative and efficient irrigation solutions to the challenging landscape designs. It is no longer necessary or acceptable to irrigate trees and planting beds with high volume turf spray, impact and gear-drive sprinklers. Simply open the arc of spray or using rotor heads to water planters and beds is wasteful, creates hazards on walkways, stains buildings and fences. Promotes plant disease and pest problems. It also violates our municipal water conservation ordinances.

Low-volume irrigation systems can be divided into four categories: drip for hanging baskets, shrubs, and trees; bubblers for shrubs and trees; micro-sprays for ground covers such as ice plants and ferns; emitter-line for vegetable gardens, closed plant rows and planter boxes; and rings for large pots and containers and loops around large trees.

Benefits and considerations when selecting a low volume irrigation system

  • Allows the design of hydro zones. Placing plant material with similar water needs together.
  • Provide pinpoint water applications in precise amounts.
  • Enables designers to accurately match precipitation rates with plant water needs and soil infiltration rates while directing root growth and establishment.
  • Bubblers or micro sprayers are more appropriate for coarse soils. Single point emission devices with low flow rates are better suited for loams or fine clay soils.
  • Always consider water quality as small orifices tend to clog up with sediment from irrigation water with high nutrient or mineral loads. Always install a filtration device.
  • Always install a pressure regulator. It will prevent non-threaded pipe from blowing apart as this systems usually work under a 25 psi pressure limit.
  • Always consider pedestrian traffic, cultivation practices, vandalism and maintenance levels.
  • Drip emitter systems can cut water use by up to 50%
  • Efficient for narrow or odd-shaped areas such as median strips and planting beds.
  • Dry foliage reduces fungus and mildew.

Install an irrigation controller that offers multiple programing and cycles

The brains of an irrigation system is the irrigation controller which controls irrigation frequencies and duration. A controller that is not adjusted properly is one of the sources of water waste. There are many styles and models that allow us to program cycles, times and frequencies. Some are equipped with moisture sensor devices and raingauges as additional features to control unnecessary irrigation.

Why is it important to have an efficient irrigation system? The primary reason is that water is in limited supply and we cannot tolerate waste. Water suppliers are increasing the price of water so it is everybody's responsibility to utilize it without wasting it. With limited water sources and increases in use, it is extremely important that landscapes and irrigation systems are designed and responsibly maintained.

Last updated: March 24, 2008