Athletic fields require a turfgrass species that can withstand traffic and recuperate from wear. In cool-season environments, Kentucky bluegrass (KBG) and perennial ryegrass are the species of choice. Conversely, bermudagrass is used extensively in warm-season environments. This presents a problem for turfgrass managers in the transition zone region of the country where no turfgrass species is ideally suited for growth. Regular use can take its toll on athletic fields. As traffic continues, wear patterns can develop, especially if the turfgrass cover has entered winter dormancy and no longer actively growing.
Crumb rubber is a product made from recycled automotive tires. Past studies have shown that topdressing crumb rubber over actively growing turfgrass can improve wear tolerance and prolong the playability of these fields. Our objectives were to determine the wear tolerance of four turfgrasses in the transition zone with and without crumb rubber topdressing under simulated athletic field conditions, and to determine if improved cool and warm-season turfgrass species can be used for transition zone athletic fields.
To test this, four different turfgrasses, Tifway hybrid bermudagrass, Riviera and Quickstand bermudagrasses, and Thermal Blue hybrid Kentucky bluegrass were evaluated with and without crumb rubber topdressing to determine the wear tolerance of each species under simulated athletic field traffic in the transition zone. In this area, bermudagrass is often used on athletic fields because of its wear tolerance and recuperative potential. These attributes make Tifway hybrid bermudagrass a good choice for athletic fields, but cost and cold tolerance limit its use in the transition zone. Riviera bermudagrass is an improved common bermudagrass cultivar that is similar to Tifway bermudagrass in density and overall quality. In addition, it has greater cold tolerance and can be established from seed, but wear tolerance and recuperative potential of Riviera had not been determined.
One of the issues concerning the use of bermudagrass in the northern parts of the transition zone is the loss of color and active growth as it enters winter dormancy in the fall. To account for this, sports turf managers often overseed to provide an actively growing turfgrass cover throughout the fall athletic season. Unfortunately, overseeding is not an option for all athletic fields due to budget limitations. As a result, these athletic fields are subjected to significant wear during periods when active growth does not occur.
Recent advances it turfgrass breeding efforts have introduced new turfgrass cultivars that have potential for use in transition zone athletic fields. Most KBG varieties do not perform well in the transition zone due to a lack of tolerance to heat, drought, and disease. Texas bluegrass (TBG), mainly a forage grass, demonstrates higher levels of heat and drought resistance relative to KBG, but has poor turfgrass quality. Thermal Blue is a hybrid of these two species and possesses genetic traits from each species allowing it to survive the hot, humid summers of the transition zone and provide an actively growing turfgrass surface during the fall athletic seasons.
To test these turfgrasses under simulated athletic field wear, the Cady Traffic Simulator (CTS) was used. The CTS is a walk-behind Jacobsen core cultivation unit with artificial feet to simulate athletic wear. Two passes with the CTS is designed to generate wear equivalent to that sustained during a football game between the hash marks and the 40-yard lines.
The four turfgrass species were subjected to 1 (low traffic) or 3 (high traffic) simulated games per week. Timing of traffic applications was established to mimic fall high school football schedules. Plots receiving crumb rubber were topdressed twice with 10/20 mesh particle size crumb rubber to achieve a depth of 0.75 in.
Results
Hybrid bluegrass (HBG) retained its color and provided an actively growing turfgrass surface after bermudagrass plots had entered winter dormancy. Riviera and Tifway bermudagrasses were more tolerant to wear than Quickstand. Quickstand consistently ranked lowest in percent cover, which shows that Riviera, Tifway, and HBG are better suited for athletic fields. Crumb rubber proved to significantly reduce the amount of wear sustained during traffic events. All plots receiving crumb rubber treatments had improved turfgrass cover at the end of the season than those not receiving crumb rubber topdressing.
Crumb rubber provided a more resilient turfgrass surfaces, reducing the amount of athletic field wear as a result of traffic. By retaining the amount of actively growing turfgrass cover, crumb rubber provided a safer playing surface. This study has introduced a new management practice for transition zone athletic field managers use to improve the overall performance and longevity of their fields.
Matt Goddard is a graduate research assistant in turfgrass weed science at Virginia Tech. Dr. John Sorochan is an associate professor in turfgrass science & management at The University of Tennessee.