New use for old tires: grind them up and toss them on athletic fields

June 18, 2001

GAINESVILLE, Fla. — If anyone is wondering what to do with millions of recalled Firestone tires, a University of Florida researcher has a suggestion: Grind them up and spread them on athletic fields and golf courses.

UF turfgrass specialist Grady Miller said ground-up tires, also known as crumb rubber, could help increase the durability of turf used in high-traffic applications.

“We want to prevent the kind of damage people can cause to turfgrass,” said Miller, an assistant professor with UF’s Institute of Food and Agricultural Sciences. “Turf can be stripped out by cleats in the goal and corner-kick areas of soccer fields and between the hash marks on football fields.

“For golf courses, it’s primarily where carts enter and exit near greens and tees,” he said.

Miller is testing the rubber product on test plots of grass on the UF campus, on a Gainesville-area golf course and several area athletic fields.

In one method, the crumb rubber — and two other compounds being evaluated — are spread evenly over the top of grass, a process known as top-dressing.

In another process called aerification, researchers literally punch small holes in the ground and fill them with test material. Eventually, the products work their way down into the soil layers, where they may deliver the strongest protective benefit, he said.

Miller said after more than a year of study, the crumb rubber does seem to protect grass to some degree. While more research is needed to assess the amount of that protection, the use of the crumb rubber could provide another benefit, he said.

“The fact that we can recycle a waste product like old tires and improve turf condition at the same time is a great thing,” Miller said. “When tires are processed into crumb rubber, the steel belts and all potentially hazardous metals are removed.

“This leaves an essentially inert compound that will stay in the soil and protect the turf for several years,” he said. “We may actually have a different use for rubber that can potentially improve how we manage turf.”

According to Miller, managers and athletes alike would benefit if grass in athletic fields could be made healthier.

“Turf managers would benefit because it might be easier to manage grass which may require less fertilizer or water,” Miller said. “End users would benefit as well in that they may be able to play on better-quality turf.”

During the course of the study, Miller said, researchers noticed an unexpected outcome from using the product.

“The black rubber absorbs a lot of heat,” Miller said, “and last year we noticed a strong greening effect with this particular treatment. This may have been caused by heat transfer from the rubber to the grass early in the spring during the period when grasses are just starting to actively grow.”

In addition to the crumb-rubber product, researchers are evaluating ordinary sand and a heat-treated clay compound Miller said could prove particularly useful in water-starved areas.

“The porous ceramic compound holds water, so there’s been a lot of interest from environmental groups and turf managers,” Miller said. “The goal is to find ways to reduce water use by holding more moisture in the soil.”

Miller said the bottom line is to determine if any of the materials actually help the grass.

“We are still trying to work out the differences between the three treatments and see if one of them has any specific advantage,” Miller said. “One may protect against physical damage better, while another may have better water retention or just may improve grass density.

“When you cover grass with sand, many times it promotes denser growth,” he said. “This may be a benefit of the sand that we don’t see with these other coarser materials.”