sand, soil, organic material or any combination of these. The key point is that top dressings add to and become part of the rootzone. Therefore, over a period of years top dressings will alter or sustain the physical and to some extent biological properties of rootzones.
Why are top dressings necessary?
Long-term maintenance of high quality turf on golf, winter pitches and bowling greens, is difficult. It is not only a matter of growing good grass, although that is an important aspect. The word ‘turf ’ embraces not just ‘grass’ but also the top few centimetres of rootzone, which determine several aspects of the playing quality of the surface. Trueness, holding character, stability and response to rain or irrigation inputs are controlled or substantially affected by the rootzone surface. It is in order to control properties affecting playing quality as well as turf grass performance that top dressings are used. Frequent applications of an appropriate top dressing will assist a Greenkeeper greatly by providing the following benefits:
1.It helps maintain a smooth, true running surface, which in turn improves mowing efficiency
2.In conjunction with scarification and verti- cutting, it will avoid excessive thatch build-up
3.Enables you to control organic matter content, water infiltration and aeration
4.It’s essential in maintaining or increasing rootzone depth
5.Improves germination on over-seeded areas
6.Improves or sustains appropriate soil texture
We generally have two options when considering which top dressing to apply to our rootzones. If we are lucky enough to have a new construction design, made with appropriate sands and organic amendments with good drainage
characteristics, our task is still not straightforward. We will still need a lot of care in choosing the top
dressing to apply to it. Compatibility is the most important factor that should be understood here. If our rootzone is not of new design and is
compacted or contains high clay content, we will want to improve this.
Compatibility
You can’t take a ‘one-size- fits-all’ approach when it comes to applying top dressings. Because they eventually become part of the rootzone they logically need to have similar composition and properties. For the majority of golf greens, bowling greens and winter pitches this means a particle size composition dominant in medium sand. But this is only a general guide it’s still essential to use a top dressing that’s compatible with your existing rootzone. If you don’t then you could be in trouble. There’s no way that a top
dressing supplier can claim that they have a good product for you without first of all testing your greens. That’s because there’s no such thing as a universally ‘good’ top dressing - what might be right for one application could be completely wrong for another because applying a mismatched top dressing can cause major layering problems to the rootzone profile. A major risk is the
creation of layers of different pore size systems within shallow depths of the rootzone. If this happens then water retention and air/water balance will be adversely affected and also rooting depth. The frightening fact is that this problem won’t become apparent for several years, by which time it may be impossible to rectify through cultivation techniques. Remember, once a top dressing is applied (good or bad) it will stay there, in the profile and it will not wash through like a chemical or fertiliser. If bad, it will haunt you for years to come. So, take extra care when selecting your top dressing.
Composition and physical properties of top dressing
The type of sand used in top dressings is vitally important and the user
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