Take a little dirt, mix with some shredded tires and presto! You have an athletic field that can bounce back after heavy use.

At least, that's the idea behind the project now under way at what will soon be the new track-and-field facility on Southern Illinois University's Edwardsville campus.

"A Michigan researcher has shown he can topdress established turf with crumb rubber (spread it on the surface) and protect it from traffic damage," says Kenneth L. Diesburg, a turfgrass expert from SIU's Carbondale campus who, with SIUC soil expert S.K. Chong, is overseeing the project.

"Crumb rubber is elastic, so the particles absorb some of the energy from downward pressure and torsion (twisting). That protects the turf's growing points, which are right at the surface."

As crumb rubber works on top of the soil, it might work even better ploughed under, Diesburg believes. Not only could all those shredded tires act as turf shock absorbers, but they could loosen up the soil. That would let more oxygen reach turf roots, making for healthier, stronger grass-and better drainage, too.

"That would help low-budget sports fields and golf courses-they don't usually have drainage fields," Diesburg says.

Illinois' Department of Commerce and Community Affairs has bought into the idea; it's investing a little more than $160,000 to see whether Chong and Diesburg can grow and maintain grass on a mix of soil and scrapped, shredded tires. If they can, they could solve a major environmental headache.

"DCCA estimates that Illinois alone generates 12 million discarded tires every year," Diesburg says.

"Those tires have to be disposed of somehow, but you can't burn them because of air pollution problems, and it's against the law to put them into landfills. If they could be incorporated into sports turf, they'd no longer be a waste requiring disposal-they'd be a resource."

Lab tests run last year by Chong showed the two researchers are on the right track-you really can change soil quality by mixing it with crumb rubber. And if the pair can make grass grow on the playing fields at Edwardsville, they'd pretty much have all the bases covered.

"This field is a silt-loam soil," Chong says. "We're also running these same kinds of field tests at our research plots in Carbondale, which are clay-loam. Most of the soils in this country are silt-loam or clay-loam."

Adds Diesburg, "The soil at Edwardsville is a good one to be using for this research because it's so terrible. There were some areas that were so hard you couldn't scrape them-a big construction endloader would just slide over the top. They tried to establish turf there in the fall of '96-and they couldn't."

Chong used his lab data to decide how big the rubber particles should be and how much to add in the field studies. He settled on testing three grades-fine, medium and coarse-in three different proportions: a 20/80 mix of rubber to soil, a 30/70 mix and a 40/60 mix. Based on Chong's work, Diesburg expects the higher proportions of coarser particles to produce the best results.

Field work at the new sports area, which lies right next to the football field, began last fall. Helped by SIUE Assistant Director for Grounds Mark Shaw, the SIUC researchers sectioned it into test plots, then began tilling in the rubber. Wet weather delays meant tilling took longer than expected, which, in turn, delayed seeding. They hope to finish by March.

Diesburg says it will take about two growing seasons before they can say for sure that this idea works. In the meantime, they face another deadline.

"The assistant athletic director is on pins and needles-he has to have turf to play on in May," Diesburg says.

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