PHYSICAL AND CHEMICAL EFFECTS
Experiment and Report prepared and conducted by
Sydney Environmental and Soil Laboratory Pty Ltd – Contact:
An accepted practice in Green construction is the incorporation of organic matter
into the soil for the root zone. The most common source of organic matter is
decomposed peat, but this has certain environmental impacts that can be avoided
through use of renewable sources of organic matter. The aim of this experiment
is to test the improvement in the chemical and physical properties of a sand
amended with Cocopeat (Galuku Coir), and its compliance with the United States Golf
Association (USGA) standards.
Sand with a particle size distribution in compliance with USGA standards provided
the basis for testing the affects of Cocopeat (Galuku Coir) amendments and its suitability for
Green construction. Physical properties of the root zone mix specified by the
USGA were tested including pore space relations, hydraulic conductivity and
organic matter. The pH, electrical conductivity, cation exchange capacity and soil
phosphorus levels were also assessed.
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A sand known to comply with the USGA particle size distribution requirements
was amended with Cocopeat (Galuku Coir) at a rate of 3% by weight (USGA suggest between
2-4% organic matter). Prior to testing, the Cocopeat (Galuku Coir) amended sample was
thoroughly homogenised to compensate for the tendency of the organics and
sand to separate. Samples for pore space relations were moistened to field
capacity prior to testing, which avoided any transit separation problems.
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RESULTS and DISCUSSION
The incorporation of Cocopeat (Galuku Coir) into the sand has had a positive effect on both
physical and chemical properties.
Table 1: Soil Physical Test Results
||Bulk Density t/m3
||Total Porosity %
||Capillary Porosity % (water holding)
||Non-Capillary Porosity %
||Saturated Conductivity cm/hr
|3% Cocopeat (Galuku Coir)||1.3||49.4||19.5||29.9||95
|USGA Range|| ||35 - 55||15 - 25||15 - 30||15 - 30
The high water holding ability of Cocopeat (Galuku Coir) has made a large difference in the
capillary porosity or water holding capacity of the sand, with minimal reduction in
non-capillary porosity. This is going to improve the manageability of greens made
from Cocopeat (Galuku Coir) amended sands in hot climates or during the Summer months, as
irrigation can be reduced, and the Cocopeat (Galuku Coir) will retain more moisture. The sand
complies with USGA requirements for capillary and non-capillary porosity after
Cocopeat (Galuku Coir) additions, compared to the unamended sand, which did not comply.
Cocopeat (Galuku Coir) is less dense than sand, and incorporating it into sand has resulted in a
reduction of bulk density.
Hydraulic conductivity of the sand with 3% Cocopeat (Galuku Coir) is almost half that of the
unamended sand. This is related to the high water holding ability of Cocopeat (Galuku Coir),
and the subsequent retention of water in the profile. A hydraulic conductivity of
95cm/hr is above USGA requirements, but indicates that Cocopeat (Galuku Coir) incorporated
at this rate will not impede soil drainage.
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The incorporation of Cocopeat (Galuku Coir) into sand has impacted on a number of soil
chemistry properties. The full chemical results are presented on the soil chemistry
profiles (Samples # 25153, 25154). The major change is the increased potassium
levels. Cocopeat (Galuku Coir) is naturally very high in soluble potassium, and has therefore
improved potassium, and raised salinity. The soluble potassium from the
Cocopeat (Galuku Coir) would readily leach out by watering the soil after spreading. This should
reduce the salinity to an acceptable level as part of normal watering practices.
Initial soil phosphorus levels were very low, and Cocopeat (Galuku Coir) addition has improved
this. Further phosphorus supplements are required as part of a fertilising program
to sustain healthy turf growth, but these levels provide a good starting point.
Cocopeat (Galuku Coir) additions have increased the cation exchange capacity of the sand. This
enables the sand to resist nutrient loss through leaching, providing a longer term
source of nutrients for healthy grass growth. Frequency and rates of fertiliser
application can be reduced, compared to unamended root zone soil.
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The use of Cocopeat (Galuku Coir) in root zone construction has had a positive effect on the
capillary and non-capillary porosity of this sand.
A large increase in the water holding capacity was the result, with minimal
reduction in total porosity.
In addition to this, potassium and phosphorus levels were improved, with a
corresponding increase in salinity.
This salinity can be reduced by leaching the sand after spreading, and should
therefore not pose a problem to the use of Cocopeat (Galuku Coir) in green construction.
Jennifer Stokes BSc
Urban Soil Consultant
The information provided is given in good faith as a general guide only. Significant
variation in local climate, greenhouse environment, cultural practices, variety, managerial
conditions and other variables are likely to influence crop performance. No liability will be
accepted by Galuku Pty Ltd or its representatives for the lack of perceived or actual
performance in response to the information provided.
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