GB2411245A

GB2411245A - Going meter

Info

Publication number: GB2411245A
Application number: GB0403728A
Authority: GB
Inventors: Donald Percy Attenburrow
Original assignee: Devon & Exeter Steeplechases L
Current assignee: Devon & Exeter Steeplechases L
Priority date: 2004-02-19
Filing date: 2004-02-19
Publication date: 2005-08-24
Anticipated expiration: 2024-02-19
Also published as: GB0403728D0; GB2411245B

Abstract

A method and apparatus for predicting the going of a racecourse is disclosed. The method comprises the steps of measuring the yield stress at the turf surface, measuring the water tension of the soil at two depths at predetermined intervals over a period of time, and predicting the going of the racecourse based on these measurements. The yield stress is measured by means of a device including a probe (16) having a flat end surface (19) having an area of approximately 1 cm<2>.

Description

241 1 245

TURF CONDITION METER

This invention relates to a method of, and apparatus for, determining the condition of a surfed surface.

More particularly, but not exclusively, the invention relates to a method of, and apparatus for, determining the likely future "going" of a racecourse.

The going (or condition of the ground) is a major factor for racehorse trainers when deciding whether or not to enter a horse in a particular race. Going is indicated qualitatively as Heavy, Soft, Good to Soft, Good, Good to Firm, Firm and Hard. The harder the ground, the more likely it is that a horse racing on it will suffer injury. The welfare of the horse is the primary concern.

The going is determined in advance of a race meeting, and an attempt is made to predict the going on the day of the meeting. Typically the going is subjectively assessed by stamping a heel or pushing a walking stick into the ground. This allows the Clerk of the Course or another suitably experienced person to use the degree of displacement of the turf in relation to the force applied to determine the going. The moisture content of the soil may also be measured, and from this information the Clerk of the Course will predict a level of going for race day. This method is highly subjective and dependent on the experience of the Clerk of the Course and so the going of the same ground may be predicted differently by different people. There is therefore a need for an objective measure of going, and for reliable prediction of the going of a particular racecourse.

Various ground condition indicators are known.

US 4,061,021 (Baldwin) discloses a recording soil penetrometer including a soil penetrating probe. The apparatus records, on recording paper, the penetration resistance encountered by the probe as it is driven into the ground.

Soil penetrometers of the type disclosed in US 4,061,021 have pointed or conical soil penetrating probes. They thus produce a response which is not directly comparable with the impact with a horse's hoof, and consequently are not appropriate for the assessment of the going of a racecourse.

Furthermore, the measurement of soil resistance alone cannot provide an adequate basis for predicting the going, at some time in the future, of the ground which is being tested. This requires an assessment of factors which can change over the time from the test being carried out to the time for which the going must be predicted. Research has suggested that the water tension of the soil is a valuable indicating factor in the prediction of the going.

Water tension is a measure of the capacity of the soil to hold water. In other words, water tension is a direct indication of the ease with which water can be extracted from the soil. This tension is provided by capillary forces within the soil and accordingly the larger the pores of the soil, the lower the water tension, and vice versa. Water tension is also affected by the moisture content of the soil; soil with a lower moisture content has a higher water tension than that of the same soil containing more water.

Therefore the water tension provides a good indication of how the soil will be affected by the water content.

According to one aspect of the present invention, there is provided a method of predicting the condition of a surfed surface, comprising the steps of: (a) measuring the current yield stress of the surfed surface; (b) measuring the current water tension of the soil at a predetermined soil depth; (c) predicting the condition of the surfed surface at a future time on the basis of the measured current yield stress and the measured current water tension.

Preferably, two measurements of the water tension of the soil are made at different times, and, on the basis of these measurements, the rate of change of water tension between the water tension measurements is determined, the prediction of the condition of the ground then being based on the measured yield stress and the rate of change of water tension.

Preferably, the interval between taking measurements of the water tension of the soil is one day. The predetermined soil depth may correspond to the depth of the grass root area of the ground. In a preferred method, two water tension measurements may be taken on each measuring occasion, at different soil depths. The two depths may correspond respectively to the depth of the grass root area and to the depth of the sub-soil.

The first soil depth is preferably not less than about 5cm and not more than loam. The second soil depth is preferably not less than lOcm and not more than 20cm.

For example, the first soil depth may be around 7.5 cm and the second soil depth may be around 15 cm.

In a preferred embodiment in accordance with the present invention, the yield stress of the turf is measured by measuring the maximum force required to push a probe into the turf to a predetermined penetration depth.

According to another aspect of the present invention, there is provided a device for measuring the yield stress of the ground, which device comprises a handle and a soil penetrating probe which is longitudinally displaceable towards the handle against the bias of a spring, read-out means being provided for indicating the displacement of the probe in the direction towards the handle, the probe comprising an elongate element of constant cross-section, terminating at a flat transverse surface.

The probe may have a cross-sectional area of not less than 0.75 cm2 and not more than 1.5 cm2, for example of 1 cm2, and a length which is not less than 2 cm and not more than 5 cm, for example a length of 2.3 cm.

The cross-sectional area of the probe, and consequently the area of the flat end face, is preferably approximately 1 cm2 so that it is possible for a user to apply to the soil a stress generally equivalent to that applied by a horse's hoof bearing the full weight of the horse. A horse (including rider) weighs approximately 500 Kg and the forefoot hoof area is approximately 100 cm2. When a horse is at the gallop, its weight is supported temporarily on each stride by a single foreleg, and thus it can be estimated that the maximum stress applied to the ground by a galloping horse is 5 Kg/cm2. Consequently, a device having a probe end face area of 1 cm2 and calibrated to a maximum load value of at least 5 Kg will be capable of imposing on the ground a stress of the same order as that imposed by a galloping horse.

According to a third aspect of the present invention there is provided apparatus for predicting the condition of a surfed surface comprising a first water tension sensor positioned at a first depth below the turf surface, a second water tension meter positioned at a second depth deeper than the first water tension sensor, and a yield stress meter for determining the yield stress at the surface of the turf.

For a better understanding of the present invention and to show how it may be carried into effect, reference will now be made by way of example to the accompanying drawings, in which: Figure 1 is a side view of a turf yield stress measuring device; Figure 2 is a schematic illustration of water tension measuring devices installed in a racecourse; and Figure 3 is a graph showing the relationship between soil moisture and weather conditions.

The turf yield stress indicator 2 shown in Figure 1 is in the form of a hand-held stick and comprises a sleeve within which a barrel 12 is slidable. Within the sleeve 10 and barrel 12 is a compression spring (not shown) installed so as to bias the barrel 12 outwardly of the sleeve 10. The barrel 12, the sleeve 10 and the spring acting between them comprises a gauge unit which terminates at a spigot 15 secured to the barrel 12.

This spigot 15 is received in a bore in the end of a rod 14, where it is secured by a nut 15. The rod 14 is preferably made of a lightweight material such as duralium. It extends from the barrel 12 in the direction away from the sleeve 10. At its end away from the barrel 12, the rod 14 is provided with a cylindrical probe 16 and limiting plate 18 of significantly larger diameter than the probe 16. The limiting plate 18 is situated between the probe 16 and the rod 14 so as to provide a substantial downwardly facing surface area. In the embodiment shown in the drawings, the length of the probe 16 is 2.3 cm and its cross- sectional area is 1 cm2. The probe has a circular flat transverse end face 19 extending over the full cross-sectional area.

The barrel 12 has a marker ring 13 which surrounds and frictionally engages the barrel 12.

To measure the yield stress of a surfed area, the yield stress indicator 2 is held perpendicularly above the surface to be tested by its sleeve 10 acting as a handle. The probe 16 of the yield stress indicator 2 is lowered in a vertical direction onto the turf. A downward force is then applied to the sleeve 10 to compress the compression spring, which in turn biases the barrel 12 and hence probe 16, into the ground. The ground provides a force against the probe, the force depending on the condition of the turf. This force causes the compression spring to be compressed thus allowing the sleeve 10 to slide down over the barrel 12 displacing the marker ring 13. Therefore, the harder the ground is to penetrate, the greater is the force required to push the probe into the ground and hence the further the compression spring is compressed.

Markings representing kilograms force/cm2 in the range O to 5 kilograms/cm2 are provided on the side of the barrel 12, allowing the user to establish, from the position to which the marker ring 13 is displaced, the maximum force required to penetrate the turf to the depth established by the plate 18.

Figure 2 shows a first water tension meter 29 having a sensor 30 and a second water tension meter 31 having a sensor 32 installed at different depths below the ground surface 34. Preferably, the first water tension sensor 30 is provided at a depth of around 7.5 cm, substantially in the grass root area of the turf.

Preferably, the second water tension sensor 32 is provided at a depth of around 15 cm, or substantially in the sub-soil region. Water tension meters suitable for use with the present application are known in the art and a suitable meter is available from ELK International Limited, of Leighton Buzzard, UK. As the water tension is affected by water content there is no need to measure the water content separately. The first water tension meter 29 has its sensor 30 positioned in the grass root area in which the water tension responds more rapidly to rain and transpiration than in the sub-soil at the depth of the second water tension sensor 32. Therefore the second water tension sensor is used as an indicator of the general condition of the ground, whereas the first water tension sensor provides an indication of how recent weather patterns have affected the ground, and therefore can be useful when predicting the ground condition at a future point in time, with reference to the yield stress at the surLacc Gild the general condition of the soil.

Therefore, in accordance with the present invention, the likely future yield stress of the turf is calculated by assessing the water tension at the first and second depths and the yield stress at the surface of the turf, analysing how these change over time (over a period before the race) , and from this forecasting the race day turf conditions.

The information from the water tension sensors 30, 32 is important as, for example, if the course enjoys a period of dry weather, water from the surface will evaporate or be lost from the grass by transpiration.

If the water tension determined by the sensor 30 is high then little water will move up from the grass root area to be lost from the surface 34. Accordingly, in the absence of rainfall or watering the surface 34 will remain dry and its going will not change substantially.

If, for example, the water tension determined by the sensor 30 is low and that determined by the sensor is 32 is higher, then if a dry spell of weather is experienced, water may be lost from the surface 34, but little water will travel from the second depth to the first depth to replace the lost water. Consequently, the movement of water from the first depth to the surface 34 is limited. If the race day is some days away the water at the first depth may be dissipated and 9 -' the surface would be firmer on race day. Alternatively, if both sensors 30 and 32 show low water tensions then water could be supplied to the surface 34 for a longer period and therefore the going on race day could be less hard than in the previous example.

Different parts of a racecourse have different soil characteristics, and so the going will vary over the course. Consequently, it may be desirable in some instances for first and second water tension meters 29, 31 to be installed at different locations on the course to provide a complete picture of the going. This would enable separate attention to be paid to parts of the course where the going needs to be modified, for

example by water.

Figure 3 is a graph of moisture in the soil (expressed as a percentage of saturation) against time in days.

Superimposed on the time axis is an indication of daily rainfall, and of general ambient conditions. It will be noted that the moisture content in the turf, ie at the depth of 3 inches (7.5 cm), tends to increase rapidly during periods of rainfall. When there is no or little rainfall, moisture in the sub-soil, ie at a depth of 6 inches (15 cm) can replenish moisture lost from the surface, so as to maintain the moisture level in the turf. This occurs even during warm, rain-free days, as is shown around days 7 to 11. It is only when the moisture content of the sub-soil begins to fall that the moisture at the upper level also begins to fall. This is shown more dramatically at the hot spell around day 20, which occurs at a time when there has been little rainfall for several days and the moisture content is already falling. The moisture level in the turf then falls very significantly until the heavy rainfall at day 24.

The graph therefore demonstrates that monitoring the moisture content at different levels provides a sound basis for predicting the turf's response to weather conditions.

Consequently, the moisture measurements provide a basis for predicting the future going of the racecourse under prevailing weather conditions, and also provides a basis for determining whether or not to water the course in order to increase the moisture content.

Although Figure 3 shows measurements of the soil moisture, a similar pattern would be achieved if water tension were measured, in accordance with aspects of the present invention. The advantage of measuring water tension instead of simply the soil moisture is that water tension is able to take account of the nature of the soil, and consequently the readiness with which moisture from the sub-soil will transfer to the turf. Soil type will normally vary around a racecourse, and so differences in water tension will be observed even if the moisture content is the same.

Although the invention has been described in the context of the going of racecourses for horses, it will be appreciated that it can be applied in other contexts, for example for golf courses and for agricultural purposes.

Claims

1. A method of predicting the condition of a surfed surface, comprising the steps of: (a) measuring the current yield stress of the surfed surface; (b) measuring the current water tension of the soil at a predetermined soil depth; (c) predicting the condition of the surfed surface at a future time on the basis of the measured current yield stress and the measured current water tension.

2. A method of predicting the condition of a surfed surface as claimed in claim 1, wherein two measurements of the water tension of the soil are made at different times, and, on the basis of these measurements, the rate of change of water tension between the water tension measurements is determined, the prediction of the condition of the ground then being based on the measured yield stress and the rate of change of water tension.

3. A method of predicting the condition of a surfed surface as claimed in claim 2, wherein the measurement interval between taking measurements of the water tension of the soil is one day.

4. A method of predicting the condition of a surfed surface as claimed in any one of the preceding claims, wherein the predetermined soil depth is the depth of the grass root area of the ground.

5. A method of predicting the condition of a surfed surface as claimed in any one of the preceding claims, wherein the measurement of the current water tension comprises measuring the water tension at a first predetermined depth and at a second predetermined depth.

6. A method of predicting the condition of a surfed surface, as claimed in claim 5, wherein the first predetermined depth is within the grass root area of the ground and the second predetermined depth is within the sub-soil.

7. A method of predicting the condition of a surfed surface as claimed in claim 6, wherein the first soil depth is not less than 5 cm and not more than 10 cm.

8. A method of predicting the condition of a surfed surface as claimed in claim 6 or 7, wherein the second soil depth is not less than 10 cm and not more than 20 cm.

9. A method of predicting the condition of a surfed surface, substantially as described herein.

10. A method of adjusting the condition of a surfed surface, the method comprising predicting the condition in accordance with any one of the preceding claims and, if the predicted condition represents a yield stress in excess of a desired level, water is applied to the surfed surface.

11. Apparatus for predicting the condition of a surfed surface comprising a first water tension sensor positioned at a first depth below the turf surface, a second water tension meter positioned at a second depth deeper than the first water tension sensor, and a yield stress meter for determining the yield stress at the surface of the turf.

12. Apparatus for predicting the condition of a surfed surface substantially as described herein with reference to, and as shown in, the accompanying drawings.

13. A device for measuring the yield stress of the ground, which device comprises a handle and a soil penetrating probe which is longitudinally displaceable towards the handle against the bias of a spring, read- out means being provided for indicating the displacement of the probe in the direction towards the handle, the probe comprising an elongate element of constant cross-section, terminating at a flat transverse surface.

14. A device as claimed in claim 13, wherein the probe has a crosssectional area of not less than 0.5 cm2 and not more than 1.5 cm2.

15. A device as claimed in claim 14, wherein the probe has a crosssectional area of approximately 1 cm2.

16. A device as claimed in any one of claims 13 to 15, wherein the probe is of a circular cross-section.

17. A device as claimed in any one of claims 13 to 16, wherein the probe has a length of not less than 2 cm and not more than 5 cm.

18. A device as claimed in claim 17, wherein the probe has a length of approximately 2.3 cm.

19. A device for measuring the yield stress of a surfed surface, substantially as described herein with reference to, and as shown in Figure 1 of the accompanying drawings.

20. A method of predicting or adjusting the condition of a surfed surface as claimed in any one of claims 1 to 10, wherein the yield stress of the turf is measured by means of a device in accordance with any one of claims 13 to 19.