Water, weather sensors make irrigation efficient
By Cherry Sokoloski
North Forty News
Back to Gardening Articles List
Water sensors just make sense in times of drought. That's the gospel being
preached by Brent Mecham, landscape water management and conservation specialist
for the Northern Colorado Water Conservancy District. His job is to research
and test different devices that can help homeowners better manage the water
used for lawns and gardens.
In these times of scarce and expensive water, there is increased interest
in technology that can help reduce the waste of this resource. "There are
more sensors available now than ever before," Mecham said.
Once the systems are set up they're automatic, but they do require some
fine-tuning to work effectively. People who are mechanically inclined can
usually install their own, and some irrigation companies are trained to
help with the job.
Rain sensors, the simplest of these devices, cost between $40 and $75,
while the soil moisture sensors and climate controllers are in the $200
to $300 range. All must be used with automatic sprinkler systems.
Sensors vary widely
Rain sensors have shut-off devices that interrupt irrigation if it's raining.
They're affordable, so there's a short payback period. "Cities and school
districts should be putting these on every clock," Mecham said, since it's
too expensive to send out personnel to shut off sprinklers. A rain sensor
can be mounted anywhere it will be hit by rain but not by sprinklers.
Soil moisture sensors are somewhat more complicated to install, but the
principle is the same: when the soil is sufficiently moist, the sprinkler
system will not run. Some involve running wire from the control box to
a soil probe, while others use valve control wires that are already part
of the system. A light on the device indicates when the lawn needs water.
With soil moisture sensors, it's important to put the probe in an area
of the lawn that is typical of the entire landscape, neither too dry nor
too wet. The advantage of these sensors, said Mecham, is that "the roots
know for sure if they're thirsty or not."
These days, a person can get as sophisticated as he wishes when it comes
to sensors and controllers. More complicated equipment, which is based
on evapotranspiration, or ET, actually makes irrigation decisions in terms
of how much to irrigate.
"They're starting to be kind of smart," Mecham noted, and the price of
equipment is directly related to its IQ. Less expensive equipment requires
more involvement and adjustment by the homeowner.
With some controllers, historical weather data is already programmed in,
and the controller will adjust the amount of water according to the month.
If the homeowner programs in the run time he wants in July, which typically
has the hottest temperatures, then other months will have shorter run times.
Some controllers have their own weather sensors, and others are tied into
nearby weather stations via satellite. These more complicated systems will
water on days that the owner programs, but the run times will vary depending
on the weather.
Most homeowners don't really know whether their sprinkler systems are set
up as efficiently as possible, or how much water the sprinkler system is
delivering. Mecham recommends having an audit done, which is free for those
using Fort Collins Utilities water. Homeowners themselves can calculate
how much water is being delivered - information they need in order to program
a sensor-based controller. For a brochure describing Mecham's measuring
method, call the conservation district at 667-2437 and ask for the Lawn
Watering Guide. The district also has information on its web site about
how much water is needed on any given day, in any northern Colorado community.
To access this, go to www.ncwcd.org, then click on "weather/ET info."
Choosing and using the appropriate sensors can be a challenge. To learn
more about the wide variety of irrigation sensors and controllers available,
Mecham suggests the following web sites:
Mecham predicts sensor-based controllers will be standard equipment on
sprinkler systems, allowing homeowners to better manage Colorado's limited
water resources.
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