If you are looking to install a new lawn or your lawn’s been down a while and not thriving as well as it did years ago, then it’s a good time to look at your pH levels. pH stands for the ‘potential of hydrogen’ and is a scale of acidity from 0 to 14. A pH reading tells how acidic or alkaline a substance is, where more acidic solutions have lower pH and more alkaline solutions have higher pH. Acids have a pH that is less than 7. Alkalis have a pH that is greater than 7. Substances in the middle that aren’t acidic or alkaline are known as neutral and usually have a pH of 7. So, with that quick science lesson out of the way let’s look at how your soil pH affects your lawn.
The best time to carry out any soil improvements if you have the chance is prior to installing your new lawn and this includes any pH adjustments that may be needed. It is quite often necessary yet practical to adjust pH for existing lawns as part of a maintenance plan which we’ll look at in some detail following. The ideal pH range for your lawn is somewhere between 5.5 and 7. Many lawn types, buffalos in particular, have been known to do quite well in more alkaline soils up to a pH of 8, but getting closer to the neutral mark will prove more beneficial to your lawn’s performance in the long-term. Basically pH affects the solubility of minerals and nutrients essential for plant growth and if your soil is out of the optimum range nutrients become difficult or almost impossible to absorb. Measuring pH and then adjusting the levels may seem daunting, but there’s not that much really involved. Ideally, what we want is a lawn with a pH value around the neutral mark. Most Australian soil types are acidic more-often-than-not and the process of scratching off the topsoil when you’re building can expose more highly-acidic clay and this will potentially affect your lawn in the long-term.
Measuring a soil’s pH is easy to do and doesn’t involve a complicated scientific experiment. All you need is a pH testing kit and they are readily available at hardware stores and nurseries, or online through Lawn Solutions Australia or our online store and a kit should cost under $30 and last for a number of years. When it comes to doing the soil test, collect a few samples from different locations around your lawn area and mix these together to get an average reading of the whole lawn, rather than just from one location. Dig down around 100 – to 150 mm (4 to 6 inches) with a hand spade or similar in a few spots and then mix up the samples in a bucket. Remove any grass or root matter and then take a small amount of soil and perform the test as per the kit’s instructions. Once you have the result you can look at a few ways to adjust the pH if necessary. For a new lawn you can cultivate or spread and rake-in the material you’re going to use directly into the new soil bed or for existing lawns you can apply and water-in to the lawn and something like a drop-spreader works best, or even cast out by hand for smaller areas.
If your soil is acidic or alkaline the you can add some easily obtained soil conditioners – readily available from nurseries and the like – with the following rates that will move the pH approximately one point on the scale.
Acidic soils (5.5 and below) can be helped with an application of lime or dolomite at a rate of approximately 100 grams per square metre. If you have a heavier loam soil use 200 grams per square metre and 300-400 grams per square metre for heavy clay soils – it is often best to apply this amount of lime over two or three applications to avoid causing any shock to your lawn.
Alkaline soils (8 and above) are a little more difficult to correct but it is possible by adding sulphur or a sulphate such as iron sulphate or sulphate of ammonia at a rate of approximately 25 grams per square metre for sandy soils, 50 grams per square metre for heavier loam and up to 100 grams per square metre for heavy clay soil. If you carry out this process over a few weeks and test in between you can get your lawn to a stage where a happy medium around the neutral 7 zone exists and your lawn will take-up nutrients, minerals and trace elements more readily.
If you carry out a test every year or so you may also be able to see if there are any things that are affecting the pH on an ongoing basis; fertilisers, water, drainage or other leaching issues If you’re unsure about attempting the process yourself get in touch with a Lawn Solutions turf grower or one of the many Lawn Solutions Centres around the country that will be happy to help with any pH woes. Getting your lawn’s pH back in balance is one of the key things before you look at a more comprehensive fertiliser regime.