Sports turf is an important area of turfgrass application. Unlike golf courses, most of the sports turf fields require a more stable playing surface to support the activities of players and facilities, and to provide protection against sports injuries. Playing surface quality is decided jointly by turfgrass and soil media (Canaway and Baker, 1993). Surface quality is usually expressed as friction, traction, stiffness, and resilience when the interaction between the surface and player is the main concern. It also can be evaluated from the ball bounce resilience and rolling resistance or ball speed when information about the behavior of sport facilities on a playing surface is needed (Bell et al., 1985; Baker et al., 1988; McClements and Baker, 1994). Of all the qualities of playing surface, perhaps the safety of the players is the most important consideration when constructing and evaluating a sports field. Many sports injuries are related to varying degree of surface stability (Valiant, 1988; Powell and Schootman, 1993; Waddington and McNitt, 1995). The interaction of several factors may contribute to surface displacement of sand-based fields. Some factors contributing to stability are; rooting, amount of traffic, compaction, sand characteristics, moisture content, shoe and athlete type, and many other factors. It is conventionally thought that a more rounded shape of sand contributes to surface instability and that this could reduce field safety. There is little information that directly relates sand type to field safety. Before any link can be made between sand type and field performance we must gain a better understanding of the role that sand shape plays in surface stability, even in the absence of grass and roots. The objective of this study is to evaluate the relative importance of sand particle size, particle-size distribution, particle shape and roundness, plant roots and root-zone water content in the stability of a sand-based sport field surface.

The study is established on an existing sand-based sports turf area at the Horticultural Research Station. The root zones were excaved from to form 5 X 10 ft plots 15 cm deep. Five treatments, Hallett mason sand, Hallett concrete sand, Sidley Proangle sand, Bunker white sand, and Hallett mason sand + 15% soil (v/v) were filled in the plots and compacted with a vibrating Whacker. The experimental design is a randomized complete block, with three replications.

Sand particle size, particle-size distribution, particle shape, and roundness was analyzed before the application of materials to the plots. We will measure the water content by TDR, penetration by a penetrometer, surface hardness by a B&K 2500 vibration equipment, traction by a torque wrench which is set on a disk-shaped football cleat. Bulk density will also be measured each time we measure the above parameters. We will seed and sod the plots with Kentucky bluegrass later on to evaluate the contribution of plant roots in the surface stability.

At this time, we are able to see the differences in stability between different treatments without the factor of plant roots. Particle shape and roundness seem to play a role but together with the other factors. Detailed analysis will be reported later this year.