UF research: Homeowners can cut irrigation without hurting lawns
GAINESVILLE, Fla. — With drought persisting across the Southeast, homeowners can slash water consumption by simply readjusting irrigation systems – with no harm to lawns or landscaping plants, a new study finds.
UF agricultural and biological engineering researchers spent more than two years monitoring 27 homes in Florida whose automatic irrigation systems had been set to different schedules. Their conclusion: Homeowners can cut water consumption by a third simply by readjusting the system to more closely coincide with soil moisture levels — a step made increasingly easy by more readily available moisture sensors and other technology.
“We set out to ask, if homeowners adjusted their systems, would they see a savings compared to homeowners who made no changes?” said , an associate professor of . “The answer was ‘yes.’”
The study appears in the September-October issue of the Journal of Irrigation and Drainage Engineering.
With Georgia, North Carolina and Alabama in the grips of a severe drought and Florida continuing to suffer from drought as well, the region’s dwindling water supply has become a prominent and controversial topic in recent months.
Many advocates argue that stepped-up conservation would solve or go a long way toward addressing what appears to be a chronic shortage. Residential irrigation is an obvious target: Nationwide, according to Dukes, at least 50 percent of household water gets dumped on lawns and plants. In the homes he studied, irrigation accounted for 64 percent of total water use, a common percentage, he said.
Dukes said the new study appears to be the first to quantify how adjusting residential irrigation systems could reduce water use in homes in the Southeast.
Researchers installed meters on 27 homes with automatic sprinkler-based irrigation systems in three Central Florida counties starting in January 2003. Although automatic irrigation systems are uncommon in older homes, most homes built today come equipped with the systems, Dukes said.
On nine homes, graduate student Melissa Haley reset the irrigation controllers monthly to account for historical rainfall and rates of evapotranspiration. Evapotransipiration is the process by which plants transpire water and soils shed it via evaporation. The goal of the resets: to apply only as much water as the lawn and plants needed.
With nine more homes, the researchers replaced sprinklers with precise micro- or drip- irrigation systems on ornamental plants in a substantial portion of the landscape. They left the last nine homes untouched.
Two and one-half years later, the results were clear. Homeowners whose controls were reset monthly slashed water use 30 percent, saving an average of 13,000 gallons per month — enough to fill up approximately six swimming pools each year — compared with homeowners with unaltered systems. Homeowners whose controls were reset, and whose sprinkler irrigation systems were replaced with drip irrigation, used half the water.
Equally important, there were no problems with brown lawns or dying plants on either of the more water-saving yards. “We did monthly to bi-monthly quality ratings of the turf grass, and there weren’t any differences on any of the homes,” Dukes said.
Homeowners with both automatic systems and traditional sprinklers can take advantage of the findings, Dukes said.
He said that most homeowners seemed to vary the amount of water they apply with only a few adjustments during the year. While that may appear to make sense, an immediate change in the weather can easily be missed.
Homeowners instead can copy the approach used in the study, setting up controllers based on guidelines developed from historical rainfall and plant water use rates. For help, Florida residents can consult the Florida Automated Weather Network site as the “Urban Irrigation Scheduler” ().
But another approach is to purchase soil moisture sensor and evapotranspiration controllers. Related research by Dukes shows that the moisture sensor controllers can reduce watering by as much as 69 to 92 percent, he said. (.)
The St. John’s River Water Management District funded the research at a cost of $220,000. John Fitzgerald, project manager, said “reducing the amount of water…also tends to help condition your landscape for periods of lower rainfall. In other words, training your landscape…helps prepare it for Florida’s inevitable drought conditions.”