Sustaining grass during drought-restricted watering schedules
Lush, green lawns may not be possible during drought-restricted watering schedules, but sustaining and maintaining their grass is something homeowners can do with proper management, according to a Texas A&M AgriLife Research expert.
The Texas Commission on Environmental Quality estimated approximately 1,000 Texas public water systems imposed water restrictions during the 2011 drought. Such water restrictions frequently limit homeowners to a two-day-per-week watering schedule.
Jim Thomas, AgriLife Research senior research associate, and Leslie Keen, with Naiad Water in Conroe, worked with a study this summer to determine what such a schedule might do to a lawn's condition.
"When you are under drought restrictions, you have a limited time to water," Keen said. "We wanted to visually see how the grass looked with water restrictions, because this can sometimes be a concern with homeowners and homeowner associations."
The study at the Texas A&M Turfgrass Field Lab in College Station compared irrigation timing and sprinkler-head types in an effort to provide guidelines for meeting the two-day-per-week watering schedule and maintaining a healthy turf.
The turf plots utilized in this study were established in the fall of 2010, Thomas said. Previously, these six turf plots planted to St. Augustine and Bermuda grasses were watered half on a four-day-per-week watering schedule and half on a two-day-per-week watering schedule, applying a full inch of water per week.
In the 2012 research project, all six turf plots were set to a two-day watering schedule with a reduced total of water applied, and the researchers compared four different sprinkler heads: spray, MP rotator, rotors and sub-surface drip.
"Coming out of last year, what we wanted to do this year was to simulate a drought and only run two days a week," Keen said. "Instead of putting a half inch of water on each of the two days, we also decided to only apply one-quarter inch and one-third inch on the watering days."
The study determined that if the grass started out healthy, "you can irrigate twice a week using less water than normal and the grass will survive," she said. "You will have less green, but it will respond when water is applied. But we need to stress, you have to start with a healthy lawn first."
The comparison of sprinkler heads/systems showed the best outcome occurred under drip irrigation, followed by the turf watered with spray heads, the MP rotator heads. The poorest performers were the rotor heads, the two said.
"No matter which system you have, you need to adjust it correctly so you don't have overspray on the street or other concrete," Thomas said. "Focusing on the efficiency of how you irrigate is key."
In the typical residential situation, he said, irrigation systems are often not properly adjusted to just hit landscape. In those situations, as much as 35 percent to 50 percent of the water can be lost to runoff.
Another key, Thomas said, is timing of the water application.
"Large cities don't restrict how much water you can put out, they just restrict how many days a week you can irrigate," he said. "If you try to apply half an inch of water in a half hour, it can create quite a bit of runoff."
He suggested using a cycle-soak system, where a small amount of water is applied and allowed to soak in and then a second amount is applied and allowed to soak in, thus minimizing runoff of the valuable water and nutrients that might be applied to the grass.
"Even a poorly installed system that is properly scheduled is going to do a much better job," Keen said.
"All this takes homeowner input," Thomas said. "You can't just set the system and six months later come back and check on it. You have to watch what is happening when the water is being distributed."
Most residential controllers can have multiple start times, the two said. They can be programmed to apply water at multiple times in one day, allowing a person to lower the application at each watering.
Another finding of the study: Brown does not always equal dead.
"It may be tapering off and going dormant due to lack of water, but dead and dormant are not the same thing," Thomas said.
Keen said the green color of the grass will respond to rain, even it if has turned a little brown.
"Even if you have had to stress it further than normal, if it still responds to rain, it is still alive," she said. "The color might not always be acceptable to homeowners, but if it was healthy, it will be able to recover once the drought restrictions are lifted."