© Brian Murdoch 2004
Brian offers some comments on this new-ish style of treatment which is
a bit radical and some people may be a little daunted by the machines. Having
some of these machines, he thought others might find his experiences useful
in reducing the "unknown" factor. He also offers a wealth of practical
- The Meadows Croquet Club in Edinburgh has a green of about 3000m2 with
a 40mm thatch layer which we inherited when we leased the site (originally
two bowling greens) about 3 years ago. Profiles taken from various parts
of the green clearly show the thatch layer. We are advised that this leads
to dry patch and fusarium, apart from a slower playing surface. As we aim
for a surface similar to a fast bowling green, this thatch has to be reduced
and we have started to use linear aeration/deep scarifying to attack this
- And if you think that all that follows is a bit much, we have to apply £400
of wetting agent in the spring to counteract the dry patch consequences of
the thatch layer and then have to be very careful to water the green during
dry weather – and we have only a hose with sufficient pressure for
one impact sprinkler – no irrigation system. Needless to say, this
does not always get done – it takes a whole day to get a meaningful
amount of water onto the green. So getting this thatch layer reduced is a
- Having said that, as anyone who has done any amount of work on greens
maintenance knows, there are no magic bullets or instant solutions to such
problems. We anticipate three years before the thatch layer is significantly
reduced, and it may take longer. One consequence is that a slightly less
than perfect job one year will not have a significantly detrimental effect
on the green.
- Lastly, there is very little money in croquet, at the moment. Therefore
we have to call on club members for the work involved in putting the green “to
bed” in the autumn. Naturally we are constantly looking for ways of
making the work easier, sometimes by acquiring machinery to help. Most of
the machinery we have ranges from old to obsolete and survives on the application
of much tender loving care. But it works well enough for the amount of use
it gets. We do hire some modern machinery, and have a recently purchased
a truly excellent 24” Allett Tournament mower.
First some quick notes about our situation.
Methods We Use For Preventing Further Thatch Build-Up
Sisis Rotorake with de-thatching blades – 4 hours per pass
- Sisis Rotorake with thatch control/verticutting blades – 4
hours per pass
- 4 foot wide Sisis grass comb mounted on our old Wheelhorse grass
tractor. Very quick – effective at ripping up dead material and lateral
growth – 45 minutes per pass.
- Heavy (30Kg) drag brush pulled by Wheelhorse. Very quick for generally
lifting the grass, especially lateral growth – 30 minutes per pass.
Methods Of Reducing The Thatch Layer
- ½” hollow tining. Shall continue to use occasionally
to depth of 100mm – right through the thatch layer and into the growing
medium (rootzone) beneath.
- Micro hollow tining to 50mm. Useful in the spring in that it improves
air and water penetration and we don’t need to top dress afterwards – the
tining holes are too small to have any effect on a rolling croquet ball.
We use hollow tines as opposed to solid tines to help with thatch removal
so that the holes stay open longer.
- De-thatching products, e.g. Rigby
Taylor Syta-Thatch. No “on
the ground” experience in local clubs that I have so far been able
to contact. These products are quite expensive and their effectiveness
on application circumstances that are hard for the inexperienced to assess.
We have no experience of using these products.
- Deep scarifying. As a complement to the hollow tining above. Compared
to ½” hollow tining at 2” centres, 2mm blades at 25mm spacing
affects a larger proportion of the green surface at one pass – almost
twice as much – although it does not go as deep.
Why Deep Scarifying In The Autumn?
- We wanted to overseed as well, and without an irrigation system,
we have found that overseeding in the spring does not work – the new
grass plants do not survive the late spring and early summer dry spells.
- We were very nervous about using this treatment in the spring
because, with no irrigation system, we were afraid that the grooves would
open up during
dry spells before new root growth had time to bind across the grooves
Now to the actual work, almost!
Before You Start For Real
Graden GS04 or
Sisis R600? On local hire costs, the Sisis won hands down. On delivery, I
checked the blades were fitted correctly – no problem.
(Previous year they were fitted the wrong way round with predictable
results – most
of the tungsten tips were knocked out and many must still be lurking
in our green. We hired from a different firm this year)
1. The start of the deep scarification
- How thick, how close, how deep? Despite many enquiries I found it
difficult to get any clear advice on the relationship between blade width,
blade spacing and working depth. Mind you, the hire market seems to offer 2mm
blades at 25mm centres – you may have to hassle for anything else.
- Avoiding overlap. If you overlap successive passes with these machines,
you risk ploughing up the area overlapped. The R600 comes with a couple of
supports for the collector box which we never use as the quantity of debris
is so large. I tape a piece of wood across the supports and, sighting from
the front of the machine, I mark the wood with the line of the outer blades – which
seem to be slightly off-set. I then use these marks as a guide against
the last groove of the previous pass.
If you have open areas adjacent to your green you will be able to
work the machine right up to the edge of your playing surface and its
maintained margins. We don’t and we have to think about finishing the “headlands” after
the main work. If you overlap the main work when doing this, there is a risk
of “cubing” or ploughing up the overlapped areas. It’s
worth thinking about how you address this problem before you start doing
You may want to mark the limit of the main work to leave yourself a workable
margin to finish off in a different direction to the main work.
- As all mechanical work on a closely mown turf surface is hard
on the grass, you should try to ensure that the grass is in a healthy growing
condition before any such work. Otherwise the grass will take longer
from the work. We had applied the autumn fertiliser about 4 weeks
before we did this deep scarifying and the grass was in quite good order.
- I did a normal scarification a fortnight before the deep scarifying.
I don't think that was a good idea - too much surface disturbance
in too short a time.
Before doing the deep scarifying, you should cut the grass or
you will find clearing up the debris afterwards very hard work. Also you
get an even effect from the drag mat as you drag the disturbed soil
back into the turf.
2. Debris and sand/rootzone material
- We experimented with increasing the depth of cut with the R600 until
we found that the turf between the grooves was becoming too unstable – this
was at a depth of about 25mm. The nature of the top layer of the green in terms
of thatch, moisture content and root matrix obviously plays a role in how deep
you can work. You have to be careful about the forward speed of the machine
as well – we worked at gearbox setting 4. At 5, the cut was too ragged.
In the end the depth of cut we achieved was a bit under 25mm.
And Now, The Actual Deep Scarifying
Friday October 8th was dry. Switched dew off surface. Deep scarified
the green (3000m2) in about 6 hours – see Pic 1. We would probably do
better next time – you gain in confidence as you use machinery like
this. Large amounts of debris were pulled up and a great deal of sand/rootzone
well. Do we really need to lift all that sand and pay to have it hauled
away? See Pic 2.
That’s It! Now For The Resultant Debris
Saturday was debris removal day. Let debris dry off for an hour in
the sun (lucky us). I thought about this mix of sand and thatch and decided
to shake out the sand with the drag mat. Amazing!! – but probably no
surprise to old hands at green keeping. Rumbling the debris with the drag mat
shook the sand out of the mix and rolled up the fluffy thatch debris into sausages – see
Pic 3. Truly, all that was left was what we needed to remove – with very
little green grass content. And the total quantity of debris to collect was
reduced to below 50% and weighed practically nothing at all – see Pic
4. Try doing that with ½” hollow tining cores.
3. Rumbling the debris with the drag mat
- Gathering the fluffy thatch debris. We tried various processes – rakes,
snow shovels, blowers, but I feel that in the end rakes and snow shovels were
perhaps the best. The problem with blowing the debris into heaps was the tendency
to blow up the sand, especially fines, as well as the thatch, leaving a heavier
layer of sand in patches on the green. It’s as well to remember to work
in the direction of the grooves when using tools that are likely to catch the
edge of the grooves – e.g. rakes, drag mats. Next year I’ll try
to get hold of wide rakes, but they’ll have to be quite light or the
arms of the club members will not survive.
- Having removed the bulk of the debris, we dragged the green again
to drag the loose sand into the turf. For a final clean we took out
an old Ransome 24 and adjusted the height of cut to avoid picking up sand
mowed off the remaining debris. And very good it looked too. This
had the additional benefit of smoothing down the surface prior to top dressing.
- Over the next few days we overseeded and top dressed the green. To
work from side to side of the green – about 85 yards – we had to
load our top dresser with ¼ tonne per pass. Despite the grooves making
the ground feel softer, there does not seem to have been significant rutting
by the sand spreader’s tyres. We dragged in the top dressing along
the line of the scarifying grooves. I then took out the old Wheelhorse tractor,
hitched the drag mat to it and did two complete passes of the green at
to the grooves.
- I think in the spring we’ll micro tine the green again – it
all helps to remove thatch and improve air penetration. Being small cores,
rumbling them with the drag mat is partially successful in dispersing
the sand content before collection.
- Next autumn, I’ll try to hire a deep scarifier with wider set
blades – say 40-50mm – and cut down to the base of the 40mm thatch
layer, working at 45 degrees to the direction of this autumn’s work.
- As we rumbled all the sand out of the debris from this work, I
wonder whether we need to top dress? Next year I might be tempted to spread
seed and drag the lot into the surface of the green. After all, apart
from a heavier dressing, what is extra top dressing going to provide in addition
to the sand/soil rumbled out of the debris? And it would save us
a great deal
of cash and work.
The concept of the top dressing penetrating the grooves in the soft
ground after so much machinery and foot traffic (had effectively closed up
the grooves) is a bit of an illusion, at least in the short term. The winter
rains may wash it into the grooves – time will tell. But the theory
is that better air and water penetration will help the natural decay of the
layer and promote root growth. Mind you or ground was quite soft after
much rain, although we were very lucky to grab the few dry days to actually
the work done. If the ground was drier, this closing up of the grooves
might not be quite so pronounced.
4. Debris with the sand rumbled out of it
- One thing that I will probably try next spring is to break up the
hollow tining cores using the normal scarifier with its blades set to just
touch the soil/thatch surface. This might kill two birds with one stone – reduce
the volume and weight of core debris to be collected and give a light
- One part of the green overhung by a tree has very weak root growth
and the machine did pull up the turf in a few places – see Pic
any ideas (short of felling the tree) for alleviating this problem?
More On Debris Collection
I don’t apologise for going on about this – making this
as easy as possible is a key part of completing the work satisfactorily without
reducing our members to hopeless physical wrecks who can’t even summon
the energy for a pint afterwards!
5. Turf damage where the root growth
- The effectiveness of all of the stages in deep scarifying probably
varies a great deal depending on the weather and moisture content
of the ground. Deep scarifying in wet ground will work and may not be very
affected one way
or the other in ground with a very high sand content.
- The problem comes with removing the debris. I was so impressed
by the effectiveness of rumbling the debris with the drag mat in the reduction
in volume and weight of the material to be removed, that I would
reluctant to do the job again if there was not a high probability
of good weather to dry the debris. Not only does this make the task of removing
to be removed much quicker and lighter, you have less to dispose
of and if using a skip, one about a third the size will do - saving cash.
- Further, if you drag the disturbed sand/soil back into the green,
you will certainly be able to reduce your top dressing, or even better, do
without it altogether, making for a huge saving in cash and effort. Using bagged
and dried top dressing for our green costs £800 and takes about 12
man hours to apply - and we have a top dressing machine. Using barrows and
hardly bears thinking about over such a large area.
I am not suggesting that you can do without top dressing indefinitely
but you may be able to go for a year or two without and use the cash
for other things - like regular overseeding to improve the grass species
All of the above are the observations of an amateur – we buy in professional
advice on a regular basis.
I hope this will help anyone else who is contemplating using one of these
deep scarifier/linear aerator machines for the first time, although you will
obviously have to interpret the above in the context of your own ground conditions.
It would be very useful if those who have used these machines before could
share their experiences as well. Also any other comments would be most welcome.
Scottish National Croquet Centre
Meadows Croquet Club
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