Wise watering keeps West from withering

By Barbara Maynard
Correspondent

Back to Gardening Articles List

Sprinkler systems have come a long way since the tractor-shaped sprinklers that follow the hose around the yard. Today's sprinkler systems can turn themselves off in the rain, automatically add fertilizer, or even drip water underground directly to roots.

All of these innovations can save precious water in the rapidly growing Front Range, according to Stephen Mill, owner of SprinklerMill, Inc., in Fort Collins. Mill addressed about 25 people at the Fort Collins Senior Center on March 3 as part of the city's 2004 Environmental Program Series.

"Sprinklers can be a tool for saving, not wasting, water," Mill said.

Efficient lawn watering not only eases the strain on limited water resources, but it also leads to healthier plants. Over-watering leaches nutrients from the soil, encourages the growth of fungus, and attracts pests.

"More plants die from over-watering than from under-watering," he said.

People considering a new sprinkler system have several options. Conventional systems are based on pop-up heads that spray water over a prescribed area. Drip or low-volume irrigation systems are the most efficient means of watering trees, shrubs and even hanging baskets, because they apply water directly to the root zone. These systems can be rolled up for the winter and re-laid each spring, so their inherent flexibility adapts easily to changing garden layouts.

The newest option is subsurface irrigation - pipes with tiny holes along their lengths buried 4 to 5 inches underground. The result is essentially drip irrigation suitable for turf. Even though the system is installed underground in rows approximately 16 inches apart, subsurface systems can be installed in existing lawns. According to Mill, subsurface systems use 55 to 75 percent less water than do conventional systems.

To prevent tree roots from growing into the pores in the piping, the system uses a filter impregnated with the herbicide trifluralin. Water carries the herbicide throughout the pipes at a concentration just strong enough to deter roots from entering the pores. Once the water leaves the plumbing and spreads through the soil, the concentration of herbicide is too low to damage roots.

High-tech sensors

Both new and existing sprinkler systems can be made more efficient by the addition of one or more high-tech sensors that turn programmed sprinkler systems off or on at strategic times. Rain sensors, for example, allow the system to skip a watering if there's sufficient rainfall.

"It drives me crazy when it's raining cats and dogs, and sprinklers are running," Mill said.

Wind sensors are similar--there's no point in watering if it is too windy, because water doesn't land where it is needed. Moisture sensors assess soil moisture, and shut off the system if no more water is currently needed.

Perhaps the most sophisticated sensor is an ET, or evapotranspiration, controller. Evapotranspiration refers to the amount of moisture lost from soils and plants, and therefore provides a measure of how much water plants need. ET controllers compute the amount of water needed at a given time, based on historic weather patterns and current data downloaded from weather satellites, and adjust the sprinkler program accordingly.

Because properly fertilized lawns need less water, Mill said, "fertigation" --adding fertilizer directly through the irrigation system--can also save water.

Before installing any system, Mill advises people to plan, plan, plan. "You can save a lot of water with good planning," he noted.

Part of the planning process includes learning about xeriscaping and considering the likely uses of a yard. Perhaps unusual for someone who makes his living selling and installing sprinkler systems, Mill encourages people not to install turf where they won't use it, such as in the front and side yards.

"It is much, much easier to create a less thirsty landscape if we plan at the beginning," he said.