Evaluating New Methods for Measuring Putting Green Surface Characteristics.

Managing golf course putting greens requires appropriate and continual balancing of plant health with playability. Precisely and objectively quantifying key features of putting surfaces such as moisture content and firmness are important in understanding the interactions between weather conditions, maintenance practices, and the demands of play. For moisture content, the FieldScout TDR300 is a quick, accurate, non-destructive, portable device which determines volumetric water content (VWC) based on the travel time of an electromagnetic wave along waveguides (rods) inserted into the soil. However, sampling depths are limited by a minimum length of the rods necessary to reliably produce accurate readings. The current minimum rod length for portable TDR meters is 3.81 cm. For surface firmness, a new device from Spectrum Technologies - the TruFirm Turf Firmness meter was compared to the Clegg Impact Soil Tester (CIST). While both devices involve dropping an impact hammer from a prescribed height, the TruFirm meter measures the maximum penetrating depth of its hemisphere-shaped hammer into the putting green and the CIST measures deceleration upon impact. The objective of this research was to evaluate the ability of newly adapted technologies to measure putting green moisture content and firmness at the playing surface. In order to measure VWC within the uppermost 1.2 and 2.5 cm of putting green samples, the penetrating depth (rather than overall length) of the 3.81 cm TDR rods were reduced and all readings were taken in microseconds, while VWC of each sample was calculated by weight. Three TruFirm and CIST readings were taken in each plot.

Regression analysis produced linear prediction equations relating the modified TDR readings in microseconds to VWC % at 1.2 and 2.5 cm depths with R² values = 0.90 and 0.98 respectively. For surface firmness a negative linear relationship between TruFirm measurements and CIST readings was observed (R²= 0.5398).