Research Report
The Impact of Turf Fans on Bentgrass Putting Greens Virginia Tech Researchers: David McCall, Turfgrass Pathologist and Research Associate, Camden Shelton and Andrew Landreth, Undergraduate Research Assistants Research Sponsors: Virginia Ag Council and Virginia Turfgrass Foundation (in-kind donations by SubAir Systems, Toro and TurfVu)
The
physiology of creeping bentgrass is negatively impacted during periods of stress, decreasing the efficiency of many plant functions. Creeping bent and other cool-season grasses grow optimally between 50°F and 65°F. Bentgrass root development slows as the soil temperature rises above 80°F, with a loss of functionality at temperatures above 86°F. To mitigate environmental stresses to creeping bentgrass, turf fans are used on many golf courses to provide needed airflow and increase transpiration. With limited data available that does not address the impact of improved
fan technologies with increased air velocity, we designed our research to quantify the potential benefits of turf fans on putting greens. The primary objective was to determine the distal benefits of turf fans on in-play golf putting greens. A secondary objective was to determine the benefits of activating fans earlier in the season to prolong optimal growing conditions.
Our research
As reported in last year’s Research Edition of the Virginia Turfgrass Journal, a pilot study in 2012 on a single putting green indicated that soil temperatures were approximately 6 degrees cooler at 20 feet from the fan base than at 80
feet. This exploratory research provided a strong backbone to support the need for future research. During summer 2013, the spatial impact of turf fans was explored in Richmond, VA. Oscillating 5hp Electric Turf Breeze 50" (TB-50-Premium) (from SubAir Systems, LLC) fans were installed on 6 in-play putting greens. Data were collected from these greens and compared to conditions on three greens without fans. Three fans were activated when soil temperatures consistently reached 70°F for three consecutive days and 18 days later when temperatures reached 80°F for three days. Using historical data, this 10°F increase in soil temperature was
Figure 1.
Figure 2. Figure 3. Figure 1. Soil temperatures (at a depth of 1.5”) were collected every 10 feet from the base of fans and regressed to indicate distal changes across the putting green. Figure 2. Rooting depth measurements were collected every 10 feet from the base of fans and regressed to indicate distal changes across the putting green. Figure 3. Canopy temperatures were collected using thermal imagery with turf fans off (left) and after running for 45 minutes (right). Canopy temperature was decreased by 18°F closest to the fan and by 6°F approximately 110 feet away. 14 | Virginia Turfgrass Journal May/June 2014 www.vaturf.org