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Researchers seek turfgrasses that thrive on salty water

The contrast is evident in the 1.5-acre checkerboard of grass plots near New Mexico State University's golf course. One square of grass, about the size of a kitchen table top, is abundant with thick, vigorous grass.

Bernd Leinauer, right, Extension turfgrass specialist at New Mexico State University, discusses the progress of turf research being done at NMSU with, from left, research specialists Elena Sevostianov, Cody Robertson and Ty Barrick. (NMSU Agricultural Communications Photo by Darrell J. Pehr)

An adjacent plot, grown under identical conditions, is almost barren, with a single clump of grass stubbornly clinging to life. NMSU's Bernd Leinauer, a turfgrass specialist for the Cooperative Extension Service, points out runners from the lively plot of grass have encroached into the neighboring plot.

The plots are among 22 different varieties of turfgrass planted about three years ago in a research project designed to test the effect of low quality, salty water on the grass. Three types of water - potable water as a control, saline water provided by NMSU's Office of Facilities Services (OFS) and a 50-50 blend of saline water and potable water intended to mimic effluent water - are used to irrigate the plots.

The results vary depending on the variety of grass. The nearly barren plot 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. "That seems to be a grass that shows promise," Leinauer said.

Why attempt to grow grass with low quality, salty water? In New Mexico, much of the ground water supply is salty, and large reserves of underground water around the state are generally untapped because they would have to be treated to be usable - an expensive process. Effluent water from municipal wastewater treatment systems also 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.

Leinauer's research also looks at the plants' ability to withstand temperature fluctuations between seasons and even between day and night. In some parts of New Mexico, like the Gallup area, daytime highs can drop 60 degrees to nighttime lows.

"That is extreme for any plant," Leinauer said.

So far, the research plots have tested the ability of the turf, whether seeded or planted with sprigs, to become established in one growing season and then survive through the first winter. Now, Leinauer, with the help of graduate student Casey Johnson and doctoral student Yoshi Ikemura, is looking at the long-term viability of each species, an important consideration when deciding what to plant in a yard or park with an expectation that the grass will grow well for many years.

Two species are showing particular promise: seashore paspalum and inland salt grass, a native New Mexico species that grows on rangeland and along the banks of the Rio Grande. Inland salt grass is exceptionally well-suited to salty conditions and is very cold tolerant.

"It can withstand water at salinity levels close to sea water," Leinauer said. Two varieties of bermudagrass, NuMex Sahara and Princess 77, both bred at NMSU, also are doing well in the salinity tests.

NMSU's reputation as a research facility for salinity testing is growing, and Leinauer's research recently expanded into a five-acre test site near the NMSU football stadium, which is being developed with support from OFS and the Water Resources Research Institute. Part of the test site will be planted with grass from seed companies that have contracted with NMSU to conduct salinity research.

"We have the capability to really screen turf grasses for salt and cold tolerance," Leinauer said. In addition, NMSU is conducting national variety trials for Kentucky bluegrass and tall fescue, which include 100 different varieties of each species. NMSU was one of numerous universities that competed for the chance to host the trials. These trials, as well, test for salinity tolerance.