Playing Through
by Dave Koch
Republished from Golf Course Management magazine, September 1999.
Most superintendents have a turf trouble spot - a nagging problem that defies solving and lingers like a bad headache. I'm no exception.
Horsham Valley Golf Course is an 18-hole public course in suburban Philadelphia. Constructed in the late 1950's the course hosts some 50,000 rounds a year. The Poa annua/bentgrass push-up greens are small, averaging less than 4,000 square feet. Years of topdressing and aerification have created a 3-inch rood zone that's clearly separated from the push-up clay beneath it. This forms a stratification of sorts, with sterile soil and little microbial activity in the clay base.
None of the aerification methods we've tried over the years to modify the soil has been effective in banishing stratification without bringing on a whole new set of headaches. "Pulling cores" relieved compaction and gave us proper aeration, but we ended up with holes up to 2 inch in diameter that took a month to heal. Our members and players were not happy.
When we tried the "drill and fill" approach, the holes were almost an inch in diameter. This resulted in serious scarring problems and generated dissatisfaction and some loss of revenue. We knew we had to find another solution.
We seriously considered renovating the greens but for a public course, this kind of expense and the potential for lost revenue are frightening. This idea died quickly at Horsham.
Then I saw a video about a machine from Land Pride called DryJect, which was designed to aerate, amend and top-dress in one step and then allow for immediate play on a smooth surface. The DryJect service features a row of seven high-pressure injectors, which blast an aeration hole about the size of your little finger through the root zone. Both the spacing (from 3 inches to 10 inches) and the depth (from 1 inch to 10 inches) are adjustable. The machine uses a patented venturi system to pull up to 8 cubic feet of topdressing material and/or soil amendment per 1,000 square feet without disrupting the surface.
Our program was simple. Starting in early June of 1998, we used the machine to inject a mixture of sand and Axis-calcined DE soil amendment into the soil. The mix was about 10 percent Axis by volume, and we installed about 300 pounds of mix per 1,000 square feet of green with each pass. We tried to do nine holes per week; in reality, we actually got to each green three times during the season and on additional time in the fall. I would close each green for only 75 minutes. Because we weren't pulling cores, there was no more soil plug cleanup. I would simply hose down or drag down the very fine amount of topdressing left by the machine.
The machine has lived up to my expectations. A cross-section of the root zone now shows the clay layer being broke up and mixed with the upper soil layer by the injection of the dry material. Oxygen is now penetrating the soil, increasing microbial activity.
The greens even held up through a dry summer last year and remained constant in the fall without disruptive core aeration. Best of all, our members and players are happy. It's a good feeling when you can turn complaints into compliments.
Dave Koch, a 25-year GCSAA member, is a partner and superintendent at Horsham Valley golf course in Horsham, PA.