Aeration and decompaction
Aeration is the secret game changer.
Aeration has many benefits – some of them surprising:
- It improves surface conditions
- Encourages improved penetration of water, air and fertiliser straight to the rootzone
- Certain machines such as deep spikers and linear decompaction machines also improve soil structure as well as rooting capacity
- May lead to longer usage from the surface
- Releases toxic gases from the soil while introducing oxygen
Did you know it is thought to be the most important groundskeeping technique in reducing player injury?
Not to mention, a well-aerated pitch is springy and dense, boosting player enjoyment and performance. In fact, expert aeration can create a controlled drop in the hardness of the playing surface when it’s needed most.
So why do we need aeration?
In essence, aeration is spiking, slicing or boring holes into your pitch. As a minimum you ideally need to do this during spring and autumn and there are a range of tools and techniques you can choose from.
The terms aeration and de-compaction are often used interchangeably but the subtle difference is that machines capable of decompaction are mechanically decompacting the soil as opposed to simply aerating it.
Without aeration, living and dead organic matter builds up and forms a compact layer called thatch. Thatch starves the roots of water and nutrients meaning the roots stay shallow and the grass is sparse. Thatch also creates an ideal environment for turf pests to inhabit and disease to develop.
Proper aeration creates holes that penetrate the thatch and reach the soil below. Oxygen, nutrients and water are channelled deeper, causing the grass roots to drive themselves deeper into the soil to reach their sustenance forming a rich network.
In the following 8-10 weeks, new grass plants appear and the deeper, richer system of roots help to improve soil structure. This, coupled with free air exchange, helps beneficial micro-organisms break down that tightly woven thatch layer.
What happens when aeration isn’t done properly?
Poor aeration will have two key effects on the field – poor turf health and poor drainage.
Poor turf health can cause sections of turf to be ripped up by players. A pitch that won’t drain properly will become increasingly saturated with water in its top layer, especially during periods of extended rainfall.
Together these can cause training disruptions, a slippery surface and a whole lot of repair work for you. Players and coaches will be looking to you for a quick fix. Better to protect your asset with a preventative pitch maintenance routine that includes proper aeration.
What’s the best practice for timing your aeration/ decompaction operations?
A decompaction/aeration operation can cause direct stress to the plant, so the task should ideally be carried out when the grass is growing and has the ability to recover.
The ground conditions need to be firm enough that the surface isn’t damaged by the machine, but moist enough to allow the tines into the rootzone.
Aeration/decompaction occurs through improvement of the turf and soil, allowing carbon dioxide and oxygen exchange as well as moisture and nutrients to move through the soil. Larger pore spaces created by decompaction allow for growth of grass roots through the soil, resulting in stronger plants with deeper and denser root systems.
There are many types of operations to achieve aeration/decompaction and each will have advantages and disadvantages, the choice will depend on factors such as:
- The type of surface and sport
- Drainage of water through the surface and into the soil
So when is best? - “When the grass is growing and has the ability to recover” is what we would recommend as best practice to avoid damage and allow your pitch to recover effectively, but don’t forget, in order for decompaction to take place the soils need to be friable, these tasks if mistimed can do more harm than good.
Slitting
Slitting has historically be the most common treatment carried out on sports turf in this country as it introduces air into the soil profile whilst causing minimal surface disturbance.
Working depth usually varies from 75mm to 150mm on pedestrian units, down as far as 300mm on the larger winter pitch aerators. Many tractor mounted units have pressure frames or are controlled by downward pressure from the tractor to give variable depth of penetration and to facilitate full depth when needed.
The myth that you should always slit as deeply as possible is inaccurate. Always aerating at the same depth is likely to create a soil pan at that depth, obviously less of a problem at 300mm than 75mm but a problem nonetheless. Frequency of slitting must relate to the quality of soil to be worked and the needs of each specific site. Anything from weekly to monthly could be appropriate.
Generally it is best to work in the same direction during any one slitting season or on slight diagonals as cutting across previous slit marks could promote serious disturbance to the playing surface, if not immediately then certainly through dry summers. Slitting can be overdone and result in unevenness; a situation exacerbated during frosty spells, or on heavy saturated soils when taking any machinery over the ground will cause more harm than good.
Starting a slitting programme for the first time can be disruptive though after a few passes lifting should be kept to a minimum. The initial damage is usually due to poor rooting, a direct consequence of no, or limited, aeration work in the past. Units drawn behind compact tractors are usually equipped with a grooming roller on the back to smooth any lifting.
