Many lawns suffer from drought in a dry summer, but scorched brown areas are often caused partly by drought and partly by very hard surface soil. Too much heavy rolling may be a contributory factor here, and heavy soils will go hard more quickly than light sandy soils, but lack of aeration (spiking) is a common fault in many lawns.

Cutting the grass too close in hot weather (not difficult with a new mower) is also a reason for scorching and, whilst such damaged turf will recover, this condition can often be minimised, if not prevented, by cutting less close under drought conditions. If a lawn surface is uneven, I.e. if there are bumps and hollows, this causes the grass to be shaven in places, and where this happens, moss often follows, although moss may be due to lack of feeding, compaction of soil, thatch, shaded conditions or leatherjackets.

A lawn which has had little feeding may be more prone to scorching or corticium disease in summer. Often the feeding which is given is mainly with nitrogenous fertilisers, or mixtures containing a high percentage of nitrogen, and the benefit is relatively short-lived, as new grass growth is mown off. Where the surface is very hard, spiking with a broad or hollow tined fork (a little at a time is best) in autumn when soil is damp but not wet, or even in early spring if such spiking was not possible in autumn, will have a two-fold benefit. Not only will improved aeration lead to better root growth, but the holes made will allow peat to be brushed in and this will give increased root growth and therefore better growth of grass. Various mixtures which include peat are often used and groundsmen have their favourite mixtures, but peat by itself is easy to obtain and easy to brush or rake into the spike holes. Rate of application can be up to 544 gms/sq.m (1 lb/sq.yd). if there are hollows in a lawn, these can be improved by lifting the turf and adding fresh soil before re-laying the turf. Bumps and ridges can be dealt with by lifting turf and removing such soil as is necessary before putting the turf back. This work is best done in autumn or early winter, but not in wet conditions. Shallow hollows can be filled in with soil and seed sown either in August, late March or early April. This may give a patchy appearance if the new grass is of finer quality than that of the main area.

Aeration of turf

Turf which is much used tends to become very compressed, and a matted surface may be formed. If this occurs during the summer, it may be treated by spiking with a roller studded with spikes. This treatment is effective as a preliminary to fertilising and also watering. Deeper spiking will be necessary to relieve the compaction of turf that has been much

trampled on. Forking is a good way of relieving this kind of compression, and straight in and out forking is very beneficial in such cases. This work may be carried out in a variety of ways:-

1. The hollow tine fork (or spiking machine). This is very useful on medium and heavy loams, removing small cores of soil and turf, thus allowing air and water to penetrate freely. It is only possible to carry out this work in the autumn and winter months when the ground is soft. The fork should be inserted to a depth of 150 mm (6 inch) at least. On sandy soils it may cause too soft growth and also increase the growth of weeds.

2. Solid tining using circular tines which do not form such a large diameter hole, and are more suitable for the lighter soils. It helps air and water to penetrate, and also aids the application of top dressings. This work is also carried out in autumn and winter.

3. Slit tinina is an alternative to the above methods. A machine is used which takes out pear-shaped slits which leave only a small opening in the surface of the turf. This obviously causes less interference with the surface. The slit tine method is being increasingly used on light sandy soils.

Tining is beneficial on both fine and general sports turf, though costs usually restrict its use to fine turf. (Hollow tining is not advisable for cricket squares.) It has been found that regularly tined turf resists drought much better than untreated turf. This is probably due to increased root development following tining.

Hand forking is rather slow, and machines are available for spiking, which can be fixed to swivelling bars, which enables the tines to enter the turf vertically, thus leaving a circular hole. Machines are also available for hollow tine forking such as the Sisis ‘Turf Piercer and the Pattisson Deep Turf Piercer which has interchangeable tines, solid, hollow and slit. The Ryan Greensaire aerator is particularly good.

Scarifying or Rakina is another means of improving turf. It assists the entry of moisture and air, fertilisers are enabled to get down into the turf and become more quickly utilised. On small areas, garden rakes or special wire rakes can be used. The Sisis Rotorake and the Powarake are also available. Scarifying reduces the build-up of thatch – old organic debris which supports diseases, worms, moss and reduces the wearing capability of the turf. The drag broom and coir or link mats are also useful in working compost into fine turf. A lute is a curious hand (or tractor-mounted) tool which helps to work in top dressings.

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