outstanding example of poor golf green construction that resulted in strong layering. “In the late 1980s, a certain golf club in South Norfolk had several loads of sand that was of unknown origin and unknown specification tipped into the greens that were then under construction. This was followed by a load of Fen rootzone that had been produced by recycled vegetable washings, from a Lincolnshire carrot factory. This tipping process was repeated, so this meant that the rootzone profile looked like an angel cake! These layers were about four inches thick. The result of all this was that the greens would neither drain or perform in any acceptable manner whatsoever” (Fig 3).
The consequence was that the
greens had to be dug up and a properly manufactured rootzone of the correct specification was then substituted. Knowing the correct specification of a material for its designated use means that the right material for the job can be selected from the outset. In the case of golf greens’ rootzones & topdressings the United States Golf Association (USGA) specification is used. The table
Leads to build up of anaerobic conditions and the creation of Black layer.
Root Break Layer
Dry area, due to lack of percolation caused by layering
Existing Rootzone
Impeded drainage. Causes this zone to act as a sponge.
Rain/Irrigation
Incompatible material causing rootbreak
represents the USGA specification for golf dressings and rootzone. It can be seen from this summary that there are strict ceilings placed on the quantities of the coarsest and finest particles. The silt & clay fraction should, as has been mentioned before, add up to no more than 8%, neither should there be a presence of any particles that exceed 4mm in diameter. A golf dressing should ideally conform to this USGA specification.
Subsoil/gravel blanket (where applicable)
FIGURE 3
Particle Size Particle Size Category
Stones
(mm) >8
Coarse gravel 8 - 4 Fine gravel
4 - 2
V. coarse sand 2 - 1 Coarse sand
1 - 0.5
Medium sand 0.5 - 0.25 Fine sand
Silt & Clay
USGA Rootzone Compatibility
No particles in this category No particles in this category
Not more than 10% of the total in this Range. Preferably no Fine gravel
At least 60% of the material must fall in this range
Not more than 20% fine sand
No more than 10% for range. No more than 5% very fine sand,
no more than 8% silt & clay
So, to avoid layering occurring in your turf ’s soil profile then make sure that you get a physical analysis undertaken on your existing rootzone. Compare this against any products that you are considering using or are currently using. Ask your current supplier for an up to date specification sheet for the material that they provide. A close correlation between both the particle size distribution of the existing rootzone and any material that is to be added will mean a low probability of layering or capping-off occurring, and thus the likelihood of rootbreak will be minimal.
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