Sand topdressing and surface layer organic matter

One of the things I’ve started looking at when doing OM246 reports is the combined OM in the top 6 cm (2.4 inches) of the rootzone. This shows the big picture of total organic material change at the surface of the rootzone.

Surface layer organic matter from putting greens at Keya Golf Club for the past five years.
Surface layer organic matter from putting greens at Keya Golf Club for the past five years.

This change in surface layer organic material goes along with relatively infrequent disruption at Keya GC.

  • 2017, 2x verticut/topdress, total sand applied 2 mm
  • 2018, 2x verticut/topdress, total sand applied 2 mm
  • 2019, 2x verticut/topdress, total sand applied 2 mm
  • 2020, 1x 10 mm core/verticut/topdress, 1x verticut topdress, total sand applied 3 mm
  • 2021, 1x verticut/topdress, total sand applied 1 mm

That’s one coring event in five years, and a total of nine topdressing events in five years. The total quantity of sand applied in five years, 10 mm, is less than the amount I used to recommend as an annual topdressing amount. That 10 mm of sand is 33 ft3/1000 ft2. It’s an average of 2 mm per year, or 6.6 ft3/1000 ft2. I used to recommend 12 to 15 mm!

I’ve showed what the playing conditions were like after this treatment for five years. I’ve also explained how to adjust for soil bulk density when calculating the OM in the entire surface layer.

These data are really useful because when one is only measuring the surface playability, there is always some concern that maybe organic matter is accumulating in the soil but we aren’t noticing it. By confirming that the playability is at the desired level, and also confirming that the organic material in the soil is under control, it’s a lot easier to have confidence that one small diameter coring and nine topdressings in five years is working. That’s the type of information that I find so useful from OM246 tests.

This testing works well to find the opposite situation too, the situation where organic material is accumulating in the soil and more work is required to deal with it. OM246 testing can be used to optimize the work. In some cases, that optimization can result in a lot less sand and a lot less disruption than I thought possible.

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