Applied and Research Potential for USGA Soil Firmness Tester.

Soil strength, also referred to as soil consistence, is a measurement of a soil’s resistance to deformation.  Over the years several methods or devices, like bulk density, penetrometers, and the Clegg Impact Soil Tester (CIT), have been used to evaluate mechanical soil strength or firmness.  Penetrometers and the CIT offer a method of testing turfgrass surfaces without substantial surface disruption but there has been debate as to testing technique and meaning of data.  Additionally, limited research has indicated soil type, turfgrass cover, thatch, and moisture content influence readings, but in depth investigations into these influences is lacking.  The United States Golf Association (USGA) has introduced a new device (name to be determined) to test surface firmness specific to golf course playing surfaces.  The technology behind the USGA tester is similar to the CIT with several significant improvements.  The missile on this device has a hemispherical face, replicating the dimensions of a golf ball, and has been calibrated to simulate the impact energy and momentum of when a golf ball interacts with a surface.  Furthermore, the data collector is equipped with a GPS and software that allows for a time history of the impact.  Acceleration is integrated with velocity to provide a penetration depth or relative firmness, firmer surfaces are associated with a shallower penetration depth.  The device and its data have been use at several professional golf events and have influenced turfgrass management decisions, especially related to irrigation.  This tester has not been used in replicated field trials under controlled conditions, however, opportunity exists for further research to begin developing a standardized scale for turfgrass surface firmness.  This presentation will present the type of data generated by the USGA tester and the anecdotal interpretations of these data.  Furthermore, research needs and opportunities for calibration by turfgrass scientists will be discussed.