device to measure turfgrass load bearing capacity under field conditions

Turfgrasses can bear some weight before they are crushed. This load bearing capacity (LBC) provides a cushioning effect that protects crown tissue from a certain degree of traffic injury and its subsequent stress. The more LBC a turf has, the less potential traffic injury may be expected. A device was designed, constructed, and tested under field conditions to measure turfgrass LBC. The LBC device was constructed to be lightweight and easy to handle. Operator-applied pressure compressed the turfgrass canopy to a predetermined endpoint. The resistance required to reach this endpoint was measured as force (N 45 cm(-2)) by a load transducer. Values were converted to kN m(-2). The device was used to measure LBC of mature turfs of 'Texoka' buffalograss [Buchloe dactyloides (Nutt.) Engelm.], 'Parade' Kentucky bluegrass (Poa pratensis L.), 'Kentucky 31' and 'Mustang' tall fescue (Festuca arundinacea Screb.), and 'Meyer' zoysiagrass (Zoysia japonica Steud.). The LBC device successfully separated turfgrasses species and cultivars. Zoysiagrass and buffalograss had the highest and lowest LBC values for the species tested, 10.7 and 1.19 kN m(-2), respectively. Intraspecific differences of tall fescues were successfully separated; 'Mustang' at 3.28 kN m(-2) had a greater LBC than 'Kentucky 31' at 2.27 kN m(-2). More testing is needed to assess the ability of the LBC device to detect potential differences among cultural practice treatments, like mowing heights and nutritional rates, and screening turfgrass selections for stiffness and rigidity.