The Great Top-Dressing Debate

Top Dressing Bowling Green

Towards the end of every bowling season thoughts 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?

The answer is simple yet full of complexity. At it’s most basic, the answer is that excessive use of sand on bowling greens causes the under lying soil to become inert; lacking life or the complex web of interactions that go to make healthy, high performance turf. The natural balance of the soil/turf ecosystem is upset and the green will never be capable of consistent high performance for as long as the folly of top dressing is allowed to continue.

The complexity comes in when we start to consider that top dressing is recommended by most experts and consultants and that this advice is religiously followed by the vast majority of bowling clubs. However, a brief look at the facts facing many bowling greens after decades of this type of maintenance makes it perfectly clear that top-dressing is not a good option for the majority of bowling greens in the UK.

In the remainder of the article I want to explore the issues I have experienced with greens that have been routinely top-dressed using high sand top-dressing composts over the past 30 years. I will explain the problems with Localised Dry Patch, Thatch, Soil Exchange, Green Levels and Surface Smoothness, Irrigation and water
management and the dilemma that all of this leaves many clubs facing.

So lets’ start with Localised Dry Patch or LDP.

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.

Thatch

Natural plant decomposition results in a release of nutrients from dead plant material, but soils low in microbial activity tend to suffer from 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 and the ongoing encouragement of soil microbial activity.

Soil Exchange

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.

By far the biggest culprit in poor levels is excessive thatch which moves, swells, compacts and contracts continually. Trying to keep up with this with top-dressing is futile.

Irrigation

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.

Catch 22

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.

The Alternative

The Performance Bowling Greens program isn’t completely anti-top-dressing, but I have found that very few greens, at least in the UK, can actually cope with the damage that would be inflicted by applying more sand. The program recognises that some greens will still require top-dressing and gives advice on this.

However, the most important aspect of the programs I recommend for most greens is that they focus on returning bowling greens to healthy, living eco-systems that are not only disease and pest resistant, but also in a condition that helps the club to provide their members with a consistently high performance playing surface that can be set up predictably over the entire playing season.

The Performance Bowling Greens Program is set out in comprehensive detail in Performance Bowling Greens, a practical guide.

The Role of Microorganisms in Soil Health

Fungi

The Role of Microorganisms in Soil Health is vast and in many cases misunderstood. For decades we have been obsessed with the potential harm that just a few pathogenic microbes can cause, instead of learning to think of the soil as an eco-system. We've learned the hard way about that approach and now that pesticide availability is being reduced we need to start taking this seriously. Excellent article here from Christopher Johns, Research Manager, Northern Australia and Land Care Research Programme

Read more

Fix your bowling green step 3

Root mass is important for a healthy bowling green

In parts 1 and 2 of this series on how to fix your bowling green, we discussed the process and importance of taking regular soil profile samples and discovered what the soil sample can actually tell us about the condition of the green. In part 3 John links this to demonstrate why each of the visual signals from the soil sample point clearly to one or more of the multitude of issues we experience on poorly performing greens. From disease outbreaks to skinning of heads and bad runs on rinks, the humble soil profile sample can tell us a lot about where we're going wrong and point to the answers that will help us create a performance bowling green in the near future.

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Fix your bowling green step 2

Thatch Layer

In this article we take the soil samples you removed in Fix your bowling green Step1 and look more closely at them to discover what's going on under your green. This is one of the most valuable practices that any greenkeeper can undertake as it can reveal a wealth of information about the condition of your green that you could previously only guess at.

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Fix your bowling green step1.

Smoothness and Colour

I genuinely believe that it's possible to come up with a formula to fix your bowling green, regardless of it's current condition. This is due to one over-riding fact that I've discovered after looking at literally hundreds of greens. They are all at some stage of what I've termed the Circle of Decline. The critical factor in making this possible is simple. You must know what you are dealing with and there is no way to find that out without carrying out some hand dirtying investigative work. So let's get dirty!

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A note on the ecology of greens (and squirrels)

A note on the ecology of greens (and squirrels)

Understanding that the ecology of greens exists and what that means is more important for greenkeepers than understanding how that ecology works or indeed any of the scientific components of ecology in isolation. Stepping back and letting nature do its stuff can yield remarkable results.
In this article you'll discover how some commonly applied greenkeeping techniques are actually rather blunt instruments that can result in more harm than good. Top-dressing, applying lawn sand and fungicides are routinely applied to greens in an effort to treat the symptoms of common problems in the soil.

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Ecology 8. More disturbing news for bowling clubs

stress

Last time, I introduced the subject of Disturbance in bowling green ecology and maintenance. I finished by posing the question; How can we use disturbance theory to our advantage in our quest to create a Performance Bowling Green?

To answer that, let’s look at what might constitute Disturbance in the average bowling green. As greenkeepers we actually have an impressive amount of potential influence we can bring to bear on the turf environment; some good and some bad. We can think of these influences as pressures and by applying them with the right force we can manipulate the bowling green eco system (to some degree) to our advantage.

Last time we also discussed Stress factors, which when compared with physical disturbance from our machinery and bowling, can seem innocuous, but the overall affect of say LDP can easily be more damaging to our turf in the long term than an obvious physical disturbance like hollow tining.

Every day Greenkeeping and bowling can have a high disturbance value and put the very grass we are tending under a lot of stress. Mowing, verti-cutting, wear from bowling, pests, diseases, disorders, aeration, top dressing, water and nutrient availability and soil pH can all cause stress to a greater or lesser degree and this will change depending on grass species, general green condition, weather and soil type/condition.

Well the answer is clear then isn’t it? Maybe if we just do nothing (which is the right thing sometimes) the green will improve on its own. If we had unlimited time and didn’t need the green to be prepared for bowling, then I would say absolutely yes, leave it alone, bar maybe a sheep or two and it would sort itself out easily. There would be no thatch, compaction or LDP either. But we don’t have that luxury so we need to intervene to get our green in the shape we want, especially if our green has been subjected to what has become conventional or traditional greenkeeping.

The transition from a failing green that is deep in the grip of the Circle of Decline to the Nirvana that is a Performance Bowling Green is something that needs a fair deal of skill and a great deal of patience and consistency of approach. Once we are in utopia with a Performance Bowling Green we can start to think of backing off on the heavy, physical maintenance and begin to implement a low disturbance diet.

Once we have reversed the process of decline the bowling green can and will improve quickly, but it’s at this time that we need to exercise caution and stick with the program, avoiding slipping back into the old patterns of maintenance at all costs.

Using Stress to Our Advantage

At that stage we can start to use the stresses of disturbance to our advantage. The plan is to create a healthy, settled green first and then put the thumb screws on the undesirables like annual meadow grass slowly but surely, all the time making sure that the techniques and intensity of maintenance we use don”t put the bent and fescue component of the sward under undue stress.

Disturbance can be used to get the ball rolling on green transition from 100% annual meadow-grass turf with squidgy, thick thatch at the turf base over a claggy clay soil. The first steps would include making sure there is physical drainage to take away excess water.

The program would then move on to the renovation phase which would start with aggressive compaction relief. Then a series of operations to physically remove thatch would follow and this could include, intensive core aeration, deep slotting/scarification and maybe even top dressing with sand (yes you read that correctly) if the conditions demanded it.

When in the grip of the Circle of Decline, greens in this condition usually need a high Nitrogen input just to tease a result out of them for play, so the fertiliser program will definitely need a revisit to reduce this. Watering will usually be too high also so we have to tweak and jiggle the program a little at a time in order to maintain grass cover during this major transition.

Finer surface aeration like verti-cutting will be intensified as will sarrell rollling and it will become increasingly important to keep the mower razor sharp with zero contact blade settings to maintain the health of the turf plants.

The Phases of Recovery

In Performance Bowling Greens I split the recovery and on going delivery of performance into 3 distinct programs of work that may or may not be used in parallel depending on the overall condition of the green in question. These are Baseline Maintenance, Renovation Maintenance and Performance Maintenance, leading to phase known as Continuous Improvement

The process of transition from a predominantly annual meadow grass, thatchy, compact and anaerobic, sickly green to a Performance Bowling Green is detailed in my eBook Performance Bowling Greens below:

Performance Bowling Greens eBook
Performance Bowling Greens eBook
NOW comes with HALF PRICE SOIL ANALYSIS! In our best selling eBook, Master Greenkeeper John Quinn explains a program for the recovery and transformation of any bowling green into a high performance green. This eBook will change your mind on how bowling greens should be maintained for ever. Includes annual maintenance schedules. more details Soil analysis offer valid in UK only.

Ecology 7. Disturbing News for Bowling Clubs

Disturbance theory

In 1988, Grime, Hodgson and Hunt published their study called “Comparative Plant Ecology – A functional approach to common British species”, which on the face of it sounds like ideal bed time reading for insomniacs. However, the work these scientists carried out might make you sit up in bed and take notice when you realise how relevant it could be to the performance of your bowling green.

In this work, the authors state that vegetation that develops in a place at a particular time is governed by environmental pressures. These pressures may be categorised as stress, disturbance and competition (S, R and C) and that these vary in their relative intensities. Individual species develop their own growth strategies in order to deal with their own environmental pressures.

In Performance Bowling Greens, I introduced the concept of Disturbance Theory which is simply a way of thinking about and defining the growth strategies of each of the fine grass species we aim to grow on our bowling greens. Furthermore, by relating this Disturbance Theory to our greenkeeping calendar we can develop programs and strategies to help us create the environmental conditions that favour the species we know will produce the finest bowling surface. In the UK these are the bent and fescue grasses, but Disturbance Theory holds up for any environment, including the warm season areas of the world.

In a nutshell, Disturbance Theory encapsulates the main themes of the previous 6 articles (imaginatively labelled Ecology 1 to 6) on bowling green ecology and attempts to become the go to tool for greenkeepers to help them manage their greens in a manner that heeds the importance of ecology in bowling green maintenance. In particular it should help give lay people an understanding of how to manage the bowling green in favour of a dominance of the finer grasses. If allowed to develop, the bent and fescue grasses will provide improved playing qualities and reduced vulnerabilities compared to annual meadow-grass.

To be able to manage your bowling green eco-system correctly it is necessary to understand the nature of the pressures.

■ Stress (S) is defined as the environmental constraints to growth. This may include soil moisture (too much or too little), poor fertility (too low or too high), low temperatures, soil acidity and/or salinity.

■ Disturbance (R) is the physical damage occurring within the environment. This is particularly important for bowling greens due to our reliance on regular mowing as the main route to preparing the green for play. Regular disturbance imposes what ecologists call “selection pressure” on the environment.

■ Competition (C) is the struggle between plants to survive and assume dominance within the environment. Some plants have evolved to naturally assume dominance given the right conditions. The continual removal of leaf tissue by mowing would seem to stack the odds against our fine grasses, but these species have developed naturally in closely grazed environments, like we see on the Machair.

Of course as we’ve increasingly become aware of over this series on ecology, environmental pressures rarely act alone. There is invariably a combination of factors and stresses at work in our greens and this is largely what dictates the nature of the growing environment.

Each species has strengths and weaknesses depending on which environment they evolved to survive in. The bents and fescues are considered to be C-S-R strategists as they do not welcome too much disturbance pressure but will put up with some stresses such as mowing quite well. Poa annua (annual meadowgrass) is considered an R strategist that thrives under disturbance but does not welcome too much stress. It is quick to establish in space but struggles to get a hold in a tight knit turf of finer grass. This gives us a strong indication that what we need to do to ensure our greens favour the finer grasses is to minimise the level of disturbance and use stress as a beneficial selection pressure against the annual meadow-grass.

To set the correct environment we need to be able to play with the pressures.

Next time we will investigate further what the greenkeeper can do to influence the level of environmental pressure on the bowling green and how we can harness the effects of ecology to our benefit.

Ecology 6. Soil Microbes

Life after pesticides for bowling clubs

Soil microorganisms exist in vast numbers in the soil as long as there is a carbon source to provide them with energy.

The microbial population is made up of 6 distinct groups of organisms. In order of average population size (biggest first) there are Bacteria, Actinomycetes, Fungi, Algae, Protozoa and Nematodes.

The actual biomass of each of these organisms can be confusing at first due to the difference in size of the individuals. For example, due to their small size, Bacteria contribute a smaller overall biomass than Actinomycetes, even though these organisms are a factor of 10 times smaller in number. Due to these Actinomycetes being larger as individuals they contribute a similar biomass to the much more abundant Bacteria.

Fungus population numbers tend to be smaller but are usually the dominant presence in the microbial biomass where the soil is left undisturbed. Bacteria, Actinomycetes and Protozoa are hardier making them more able to tolerate disturbance of the soil than fungal populations. Bowling greens are probably a half way house; not being subjected to excessive tillage, but not entirely undisturbed either.

Here’s the really interesting bit:

There are more microbes in a teaspoon of soil than there are people on the earth!

The Circle of Decline is largely predicated on poor soil microbial populations due to inappropriate maintenance practices.

the Circle of Decline, the reason many greens never improve
the Circle of Decline, the reason many greens never improve

Microbes and plant nutrition

Soil microbes are abundant in the soil and are vital to the recycling of organic matter in the soil to provide nutrition for plants. The smallest and most hardy of these are the Bacteria which can survive under the harshest of conditions and are especially resistant to tillage or the mechanical cultivation of the soil as happens in the top 100-150mm of the bowling green through aeration practices.  Fungi are more specialised and need a constant food source meaning that they survive and thrive more readily in uncultivated soils.

Soil organic matter consists of a mix of living microorganisms, dead leaves, shoots and roots (fresh residues), and the older decomposed plant material called humus. Fresh plant or animal material provides an ideal food source for microbes and is composed of easily digested sugars and proteins.

Soil cultivation through aeration (incorporating oxygen) destroys soil organic matter through oxidation and allows bacteria and other microbes to rapidly decompose organic residues. Warmer soil and the presence of moisture speeds up this process by supporting an increased microbial populations in the soil. Organic matter with a low carbon to nitrogen (C:N) ratio (green material) is easily decomposed and nutrients are quickly released (4 to 8 weeks), while organic matter with a high C:N ratio (woody material like roots, rhizomes and stolons) decomposes more slowly and the microbes will tie up soil nitrogen to decompose the residues. Protozoa and nematodes consume other microbes in the soil and release the nitrogen as ammonia, which becomes available to other microorganisms or is absorbed by plant roots.

Bacteria Graphic http://www.soils4teachers.org/