Turf has been successfully used in many situations to repair damaged ground, from coastal cliffs to mountain slopes at 1200m. Moving turf is possible at any time of year, but should not be attempted during a prolonged drought.
Where a path has braided, leaving isolated patches and strips of turf, these can be removed and reused along the sides of the path. Extra turf will usually be needed, and should be dug from the nearest place where its removal will not be too obtrusive in the landscape, and where there is no possibility of erosion occurring before the cover has re-established. The turf must be of a type that will blend with the surrounding vegetation, and fulfil any function required, such as being resistant to trampling.
Suggested sites are as follows:
- It may be possible to take turves from the edge of an adjoining field, close to the wall or hedge. Permission must of course be gained from the landowner.
- On open hillsides of rough vegetation, turves can be taken at random. Consent from the statutory nature conservation agency is needed on Sites of Special Scientific Interest. Turves of heather and rough grass have to be cut quite deeply if they are to survive, and you will probably have to remove a sod about 150mm thick. The resulting hole should be backfilled with peat, small stones or other local material, to aid recovery of the sward.
- In order to avoid creating these scattered holes, it may be better to cut a ditch, especially if there is little material for backfilling. As well as being less hazardous to walkers, this also minimises the disturbance to the ground during turf-cutting. This is very important on wet moorland, which is easily damaged by trampling.
Often the ditch can be part of a drainage scheme for the path, but if not, align the ditch along the contours so that is does not act as a drain. The ditch will gradually fill as the sides collapse and blown material collects. - If there is an expendable piece of ground nearby it may be permissible to strip the turf in commercial fashion.
Reseed it and fence as necessary to hasten recovery. Cut the turves as neatly as possible to avoid wastage. The standard horticultural turf is 300mm x 900mm, which gives a guide to the size that is reasonable to handle. A crawler tractor will cut turf in long strips which should be cut into manageable pieces, or it will only be broken in transit. Beware, however, of merely transferring the problem to the source site. A flat area stripped of turves to repair a nearby eroded slope on Badbury Rings, Dorset, took many years to recover, probably due to lack of management of the source area.
A recent successful project in the Lake District involved cutting turf from an area of about 150 m2, and relocating it on a badly eroded rocky area lower down the slope. A group of 25 people cut and moved the turves in one day by hand. The source area had sufficient depth of soil that enough was left to support regrowth after removal of the turf. Occasional clumps were left undisturbed to provide some stability and a seed source, and the source area was reseeded. This work was done after completion of a new path at the base of the slope, so that trampling was kept off the entire area. Both turfed and source area rapidly recovered.
Stretched turves
A technique to make turves cover up to twice their original area is to pull the turf apart either by hand, or with a pair of forks back to back. However, this makes the turf more vulnerable to drought, and extra topsoil may be needed to fill gaps (Bayfield and Aitken, 1992). A similar effect, though with less gain in area covered, is made by bashing the turf down into position with the back of a spade, thus breaking and spreading it, as well as binding it to the ground. Breaking the turf may also encourage germination of seed that was buried within it.
Spot turfing
This technique can be used where insufficient turves are available. The turves are cut small, about 100 x 100mm for grassy vegetation, and about 200 x 200mm for shrubby vegetation, and placed in a grid pattern between 150mm and 1.0m apart, depending on availability. The bare areas between are seeded (Bayfield and Aitken, 1992).
Landscaping path edges
Path edges are very vulnerable to trampling and erosion, and it is worth taking great care with landscaping the edges to encourage people to keep to the surfaced path, and to prevent the erosion of unprotected soil. It is usually best to concentrate the turfing along the path edges, together with any placing of boulders or stones, and use the poorer turves or reseeding away from the edges where trampling pressure is less.
Exposed vertical ‘cliffs’ of soil along path edges should normally be reprofiled by cutting away the soil until the turf can be laid down to the path edge. Slits can be cut in the turf, to allow the pieces to be repositioned without falling apart.
Where there is insufficient turf to restore braided paths, concentrate the turf in selected areas to visually break up the line of the braids and so discourage their use.
See also pages 34-35.
Protecting the turf
When replacing turves on slopes, it may be necessary to protect them in some way to prevent them slipping before they have become established. The same device may also serve to keep people or animals off.
One method is to pin 25mm chicken wire over the turf, using loops of galvanised fencing wire. Pin at least every 200mm along the edge to discourage dogs and other animals burrowing underneath. Public access should be prevented, or the chicken wire will rapidly be exposed and the erosion problem recur. The chicken wire will eventually rust away.
Chicken wire can be held down by pegs of locally cut wood, which may help discourage access, though conversely it may attract vandalism.
Various geotextile products are available which can be used for turf protection and reinforcement (see below). Wire mesh and geotextiles are only suitable for close-cut turves, as the mesh must be in close contact all over the surface of the turf, for it to bind securely.
Brashings can be spread over the turves to discourage trampling, and staked to prevent slippage. This method is best used on rough turves. The brashings can be left in place to rot down, or removed in winter when grass growth is low, and there is less chance of tearing up any turf with the brashings.
Turf reinforcement
Many methods have been tried to reinforce existing turf to encourage growth and increase resistance to trampling. These methods include fertilising, seeding or other treatments, and laying geotextiles to reinforce the turf. These techniques are widely used to maintain turf on sports fields, but do not transfer easily to footpath management. The main problem is that most footpaths have to be kept in use continually, and even if it is possible to close off a section while repairs are being done, this only transfers the trampling to another section which then becomes damaged. On some sites, particularly on open grassland, it is possible to rotate the use of routes to allow repair and recovery, but on many sites it is not possible. Other problems are that paths are not usually of smooth turf, making mechanical treatments difficult, and access for materials may be a problem.
Having said this, turf management of paths can be successful, especially if done in combination with control of grazing, path improvements and so on. Various trials of fertilisers were carried out in the Yorkshire Dales (Three Peaks Project, 1993), with limited success. In other areas, anecdotal evidence of using simple treatments such as a slow-release inorganic fertiliser (eg Vitax Q4), or a cheap general purpose fertiliser (eg Growmore) appear to be successful.
A simple technique suitable for open areas of grassland is to mow areas of long or rough grass adjacent to eroded grass paths, to encourage walkers to spread out. If possible, keep the new line fenced off until it has been cut several times, which will encourage the growth of a lower-growing, trample-resistant sward.
For maximum effectiveness, geotextiles for turf reinforcement are best laid on bare soil, and then seeded to allow the new grass to grow up through the geotextile. Trampling must be excluded until the new turf is established. This is often not possible on paths and amenity sites, and the geotextile has to be laid instead direct onto the remaining vegetation, which then grows up through it. Where other factors of trampling and grazing remain the same, this technique has not been generally successful. Seeding, fertilising and addition of topsoil may aid success, particularly where a three dimensional mat is used. Various products have been tried, including Wyretex, Broplene Land Mesh, Fortrac and Macadamat (see Three Peaks Project, 1993, and Bayfield and Aitken, 1992). The verdict seems to be that they have only limited use on amenity sites for the reinforcement of trampled turf, and they are expensive and often difficult to transport and lay on inaccessible sites. The use of geotextiles for protecting and reinforcing untrampled slopes is discussed here.
