Moderating surface hardness and rotational traction of natural turf community-level football fields in drought

Excessive surface hardness and high rotational traction are two factors linked to non-contact injury risk in football. Soil moisture has the greatest influence on surface hardness. However, irrigation was prohibited on the majority of sports grounds during the recent drought in Australia, leading to the closure of many grounds for safety reasons. In the absence of irrigation, this study investigated alternative agronomic strategies to moderate hardness. Turfgrass coverage prevented excessive hardness even on a drought-affected, compacted native soil profile, and the conclusion was that turf managers should select turfgrass species that best sustain full grass coverage. Without irrigation in southern mainland Australia, only a C4 grass such as bermudagrass (Cynodon dactylon and hybrids) could do that. However, epidemiological research in Australian football had concluded there was a higher risk of knee injury on bermudagrass compared with perennial ryegrass (Lolium perenne), which was attributed to bermudagrass having a higher rotational traction. In replicated plots in this study, bermudagrass actually had significantly lower rotational stiffness than perennial ryegrass on four out of eight assessment dates, and the mean rotational stiffness of bermudagrass was never higher than that of perennial ryegrass at any assessment. There appeared no reason to recommend against the use of bermudagrass on the basis of rotational traction. In fact, there were greater differences in rotational traction due to other agronomic factors, especially variation in grass cover. Once again, the study concluded that turf managers should select the turfgrass species that best sustains full grass cover over the whole ground and through the whole season