In less than a week my new book, Performance Bowling Greens will be launched on this site; 15th of February to be precise. In the lead up to the launch we have been looking into some of the obstacles that stand in the way of the average bowling club achieving the performance they desire from their green. Today I want to look at one of those obstacles more closely and that is the obstacle that Tradition puts in our way. The trouble is that many of these “traditions” are really not that old. One of the most damaging of these is the “tradition” of top-dressing our greens with high sand content dressings every year.
Now I should warn you at the outset that this is a long one and you might want to grab a coffee before we get started. The reason for the length of this article is that I don’t just want to discuss the process of top-dressing; I also want to show you how damaging it can be to your green and how damaging it can be to your wallet. To do that I am going to re-present to you 3 of the most clicked on articles we’ve ever published on this site (which shows, I think, that many clubs already understand the problem). So here we go:
At most bowling clubs the end of September is when thoughts will start to turn to the autumn renovation program or the “closing of the green” as many clubs call it. Bowling clubs throughout the UK will take delivery of between 3 and 10 tonnes of very expensive top-dressing compost, which will be applied to the green after hollow tining or some other aeration operation, in the belief that this will ensure that the green is in perfect condition next season. However, too much top-dressing can actually harm the green and in many cases, clubs simply shouldn’t be doing it at all…but why?
Localised Dry Patch
Over the last 20 years Localised Dry Patch (LDP) has become a major problem on bowling greens, and although this is not wholly attributable to top-dressing, the excessive use of sand in the top-dressing mix has caused water retention problems on a lot of greens.
It is of course desirable to have a free draining soil profile on a bowling green to help to encourage deep rooting of the grasses and to maintain a reasonable green speed for play. However, continued application of bulk sandy dressings is of limited benefit to most greens and actually harmful to many due to their already high sand content and related lack of soil microbial activity.
Natural plant decomposition results in a build up of organic material (thatch) at the soil surface, which will become much more water retentive than desired. However, the answer to this does not lie with dilution of the organic layer with huge amounts of sand, but rather in reducing this layer through judicious and very regular aeration and core removal.
Where the soil is less than perfect for fine turf production, soil exchange programs consisting of hollow tining followed by top-dressing with a more desirable growing medium will still be required, but this is an entirely different subject.
Green Levels versus Surface Smoothness
There is a great difference between “Surface Smoothing” and “Surface Levelling”. Surface smoothness in this context relates to very minor discrepancies in the surface which can be rectified by a combination of surface aeration, rolling and light top-dressing.
Surface levels on the other hand cannot generally be greatly improved through even “Heavy” top dressing work. This term relates to much more severe changes in level which can be measured by laser survey and can be seen to have a visible affect on a wood’s traverse across the green.
“Heavy Topdressing” usually defined as dressings over 6 tonnes will not have a dramatic effect on surface levels and are more in keeping with the type of operation required by new greens for the first 2 to 3 seasons to achieve the final levels not ironed out during construction.
I say this because if you do the calculations, a 10 tonne dressing over an average green (1400 m2) will result in a maximum coverage of 4mm, which is only suitable for smoothing out the smallest of imperfections.
Going back to the main issue of greens drying out, the average bowling club in the UK is finding it difficult to find the money to irrigate the green sufficiently during dry weather. Again when we look at the numbers, the average automatic irrigation system throws out approximately 1mm of water for every 2 minutes of run time.
Now I visit a lot of bowling clubs and I know that many of them rely on “rule of thumb” measurements like 4 minutes per head etc when timing irrigation. Well, on average a green will lose 25mm of moisture to evapo-transpiration (a measure of the combined effects of soil evaporation and plant transpiration) and that’s from a healthy green in a normal dry week. This doesn’t take account of excessively high sand content, drying winds or existing dry patch problems etc.
To simply replace the moisture lost from one day’s evapo-transpiration you need to run your irrigation system for 8 minutes per head, that’s double and in some cases several times what many clubs are doing. Over a 7 day period this equates to 50 minutes of run time per head.
Turning back to Localised Dry Patch. This is a condition that causes large sections of the green surface to turn brown due to lack of moisture. No amount of irrigation will make these areas re-wet. They are literally “hydrophobic” or water repellent. Careful use of wetting agents and hand watering can make some improvement, but usually it takes a wet winter to bring about full re-wetting. The main trouble with LDP is its tendency to make the green bumpy. This happens when the baked dry thatch layer on top of the soil starts to shrink below the surface of the surrounding healthy turf. Irrigation makes the problem worse as the healthy areas grow more and the dry areas recede further.
To crown it all, continued heavy use of the irrigation system in the desperate effort to bring these areas back to life, starts to encourage thatch fungus, which eventually sinks and causes an even more uneven surface.
A Closer Look at Localised Dry Patch
Localised Dry Patch (LDP) is a condition that causes turf to become hydrophobic (water repellent).
Once LDP has taken hold, irrigation simply causes the unaffected areas to get lusher while the LDP affected areas get drier. This exacerbates the problem making the green increasingly frustrating to play on.
Soil sampling will reveal powder dry soil. Unsightly brown patches of turf start to spread over most of the green. The turf on these areas recedes causing a bumpy surface and in most cases the weakened grass will be taken over by moss. But what can be done to cure the problem?
Research shows that fungi can contribute to the onset of this problem. Fungal mycelium may coat individual soil particles making it impossible for water to adhere to them.
However, in our experience thatch control and irrigation management are the two most critical factors in the management of this problem.
By the time the problem is visually evident it is already too late to achieve an effective cure. This is because the problem is inherent in the green and usually only becomes visible at the height of the season.
Irrigation management requires an understanding of Water Balance in the soil and this is detailed in our Irrigation Management Factsheet. Just look at the infra-red thermographic image on the right, it shows an infrared image of a bowling green. The red areas show the extra heat that is being kicked out by the LDP affected areas, and that is directly related to the lack of moisture retained in the soil in these areas. In the standard photo further down the page, the LDP is barely noticeable at this stage, but will get steadily worse.
Frequently we are now seeing that areas affected by dry patch disorders have suffered a complete depletion of moisture and that the soil structure has failed, turning to powder. Traditional wetting agents have sought to address dry patch from a very limited viewpoint, namely the reduction of water surface tension making it easier for water to be attracted and held around individual soil particles.
Although Wetting Agents can be used to good effect on LDP once dry patch has progressed to what we call breaking point, no amount of simple surfactant wetting agent will help it re-wet sufficiently to ensure a full recovery of the turf with full grass cover. Typically the manager has to wait for the turf to over-winter before full grass cover is returned.
This makes it all the more critical that we ensure that the products we use are effective in both results and cost.
As LDP is a disorder within the soil it is important to keep one eye on re-wetting and one on re-building the soil’s health. This can best be achieved by ensuring that you use a wetting agent product which can supply carbohydrates to the soil in addition to their soil re-wetting properties. The addition of a high volume of Carbohydrates ensures that the products also contribute to the maintenance of soil structure while helping stressed grass plants hang on to life for longer while the soil is re-wetting.
Excessive use of sand on bowling greens over the years has been the single biggest influence on the occurrence of LDP and we cover this in other posts under the top-dressing and LDP categories which you can browse at your leisure.
This Tradition is Seriously Bad for your Wealth
Now that we have seen how relatively recent this “tradition” of top-dressing is and how potentially damaging the procedure is I would like to finish by looking briefly at the effect it has on the club’s finances.
I have lost count of the words I have written, conversations I have had and arguments I have inadvertently started about one of greenkeepings’ greatest follies; routinely top-dressing your green with high sand content top dressing composts year in and year out. During my greenkeeping career over 3 decades and during countless hours of research I have been amazed to find clubs where 5, 7 or even 10 tonnes of top-dressing is being applied every autumn.
The really tragic thing about this practice is that in every case the club are paying for a contractor to hollow tine (core) the green and then apply this material.
Let me ask you where the cores from your green go after they are lifted?
I would hazard a guess that you either spread them on the rose beds around the green or give them away to members for their gardens.
Now hollow tining is typically carried out to a depth of 100mm (4 inches) and usually only 10-15 percent of the core is unwanted thatch.
So that means that 85-90% of each core is made up of all of the expensive top-dressing you have been applying over the years. No wonder the roses look so good!
With top-dressing now costing around £130 per tonne, its easy to see how hundreds of pounds are wasted like this on nearly every bowling green in the UK every year.
In addition to this there are a lot of negative agronomic impacts associated with this practice as we have seen:
Localised Dry Patch is exacerbated by excessive sand content. This causes areas of the green surface to become impervious to water and dry out completely. The end result is an un-healthy, bumpy green which becomes susceptible to disease, moss infestation and loss of grass cover.
This is just one instance of good money being thrown after bad at just about every bowling green across the land.
Now this is not to say that top-dressing is never required or isn’t a valuable tool in the greenkeepers arsenal. There are times when top-dressing is absolutely the right thing to do.
However, there is generally no need to blindly apply several tonnes every autumn, only to keep the roses looking good!
In my new book Performance Bowling Greens, I will be detailing a more measured and calm approach to bowling green maintenance based on scientific fact, a deep understanding of nature and the interaction between turfgrass and soil. An approach, in fact a full program you can follow to ensure that your green performs to a very high standard at a reasonable cost.
Tomorrow we are going to look at the folly of what is considered “conventional” Bowling Green Maintenance and how this sends a high proportion of the UK’s greens into a tailspin towards disaster.