Your biggest fan

The dreaded combo platter of high heat and high humidity that Mother Nature serves up each summer throughout much of the U.S. used to be a sure recipe for indigestion for golf course superintendents, particularly those charged with keeping bentgrass greens healthy. Today, thanks to improved technology in the development and use of both above-ground fans and sub-surface systems, superintendents and their greens’ root systems can breathe easier in August.

“Fans have revolutionized the superintendent’s ability to maintain bentgrass greens at a different level than they used to,” says Mark Langner, director of agronomy at the FarmLinks research and demonstration golf course in Sylacauga, Ala. “Come July 1st, bentgrass greens are in ICU, and even Bermudagrass can have heat stress in a low air movement environment. Rain is our nemesis in the South, but we figured out that by using fans, we could keep our greens dryer, and with sub-surface systems, either vacuum or pressure-based, we can also either heat or cool the root zone as needed.”
 

Winds of change

While they are relatively small in relationship to the amount of turf they’re charged with cooling, fans can lower greens surface temperatures by as much as 10 degrees Fahrenheit and soil temperature by 4 to 6 degrees Fahrenheit, according to a study by David McCall of Virginia Tech University.

In addition to reducing moisture left over from morning dew, fans increase transpiration by cooling the turfgrass plant internally. Interestingly enough, there is some disagreement among agronomists, even within the USGA, as to whether the primary benefits of fans are cooling or drying, but regardless, the air movement generated is beneficial. Chris Hartwiger, director of the USGA’s Course Consulting Service, for instance, refers to the process as “evaporative cooling,” which he says is not really drying, but instead assists plants in evaporating moisture from the plant stoma in excessively wet or humid conditions.

Superintendents have a variety of options for dealing with greens turf stress during periods of high heat and humidity, depending on the number and surface volume of greens affected, the availability of electrical power for installed fans and, of course, the size of the maintenance budget. Some high-end courses have as many as 40 installed permanent fans while others have only one or two for consistently problematic greens areas and obviously many courses have no installed fans at all, especially if they’re in low-humidity climates.

Other courses, due to either limited need or limited budgets, make do with one of a variety of portable fan units available, which can cover a variety of problem spots and do not require access to a permanent power source.

Others are even more low-tech and less expensive, sometimes using a Buffalo blower or a trailer-mounted turbine blower just to get some air movement across the greens.

Technique can also be used to get sub-surface air movement with USGA-spec greens, by plugging the outflow for the sub-surface drainage and blasting air into the other end, Langner says. Regardless of the technology used, superintendents and agronomists are in agreement that any air movement in hot and humid conditions is better than nothing.

Alex Stuedemann, superintendent at the TPC Deere Run facility in Silvis, Ill., which hosts the annual John Deere Classic, has wall-to-wall bentgrass turf and the hot and humid Midwest summer to manage. He has recently added another permanent fan to the four TurfBreeze fans installed at Deere Run in 2006, and purchased a portable, gas-powered fan, as well.

“We utilize the fans on the saddles of our problem putting surfaces from May to August, and we recently purchased a TurfBreeze portable because we have some greens that are enclosed by the stands and other structures for the John Deere Classic,” Stuedemann says. “We just use it on those greens that challenge us on air movement, but if we get heavy rain and heat, we use all the technology we’ve got at our disposal.”
 

Where, when and for how long?

As is the case with much of the discussion about the use of fans for cooling/drying of greens turf, there are a number of opinions regarding the length of time that greens fans should run. Many turn the fans on at the onset of the summer heat and humidity and leave them on until those conditions abate. Hartwiger, though, suggests “in all but the most extreme cases, it’s probably not the best bang for the buck to run (the fans) 24 hours (a day).”

Deere Run’s Stuedemann is in the 24-hour club once he turns the fans on for the summer, barring a significant drop in temperature and humidity. On the other hand, it isn’t costing the course an inordinate amount of money to run the fans.

“Our power cost, using 220 single-phase power, is about $70 a month per fan,” Stuedemann says. “For the portable fan we bought, it uses 10 gallons of fuel every 14 hours, so there’s a higher daily cost with it, but on the other hand, it cost $10,000 to get power to the permanent fan that we installed last year because it needed almost 1,000 feet of wiring. You need to consider the proximity to a power source when you’re considering installation costs.”

Once the decision has been made to purchase a fan, or multiple fans, the next question is where to install them. The things to consider are the power source, the coverage necessary and the golfers. As Stuedemann notes, the distance from the power source necessary to operate a permanent fan can make a big difference in initial cost, in large part due to the cost of the copper wire needed for conductivity.

The fan will also need to be located in a spot where its air flow will reach the problem areas of the green, ideally traveling at a speed of at least 3-4 mph across the affected surface. The prevailing wind direction at the affected site will factor into this, as well. Superintendents can measure the length of airflow coverage in a variety of ways, using engineering flags at intervals across the green, smoke bombs or other indicators, combined with more high-tech devices such as infrared thermometers or soil probes.

The other consideration is the player: Is the fan directly in the line of sight of approaching players or distracting in any way? On the other hand, as Andy Masciarella, owner and president of fan manufacturer Precision USA says, “When the green looks good, the fan goes away.”

While some courses prefer to run permanent fans around the clock in the summer, others either don’t require that level of air movement or have to moderate their run times to accommodate nearby residents who object to the noise at night or in the early morning. Some newer models can be programmed to turn off and on according to irrigation cycles and moisture levels. Additionally, some are available which are less noisy than earlier fans.

At the end of the day, superintendents strive to do as the USGA’s Hartwiger suggests, namely to “find a balance between what is good for the grass and what is good for golf.” Fans can help to achieve that balance when humans and plants alike are sweltering.

Jim Dunlap is a writer based in Encinitas, Calif., and is a frequent GCI contributor.