Researchers at Oregon State University believe they've come up with a winning formula for making putting greens fast and healthy – and they have the numbers to prove it.
They examined different rolling and mowing techniques on annual bluegrass putting greens and found that golf balls rolled the farthest when the greens were mowed daily and rolled immediately afterward. The balls traveled an average of 11 feet when rolled at a controlled speed, which was 15 inches farther than on grass that was only mowed daily, not rolled.
The next greatest distance, an average of 10 feet, was on plots that were rolled daily but mowed only four days a week.
The study is important because the grass was mowed at a higher-than-normal height, which kept the grass healthy and vibrant and proves that putting speed can still be fast on taller grass.
According to the United States Golf Association, the putting greens at most American golf courses have ball-roll distances of seven to 12 feet. The organization considers a ball roll distance of 8.5 feet "fast" for regular course play and 10.5 feet fast for championship events.
A 2010 online survey by the organization found that of 227 golfers who expressed a preference on green speeds, 218 preferred to play on greens where the ball rolled between 9 and 11 feet. Also in the survey, 451 course maintenance workers out of 476 who expressed a preference said that that same distance provided the best compromise between healthy turfgrass and golfer satisfaction.
The OSU study tested a variety of treatments on 60 turfgrass plots at OSU's Lewis-Brown Horticulture Research Farm near Corvallis. Other treatments in the study included mowing daily and rolling Mondays, Wednesdays and Fridays; rolling daily and mowing Mondays, Wednesdays, Fridays and Saturdays; and alternating mowing and rolling.
Rolling greens smoothes the putting surface. Researchers in OSU's study rolled plots with a 1,140-pound electric roller and an 845-pound gas roller. While both provided about a 1-foot increase in ball roll distance compared to non-rolled plots, there was no difference in ball roll distance between the two rollers.
Researchers mowed all 60 grass plots at a height of 0.15 inches, well over typical golf course mowing heights of 0.10 to 0.125 inches, said OSU turf grass specialist Rob Golembiewski, the study’s author. The turf was cut at 8 a.m. with a walk-behind greens mower. Green speed was measured at 9 a.m. and 2 p.m. each day. Distance measurements were taken using a Stimpmeter, an aluminum bar that applies a known velocity to a golf ball.
Mowing turf very short to increase ball roll distance has become standard practice, Golembiewski said, but that can potentially damage the grass. The study shows greens can be fast without being cut so short that the health of the grass is compromised, providing a happy medium between golfers' expectations and the interests of course supervisors, he said.
"Now we’re showing you can receive ample ball roll distance at a higher height of cut, which means less stress on the turf," said Golembiewski, who holds the N.B. and Jacqueline Giustina Professorship in Turf Management at OSU. “In the long run, that translates into a much healthier turfgrass stand.”
The findings mirror results from similar studies on creeping bentgrass, which is the most popular turfgrass used for U.S. putting greens. Annual bluegrass, the focus of OSU's research trial, is more common in the Pacific Northwest and has been relatively unstudied, Golembiewski said.