A There are many sound reasons why top-dressing a sward is good practice. It is one of the best ways to restore a level surface and can also improve the soil by changing the particle size distribution. Indirectly, top-dressing may also increase aeration and drought resistance, maximise the effectiveness of irrigation, aid drainage by improving the porosity of the soil and help reduce surface thatch.
To enjoy these benefits, quantities of an appropriate bulky material are applied during the growing season, so the grass can grow through it. But because of the volumes of material required and the work involved, top-dressing is not done nearly as much as it should be.
Sand-construction football pitches and sports facilities where sand-slit drainage needs to be maintained can take as much as 100 tonnes of sand per year. The expense of such operations often restricts top-dressing applications to only the very best of winter games pitches and to golf and bowling greens, tennis courts, cricket tables and high-quality lawns.
Q How should top-dressing material be applied?
A Traditionally, top-dressing materials were applied by shovel, sometimes from the back of a tractor and trailer, but a wide range of machinery is available today so we no longer have to rely on muscle power and skill.
Q What types of kit are available?
A There are two basic types of top-dresser: the drop spreader, where material is mechanically brushed from the rear of the machine to give coverage matching the width of the machine; and those with spinning discs, designed to throw material in a uniform pattern across an adjustable bout. The latter are increasingly popular where frequent topdressing of large areas is required.
Pedestrian-operated machines are available for use on small areas such as bowling greens and tennis courts. For larger areas, take a look at machinery that mounts onto utility vehicles or trails behind a tractor.
Q What features should be considered when purchasing a top-dresser?
A Hopper size is the main consideration when comparing potential purchases. A large hopper will mean less frequent filling, but it will result in a heavier machine. Large flotation tyres will help to distribute the weight, and ideal ground conditions will help lessen the impact of the weight and the risk of compaction.
It is also important to think about how the hopper will be filled. Usually a tractor, fitted with a front-end loader, will be employed. To avoid spills and wastage, choose a top-dresser that is wider than the loader. Also, check out the conveyor belt in the hopper. The belt is there to help move the material to the rear of the machine. Ribbed belts tend to be the most effective at doing this.
Machines should be easy to calibrate to give a uniform distribution of material, though it is always worth considering halving the material and making passes from opposing directions to achieve a full and even cover.
Q What should be considered when choosing top-dressing material?
A First and foremost, only use high-quality materials from reputable suppliers. Materials need to be compatible with the existing topsoil. If possible, use the same material that makes up the rootzone. Materials should also be of a known source. They should be free of weed seed, pests and disease and also coarse particles.
If you choose to prepare your own topdressing, make sure the materials are mixed thoroughly. Always use the same material for top-dressing — using different materials will lead to layering and cause problems with drainage, aeration and root growth, which can change the playing characteristics of the facility.
Q What happens after application?
A The material needs to be incorporated into the sward. A wide range of brushes and dragmats are available to achieve this.
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