Every other Friday, the Outside/In team answers a question from a listener about the natural world.
This week, Ned from Cincinnati, Ohio, called in to get the record straight on turfgrass: “Does turfgrass take up a lot of water because it inherently needs that much, or is it because irrigation systems for watering grass are ineffective?”
Rubab Saher, a postdoctoral research fellow at the Desert Research Institute, gave us the short answer: “Even with the finest irrigation system, your grass consumes relatively more water than a smart landscape.”
Turfgrass isn’t just grass that you walk or play golf on — it’s a category of grass characterized by narrow leaves and roots that form a bonded layer of grass and soil. There are a lot of varieties, sorted by the kind of climate that they're suited for: cool-season turfgrass for northern regions of the U.S., warm-season turfgrass for southern areas, warm-season crossover turfgrass… You get the gist.
Having grass on your lawn that best suits your climate ensures optimal water usage. Unfortunately, some of America’s favorite grasses are also the thirstiest, and they’re not always grown in places with enough rainfall to support them.
To be clear: It’s not imperative for you to water your lawn. No matter what variety of grass you choose, you could leave it all to nature and have your lawn feed off of rainfall. It’s just that if your grass doesn’t get enough water, your lawn could become patchy or brown.
That’s why, to keep their lawns green and healthy, many people choose to irrigate their grass. In fact, lawn grass is the most irrigated crop in the U.S. — even more than wheat and corn.
Saher, at the Desert Research Institute, says there are two common ways to irrigate plants: typical sprinkler systems and drip irrigation systems. Saher says drip irrigation systems feed water more slowly and precisely.
“Its efficiency is higher than the sprinkler irrigation system,” she said. “So we would maybe save water by 10% or 15% because of their irrigation efficiency.”
But according to Saher, drip irrigation isn’t usually ideal for watering an entire lawn — so homeowners are left with the inefficient sprinkler method.
Smarter landscapes
As more regions in the U.S. become hotter, drier and more arid, urban planners and researchers — like Saher — are looking to employ environmentally sustainable landscape practices and designs that can sustain cities.
Vegetation, Saher says, “is like the lungs of the cities.”
“If you take it out,” she said, “I don’t think a city can breathe comfortably.”
Since many concrete structures in cities retain heat and raise surface temperatures, Saher says having green landscapes that keep water use low and reduce surface heat can help cities stay cool.
“To compensate for all the concrete structures that we have, we need to have vegetation to mitigate those heating challenges,” she says.
Saher’s most recent research, which targets cities out West, modeled three vegetation landscape designs ranging in water consumption requirements to see which would be the best in both saving water and reducing heat. Her team found that while grass keeps cities cooler, it doesn’t provide any shade and it takes a lot of water to maintain, so the tradeoff for having lawns is not worth it.
Her research shows that “water smart landscapes” — landscapes that use a combination of trees, shrubs and bushes — are far more sustainable for arid regions. They provide a little less cooling than grass, but provide shade for people and take less water to grow.
They’re also more interesting to look at — in my mind, anyway. But the attraction to green lawns is pretty powerful, and getting rid of them can be a tough sell — a point even Saher recognizes.
“I understand the hesitancy… because it has a sentimental value,” she said. “So yeah, there is a psychological aspect to it too, that I feel needs to be more studied.”
If you’d like to submit a question to the Outside/In team, you can record it as a voice memo on your smartphone and send it to outsidein@nhpr.org or call the hotline, 1-844-GO-OTTER.
