COLLEGE STATION — The drought and soaring temperatures in Texas have homeowners and farmers alike scrambling for more information about how to water more efficiently. Some help is on the way with a new potential evapotranspiration (PET) site on the World Wide Web.
The site contains summaries of daily weather and PET data from a number of special weather stations located in Central and South Texas, according to Dr. Guy Fipps, agricultural engineer with the Texas Agricultural Extension Service.
The site includes a calculator which allows the user to determine actual irrigation water requirements of crops and turfgrasses, he said.
The information has already been used in during a summer project at four middle schools in San Antonio, the site of one of the weather stations.
Karen Guz, research coordinator for the Master Gardener program, said students participating in the “Get Set,” (nicknamed “Water in the ‘Hood”) program used the data to water 10 feet by 10 feet plots at different evapotranspiration rates.
“It’s a nice applied science project,” Guz said. For homeowners, the PET allows them to save water — especially important in these areas where voluntary rationing and alternate watering days are the norm, she said.
It’s estimated that people overwater their grass by 40 percent to 50 percent, she said. The PET allows them to calculate how much water has been removed from the soil under the grass.
Fipps said, “For crop growers, irrigating with PET should boost crop production and maximize water use efficiency.”
Evapotranspiration is a measurement of total water needed to grow plants and crops. It includes evaporation from the soil and water used in photosynthesis and which is transpired by plants, he explained.
The Web site — a project of the Extension Service’s water conservation and quality initiative team — is the only one of this type that Fipps is aware of the United States.
“There are a lot of sites that provide weather information but only a couple that provide information on the water requirements of plants. As far as I know, we’re the only one that is providing PET information as well as crop and turf coefficients and the calculator,” he said.
“The Internet is the quickest and least expensive way to get this information out to growers during this drought,” Fipps added. “Over the next few months, we hope to work out cooperative arrangements with water management districts and utilities to provide for local dissemination of PET data for users who do not have Web access.”
In addition to San Antonio, the weather stations that are “on-line” are in College Station, San Benito, San Juan, Harlingen and Medina County. By adding a planned “link” to the North Plains PET Network later this summer, the Web site will effectively cover about half of the 6 million irrigated acres in the state.
Site coordinators hope to add weather stations in Stephenville and the Seymour Aquifer area later this summer.
When the drought breaks, the San Antonio Master Gardeners hope to experiment with the PET data in order to find out exactly how much water grass needs in that area. In particular they want to know whether the grass needs all of the water that was removed, or if it can look good replacing only three-quarters or even half of the water used.
“Even if we could get people to replace only the water that’s lost, that would be a big savings,” Guz said.
The Web site may be found at http://www.agen.tamu.edu/wqit/pet/pet.html.