Measuring sod strength of Kentucky bluegrass and Supina bluegrass

The extent of root, rhizome, and/or stolon growth determines turfgrass sod maturity. In 1998, at Michigan State University, the Calrochan Sod Puller (CSP) was developed to measure the force necessary to tear a piece of sod. The CSP uses a battery powered hydraulic pulley to provide a consistent pulling force, and is attached to a load cell. In August 1999, sod strength measurements of different turves were collected from the Manderley turfgrass sod farms in Napean, Ontario, Canada. The objective of this investigation was to introduce the CSP as a method for determining turfgrass maturity. In short, sod strength measurements for Kentucky bluegrass increased with sod maturity and maintenance intensity. Results suggested that a minimum sod strength value of 38 pounds (17 kilograms) is necessary before Kentucky bluegrass sod (16 inches x one-half inch) is mature enough to harvest for commercial sod production. The consistency of the sod pull measurements suggest that the CSP is a useful tool for evaluating turfgrass maturity. Applications to other turfgrass research, particularly establishment investigations, are warranted.