Noel Mackenzie: What aeration machine and technique should you deploy?

Alistair Dunsmuir
By Alistair Dunsmuir October 30, 2011 14:19

Noel Mackenzie: What aeration machine and technique should you deploy?

Sticking holes in turf has been a mainstay activity for greenkeepers for a very long time. In the early days of greenkeeping it was recognised that the removal of worms from the soil demanded that the soil be treated to some form of spiking to allow water off the surface and encourage exchange of gases from the soil to the air and back again. In the early days it wasn’t really understood why gaseous exchange was important to the same extent that it is today, but the greenkeepers knew that the soil and roots needed to ‘breathe’ and stale soils needed ‘fresh air’. Of course, we have come a long way in our understanding of soil ecosystems (although this is still a very young and complex science) and the realisation is that the micro-organisms that are involved in efficient nutrient cycling and decomposition processes within the soil depend, largely, on the availability of oxygen.

There is a vast array of different methods by which to aerate turf these days. Most greenkeepers are familiar with the three main tine types: solid, hollow and slit tines. These three tine types still form the majority of aeration methods used in sportsturf today – though not without considerable variation in the method by which they are applied. Traditionally these tine types were employed using rotating drum type spikers such as the Patterson and Sisis AutoTurfman machines and their larger tractor-mounted equivalents. With the growth of golf came ‘greens friendly’ versions for ride-on machines such as the GA30 or PTO powered machines for Cushman and mini-tractors, for example the Coremaster 12, Ryan GA30, ProCore and so on.

While rotating drum type spikers are very suitable for slit tine aeration due to the speed and ability to get good penetration depth despite their light weight, they are less suitable for solid and hollow tine aeration work. The pressure required to push solid or hollow tines into the soil is greater and to get adequate penetration the density of tines on a rotating drum has to be reduced significantly or the machine weighted very heavily which causes other problems.

A solution arrived in the late 70s / early 80s with the development of punch action spikers such as the Ryan Greensaire. I have fond memories of using this machine walking backwards over greens for a week at a time at about half a mile an hour (if that). What these machines could do though was really get a solid or hollow tine into the ground at least 75mm, often 100mm. The downside was that there was extra work required shifting cores that were proper cores, not the old ½-1” ‘fag butts’ produced by the rotating drum spiker which were light and quick to shift.

Not only were the cores deeper but the density of cores taken was much, much higher! Tine spacings of 50 x 50mm (2” x 2”) were possible and later more density with 25 x 50mm (2” x 1”) spacing in contrast to the 100 x 100mm (4” x 4”) spacing obtained on many rotating drum machines. Suddenly fine turf went from having a few holes poked in it to being thoroughly peppered by steel to really open up the surface in a significant way with about five per cent coverage achieved.

With this new technology came a diversification of tines available. Until the punch action spiker appeared the smallest tines were on sarrel rollers where a high density solid tine of around 5mm (3/16”) diameter and up to 25mm (1”) long could be pushed into the surface along with regular tines of 9mm (3/8”) and 12mm (1/2”) of around 75 to 100mm length (3-4”). With the new powerful punch action spikers fitted with turf plates (to hold the turf down) tine choice mushroomed. Diameters increased and decreased simultaneously with 5mm needle tines (up to 100mm length), 9, 12, 15 and even 18mm tines coming to market. In hollow tines microtines of 5-6mm diameter allowed virtually undetectable coring of golf greens to take place as well as larger hollow tines speeding up the rates of soil exchange.

These technologies allowed greenkeepers the scope to fine tune their work to minimise disruption to playing conditions yet still improve greens’ condition in the longer term. They allowed greenkeepers more finesse in their work. They improved the effectiveness of greenkeepers. They improved the efficiency of greenkeeper’s work. The changing of tine application technology from rotating drum to punch action was revolutionary in a way we probably didn’t quite realise at the time!

At around the same time a new type of aeration was being talked about due to the introduction of the Verti-Drain machine. This larger machine punched the tine into the ground then levered it up to fissure and crack the soil apart thus re-introducing air spaces into the soil. This helped to combat two problems associated with normal punch spiking; compaction / compression or soil around the tine hole and, particularly with hollow tining, compaction just below the furthest depth of the tine penetration. Punch action spiking would be here to stay but ‘Spike and Heave’ technology was another tool in the greenkeeper’s amoury.

Soon Verti-Drains were being utilised on fine turf, having escaped from their original operational zone on coarser turf such as football pitches, fairways and so on, and the range of machines developed to reflect the needs of the greenkeeper working on greens. Used skilfully, the development of ‘Spike and Heave’ technology (be it from the Charterhouse Verti-Drain, Weidermann TerraSpike or Huxleys/SISIS Soil Reliever) has had a very big impact on the condition of playing surfaces – be they greens, tees, approaches or fairways, especially as the machines have evolved to become ever more tactile and flexible.

Traditionally, poor drainage could be tackled with sub-soiling and mole ploughing on compacted or clay rich soils but ‘Spike and Heave’ aeration / compaction relief gave a new and exciting possibility. Many are the fairway and football field that have been improved by the simple sanding and ‘Spike and Heave’ treatment when otherwise drainage would have been installed. Sadly, this point is still very often missed today.

Any action that reduces water content of soil pores and increases air content of soil pores could, reasonably, be called ‘aeration’. For that reason we should include devices such as the mole plough and sub-soiler, both of which produce ‘heave’ of the soil, can break up ‘pans’ and in the case of the former, create a smoothed ‘bore’ within the soil to speed up water movement out of the ground.

Similarly, vibrating mole-ploughs such as the often overlooked but very valuable Twose Turf Conditioner or the GreenCare Shattermaster could be relied upon to undertake valuable aeration work and enhance surface water infiltration when used under the right conditions. These machines are seldom seen these days which is a pity as they are highly effective but suffering a loss of fashion.

The most recent additions to the armoury of those wishing to aerate at depths of around 200mm+ are the ‘EarthQuake’ type machines. These large, rotating blade devices are useful in alieviating compaction of soils and work to a good depth (usually 300mm or so) in much the same way as vibrating mole ploughs do.

A few years ago rootzone injection machines were becoming the latest thing. The best known of these is the Toro Hydroject which was one of the first devices to appear and still remains available. These machines work on the basis of firing pressurised water into the soil or rootzone to ‘blast’ the soil particles apart. As an aeration method these tend to exist at the fringe due to their cost and lack of easy availability and adaptability. Nevertheless, they still represent a valuable option in certain circumstances. Most of the injection machines use water, but soon-compressed air treatments were employed by the likes of Terrain Aeration and later SISIS (Aer-Aid) which are quite different devices. The SISIS Aer-Aid machine is like a traditional spiker but with the added advantage of blasting out compressed air. The Terrain Aeration approach is aimed deeper within the soil profile and can be very effective indeed in overcoming panning and compaction problems.

Each of the techniques covered here has the potential to do much good. But under the wrong conditions the value of the technique may be much reduced and could even be detrimental. Most aeration needs to be carried out under conditions where the soil has some moisture. Too dry and the turf may rip or be over-stressed by the works. Too wet and the soil will be compacted or smeared. Good conditions are typically when the top 10 to 20 per cent of the depth of aeration are dryish but the underlying soil retains some moisture. The only exception is mole ploughing which requires some moisture in order that the expander plug on the plough can smooth the clay to create a ‘pipe’ within the clay.

Probably the area of greatest importance is for the greenkeeper to choose the right technique for his site. That will be contingent on what his / her issues are. Deep compaction problems at 300mm depth will not be tackled by hollow tining at 75mm depth. This sounds obvious and yet it is often the case that greenkeepers make these types of mistakes through inadequate diagnosis of on site problems or have inappropriate objectives or expectations from aeration treatments. This is an area where consultant agronomists working with the greenkeeper to undertake more careful observation of the course can help.

Alistair Dunsmuir
By Alistair Dunsmuir October 30, 2011 14:19
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