WO2000035263A1

WO2000035263A1 - A method for the aeration of turf, especially on sports fields

Info

Publication number: WO2000035263A1
Application number: PCT/NL1999/000718
Authority: WO
Inventors: Felix Pieter Oudshoorn
Original assignee: Hoek Loos BV
Current assignee: Hoek Loos BV
Priority date: 1998-11-23
Filing date: 1999-11-22
Publication date: 2000-06-22
Anticipated expiration: 2001-05-23
Also published as: AU1416600A; NL1010626C2

Abstract

The invention relates to the aeration of turf, especially on sports fields, in a space that may as may not be enclosed. Aeration of the turf occurs using a mixture having an elevated oxygen content, which mixture is preferably injected into the soil. The mixture having an elevated oxygen content contains more than 21 vol.% of oxygen. Normally, aeration with a mixture having an elevated oxygen content occurs at a pressure of 0.1-3 bar, and preferably at a pressure of about 0.5 bar.

Description

A method for the aeration of turf, especially on

fields

This invention relates to a method for the aeration of turf, especially on sports fields, in a space that may or may not be enclosed.

It is known that a lack of oxygen inhibits the growth of the roots of grass, which problem is especially disadvantageous when using turf on sports fields, both in the open field and in a hall or completely enclosed space. Insufficient root growth of the grass plants of turf results in their not, or insufficiently growing into the subsoil whereupon they are placed, with the result that the grass plants or turf come loose during intensive use of the sports fields.

Normally this problem is countered by aerating the turf, whereby the turf is perforated to improve aera- tion of the soil, and by drainage.

However, it has been shown that such an approach on sports fields in general, especially in semi- or completely enclosed spaces such as soccer stadiums causes other problems. Such a problem has, for instance, been occurring since the opening of the Amsterdam ArenA. The poor quality of the turf causes the players much irritation. Because of the insufficient growth of the roots of the grass plants, the grass plants or turf come loose from the subsoil, mak- ing the turf slippery and uneven, leading to injuries of the players, especially groin injuries, which are of course not desired.

It goes without saying that such a situation has an unfavourable influence on the players' quality of play. To somewhat solve the problem of the poor turf, the turf has to be replaced by new turf at least twice a year. This is very time-consuming and expensive and seems to be only a spurious solution because after some weeks the turf appears to actually have the same, above- mentioned problems. Thus, solutions for this problem are needed.

It is an object of the present invention to provide a method to solve the above-mentioned problems. To this end the invention comprises a method for the aeration of turf, especially on sports fields, in a space that may or may not be enclosed, characterized in that, as a gas a mixture having an elevated oxygen content is used. Surprisingly it has been shown that using the mixture having an elevated oxygen content the above- mentioned problems can be solved in an effective way.

Indeed it has been shown, that by using the present method the oxygen uptake by the roots of the grass plants is promoted resulting in a relatively fast growth of roots, producing a well developped, branching root system and well anchored grass plants, or turf, in the layer underneath. After some time the roots penetrate into the layer underneath to a depth of about 10 to 20 cm, which roots are furthermore strongly branched. As a result a good anchoring in the soil is achieved. It will be obvious that the coming loose of the grass during intensive use, such as during a game, is limited to a minimum. Also, the turf remains intact and will not show unevenuesses, so that injuries of the players are restricted to a minimum. Time-consuming and expensive replacement of the turf can be deferred for quite a long time, thereby realizing great savings.

Especially good results are obtained according to the invention when a mixture having an elevated oxygen content is injected into the soil. This injecting takes place with the aid of specially produced hoses or tubes provided with holes, which holes are positioned at a predetermined distance from each other, to allow the passage of a mixture having an elevated oxygen content.

An example of a hose that is especially suitable for the injection of a mixture having an elevated oxygen content is a tube made of polyester yarn-reinforced plas- tic (EPDM) , which is made on request by Linde in Germany. This hose for oxygen aeration is provided with holes which holes are positioned at a distance of about 6 mm from each other, and are staggered. The hoses have a diameter of about 18 mm.

Usually those hoses are placed in the subsoil under the turf as a separate system in addition to the drainage system. However, they may also be incorporated in the drainage system itself. Finally, the method according to the invention may be executed with the aid of a specially manufactured hose or tube, which is placed in the soil under the turf. The turf has a thickness of about 5 cm, and the subsoil underneath has a thickness of about 70 cm. The oxygen injection hose is normally placed at a depth of about 20 to 60 cm.

Such hoses are connected to an oxygen source with the aid of the usual means, such as reducing valves, etc., which oxygen source may be an oxygen cylinder or an oxygen storage tank.

Usually, the aeration with a gas having an elevated oxygen content occurs at a pressure of 0,1-3 bar, and preferably at a slight overpressure of about 0,5 bar. The oxygen content of the mixture is more than 35 vol.% oxygen.

The drawings show a plan view of a sports field, on which the positions of the measuring points are given, as well as graphs of the measuring results of several measurements of the gas concentration in the soil. Fig. 1 shows a plan view of a soccer field, on which measuring points A-N are indicated serving as a measuring point of the gas concentration in the soil. The upper part of the drawing corresponds to the north. The measuring points C and M are placed on the southern half of the field and generally receive no sunlight.

Figures 2 and 3 show the oxygen and carbon dioxide concentration of the measuring points C and M. The measurements 1 to 10 were realised in the period from March to July, once every two or three weeks. In the test areas (10 x 10 m) wherein the measuring points C and M are located, a gas was injected into the soil, which gas comprised essentially oxygen (>99%) . The gas flux was about 3 litres per minute. Figure 2 shows clearly that during the fourth measurement a highly elevated oxygen concentration and a lowered carbon dioxide concentration was measured. This can be attributed to the fact that shortly before the measurement a new turf was laid on the field. Figure 3 shows clearly that during the last measurements a change in the oxygen concentration was obtained. From measurement 9 an oxygen-enriched mixture was applied, having an oxygen concentration of more than 21%. In this case, the flux was twice as high as in the preced- ing period. By this change of application, an elevated oxygen concentration and a lowered carbon dioxide concentration in the soil was obtained. This is probably the result of the elevated total gas flux through the soil, whereby a better discharge of carbon dioxide was obtained. Figures 4 and 5 show the oxygen and carbon dioxide gas concentrations at two other locations in the sports field. It is shown clearly that the gas concentration in the soil depends largely on the position on the sports field, and that no clear general impression can be given of the concentration of these gases in the soil. The present invention provides a particularly simple and elegant method of maintaining the condition and the quality of the turf in soccer stadiums in general and covered soccer stadiums in particular, in top condition for a long period of time.

It is a further object of the present invention to improve the environment in favour of the growing conditions of aerobic processess in the soil as well as the oxygen/carbon dioxide ratio above the soil or turf. Furthermore, a carbon dioxide blanket, located above the grass is removed, or rarefied.

However, a further consideration is that with the aid of the present invention the turf may be maintained in top condition in the case of the turf being covered with a floor, for example, during jazz concerts or other events in a stadium that may or may not be enclosed.

Claims

1. Method for the aeration of turf, especially on sports fields, in a space that may or may not be enclosed, characterized in that as a gas a mixture having an elevated oxygen content is used.

2. Method according to claim 1, characterized in that the mixture having an elevated oxygen content is injected into the soil.

3. Method according to claim 1 or 2, characterized in that the mixture having an elevated oxygen content contains more than 35 vol.% of oxygen.

4. Method according to claims 1-3, characterized in that the aeration with a mixture having an elevated oxygen content occurs at a pressure of 0,1-3 bar.

5. Method according to claim 4, characterized in that the aeration with a mixture having an elevated oxygen content occurs at a pressure of about 0,5 bar.

6. Method according to one of the preceding claims, characterized in that the mixture having an elevated oxygen content is injected with the aid of a spe- cially manufactured hose or tube, which is placed in the soil under the turf.