In the latest nomadgroundsman.com cricket blog, Iain James, ECB consultant answers questions on winter aeration.
Iain with a clegg hammer and moisture reader
Cricket - winter aeration questions
I'm Iain James, Technical Director at TGMS. I work as a consultant to the ECB and many of the first class counties and test grounds to improve their pitches, outfields and practice facilities for cricket. I also work with clubs and schools to build new, reconstruct or improve cricket grounds. Before TGMS, I was Senior Lecturer in Sports Surface Engineering at Cranfield University and led both the rolling and aeration in cricket projects there. Both projects were funded by the ECB, the UK government and in the case of the aeration project, also the IOG.
I also work with my team of volunteer groundstaff at Olney Town Cricket Club in Buckinghamshire, trying to deliver the best pitches we can on a tight budget, a small shed of equipment and all the time and enthusiasm we can muster.
Does spiking a cricket square decompact it?
No, not if you're doing it right. Sounds strange doesn't it? When spiking outfields, and in particular winter games pitches, the spike is heaving (it goes in and then lifts up) - this decompacts. When spiking a cricket square there should be minimal heave to avoid disrupting levels - so decompaction in the sense of reducing the bulk density of the soil (the weight of soil in a particular volume) does not happen.
Should we be looking to decompact our square; if not why should we aerate?
No, we can only decompact by lifting the soil, damaging those surface levels we spend so much time trying to improve through the summer and during renovation. But this does not mean don't spike. The aim of spiking a square is to break through the sealed surface layers of the square and allow water and oxygen to penetrate deeper into the profile. It also allows roots to penetrate deeper into the square.
What are the main benefits of aerating a cricket square?
Water, air and roots deeper in the profile. More water, deeper in the square creates better pitches by improving rolling, the durability of pitches, and pace, bounce and consistency. The over-winter period is vital for getting water into a square - particularly in 1st class pitches where they are under cover so often. In the winter when temperatures are cooler and the plant is more dormant, water can build up in the soil profile. This reservoir of water deeper in the profile is important to pitch performance later in the year. I'm not talking about wet pitches at the surface but a square that has moisture stored at depth will produce better pitches.
Getting more air in will help improve soil health, encourage bacteria that break down organic matter and thatch and encourage deeper roots. This will result in more wear-resistant plants that can dry pitches and harden them more in the summer during prep. Root depth is not the be-all and end-all of pitch performance (grass cover has a much bigger effect) but resilient plants really help maintain cover and pace for longer and to dry the pitch more evenly.
How many times over winter should we be looking to aerate?
The Cranfield University research showed that most of the benefit was seen in the first aeration and that second and third treatments were less effective. Get it right first time and you should be ok. It does depend on the equipment you are using and how well you can manage moisture. When aerating a square that is too wet, the machinery seals the surface or causes damage - negative impacts that far outweighed any benefits. The trick is to time your aeration for when the square is just wet enough to get the tines in without causing damage to the square or the machine. Do it once, well.
Is there a benefit from spiking at different depths and what type of tine is suitable?
The primary aim is to spike as deep as possible - ideally to 100 mm. This normally requires pencil or needle tines just because of the high penetration resistance of cricket squares - but be careful not to break tines. If you spike at the same shallow (less than 75 mm) depth you can contribute to root breaks and the build-up of a compaction pan - although natural shrink and swell will help minimise any pan.
Pedestrian spikers with worn tines are usually culprits for spiking too shallow - check your tine length and if you were shallow last year, try and get new tines and go deeper this year.
Does a cricket square naturally decompact over winter, with frost heave?
Yes, frost heave to an extent, but more importantly swelling due to wetting of the soil does de-compact the soil - particularly at the surface (this is why pre-season rolling is necessary). The soil will swell and can reduce bulk density by 20% in some cases. This is a natural process and is why many squares are fine without spiking and aeration.
Should we aerate with solid tines, or deep spike (tractor mounted) or use the deep drill method?
Horses for courses and will depend on resources. The deep drill is a good machine for layered soils where there is a risk of separating layers in the soil by spike aeration pulling the layers upwards as the spike is withdrawn - but the deep drill does remove material, reducing density which needs to be addressed over time by repacking - depending on the size of drill bit used.
The tractor spiking method is effective but needs the right machinery to get deep enough without causing surface damage to the square. Spiking with a pedestrian spiker can be effective but monitor the depth of spiking and avoid shallow spiking at the same depth.
What form of aeration should not be carried out on a cricket square and why?
Anything that lifts the surface or causes damage to the surface. Spiking with large tines with heave, spiking with the single/dual tine compressed aeration machines should both be avoided. Even sarrell rolling in the very wet should be avoided because the drum sinks in and seals the surface.
What time of the year should we be looking to aerate and when the cut off?
Try to aerate as the soil is getting wetter, not as the soil is getting drier. This is why aeration before Christmas is more effective than too long after Christmas. By aerating as the soil is getting wetter you can get more water into the profile, you will find your square easier to manage and the swelling forces of the wetting soil will help close the tine holes over time. If you spike as the soil is getting drier your tine holes will start to expand and this can cause problems.
I would say mid Jan at the latest and then use February to start thinking about nutrition and getting ready for pre-season rolling and then waiting until March.
What is the best soil state for spiking and what happens if we carry out in the wrong conditions?
If the soil is too dry, you will probably not be able to get the tines in and you will be snapping tines, breaking machinery or have a higher risk of surface damage. If the soil is too wet, you will have problems with the machinery causing surface damage. The ideal conditions are when you can just get the tines in and out of the ground cleanly, but the machinery is not smearing or rutting the surface. Use common sense.
If you aerate in the wrong conditions, at best you will be wasting your time, at worse you will be looking for another square to use for the coming season.
Any tops tips for what to do and not?
Top tip - get a corer and look at your profile before you do any spiking. Do you have layers? How deep are your roots? Is their moisture at depth? How dense is the profile? Are your problems caused by thatch? Spiking is an underground tool solving underground problems - so you need to look underground to identify the problems and see whether what you are doing is working. For example, if your problem is thatch, spiking doesn't solve that - you will need to look at more effective scarification.
Linear aeration slicing deeper into the profile with scarifying blades) is not aeration - this is scarification and will help with managing thatch but will not get water to 100 mm deep in your profile.
If you have a dry friable profile at depth, you need to wet this up and spiking with the right tool in the right conditions will help.
Top jobs for December from the Nomad Groundsman
- Avoid frost and maintain the cut at 18-22mm
- Possible application of a granular fertiliser with a bit of iron to strengthen the plant, avoiding frosts pockets
- Keep surface clear of sticks and debris either by hand or with the use of a brush type machine - not to aggressive
- Keep corner of square marked will save a lot of time in spring
- Clear any leaves around square fence lines and cut to prevent dead grass come spring
- Machinery servicing - to avoid a last minute rush when you need the machines the most
Big thanks for your continued support in readings and a massive thanks to Iain.
Brian Sandalls, Preston Nomads CC