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By TREVOR SIVIOUR,
Principal Consultant,
Turspec Pty Ltd
Ph (02) 9804 6211
Why do you add amendments to sand green
profiles? Is it to improve moisture retention,
cation exchange capacity (CEC) or both? Maybe
you believe amendment is not necessary?
Sands are such biological deserts that I believe
both chemical and physical adjustments are
necessary. My first priority has always been to
achieve the correct balance of capillary and noncapillary
porosity in the root zone.
In greens this is usually the top 150mm of a
300mm profile, as the effective rooting depth is
determined by mowing practices.
It is critical that the amended root zone has
sufficient available water for at least two (2) days.
Based on a crop loss of 7mm per day and allowing
for 50% depletion of the root zone (150mm), you
need a volumetric moisture content of at least
18%.
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I am also sceptical of the contribution that the
USGA perched water table (PWT) can make.
Moisture in the PWT will not automatically move
upwards, as it is held at pore tensions that prevent
this. So, if this PWT water is at 200-300mm and
the roots are at 0-150mm, what is its function.
Using the same argument, if there is plenty of
water in the lower profile, why amend it with peat?
Peat and Cocopeat products are however the best
for improving capillary porosity, as they are not
readily decomposed. Manures, seaweed products
and the like will decompose rapidly and are no
substitute. They, and products such as zeolite, are
excellent at improving CEC and/or nutrition. In a
new green, short-term organic products added to
the seedbed can also moderate surface moisture
loss during turf establishment.
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As a professional consultant I have had the
opportunity of putting this into practice. Two of the
more recent projects have been the Greg Norman
designed Ellerston Golf Course (for Mr. Kerry
Packer) and Vintage Golf Course (for Stevens
Group).
The companies Vieband Sands Pty Ltd and Galuku
Pty Ltd were contracted for both of these projects
to supply sand and Cocopeat amendment
respectively. As part of our brief Turspec was
responsible for profile design, laboratory testing
and quality control.
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Peat amendment addition has always been quoted
as x%. This is very vague, as peat will vary in
moisture content and density. Moisture content
will influence expanded volume. For example, 1.0
litre of air dry peat can expand to 1.5 litres when
wetted to 50% of maximum water holding
capacity. This means that in a volume blend, the
actual organic matter by weight and hence
capillary porosity, may vary depending on the
moisture content of the peat that is added.
To avoid this problem, the expertise of Galuku and
Vieband were able to maintain even moisture
content in the Cocopeat and we were able to check
quality control by measuring percentage organic
matter by weight in the mix even though the
blends were prepared on a volume basis.
It would be nice to have a root zone mix where the
p hysical and chemical conditions are ideal,
however there is usually a limit on expense and
the technology of blending operations needs
significant improvement.
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In conclusion, I believe priority should be to
achieve the correct air/water balance in the root
zone. Peat, and particularly Cocopeat is excellent
for this purpose. Off site mixing is essential, as a
satisfactory root zone mix cannot be achieved by
rotary hoeing of amendments. A new green or green
reconstruction is the opportunity to ‘get it right’ so
- Identify reputable suppliers with quality materials.
- Have the necessary testing done to design the profile.
- Retain someone to monitor quality.
Be prepared to pay more for the correct result – it
will help you sleep more soundly on Christmas Eve
when the temperatures are 400°C.
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