Keeping sports pitches drained over winter

Keeping sports pitches drained over winter

(Turf Business, September/October 2007)

It is now too late for any drainage installation or severe disturbance of the grassed surface – what is uncompleted must remain so. However, there are a number of treatments that can assist in maintaining pitches in as good a playing condition as possible. October through to November can produce weather extremes yet there still remain windows of opportunity to complete preparation for the winter ahead. Hard frosts are generally not expected until early November and certain essentials are not completely dependent on the weather.

Surface drainage

Special attention should be given to ensuring there are no depressions where water can collect. This treatment should have been completed in the summer but if not, somehow surface water must not be allowed to pond anywhere on the pitch. Special attention must also be given to preventing surplus water from higher ground entering the pitch area. This surface water run-off can be diverted by a catch-water mound or a swale. Where pitches are located at the foot of a cut slope the creation of a swale drain at this point is the only permanent measure of preventing the surplus water entering the pitch. In many cases there is not enough space for a swale drain in this location and if so a cut-off drain at the toe of the slope must be annually cleared of debris, silt and thatch to ensure the drain is as receptive as possible. There should be a drainage outfall and every effort must be made to lead or divert surplus water to this location. Where a ditch reticulation exists these areas should be checked and cleared well in advance of the autumn rains.

Where slit drains have been installed or slitting has resulted from ‘earthquake’ or similar operations operations, contraction in the clay causes these openings to increase and in the case of the slit drains the aggregate infill is lost to lower depths. This inevitable occurrence in hot dry summers is the one main downside to the slit drain operation. To a degree the intensity of cracking open can be reduced if good vigorous grass cover is established over the slits by adequate nutrition and regular mowing to create a good density of plant shoots. At this time it is essential to check the grass cover over all slit and lateral drains and ensure the aggregate at the surface of the drains is firm and level with surrounding ground. Actually, this exercise should be undertaken as soon as failure becomes apparent in order to allow maximum time for grass cover recuperation.

Deep aeration without impairing the grassed surface promotes drainage in heavy soils. With most pitches constructed with clay loam topsoils with or without primary and secondary drainage measures installed, compacted surfaces encourage water ponding in micro-depressions within the playing surface. The use of the vertidrain is recommended to alleviate this condition since the ‘earthquake’ implement, which creates better decompaction in many instances, would be too damaging on the grass surface at this time with play now underway.

While the ground is still firm at the surface, the application of the annual sand dressing will prevent the development of a greasy surface. The texture of the sand is important. It should have negligible content over 1mm and less than .1mm. The application rate is in the region of 140 tons per hectare and this can be applied in two applications if the grass cover is not vigorous. The sand layer also promotes lateral movement of the surplus surface water to slit drains or the pitch boundary where there is adequate gradient. It is therefore important that there is an even grade and there are no depressions.

Vigour of growth

At the commencement of the playing season in August/September the vigour and density of grass cover should be as good as possible. While summer applications of fertiliser should have been made it is essential that an autumn application of a low nitrogen high potassium formulation should follow now. Soil analysis should be carried out on samples taken from the top 100mm at least every two years. Any shortfall in deficient mineral elements should be made up at this time. Ryegrass will grow actively through to November and every effort should be made to enable grass cover to be growing as actively as possible before the hard frosts begin.

To maintain a healthy grass cover earthworm activity must be controlled. Spraying with carbendazim becomes essential as soon as the temperatures drop and there is sufficient moisture in the top layers. Failure to control the earthworm invasion on sports pitches enables the accumulation of clay casts that soon reduce grass cover and create a slippery playing surface. A sound grassed surface can not be maintained while earthworms are active.

Surface treatments

After a warm summer with good growth and particularly following a cricket season, there is a build-up of dead grass and cuttings at the surface. The layer formed tends to hold water and restrict infiltration. If scarifying has not been undertaken at the time of renovation after the previous football season, it is invaluable to remove this surplus material even if the treatment is now less harsh. With improved infiltration surface drainage is significantly increased. Furthermore, at least monthly slitting of the surface should be undertaken with suitable equipment. This helps to keep the surface open to air and water penetration through the heavy clay loam topsoils that normally exist.

Weed growth should have been controlled in the summer months. In the hot dry months the height of cut and frequency of mowing would have been relaxed. Now with the cooler months approaching and autumn fertiliser applications made, the vigour of the grass is naturally increased. The desired playing height of around 35mm should now be continually maintained so as not to allow the accumulation of grass cuttings. This will involve more frequent mowing with special care and setting of the cutting blades in the individual gangs. Regular use of a drag mat or up-turned chain harrow helps maintain and even surface and so prevent the development of depressions that can hold water. In order to maintain durable grass cover in the goal mouths it is advisable to increase the grass height in this area. This endeavour prevents exposing the soil surface to a degree and so restricts the development of muddy areas.

In summarising, though no further drainage installation can be undertaken at this late stage in the year, a number of treatments can be made to promote the best possible drainage in the circumstance and create a vigorous and debris-free grass sward that will permit improved infiltration and provide a more durable and firm playing surface.

Gordon Jaaback

October 2007