It is true to say that one of the commonest problems on bowling greens is a slow and heavy surface. Unfortunately, many bowlers still believe that the solution to this is a straightforward one and can be rectified by simply mowing very close and by the repeated use of a heavy roller.
Whilst a shaving and rolling programme will sometimes produce an immediate improvement in the pace of the surface, the longer term side effects of these operations can be, and often are, next to disastrous. Excessively close cutting only serves to weaken even the finer turf grasses and, ultimately, leads to the appearance of moss, bare thin swards and weak grass growth, resulting in stressed sward with low wear tolerance, which lacks colour, vigour and appearance. The players and members want immediate rectification and the greenkeeper needs to act quickly. So, he feeds with inorganic fertilisers to change the appearance, i.e. a quick fix mentality.
Heavy rolling compacts the soil and leads to drainage difficulties. In wet and compacted soils the grass sward has real difficulty in producing adequate root growth. This can make the sward prone to drought in the summer and generally makes growth weaker than it should be. More salt based inorganic feeds are added to improve the aesthetical value of the green. Compact soil conditions also encourage undesirable weeds and weed grasses, particularly our common enemy Poa annua (Annual Meadow Grass).
In order to determine the exact pace of a particular bowling green, it is only necessary to roll woods across its surface roughly from ditch to ditch, with the aim of getting the bowl to stop before it falls in the ditch. If this is repeated several times in different directions, and each wood timed with a stop watch, then an average can be obtained.
If each wood takes roughly 18 seconds to cross the green, then the surface can be classified as fast. For greens of average pace, the woods will take 14 seconds. If a figure below 14 seconds is recorded then woods are having to be bowled too hard and too fast, and the classification is excessively slow.
In order to effectively deal with a slow green it is essential to appreciate exactly what is causing the slowness of the surface and not simply turn to the myth that if you cut short and roll, it will sort it out.
The most common cause of excessively slow bowling greens is the presence of thatch. This is found just below the surface and is created by the accumulation of matted grass stems. It is easily detectable when you simply walk across the green as the surface feels soft and spongy, rather like a mattress, and one sinks slightly into it leaving behind a distinct footprint.
It can be useful to cut a slice out of the surface of the green just like a piece of cake. Examining the soil profile will often show some 50 to 75mm of fibrous material. I tend to use the one or two fingers guide; place your index finger horizontally to the surface, just at the base of the green leaf section. If the fibre is only as thick as your finger then that is not too bad, but management is required. If the fibre is as thick as two or more fingers, then real problems are evident. If this is a feature of the green then, in order to speed up the playing surface, it is fairly obvious that major concentrated mechanical operations must be employed to eliminate the thatch.
The fact is that there are several different types of thatch. Sometimes one encounters a layer of material which is brown in colour and often looks like coconut matting. This is often produced by excessive acidity and a soil test can show exactly what the pH figure stands at. Excessive acidity levels reduce bacterial action in the soil and the natural breakdown of the fibre is, therefore, slower than it should be. If you try to change the pH other undesirable side effects will be observed, such as worms, weeds, course grasses and disease.
More commonly the thatch layer has a spongy yellow appearance and, in wet weather, can smell sour and unpleasant. Thatch of this kind is usually caused by poor drainage, of which compaction is likely to be the underlying problem.
Greens over fifty years old tend to have been built using Cumberland sea washed turf. Due to years of fertiliser and topdressing applications, the sea turf now commonly sits some millimetres below the surface. This is the original turf level which has become buried over the passage of time. The infected water holds within the thatch, likewise the artificial salt based fertilisers are held in the fibre, hence further thatch accumulation is promoted.
As in the case of acid, fibrous thatch bacterial action is lacking due to the waterlogging soil conditions, and dead and matted plant material gradually builds up.
Today's greens are made up largely of annual meadow grass (Poa annua). This plant readily grows better than more desirable turf grasses in the shallow situation. The problem is worsened by the fact that annual meadow grass is particularly prone to thatch production, hence the problem snowballs. Over watering and over fertilising with salt feeds will drive the grasses into unwanted and unnecessary leaf production, so you cut more often and, furthermore, slow the run of the woods. As this green and pleasant sward subscribes to more annual meadow grass, more thatch is produced.
In the above aforementioned comment, it is obvious that the physical removal of thatch is the only effective way of producing a firmer and faster bowling surface.
If the thatch is yellow in appearance then aeration and carefully selected topdressing are probably the most important operations.
A thatchy green of this kind should be well spiked during the off season. Once the machinery has been provided, in season aeration must also be encouraged from surface pricking to micro solid tining, providing it does not cause excessive interference with play. Aeration using the flat knife type of tine should be regarded as standard, but it is often also useful to carry out hollow tine aeration work at the end of the season, ideally no later than early October.
Once the cores have been removed, and the surface cleaned, an application of a carefully selected topdressing can be given to the green. In very severe cases, some four tonnes, with a high sand content, is regularly prescribed to help aerate the soil whilst assisting in the firming up of the thatch.
Carbon is often applied as a food source to assist in the natural breakdown of thatch by way of soil macro and micro organisms. They are the factory by which all soils become productive once more.
The long term good in maintenance work is to aim at:
• Reducing annual meadow grass.
• Improving soil conditioning.
• Improving micro organism activity.
• Applying amine stable Nitrogen feeds.
• Improving the natural well being of the grasses.
• Removing artificial fertilisers from usage.
• Watering copiously, not to over water.
• To topdress little and often by testing the surface if at all possible.
When faced with an excessively slow bowling green one should always investigate the cause of the slowness.
For further information contact David H. Bates Agronomy Services on 07736 066031 or email: DHBatesservices@aol.com