Answer

What type of aeration is most affective?

There are no set guidelines for frequency or ‘tine type’ although turf managers normally prefer to use larger diameter tines in the autumn/winter and the smaller tines in the spring, although number of treatments and timing depend on individual circumstances. It is also worth noting that the larger tine will cause more surface disruption, which might not be acceptable. The Verti drain type machine is now probably the most common aeration treatment on golf courses and sports fields, although it is not so commonly used on bowling greens, cricket squares etc. This type of machine is designed to relieve deep compaction, although various types of tine can be fitted to carry out different treatments. Slit tine aeration normally aerates the top 75mm-200mm. There are various methods, which include ‘chisel’ or ‘diamond’, although the ‘slit’ tines are the most common. Apart from encouraging ‘cracking’ within the soil profile, the slitting action also produces a channel for water to run into. The other benefit is that slitting will encourage deep rooting, either directly by allowing roots to move through the created cracks or indirectly by generally improving the root zone. Suitable implements are either self propelled or attached to tractor units. Slitting can be over done! Research has shown that too much slitting can actually reduce grass cover. Every situation is different although slitting can be carried out approximately every three weeks from September to January, in good weather and ground conditions. However, it is really a case of trying to get the balance right according to the surface conditions. Other methods of aeration are available such as solid tining and hollow tining. Solid tining is useful for allowing air into the upper layer of the rootzone and therefore plays an important role within the aeration program. Solid tining does not relieve compaction (in clay dominated soils). Solid tining can be carried out throughout the year on a regular basis, although it is more common in the Spring and Summer. Solid tining is particularly useful for sandy rootzone that do not need so much compaction relieve, for example breaking up sand that has ‘crusted’ together. Hollow coring is used to remove accumulated fibre at the base of the turf sward. It is also sometimes used to allow exchange of a poor soil for a better one to be introduced through top dressing. It is also used for over sowing during renovation, although we would recommend the use of a specially designed over sowing machine rather that this method. Hollow coring does relieve compaction. Various other methods of aeration/compaction relieve are available. Machines such as vibrating mole ploughs are useful if there are isolated wet areas, although the channels created by the machine must be cut into a positive outlet so that the water can move away. Probes that penetrate deep into the soil profile and release compressed air are sometimes used to ‘re-structure’ soil profiles (e.g. Robin Dagger). High pressure water jets on machines such as the Toro Hydro jet have also been successfully used for compaction relieve and are also useful for re wetting soils affected by Dry Patch. Drilling machines are also becoming more common for specialised compaction relief and soil exchange.