Deep penetration aeration – the waterlogging solution that digs deeper

Tony Hawkinsin Drainage & Irrigation

Landscapers, groundsmen and gardeners responsible for large grassed open space areas such as parkland, sports pitches, golf courses, bowling greens and avenues of trees, right through to domestic gardens, all share a common problem. Compaction of the soil and panning lead to waterlogging which renders areas unusable, in many cases for long periods of time. The usual focus will be on aeration to relieve compaction and open up the soil to allow air to get to the roots and improve drainage.

Essential work to keep playing surfaces usable and maintain the grass but, if the ground is too hard, the tines bounce and the area remains untreated. Similarly, where aeration is regularly carried out to a depth of 300mm the effect over a period of time will be to actually create a pan layer at 300mm. What is needed to relieve the resultant waterlogging is fracturing of the soil below this depth and that calls for a specialist approach to the problem.

Deep penetration aeration has proved successful for many years and is well known by golf courses for relieving compaction panning on their greens, tees and even around tree roots. In fact, the technique was introduced with the invention of the Terralift machine in Germany in the early 1970's. There is many a Greenkeeper who will testify to the success of the treatment. The first in the UK was carried out at Sittingbourne and Milton Regis Golf Club in 1985, with a return visit for just one day's top up treatment on four greens being requested some 15 years later! Since then, different chassis versions of the Terralift have been designed to work in a wide range of applications.

What is unique is the ability to hydraulically hammer a probe one metre into the soil and release a blast of compressed air at a pressure of up to 20Bar (280psi) which fractures the compacted soil. At a depth of one metre the probe has effectively passed though pans created by other aeration machines, opening up the soil and creating fissures. On the tail end of the air blast dried milled seaweed, a natural eco-friendly product, is injected via the probe and this sticks to the walls of the fractures and fissures, swelling and contracting with the moisture content in the soil.

The machine moves on two metres and repeats the operation, completing two metre spacings on a staggered grid pattern and each shot connects with the previous ones so the whole area is aerated and treated. The Terralift can treat approximately 2,000m² of turf in a day. It's recommended that the probe holes are backfilled with aggregate to provide a semi-permanent aeration/ventilation shaft. The preference in the UK is to use claybaked balls which are inert, porous and allow air and water to penetrate into the probe holes.

Typical applications for deep penetration aeration have broadened from the original golf course treatment into football and rugby playing fields, bowling greens, cemeteries, National Trust properties, estates and private gardens. The long-term solution causes little surface disruption and allows immediate play on sports pitches and greens after treatment.

In the case of public parks the deep penetration treatment is often used around trees which suffer from compacted ground due to heavy foot traffic. Deep aeration is carried out one metre inside and one metre outside the canopy drip line as this is where the growing roots lay. By going to one metre depth excess water is taken away from the root zone to stop anaerobic conditions.

Well aerated soil around the root zone allows a better uptake of oxygen for the trees and a better access for rainwater, in turn resulting in a stronger root growth and canopy spread. Phytophthora can also be stopped by using the Terralift to aerate the soil, keeping the soil open with the injection of the seaweed, with fissures opened to allow liquid fungal treatment product to be watered over the top surface.

The Terralift deep penetration aeration service is owned and operated by Terrain Aeration 01449 673783