It rained Saturday morning as landscaping volunteers dug hundreds of holes for a water conservation research project in San Antonio's Southside.
Mud-caked shoes and shovels slowed the work pace, but didn’t diminish enthusiasm as more than 30 volunteers from Bexar County and beyond began planting the outdoor laboratory at the heart of the Drought Survivability Project of Texas A&M University’s Institute of Renewable Natural Resources (IRNR). Its goal is to learn how little water is needed for drought-tolerant plants (a.k.a. xeric plants) to survive and remain attractive.
Residential landscaper Charles Bartlett, president of Green Haven Industries, Inc., happily lent his expertise and strong back to the planting effort.
“This is the first time we’ll have scientific evidence showing us just how little water is needed to sustain a wide variety of plants that grow well in San Antonio soil and climate,” Bartlett says. “Up to now, we’ve had to rely on our own experience.”
Here’s how the study will work. Two identical beds of 100 common landscape plants are located on either end of a large structure called a drought simulator, said to Calvin Finch, Ph.D., one of the lead researchers and director of the Urban Water Program for the IRNR. A galvanized metal roof is positioned in the middle. When rain falls, the roof automatically moves to shield the plots being tested under drought conditions. Thirty minutes after the rain stops, the roof moves back.
Once planted, the four beds will be watered well for three months to get them established. After that, researchers will subject each bed to different levels of drought conditions. At the extremes, one bed will receive only rain and one will receive the amount of water now recommended for drought-tolerant plants from rain plus drip irrigation. The other two plots will receive water levels in between those extremes.
The land for the study is owned by San Antonio Water System (SAWS) and is located next door to its Leon Creek Wastewater Treatment Plant on Mauerman Road. SAWS Conservation Project Coordinator Mark Peterson said utility personnel from many departments have been at work since last spring to repair the simulator, install drip irrigation to water the 1,600 plants and remove vegetation from the plant beds. He sees a number of ways that SAWS will be able to use the research findings.
“If SAWS needs to limit outdoor watering, we will know how much we can restrict without hurting and killing plants,” Peterson said. “We are confident the research will support our belief that you can keep drought-tolerant plants alive and looking attractive if you water only four to 11 times a year.”
Peterson said SAWS recommends that property owners do not water xeric plants as long as they receive an "effective rainfall" (between 1/4 of an inch and one inch) twice a month. Peterson notes that San Antonio received three inches of rain in January.
“No one should have watered their yard,” he said.
Another partner, the San Antonio River Authority (SARA) is “particularly interested in plants that are suitable for rain gardens and bioswales which alternate between wet and dry conditions,” said Steven J. Raabe, director of technical services for SARA. Bioswales are drainage courses with gently sloped sides that are filled with vegetation and compost to remove silt and pollution from surface runoff water.
How did researchers come up with the 100 plants for their list? Amy Truong, an extension assistant with the Urban Water Program, surveyed the scientific literature and a committee of experts in San Antonio and Austin weighed in on the final choices. The list includes all the plant types found in a varied landscape beyond turfgrass and shade trees: small trees and shrubs, perennials, vines, groundcovers and grasses. Anyone planting this spring could choose from this list with confidence that the plants will tolerate at least moderate drought.
Click here to download the full list.
Landscaper Bartlett notes that this information is helpful not only to homeowners and businesses who want to conserve water, but also to those who are unable to water their property consistently because of travel, absentee ownership, poor health, disability, or lack of access to outdoor water.
Initial findings for the study are expected early in 2016. The Drought Survivability Study is funded by the SARA, SAWS and the cities of Austin and Georgetown. Later this year a similar field study will be conducted in Georgetown, where a simulator is being built.
Saturday’s workday succeeded in getting half of the 1,600 plants in the ground. A second workday is scheduled for Saturday, Feb. 7 at 8:30 a.m. If you can volunteer, please email Calvin Finch (firstname.lastname@example.org) with the number of people in your group, or feel free to come alone. Refreshments will be provided. He will send you details about where to meet and what to bring.
*Featured/top imageL Behind the folks planting is the drought simulator roof that quickly moves over the plants when rain begins so that plants only receive the water provided as part of the experiment. Photo by Karen Stamm.