UNDERSTANDING TURF CULTURE
In this article continue to write about the basic principles and understanding of turf culture to provide suitable bowling facilities for outdoor bowls. I will also be taking into consideration all aspects of hollow and solid tining. This all follows on from the articles in the last two issues.
In the early days of bowling green construction, little is documented about maintenance because of the limited amount of play on them. Most of the greens were composed of local sands, which were free draining, overlaying well drained soil.
Requiring reasonable drainage below, they often inserted a raft system of clinker and ashes from the local gas works which was cheap and freely available. This method was superseded by broken stone, as shown in the November issue, which is incompressible.
Turf culture is about understanding the requirements of the grasses and how to treat and maintain the grass plant. It is also about understanding the use of various tools and equipment that are available to assist us in producing the best results.
The laws of the game of flat green bowls require that the surface be flat and as level as possible. Nowadays, laser levelling equipment would give a result of plus or minus 2.5mm to 4mm over the whole green, assuming the green is constructed properly.
This would include firming the root zone at each construction level in order to remove the excess air. Firming down should be done by raking and treading, and not done by the roller which will just follow the existing contours of the surface and press them together rather than flatten out bumps.
Looking at the March issue which discussed soil profiles, it could be seen that the soil profiles were all completely different below the turf, but all illustrated one major problem – a layer of silt, compressed and light in colour, near the bottom of each picture, which was supplied in the first instance by sea washed turf.
Unfortunately, this was the only turf available at the time, but it was second rate material that did not contain sufficient sharp sand content suitable for use on a bowling green. The regular supply of the best and most suitable turf had all been used up and this second rate turf with a silt base (Silloth turf) was all that was left for purchase as a sea washed turf.
It was sold with a set of instructions on how to improve the structure by integrating sharp sand (lime free to discourage worm activity) into the silt turf by hollow tining followed by solid tining.
The recommended practice in the profiles shown has been ignored as the layer of silt has not been cultivated at all and is a solid layer, which does not allow water to pass easily through it. Once it has dried out it will become hard, dry and parched, as well as being impermeable – Figure 1is a prime example.
Looking at all the profiles from the March issue, the original grass level would have been sitting right on top of the silt layer, so what, you ask, is the profile composed of above the silt layer?
The simple answer is years and years of neglect and an accumulation of dead grasses, thatch and layers of top dressing. The top dressing, no doubt, has been applied to cover up a bad surface and bury the problem. There has been no attempt at regular turf maintenance to integrate the silt level or to clean out the debris of dead and dying grasses at the end of each season. If there had been any turf maintenance, the soil would all be the same colour and mixed together.
A major problem that becomes obvious is that the original playing level has been compromised by being built higher and higher because the debris has not been cleaned out and top dressing has been regularly applied. The existing level of the green has risen well above that intended when it was first laid, so it is getting further and further away from the drainage level which would have been the costly part of the original construction.
We can also see that in most cases hollow tining has not been carried out, otherwise the silt would have been unplugged and integrated. Picture 4 shows some hollow tining has been done, but because the built-up layers of dead grasses and top dressing the tines could not reach the silt layer below, so obviously no water could penetrate either.
Unfortunately, there is no quick fix for any of the greens involved in these four profiles (other two can be seen in the March edition). They are all the result of a history of neglect and poor turf culture practice and perhaps misleading advice. Because of my knowledge and experience, I was able to give guidance on the way to make some improvement on all the greens. However, if they want a better green with correct levels, they are all looking at a major job sooner or later.
I’m able to say this with some authority, having been involved with bowling green construction and maintenance for 65 years. I have lectured all over the UK; completed 27 years’ teaching at a London college and still run nationwide courses on turf culture. For the last 30 years I have been involved in seminars for leading turf equipment manufacturers Dennis and SISIS, and I have been an active member of the Institute of Groundsmanship (IOG) for 66 years, during which time I have carried out many and varied tasks for national bowls associations and a multitude of clubs.
IMPORTANCE OF HOLLOW TINING
I would like to reiterate the importance and benefit of hollow tining. The idea was realised by a Mr Paul who, having built three bowling greens in Scotland, returned 18 months later to discover the turf had risen above the wooden surrounds by one and a half inches.
On reflection, he found that the grass roots had become established and caused the soil in the root zone to swell and rise, helped by the rain being held in the turf. He concluded that the soil had become compressed by the roots and the bowlers and had become too dense, therefore the turf could not expand sideways.
He experimented and came to the conclusion that to reduce the density within the green he would have to remove cores of soil material from the turf by using a hollow tine and this would allow the level to drop and air, water and other nutrients to integrate back into the green.
This resulted in about four and a half tonnes of material being removed from the green which reduced the density and enabled the surface to return to its original level. He left the holes open for two weeks to allow bacterial activity and root development and then finally he used a solid tine between the hollow tine holes to press the soil back together. He did not use top dressing to fill up the holes, otherwise he would have put back the same amount of material that he had just removed.
Hollow tining and solid tining (we can use hollow tines and chisel tines today for more efficiency) have become established practices in turf culture and should be carried out every three years in order to reduce the green density. Having been removed from the original turf and soil, the cores are therefore compatible with the green and can be weathered, sieved and stored in a contained area beside the green and used for any operation where you may need to use a carrier such as for fertilisers and also for dressing any low spots on the green. That way you are using your own materials all the time with no waste or extra expense.
I should also add that the hollow tining operation is carried out at the end of the season. If the turf is dry, you must prepare for the hollow tining by ensuring that the green is thoroughly soaked to allow the hollow tine to penetrate to its maximum depth.
Leave the holes open for two weeks to allow bacteria and soil life to optimise ideal conditions. After two weeks, continue to regularly solid spike as often as possible, maybe twice a week until spring rolling starts in March, which will consolidate the green back to where it was before hollow tining, but it will be less dense.
Solid spiking should continue until the start of the season, but do not use chisel tines after February/March in case there is a dry spring as the dry weather could cause the slits to open up and influence the run of the bowls.
Hollow tining may be carried out in any direction, but once the playing season approaches, say from the beginning of April, all operations on the green must be carried out on the diagonal to prevent any influence on the run of the bowls.