Brookvale Oval Investigation - Warringah Council - NSW Government

The presence of the thatch material over the field is quite typical of a mature kikuyu turf sward,
but the density of this layer will impact significantly on the performance of the soil profile, and
on the actual playing surface.
The thatch layer will retain moisture, reducing the infiltration rate of the profile. In terms of
playing surface performance, the thatch will provide a softer surface but this will result in a
heavier playing surface and potential energy-sapping of player performance.
The test holes show a variable depth of sandy loam topsoil ranging from 290mm – 460mm over
a sub-base of clay loam.
Laboratory tests show that the sandy loam topsoil has a drainage capacity of 11 mm/hr which
is very slow. The desired drainage capacity of a rootzone material in a high quality sportsfield is
200 - 300 mm/hr.
It was reported that there is no sub-surface drainage system in this field so the only way for
excess water to move away is via the very slow infiltration or across the surface. This can lead
to surface damage particularly if traffic occurs during periods when the soil is saturated.
• Soil Nutrient Analysis
An analysis of the topsoil was carried out and the results are:
Ideal
Ideal
Oval
Range
Range
Oval
pH (water) 6.0 - 7.0 5.7 Trace Elements
Electrical Conductivity (mS/cm) < 0.27 0.04 Sulphur (ppm) 10 - 50 4
Total salts (ppm) < 800 119 Zinc (ppm) 1 - 10 4.1
Phosphorus (Colwell) (ppm) 50 - 80 210 Copper (ppm) 1 - 10 1.5
Exchangeable cations Manganese (ppm) 0.1 - 4.0 6.0
Potassium (meq /100g) 0.5 - 0.6 0.2 Iron (ppm) 10 - 60 240
Calcium (meq /100g) > 3.5 1.4 Boron (ppm) 0.3 - 1.0 0.1
Magnesium (meq /100g) 0.8 - 1.0 0.6 Chloride (ppm) < 100 22
Calcium Magnesium Ratio 2 - 5 2.3
Cation Exchange Capacity (meq/100g) > 5 2.3
Base Saturation Levels (% cations)
Potassium (%) > 10 7
Calcium (%) 60 - 70 60
low acceptable high
Magnesium (%) 20 - 23 26
Sodium (%) < 5
3
These results show:
• strongly acid pH – needs lime to modify acidity;
• normal level of Total Salts – no concern;
• high phosphorus level – sufficient for turf maintenance, no remedial action;
• very low potassium level – needs improvement;
• very low calcium and magnesium levels – extra calcium and magnesium needed;
• low sodium level – no concern;
• other elements generally adequate for turf growth.
Brookvale Oval Investigation Final Report (February 2010) Page 6