By Todd Layt
Obviously the best time to improve soil is before the turf is laid, but there are still things you can do to an existing lawn to improve its health.
The simple application of a good slow release fertiliser will help at the nutrient level. Slow release fertiliser works every time it gets watered and lasts for months, while a regular fertiliser only works for a couple of weeks.
Aerating your lawn will reduce compaction, and using organic fertiliser when aerating will get a small amount of organics into the soil. A coring maxing that drills holes works even better but they are harder to find for rental.
Topdressing with an organic top dressing mix will greatly improve the soil quality. Spread the organic soil mix so some leaves are still showing through. Topdressing also helps rejuvenate the lawn, reduces thatch, and get new growth throughout the turf.
Organics will help the lawn better than a sandy loam top dressing. Aerating first before top dressing will get organics into the lawn. Clay soils can have gypsum added at time of aeration which will help over time to reduce compaction.
A simple pH test can tell you if your soil has the correct pH. It is important to not be too acidic or too alkaline, as the lawn will not be able to process the nutrients. To raise the pH of your lawn add lime and to lower the pH add sulphate of iron.
A pH of between 6 and 7.5 will see good amounts of nutrient being processed by your lawn and the lawn will generally grow OK. If you are fertilising your lawn with little result it is often an out of balance pH causing the problem. Wetting agents can really help a hydrophobic lawn that repels water.
Dry patch is often observed in summer. Some parts of the soil may repel water while other parts allow water through. Not all parts of the soil are uniform. If the lawn repels water use a wetting agent. It may be necessary to apply a wetting agent a few times over summer, but for longer term relief from a water repelling soil, completing the other steps in this article will have a more lasting effect.
The simple step of providing long deep watering rather than lots of short irrigation applications will help your lawn grow better, and enhance a deeper roots system in the turf, which will also reduce the side effect of water repelling soils. Using a mulching mower will help add organic matter to your lawn improving its health.
Using Mycorrhizal fungi will help your lawn grow better roots, help prevent disease, and allow your lawn to grow with less fertiliser. It will aid the lawn by making a strong living soil, that better allows the roots of the turf take up nutrients by attaching themselves to the roots of the lawn.
If you are installing a new lawn, try to use lots of organics mixed in with the existing soil. If you need to bring in topsoil try to get a mix rich in organics. Your lawn will thrive for years to come with far less work. If your soil is of a clay type, add gypsum and mix it into the soil profile, but still add some organics, as this will have a better long term effect.