Turf research to identify drought tolerant grasses

Texas

It's a turf battle, and the "combatants" are various Central Texas turfgrasses. Numerous turf types and cultivars will be denied water for 60 days to evaluate their drought recovery potential. Only the fittest will survive.

To establish this research, Texas Cooperative Extension specialists in soil and crop sciences and agricultural engineering entered into an agreement with the San Antonio Water System Conservation Program and the Turfgrass Producers of Texas.

Earlier this year, researchers discussed methods that would meet San Antonio Water System needs for developing turfgrass recommendations. Through their trade organization, turfgrass producers provided sod, as well as input on the types of grasses to be evaluated.

Ultimately, 25 types or cultivars of grasses were chosen for the two-year-plus study. One buffalo grass, eight Bermuda grasses, seven St. Augustine grasses and nine zoysia grasses were selected.

"We needed to set up a field research site where we could test the drought tolerance and recovery of grasses in the San Antonio area," said Dr. David Chalmers, Extension turfgrass specialist and one of the principal investigators for the study. "It was also important that these results could be put to practical use by our research partners."

During August and September, team members constructed a research site south of San Antonio and sodded plots with 25 grasses. Grasses were planted on 4 inches of native soil over an impermeable plastic barrier. Washed sod was used to reduce differences in rooting from the soil on the sod.

Later this year, a 5,000-square-foot shelter will be built on the site. The shelter will act as a barrier to rain in order to maintain a consistent 60-day drought period. After that period, the grasses will be irrigated for 60 days to allow for recovery. Each grass will be evaluated during the drought period and the recovery period.

"Drought studies are scheduled to begin in July 2006 on the grasses we've already planted," said Roger Havlak, the Extension turfgrass specialist in charge of data collection and plot maintenance. "The same set of grasses will be planted in a second set of separate plots in September 2006 to repeat the 60-day drought cycle, beginning in July 2007."

Grasses will have been established for more than nine months before the 2006 drought treatment, he said. And data from the 2006 study will be used to produce a list of drought-tolerant grasses.

"This data will be helpful because the City of San Antonio has passed a conservation ordinance that addresses new turf installation that is supposed to go into effect January 2007," Havlak said. "The ordinance will require new home construction to have at least 4 inches of topsoil before a lawn is established, and that's the amount we used in our plot testing. It will also require that during new home construction, landscapers plant grasses most likely to survive a 60-day drought. Of course, it's imperative that this is all based on good science."

Similar drought conservation measures may be adopted in other municipalities where water conservation is a priority, Chalmers said.

"This study and similar studies that may come after it will be a good thing for turf in Texas," he said. "We will have practical, science-based data that will allow for better turfgrass selection and to help promote the conservation of water, which is a vital resource for our state."

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The first phase of construction for a research site to identify drought-tolerant grasses has been completed. Beginning next year, research on the tolerance of 25 types and cultivars of grasses for use in the San Antonio area will be tested and evaluated using 60-day drought trials. (Texas Cooperative Extension photo by Roger Havlak.)