Golf Course Management

JAN 2018

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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100 GOLF COURSE MANAGEMENT 01.18 one that maintains firmness, drains quickly, does not easily erode from slopes after moder - ate rainfall or irrigation, and is sized similar to those used for sand-based root zones so when it is splashed onto the putting surface, it does minimal damage to the mowing equipment when picked up during mowing and does not negatively impact the composition of the sand-based root zone over time." Rules of thumb Golf course architect Jan Bel Jan, who is based in Jupiter, Fla., says, within all of those criteria, her general rule of thumb in select - ing a bunker sand is to choose the "same sand you'll use to topdress." But even with that rule of thumb, the USGA research cites several criteria for sand selection, including particle size and shape, which determine whether sand is too uniform or too soft and will produce washouts or fried- egg lies. "You need a variety of particle sizes," says Bel Jan, a member of the American Society of Golf Course Architects and a 22-year member of GCSAA. USGA recommendations for root-zone sand mix and the research on bunker sand line up for particle size distribution. A ma - jority (at minimum, 60 percent) of the sand particles in the bunker-sand mix should be medium and coarse sand in the 0.25 to 1.0 mm range. No more than 20 percent should be fine sand (0.15-0.25 mm), and less than 10 percent should be very fine sand, silt or clay (0.002-0.15 mm). At the opposite end of the spectrum, less than 10 percent should be very coarse sand or fine gravel (1.0-3.4 mm). "Some bunkers have a crust on them. You walk through and leave holes like poking into a pie crust," Bel Jan says. Bunkers that crust generally have too much silt or clay in the sand mix. Particle shape is also important. Bel Jan says having sand all the same "spherical shape, like marbles" is undesirable. Instead, she says, "The more angles it has, the better it stacks. The better it stacks, the less it will wash. It will Golf course architect Jan Bel Jan says superintendents should choose the same type of sand for bunkers and topdressing. Photo courtesy of Jan Bel Jan be more stable and prevent the fried-egg lie." The USGA research measures shape by ex - amining relative sharpness of the edges (an- gularity) and the overall shape (sphericity, or roundness). "These characteristics can have a strong in - fluence on surface firmness and resistance to erosion," the USGA report says. "For example, a low-sphericity, very angular sand generally has a high surface strength and would likely stay in place in bunker faces. By contrast, a high-sphericity, rounded sand is more likely to be soft and more prone to erosion during reg - ular maintenance or following irrigation and rainfall events." Sand type, source and amount The material the sand particle is made of should also be evaluated. The USGA re - search says silica sand is "preferred since it re- sists weathering and retains its original shape longer." While other materials may be suit - able for bunker sand use, the USGA research warns that "limestone sands are more prone to

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