KINGSTON, R.I. July 2, 2008 Standing in a greenhouse at the University of Rhode Island, Rebecca Brown was smiling even though it appeared that something had gone terribly wrong. Almost all of the 16 species of grass she planted last February in hundreds of small pots were dead.
The associate professor of turf science wasn't surprised. That's because the pots had been sitting in increasingly saltier water for five months, and few varieties of grass can put up with that environment.
Her aim, with funding from the Rhode Island Department of Transportation, was to identify a salt tolerance limit for native and ornamental turf grasses in hopes of finding a variety that can be used along highways without being killed when roadway salt mixed with melting snow is splashed onto the grass.
"The grasses we use in our lawns and along the roads in Rhode Island aren't adapted to salt, and they don't adapt over time because we don't allow them to go to seed," Brown said. "And salt tolerant western grasses may not grow well here because our salinity is only seasonal -- in the winter the grass has to survive the road salt, but during the rest of the year salt isn't a factor because our soil doesn't hold the salt."
So she used an ebb and flow hydroponics system to pump salt water into trays of grass to ensure consistent salt levels, starting with 2,500 parts per million of salt in February and increasing it by 2,500 parts per million every other week. In June, when the trials ended and most of the grass was dead, the salt concentration in the water was 22,000 parts per million, which is two-thirds the level of seawater.
Brown was pleased with the results. She pointed out a few tiny blades of green grass amidst the carnage, most from a variety of alkali grass that is known to be somewhat salt tolerant, as well as a couple samples of tufted hair grass and one red fescue.
"That one must have good genes," she sai
|Contact: Todd McLeish|
University of Rhode Island