Tony Koski dreams in green: a beautiful green carpet of grass that grows very slowly, needs very little water or fertilizer, doesn't get ugly when the kids romp on it, and stays green and healthy despite disease and drought. Koski's not the only one dreaming it. Turf managers and grounds keepers at corporations, city parks, schools, and golf courses all wish that Koski's dream could become a reality. Of course, anyone concerned about the environment loves Koski's dream with its implications of reduced fertilizer and pesticide use. And homeowners would love the hundreds of thousands of dollars that could be saved with lower water bills.
"We're working on it," says Koski, turfgrass researcher and associate professor in the Department of Horticulture and Landscape Architecture at Colorado State University. These advances don't come easily, though — especially since there are so many variations in Colorado soils, turfgrass use, water quality, availability, and price.
"It's impossible to prescribe one kind of grass or one kind of watering scheme that solves all problems," says Koski.
It has been said that the lawn is America's biggest contribution to landscaping. The endless green carpet continues across property lines and on for miles through subdivisions, suburbs, and even entire cities. Colorado is no different. Yet here, in the West, there are other considerations — mainly, the scarcity of water. During the. growing season, average Colorado residents devote anywhere from 40 to 60 percent of their domestic water use to lawns and gardens. Add this to Colorado's skyrocketing population growth, and you can see an enormous problem taking shape in Colorado's future.
Koski's team of turfgrass researchers is looking under every leaf, so to speak, for ways to head off crises. A summary of their findings:
Contrary to popular belief, the larger, more massive root systems of some Kentucky bluegrass varieties don't make them more drought resistant. The best drought-resistant varieties have a greater percentage of their roots more deeply rooted in the soil. Deep rooting often depends more on soil structure and variety characteristics than on management techniques, Koski says.
Leaving clippings on the lawn during mowing doesn't lessen water requirements, but does partially recycle nitrogen and other nutrients. Annual fertilizer needs were reduced by as much as 30 to 40 percent.
A plant growth regulator called trinexapac-ethyl or TE could improve the ability of Kentucky bluegrass to resist traffic damage like that sustained on sports fields. Because TE reduces vertical shoot growth, its use on golf courses reduces clipping production 40 to 55 percent. That alone can provide significant savings in wages, equipment, and maintenance. It does not, however, reduce water use.
Studies on Kentucky bluegrass, tall fescue, and buffalograss show that buffalograss can provide acceptable lawn quality when irrigated with just 35 percent of the water recommended for Kentucky bluegrass. Also, current irrigation recommendations for Kentucky bluegrass may be overstated; acceptable quality may be obtained with 10 percent to 15 percent less water than most people use now.
Frequent, light irrigation may produce a higher quality bluegrass turf than the current practice of less frequent, heavy irrigation. Koski cautions that this finding flies in the face of what has been taught for many years and that more research is needed before he recommends changing watering practices.
Koski says these results don't mean they have all the answers for the perfect green carpet. "It does mean that we have some answers that get us closer, considering resources, environment, and desires of people — and that's what research is for."
In the meantime, he'll just keep on dreaming.