pH of Your Lawn
Lawns usually prefer a slightly acidic or neutral soil.
Check the pH, the acidity or the alkalinity of the soil, by using a simple pH test kit.
If a test result is between 6.5 and 7 you need do nothing because that range is ideal for lawns. But a 5.5 result means the soil is slightly acidic, and so probably needs “sweetening”.
If the soil is too acidic
Add lime and dolomite. In this case dolomite is preferred because it also contains magnesium. And magnesium is necessary for plants to produce chlorophyll that allows them to produce energy. Most Australian soils are deficient in magnesium and it’s readily leached from the soil, so dolomite has a double action.
Lime on a heavy clay soil helps break it down from really heavy clods, so that it becomes crumbly. This makes the soil easier to work, and also aids root penetration deep into the soil.
As a rule of thumb, apply a handful of dolomite per square metre. But for highly acidic soil, double the amount, then water it in.
If the soil is too alkaline
For alkaline soil, that is, readings greater than 7.0, you will need to apply a sulphur product such as sulphate of ammonia. 100gm per m2 of sulphate of ammonia reduces the pH by 1 unit.