Understanding Soil pH

Soil pH Test KitOne of the most important factors in how well your lawn performs can’t even be seen – the soil below. Just like our skin’s pH (potential hydrogen), the soil’s pH level will determine if conditions are optimum for growth and overall health. Reading pH levels and adjusting the levels can be daunting but it doesn’t have to be that way.

pH measures how acid or alkaline your soil is. This balance of acidity and alkalinity affects the grass plant’s ability to access and therefore benefit from the nutrients in the soil. In many instances when your lawn has stunted growth or yellowing blades it can be directly attributed to an incorrect pH balance.

Most plants like a neutral soil – a pH level between 6-7. When the pH falls below 6 the soil is said to be acidic. When the pH is above 7 the soil is said to be alkaline.

pH testing

You can purchase a simple pH soil testing kit or take a sample (about ½ cup of soil taken from the top 10-20cm) of your soil to your local lawn care provider.

How to correct an imbalance in the pH

Acidic soils 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 2 or 3 applications to avoid causing shock to the lawn.

Alkaline soils are a little more difficult to correct but it is possible. A quick fix may be to add sulphur or a sulphate such as iron sulphate at the 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.

A more helpful fix over the long term is adding organic matter such as compost, pine needles and sawdust. If the alkalinity persists there may be more to the soil than what meets the eye – limestone soils, limestone and/or cement building structures and debris under the ground can leach lime for years and years causing your soil to become alkaline.

We recommend also conducting a soil pH test prior to adding anything to your lawn to ensure your soil gets exactly what it needs – it’s never a good idea to just assume.

Contact the team at Harden Park Lawns for more information or to purchase a soil pH test kit. We also stock a range of soil treatments through our online store which can be found here.