Aeration of Sports Pitches Guide
Aeration of sports pitches is just some research l have done, which l thought l would share. I do NOT claim to be an expert just wanted to bring this information together and to learn from it.
I have tried to unpack the whole subject and provide answers for common questions such as, how do we know if the soil is compact, what is aeration and in what soil conditions is ideal.
I have also included a guide for each sport in terms of aeration.
Why do we need to aerate?
To maintain a free draining surface, which will assist in preventing compaction, weeds, waterlogging and shallow rooted plants that struggle in high stress conditions.
To maintain an open network of pore space throughout the soil is also vital to ensure roots go down deep and any gaseous gases are exchanged for oxygen.
What we want to create is an open network of pore space where, water and nutrients and oxygen can exist to encourage a deep dense root system. Which will equal in a strong plant and good soil infiltration rates.
What creates compaction?
Foot traffic/play seals and caps the top inch or so, especially when play is undertaken in unsuitable condition i.e. wet with little grass cover.
Machinery of all types
Signs your carrying our aeration in the wrong conditions?
Smearing and or capping of the soil profile or in and around the aeration channel.
Water appearing under foot/machinery, could lead to capping/sealing of the surface and it must be remembered you cannot create pore space properly in wet soils, as the soil will not fracture.
How to access whether your soil is compacted?
Visual inspection of the rootzone
If the sub soil smells like egg/sulphur upon disturbance, this is a sign of gas build up occurring due to compaction.
Compaction testing tool
The use of testing equipment like a clegg hammer.
A top cricket pitch can clegg read at plus 300, and the aim of some top professional football clubs is to be no higher than 90.
Two Major forms of compaction on winter sports pitches, are via treading which is said to compact the top 30-60mm and the other is via smearing of the soil to a depth of 30mm. Compaction though can be measured as far as three times lower in horse racing environments.
Two ways to decompact?
1 Raise the soil surface up
2 Removal of a segment of soil
Both not suitable for all situations.
What is aeration?
Rieke and Murphy defined aeration as :
Relieving of soil compaction
Aiding in thatch control
Disrupting undesirable soil layers
Preparing the soil for top dressing or overseeding
Enhancing the penetration of fertiliser and chemical input
Stimulating turf density by stolon’s and rhizomes
If a soil is completely compacted what options are left to dry the surface and rootzone?
Transpiration -The drying of the rootzone, via roots pulling water out of the soil and up through the leaves.
Evaporation -The surface drying from the heat of the sun etc.
Often the only options of a consolidated cricket square, where pore space is very limited to rolling etc.
Often the only option for a compacted cricket square and also important to consider the importance of a slope on a square, to shed water.
This video, is more aimed at golf/greens but still a informative video for all sports surfaces.
Types of Aeration
Deep drilling -A collection of 12-inch drill bits, with 6-inch centres drill in union, drilling into the soil profile with no heave or lifting and this is an especially useful tool for working through compaction pans, root breaks etc. These holes can be back filled with the appropriate rootzone to increase infiltration.
Linear- Is a great tool for winter pitches and golf fairways etc, the linear action creates a narrow continuous vertical/slits, which decompacts by side way displacement of soil blocks. These lines are ideal for improving drainage and root growth.
Air injection/probes -Blasts air deep within the soil profile and decompacts pore space, helping to break up compaction and opens up the soil to make it more free draining, with little surface disruption. The machine can blast air as deep as 12 inches by 9 inches in diameter.
Solid tines – Solid tines aeration involves inserting a solid spike into the soil profile, these come in different lengths and widths and are commonly used as part of a regular aeration programme, there is a small amount of heave in this technique.
There are some arguments that solid tines do not decompact, as they force soil to compact around and below the tines, but still a useful tool for infiltration of water.
Hollow tines– Hollow tines are just as they sound, hollow. Hollow tines remove a plug of rootzone and is a great tool for green and winter sports, with the benefit of breaking up compaction, removing thatch and soil exchange.
Hollow tining use in cricket is rare due to concerns regards settlement, but can be a useful tool in the lowering of high ends (saddles)
Chisel tines- As suggested in the name, they are shaped like a chisel and are mostly used on bowls greens, during the autumn and winter. They are used less often in spring/summer as there is a risk the slits could reappear on surface drying.
Chisel tines also come under the family of slit tines, which come in a variety of shapes(knife/diamond) and are very commonly used fitted to a tractor on winter sports pitches.
Hand fork- Still a place for the good old hand folk on small areas. If inserted as deep as possible at a near vertical angle, then a gentle pull back a few inches and then heave is created and in turn a level of decompaction.
Scarification is also another known form of linear aeration.
How aeration of sports pitches occurs?
Soil fracturing or loosening (Air injection/ Probe)
Mechanical fracturing (deep spike/tines)
Optimum timing for aeration?
Generally speaking, the optimum timing for aeration is when the soil is dry enough for the soil to fracture around the tines/blasts and open up the soil to create new pore spaces.
If aeration is carried out when the soil is moist/wet smearing occurs of the side/base of the holes occurs, and as a result no new soil fractures been created, only a drainage channel
If the soil is too dry however you will not be able to get the aeration equipment deep enough into the soil profile, unless a sand-based pitch so timing is everything.
Not all aeration equipment is fit for all sports surfaces, so please see below for a basic guide and this isn’t a technical document only some basic research.
Heave– is a description of the soil beneath expanding and being pushed upwards.
Decompaction-the introduction of air into the soil profile and the creation of pore space.
Compaction-is the result of compressing the pores together, which decreases pore space density to block infiltration of water and create low oxygen levels within the soil.
Pore space- Are the spaces between minerals and organic matter, they are filled with either air or water, well and oxygen and nutrients.
Root breaks – is a horizonal weakness within the soil profile, which can occur as a result of buried layers of organic matter or non-compatible soils.
Cricket is a tricky one, as groundsman we do all the wrong things i.e. compact the profile with a roller which put the plant under a lot of stress, in most other sports it’s an opposite approach.
Cricket clay has a memory and once it dries it shrinks and if aeration is carried out too near the season, these holes can reappear.So best to get any aeration done, by mid January.
Timings wise for aeration in cricket is from November to mid/end of January. Trying to aerate earlier than November can be tricky for a couple of reasons
1- The seed is still young and could pluck out.
2- The soil profile needs plenty of rain after renovations to assist the penetration of tines.
Shallow aeration can also take place during renovations, to help seed and loam incorporate into the surface.
If the surface plucks or lifts, you are going too deep for the level of moisture present within the soil, if this is the case re wet or allow weather to, or long-term damage can occur.
If you want to see a blog we did last year on aeration of cricket squares, take a look at the below link. This blog answers things like, does spiking a cricket square decompact it- https://turfcareblog.com/a-need-to-breathe-aeration/
Suitable aeration techniques for cricket – Solid tine and if looking to pin together root breaks possible deep drilling, but take expert advice prior.
Winter Sports Aeration
Grassroots – At some levels only a garden fork is avaible for localised areas and maybe the odd deep spike via a contractor post renovation or once in autumn. Sports sand can also be brushed into fork holes on goal mouths, which will assist in the drainage of the area.
Due to the availability of Football Foundations grants many grassroots clubs can now gain grant funding towards a tractor and/or a multi tool attachment, which includes a slit tine or a stand-alone aerator. For more information on grants talk to your local football association.
Ideally a pitch should be spiked/slit once or twice a month, when the soil is receptive to take a tine and is not wet.
If possible, the use of a deep spiker with a small amount of heave to go beyond 5/6 inches is the aim once/twice during autumn, prior to wetter ground conditions in winter. These deep channels will help remove water from the surface to the subsoil.
Pro Sports clubs with more resources now often use pedestrian aeration equipment, such as a Toro pro core or John Deere Aercore in the aim to keep heavy tractors off. They also avoid anything that will compaction the rootzone, as possible as even sand has the ability to compact.
Suitable aeration techniques winter sports- All aeration types could be utilised to fit the requirement.
Aeration of Sports Pitches –Bowls/Greens
The most commonly used aeration on bowls greens is traditional either a form of slit tines, often chisel tines. Chisel tines are usually used during the autumn and winter period and solid tines are used during spring, meaning less chance of the holes gaping/opening up during dry spells.
Air Injection is becoming popular especially when there are deep undelaying compaction issues and there is also a role for deep drilling in the case of root breaks and compaction pans.
Hollow tining can be used every bi-yearly to reduce compaction and or to remove thatch/fibre and incorporate a free draining rootzone material. If hollow tining is done too regularly, disabling of the surface can occur.
Suitable aeration techniques bowls/greens – All types other than linear, though scarification is a form of linear aeration.
Aeration of Sports Pitches-Summary
Being a cricket groundsman and spending half my life sitting on a roller compacting loam to the hardest degree, which l know is the opposite of what aeration is all about. This is why being a cricket groundsman working on loam is a unique position and very non-transferable to winter sports and bowls greens.
Obviously winter sports/bowls is all about keeping the surface open, keeping infiltration rates high as possible into the rootzone as a priority and in this maintaining/creating pore space to the max.
Three keys things l have taken from this blog are
1 – look into the soil profile, is there an eggy smell, is there shallow rooting or compaction, and if so why?
2- Be more intentional and ensure the aeration equipment your using/plan to buy/hire is purposeful for the aims you are trying to achieve.
3- Aerate during optimum periods is key to success.
I hope you enjoyed aeration of sports pitches, sorry it is a bit long but l hope you can cherry pick the bits most useful to you.
As with any blogs l write l do not claim to be a expert, just a keen learner and like anyone l have gaps in my knowledge, if you have any thoughts please feel free to leave any comments below.