Seeking Salt-tolerant Turfgrass

By Darrell J. Pehr

Two adjacent squares of grass, each about the size of a kitchen table top, clearly show how well different grass varieties respond to a steady diet of salty water at a 1.5-acre research plot near New Mexico State University’s golf course. One square is covered with thick, vigorous grass. The adjacent square, grown under identical conditions, is barren except for a small clump of grass. Bernd Leinauer, turfgrass specialist for NMSU’s Cooperative Extension Service, points to runners from the lively square of grass that reach into the barren square.

The squares are among 22 varieties of turfgrass planted about three years ago in a research project to test the effect of lowquality, salty water on grass. Three types of water – potable water as a control, saline water provided by NMSU’s Office of Facilities Services and a 50-50 blend of saline water and potable water intended to mimic effluent water – irrigate the plot.

The nearly barren square was planted with tall fescue, a cool-season grass often used in residential landscaping. The vibrant, salt-loving grass – seashore paspalum – was discovered growing on a Hawaiian golf course.

Why attempt to grow grass with lowquality, salty water? In New Mexico, most groundwater is salty, and large reserves of groundwater are untapped because treatment would be so expensive. Effluent water from municipal wastewater treatment systems is limited in how it can be used. But using poor quality water for yards, parks and recreation fields is a way to save better water for human consumption.

Salts not only affect the plants’ ability to grow but can also alter the soil structure, causing pores to collapse and preventing root growth.

“Having salt-tolerant plants only addresses part of the issue; monitoring the salt content in the root zone is equally important to protect a soil’s structural integrity,” Leinauer said. “If salinity builds up beyond a soil’s threshold to promote root development, even the most salt-tolerant plant cannot survive.”

The researchers also are developing ways to measure salt build-up in the root zone.