Compass Minerals’ Protassium+ fertilizer contains two essential nutrients, potassium and sulfur, says Dr. Larry Murphy, owner of Murphy Agro and consultant for Compass Minerals. Sulfur is right up there with N-P-K in acting out a prime role for sustaining turf health. “It is an essential nutrient and actually used by the plant in almost the same quantities as phosphorus,” he says. It makes up 17 percent of Protassium+.In the North, South and Transition Zone, superintendents can benefit from sulfur, which synthesizes proteins and produces chlorophyll, Murphy says. “A plant consumes a large portion of the energy that is stored as sugar and produced with the involvement of chlorophyll,” Murphy says. “It uses a lot of that stored energy.”
Superintendents who use potassium sulfate products are less likely to have issues with tip burn than those who use potassium chloride products, which might give members an unwanted surprise for a period of time before crew mow again, says Dr. Michael Goatley, professor and extension turfgrass specialist at Virginia Tech.
Still, as with other turf management practices, precision and care are required to incorporate potassium sulfate into the soil profile to avoid potential monetary losses. A number of issues can present themselves when making a potassium sulfate application, from missed opportunities to water in, to granule segregation, to instances when mowers can, as Goatley says, “pick up your investment with your mower and cart them all away.”
Typically, superintendents would want to make their potassium applications by the time November arrives and turf is beginning to enter dormancy, versus after they have blown out their irrigation or when rain has ceased to fall, Goatley says. “My thinking with potassium would be, ‘Let’s make sure that plant has everything it needs before that cold weather arrives,’ because once that horse is out of the barn it’s out of the barn, so we want to make sure our plants are primed and ready to go with plenty of potash nutrition,” he says.
Granule segregation is a possible issue for superintendents who apply Protassium+ with other products, Murphy says. Those superintendents will get the best return on their investment if they make sure those products are compatible in size with the Protassium+ granules. The granules come in different sizes, including 220 SGN for roughs and fairways, 140 SGN for fairways and tees and 90 SGN for greens.
Improved mowing technologies and new grasses that tolerate low mowing heights could adversely affect superintendents in situations where they apply granular fertilizers, because mowers could pick up those granules more easily, Goatley says. To avoid such issues, superintendents applying granular fertilizers can maximize budget efficiencies by pairing potassium applications with other cultural practices, such as aeration. “The expectation is—and matter of fact the performance will be—that those are going to stick around longer in the rootzone and feed those roots and ultimately the shoots as those roots explore deeper,” he says.
The manpower required to make a fall fertilization is relatively small, says Dr. Cale Bigelow, professor of agronomy at Purdue University. “At the end of the day, it’s not a lot of labor,” he says. “Whether you have someone that’s mowing an area or fertilizing an area, you still have somebody out there and the grass does slow down. But the important part is to fertilize in the fall. This has been probably the most stressful summer for folks since 2012, so making sure people are able to feed the plant, get the plant healthy and vigorous again, that’s really key this fall.”
Patrick Williams is a GCI contributing editor.