Ground tires help absorb chemicals.
The researchers have shown that ground tires can absorb excess chemicals from fertilizers and pesticides, preventing them from leaching into groundwater and contaminating the surrounding environment.
Golf courses are designed to improve playability, not environmental impact, says Jae (Jim) Park, a professor of civil and environmental engineering at UW-Madison. Park is aware of the unintentional side effects of the fertilizers and pesticides applied to the golf-course greens to keep them looking green. These products contain chemicals that trickle into groundwater sources and contaminate the surrounding environment, he says.
"Because many greens are built near groundwater levels or wetlands," explains Park, "it is vital to consider the mitigation of environmental contamination caused by the pesticides and fertilizers applied to golf courses."
Used tires could provide a barrier, according to the new research led by Park.
Park has been studying the characteristics of tires for the last 12 years. In that time, he and his colleagues have shown that tire chips--ground-up pieces of this rubber material--can absorb harmful organic compounds from the environment. The findings, he says, suggest that they could be used as landfill barriers to prevent the leaching of pollutants into the ground.
Tire chips' ability to block these pollutants led Park, civil and environmental engineering graduate student Bob Lisi, and horticulture professor John Stier to consider another application: placing ground-up rubber beneath chemically treated golf-course greens.
In the latest study, he and his team found that tire chips can absorb nitrate--one of the main chemicals in fertilizers.
For the study, the researchers inserted tire chips between layers of sand and peat root mix and gravel, both of which are commonly found beneath golf-green turf. The researchers conducted their studies both in the lab and on the field. While the field sites were seeded with a grass, the lab samples were left bare.
To test the ability of the tire chips to absorb chemicals, the Wisconsin scientists applied water spiked with different concentrations of nitrate to each sample. Then, they measured the concentration that seeped out of the bottom gravel layer.
The main goal of the experiments, says Park, was to determine if the rubber layers would filter out chemical compounds carried in the water without affecting the health or quality of the grass.
In all experiments, the researchers found that the rubber layers did absorb the compounds. Compared to the control samples, the lab experiments released 17.9 and 21.7 percent less nitrate, respectively, after one year of testing. During this time, the rubber layers in the field released 23 and 58.6 percent less nitrate, respectively.
Based on the experiments, Park says, "Excess amounts of fertilizer will be absorbed by ground tires. They'll be trapped right there instead of traveling." Over time, he adds, soil microbes will remove the nitrate from the rubber layer, which could remain intact for years.
As part of the current study, Park and his colleagues visually assessed the quality of the field plots from seed germination to the end of the sampling period. Turfgrass quality, color, density, or germination rate did not appear to be affected, he says. He adds that about one year later there was no significant difference in grass quality or density among the three putting green profiles, suggesting the rubber layer did not alter the turfgrass.
Besides absorbing chemicals harmful to the environment, Park says the characteristics of tire chips make them even more attractive: they're lightweight, allowing for easier transportation and installation; they absorb shock, possibly alleviating foot pains of golfers; and they trap heat, promoting turf and root growth longer into autumn and earlier in spring.
But, above all, he says, "The technology reuses a waste material that's hard to dispose while it protects the environment."
For more information contact Park at 608-262-7247, email@example.com.