U works to develop salt-resistant grass for winter

Minnesota’s climate hits all extremes, leaving little more than brown grass on the roadsides come spring. But researchers at the University of Minnesota are working to discover which grass best survives the salty, humid, icy and construction-prone roadsides of the state.

Brett Troyer, erosion and stormwater management engineer for the Minnesota Department of Transportation, said the agency approached the University’s Department of Horticultural Science in 2009 with the problem.

“We always had a problem with salt-tolerant sod on our roadsides,” Troyer said.

Eric Watkins, assistant professor of horticultural science, told MnDOT about new varieties and seed mixes, Troyer said.

Watkins received a four-year $175,000 grant from the Local Road Research Board, a group based in Roseville, Minn., that regularly works with MnDOT in improving roadside conditions, to research salt-tolerant turf grass mixes. The study began in 2010.

LRRB member and Roseville city engineer Deb Bloom said the grant funding comes from a small percentage of the state gas tax.

Bloom said the two most important goals of the research are to find ways to satisfy the customer and to save money.

When construction is done on roadsides, it’s a major inconvenience to home and business owners, “so we want to make sure we get it right the first time,” Bloom said.

The research being done at the University will help engineers throughout the state do their jobs more efficiently by decreasing the number of replanting projects necessary, therefore saving money, she said.

Josh Friell, a graduate research assistant, is in charge of the day-to-day research for the project. Friell said the researchers already discovered more efficient turf mixes than MnDOT currently uses.

The hundreds of mixes are tested both indoors and on roadside plots. Researchers do much of their research in greenhouses on the St. Paul campus and along Larpenteur Avenue.

The goal is to find mixes that survive winter’s cold and salt exposure as well as the heat and humidity of the summer. Researchers judge the success of the grass by how thick it remains and whether it stays green, Friell said.

MnDOT plays a large role in the project by helping researchers find roadside sites for planting. The agency uses the research recommendations to decide on changes for sod mix standards, Troyer said.

“Everyone has this conception of turf grass as perfect home plots and golf courses ‚ but there are so many other places it’s used,” Friell said.

Indoors, researchers have designed a sample pallet, holding hundreds of mixes of turf grass. They planted the grass in pots of sand, supported by a nutrient solution containing everything the turf needs to survive, Friell said. The nutrient solution is altered by increasing the sodium content, and then each pot of grass is studied for its reaction.

Outdoors, four plot locations are planted with the same turf grass mixes. These are measured in the spring and fall for reactions to weather conditions throughout the year. Friell said it’s ideal that the indoor and outdoor results match, leaving them with the most salt-tolerant mix.

Friell explained that each species of grass contains several varieties, which change the characteristics of each grass mix. For example, the alkaligrass performed well in the study for salt tolerance, which is the study’s main focus, but performed terribly for most other conditions, such as heat exposure.

So far, Friell said, variations of fine fescue have been the most tolerant mixes overall.

The first year showed which seeds worked best, Troyer said. The second year of research will be focused on which mixes create the most efficient balance.

The researchers will meet with MnDOT to discuss the results from the first year of research and determine which mixes can be used right away.