Realistic traffic simulation is crucial to the validity of athletic field research. Previously developed athletic field traffic simulators contain studded drums that turn at different speeds, creating shear forces at the playing surface. The Cady Traffic Simulator (CTS) (a modified walk‐behind core cultivation unit) was developed at Michigan State University in 2000. The objective of this study was to compare the magnitude and direction of the forces produced by two traffic simulators: the Brinkman Traffic Simulator (BTS), a pull‐behind unit, and the CTS. Both simulators were operated over an in‐ground force plate, which measured the forces in three directions: front to back, side to side, and vertical. The CTS produced a higher compressive stress and net shear stress when operated in either direction than the BTS. The average peak compressive stress produced by the feet of the CTS when operated in the forward direction was approximately 30 times higher than the combined compressive stresses of both BTS drums. The average peak net shear stress produced by the feet of the CTS when operated in the forward direction was approximately 15 times higher than the combined net shear stresses of both BTS drums. Operating in the reverse direction, the average peak compressive stress produced by the feet of the CTS was greater than five times the compressive stresses of both BTS drums combined. The average peak net shear stress produced by the feet of the CTS was approximately four times higher than the combined net shear stresses of both BTS drums.

Turf use in covered stadiums and other environments with reduced irradiance is limited due to lack of suitable turf species and management practices. This study compared the tolerance of supina bluegrass (Poa supina Schrad.) and Kentucky bluegrass (P. pratensis L.) with reduced irradiance of approximately 1 to 5 mol m−2 d−1 Treatments included trinexapac‐ethyl {[4‐(cyclopropyl‐α‐hydroxy‐methylene)‐3,5‐dioxo‐cyclohexane‐carboxylic acid ethyl ester]} (TE), foliar iron, and simulated athletic traffic inside a covered stadium simulator facility. Analysis of variance showed supina bluegrass was more responsive to TE than Kentucky bluegrass. Trinexapac‐ethyl reduced supina bluegrass clipping yields approximately 60%; Kentucky bluegrass yields were reduced by 20% or less. In non‐trafficked turf, TE increased supina bluegrass tillers by 50% and leaves by 33% but did not change tillering and leaf number of Kentucky bluegrass. Without traffic, TE‐treated supina bluegrass provided an acceptable turf at 10 to 15% solar irradiance for at least 4 to 6 mo, while Kentucky bluegrass and untreated supina bluegrass became unacceptable within 2 to 4 mo. Under traffic, TE‐treated supina bluegrass provided acceptable turf for up to 5 wk, while Kentucky bluegrass did not provide acceptable turf for more than 2 to 4 wk. Trinexapac‐ethyl enhanced supina bluegrass color and increased chlorophyll levels of both species. Foliar applications of iron had negligible effects on all of the parameters evaluated. Supina bluegrass is a useful turf for reduced irradiance situations but requires more than 5 mol m−2 d−1 to sustain traffic for periods longer than 5 wk.

Playing quality of athletic fields is critical to an athlete from the safety and performance standpoints. Use intensity and maintenance practices affect playing surface quality and impact characteristics within and among fields. The objective of this study was to quantitatively assess the effects of cutting height, compaction, soil water content (date), and turf cover on the impact absorption characteristics of Ken· tucky bluegrass (Poa pralensis L.) turf. Treatments were four cutting heights (0 [bare soil), 19, 38, and 57 mm), and two compaction levels (with and without) for Exp. I, and three cutting heights (19, 38, and 57 mm), two compaction levels, and three surface types (full turf, no verdure, and no thatch) in Exp. II. Surface impact characteristics measured were peak deceleration, time to peak deceleration, and im· pact duration. Two hammer weights, 2.25 kg and 0.5 kg, were used to assess impact characteristics on four dates and to obtain data for soil water conditions of0.263, 0.197, 0.163, and 0.064 kg kg-'. The highest peak deceleration values and shortest time periods were as· sociated with the periods of low soil water and compacted conditions. Only the 0.5-kg hammer detected differences in impact absorption characteristics between cutting heights. Significant cutting height-by· compaction-by-date interactions occurred for each impact characteristic, indicating interdependence of one of the factors on another. It appears that field management practices that influence soil water content, soil compaction, and turf cover are more important than cutting height in altering the impact absorption capability of Kentucky bluegrass turf.

The Brinkman Traffic Simulator (BTS) has been a useful tool to simulate sports field traffic. However, rate of traffic stress produced by the BTS, a pull‐behind unit with two differentially connected studded rollers, has been questioned. The Cady Traffic Simulator (CTS), a modified walk‐behind core cultivation unit, was developed and tested to potentially produce more aggressive traffic stress. A comparison study was initiated between the BTS and CTS to evaluate these simulators on a Kentucky bluegrass (Poa pratensis L.) stand. Playing surface data collected were surface hardness, traction, soil moisture, bulk density, porosity, and plant counts. Higher surface hardness, lower traction, and lower plant count values resulted when the CTS applied 10 passes per week (PPW) compared with other treatments. Surface hardness, traction, and bulk density values were statistically similar when the CTS applied 2 PPW, and BTS applied 10 PPW.

Topdressing plays a vital role in turfgrass subjected to traffic. Sand is commonly used for topdressing; under suboptimal growing conditions, however, methods to maintain wear tolerance are limited. There has been recent interest in using crumb rubber from recycled tires as an amendment for turfgrass areas. A topdressing study was initiated in July 1993 to determine the effect of crumb rubber on turfgrass systems subjected to traffic. A factorial randomized complete block design with three replications was implemented with two crumb rubber particle sizes (large, 6.0–2.0 mm; small, 2.0–0.05 mm) and five topdressing rates (0.0, 17.1, 34.2, 44.1, and 88.2 t ha−1) on a 1‐yr‐old Kentucky bluegrass‐perennial ryegrass (Poa pratensis L.‐Lolium perenne L.) stand. In 1993 and 1994, 96 passes were made with a Brinkman traffic simulator. Surface hardness characteristics measured were peak deceleration, time to peak deceleration, and impact duration. The small crumb rubber size was more effective in increasing impact time periods than the large crumb rubber, but had no effect on peak deceleration values. Shear resistance values decreased by as much as 40% as crumb rubber volumes increased in 1993, but were increased by 20% in 1994 after rubber particles had settled to the soil surface. There was generally an increase in turf cover under traffic as crumb rubber rates increased above 34.1 t ha−1, and the small crumb rubber was more effective in 1993. Our results suggest that crumb rubber can alter surface characteristics and increase wear tolerance of turfgrass exposed to traffic.