End of Season Maintenance (May): Part 1
Introduction
With only some 10-12 weeks available before the start of the next season, renovation of the pitch must commence and be completed in as short a time span as possible. This will give the rejuvenated pitch as long a period as possible to build up a reasonable level of resilience, as well as to achieve the desired performance standards.
A typical programme of renovation may include some or all of the following:
Deep Spiking
This can be done with a vertidrain machine, or similar, penetrating to 300mm or so. If any underground heating or irrigation pipes are present - being generally at a depth of 250mm or so - then obviously the depth of penetration will need to be adjusted to ensure the pipes are not punctured.
A sand top-dressing is sometimes applied before a vertidrain operation so that some of the sand is 'punched' into the rootzone. How effective this is in practice is debatable given that just 5 - 10% of the surface area is actually penetrated by the tines in the first place.
Applying sand before vertidraining may be more useful on surfaces which are bare and muddy as the sand will help to dry the surface , providing an improved grip for the tyres. Additional top-dressing may be needed following the vertidrain operation, although this will depend upon how much material is required to produce the desired standard of surface evenness.
Other Aeration
Hollow-tining of the surface layer of the rootzone, say to 100mm depth, using 12-18mm diameter tines can also be carried out as a way of further reducing compaction in the surface layer.
The extracted cores can either be removed, especially if the aim is for soil exchange to improve the underlying rootzone, or can be recultivated and broken down where they are ejected, allowed to dry and then worked back into the rootzone. This second procedure is suitable if the cores are of a suitable textural composition and the aim was just to relieve surface compaction.
Solid or slit tining to 150mm depth may only be required if the pitch does not need much in the way of renovation.
Compressed air injection or water injection (Toro Hydroject) may also be suitable to supplement other forms of aeration. There is a wide range of equipment available to the groundsman to aid the renovation process.
Turf Surface Preparation
A heavy scarification to tear out any annual meadow grass and trailing weeds, such as knotweed or clover, should be carried out to clean the turf surface.
Following scarification, mow the sward to 20-25mm in height and box off, to help remove any loose vegetation and tidy up the surface.
A Twose turf conditioner ( i.e. a vibrating mole plough) can also be used to decompact the surface of the pitch to supplement the work carried out by a deep spiker.
A thorough cleaning and effective removal of the top surface layer can be carried out using a Koro Field Topmaker which has spiral knife type blades that can be adjusted to either scarify the surface or to penetrate down to 40mm depth for clearing out the surface layer. This operation has also been carried out during the playing, for example, at Chelsea F.C. in February 1999 the surface was removed prior to it being returfed.
If a pitch is in a particularly worn condition then a powered harrow may be used to thoroughly cultivate the surface,
Some professional pitches have decided to incorporate the Desso Grassmaster system of artificial grass 'strands' into the pitch as part of the renovation (probably better described as a major overhaul) process, with some 3% of the ground cover being provided by the artificial grass. Although a very expensive operation, some impressive results have initially been achieved on pitches such as Huddersfield, Aston Villa, QPR and Watford.
End of Season Maintenance: Part 2
Fertiliser
Apply a suitable fertiliser for the pitch construction and rootzone type.
The yearly input of nitrogen for a football pitch can vary considerably. Two examples can be given:
- A general football pitch, in a parks type situation, may have the equivalent of 100-150 kg/N/ha applied, whilst
- A high specification pitch may have the equivalent of 200-250 kg/N/ha applied.
The 'optimum' yearly ratio of nutrients required by turf is usually given as 4:1:3 (N:P2O5:K2O) or 9:1:6 (N:P:K). (Source: Gibbs & Adams, (1989), 'The nutrient requirements of grass', The National Turfgrass Council : Workshop Report No.15, Turf Nutrition '88, pp5-19)
Consideration will, however, need to be given to the P & K which is available from the soil solution, as this may reduce the required amount of these two nutrients in the applied fertiliser.
Example Nitrogen fertiliser programmes
A pitch that requires the equivalent of 100 kg/N/ha/year may have an application at the end of April / early May of a 20% N fertiliser @ 25 g/m², which will supply 50 kg/N/ha [6 x 25kg bags];. A similar application will probably be given during August.
In contrast a higher specification pitch, requiring about 225 kg/N/ha/year, may have the following fertiliser applications given:
- Mid-end February, 20% N (controlled release) @ 25 g/m² = 50 kg/N/ha; [6 x 25kg bags];
- May, 15% N, @ 34 g/m² = 51 kg/N/ha; [8 x 25kg bags];
- Mid-June, 15% N, @ 34 g/m² = 51 kg/N/ha; [8 x 25kg bags];
- End July - early August, 15% N, @ 34 g/m² = 51 kg/N/ha; [8 x 25kg bags];
- Mid-September, 10% N, @ 25 g/m² = 25 kg/N/ha; [6 x 25kg bags];
The total application being 228 kg/N/ha.
There is such a wide range of fertilisers available that it is best to check out a number of suppliers beforehand to see which are available.
Top-dressing
This will generally be with a medium-fine sand and applied at a rate of 10 tonnes per 1000m². A full sized pitch will therefore require 60 - 80 tonnes.
It may be more suitable to apply the top-dressing in two parts: 30-40 tonnes first and then work it in; followed by overseeding and then the remainder of the top-dressing.
Other pitches may use a general top-dressing which will be termed '70/30' (i.e. 70 parts sand and 30 parts soil, by weight), '80/20' or even '90/10'. It is a good idea to ensure a proper particle size analysis is provided with all top-dressings that are to be applied, otherwise it can be quite feasible to end up top-dressing a football pitch with a material that contains an excessively high amount of clay. Needless to say, this would have disastrous results for drainage and playability.
Work the top-dressing in by drag-brush or chain harrow (smooth side down), or similar implements, to ensure a fairly even spread.
Where a deep spiker has been used and especially if the weather is dry afterwards, the pitch may require additional top-dressing applications. Don't forget to take this into account when ordering materials for the renovation programme.
Football pitches that have a sand-gravel, or similar, slit system will require a regular top-dressing maintenance programme. If this is not undertaken then the slits will deteriorate in a number of ways:
- They will become capped over from soil and/or earthworm activity, reducing the drainage rate;
- They will become dangerous and the pitch will be unsafe to play due to the potential for twisted ankles or worse;
- Erosion of the slits will occur due to the action of the players (sliding tackles and divoting) and the weather (especially when hot and dry) leading to less ground cover over the slits;
- With the natural filtration of particles through the slit profile, despite the best efforts made during construction and the material used, the material within the slit will sink producing an uneven playing surface which would ultimately be unplayable.
The type of material used for top-dressing a sand-gravel slit pitch will need to be consistent and compatible with the sand in the slit, to ensure a continuity is maintained between the pitch surface and the slit itself.
Failure to maintain a sand-gravel slit system properly will result in the design failing, making the initial expensive investment a potential waste of money.
End of Season Maintenance: Part 3
Overseeding
Apply a suitable grass seed mixture for the situation. The mixture will either be 100% perennial ryegrass (with blends of different cultivars) or one that is predominantly perennial ryegrass, say 60-70%, with the balance being made up of smooth-stalked meadow grass, strong creeping red fescue, browntop bent or tufted hairgrass.
A typical application rate will vary from 17-50 g/m², which works out as 2/3rds - 2 bags (of 25kg per bag) per 1000m², therefore a 6000m² pitch would require some 4-12 bags.
The seed can be applied using a seed drilling machine, especially if only a small amount of top-dressing is being planned. If a further top-dressing is being applied following the application of the seed, then broadcasting with a spreader might be quite acceptable, although scarification should ideally have been carried out beforehand to aid subsequent seed establishment.
Sowing grass seed at too high a density can result in narrow, relatively weak plants that struggle to develop due to increased competition producing a turf that is not as wear tolerant as it should be.
Goal Mouths etc.
In goal mouth areas, a top-dressing with some soil content (e.g. a '70/30') may be preferred as this may help to reduce soil erosion, especially during the dry summer months and may be a more suitable proposition for local authority pitches which may be on a sandy soil and which have a limited means of irrigation.
Goal mouths and centre circles will probably require hand forking, digging over (down to some 100 depth) and relevelling, otherwise a suitable surface may not be achieved. The prepared areas can then either be seeded or turfed, with deep turfing being particularly suitable for these high wear areas.
Germination sheets can be used to protect a seeded area, although these would only be used for a short period of time, say no more than 5 days, to allow germination to take place. The sheets should not be left down for too long otherwise disease attack will be almost inevitable. There will be a higher risk of disease due to the germination sheets effectively nullifying any wind aeration and increasing humidity and temperature beneath the sheets.
Raising the sheets for part of the day and making sure they are left in place overnight might help to reduce the problems associated with leaving the germination sheets down permanently for the few days they are down.
Irrigation
Following germination make sure the seedling grass is irrigated frequently, otherwise drying winds will rapidly desiccate the grass, resulting in a further overseeding being required.
Black Layer
This can be a problem on some high sand content pitches. Deep spiking, hollow-tining and sanding is sometimes used to help alleviate the problem, although this may not provide a solution.
Power harrowing can cultivate the surface layer, exposing and breaking down the black layer which results in a significantly increase in aerobic exchange.
Ultimately, however, the pitch may need to have the rootzone removed to the depth of the problem. This is what happened to the Aston Villa pitch in the summer of 1996, where the top 50-60mm of the rootzone was removed and replaced with additional material (Source: 'Turf Management', July 1996, p.15).
Disease
Keep a careful watch out for disease attack, especially any signs of seedling diseases. To help prevent this, make sure that the grass is kept relatively dry and free from dew and that adequate air circulation and light levels are maintained.
Grass seed treated with a fungicide (for example Advanta Seeds 'Headstart') might help to reduce the probability of a disease attack, although this should not be seen as an excuse to reduce important cultural operations, but as a useful aid in keeping disease attack at bay.
Mowing
Mow newly establishing grasses at 37-50mm to achieve a balance between root development and sward thickening. Ensure that the amount of leaf that is removed is about 1/3rd of the total leaf height, so as to encourage tillering and prevent the sward from thinning out too much, as this latter effect would occur if too much leaf is removed on each cut.
If, for example, the grass is left to grow to 60mm, then try not to set the height of cut to below 40mm.