Magazine: The Penetrometer
By Editor in Racing on 18th Aug 2008 8:00
The Penetrometer has been used for many years assisting Racecourse Managers and Stewards with track ratings. This device comes from the road building industry where they used a device to measure the road profile prior to the final surfacing of asphalt. The device was modified to measure soil hardness turf.
Soil penetration resistance is an important mechanical property that can be used as an indicator of soil compaction and is important in determining the least limiting water range.
Soil strength is an important characteristic affecting many aspects of soils, such as the performance of cultivation implements, root growth, least-limiting water range and the trafficability. The strength of soil results from cohesive forces between soil particles and their frictional resistance to sliding past or over one another. Penetrometer readings are unique only to the track they are taken on, due to different soil compositions of individual tracks.
Penetrometers are used in the thoroughbred industry by many metropolitan tracks and also some major provincial clubs. The penetrometer is constructed out of a metal (stainless steel) and is currently manufactured in Melbourne. The penetrometer description is as follows:
A 1 kilogram weight is released by a trigger action and falls 1 metre down a shaft, which in-turn hits a 1 centimetre square rod into the soil profile. The 1 centimetre square rod has 1 centimetre increments as the measurement for the depth the rod that has entered into the soil profile. This action is undertaken 3 times in the one position, therefore giving 3 readings eg: 2.5, 4.5, 6.5.
A formula is used to calculate the reading and is based on the average figure for the entire course. To obtain this figure there are 6 readings taken every 200m around course. Three of the 6 readings are taken 2m from the running rail and then the remaining 3 readings are taken 4m from the running rail. Each reading is recorded and then all figures are entered into a formula that will provide an average. This average then becomes your race day penetrometer reading and will correspond to your set ratings – Fast / Good / Dead / Slow / Heavy. Eg: Track - “Good”, Penetrometer – 4.25
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The Penetrometer has been used for many years assisting Racecourse Managers and Stewards with track ratings. This device comes from the road building industry where they used a device to measure the road profile prior to the final surfacing of asphalt. The device was modified to measure soil hardness turf.
