If your soil is sitting above 7.5, then you will need to lower or acidify it. The most effective way to lower soil pH is to add Yates Soil Acidifier Liquid Sulfur, which contains elemental sulfur (S). Soil bacteria convert the sulfur to sulfuric acid and thereby, help lower the soil pH. This is highly dependent on soil bacteria, so it’s best to apply when conditions are warm. For best results, apply every 4 weeks until the desired pH is achieved. Take care not to overapply – this will not make the process faster and it can lead to issues with sulfur toxicity and cause the pH to drop too low.
Adding aluminium sulfate is a fast way to help decrease soil pH. However, it is easy to overapply and consequently, can lead to issues with aluminium toxicity. A build-up of aluminium in the soil will significantly impact plant health and vigour, so it’s not recommended as a long-term solution. Similarly, adding vinegar to lower soil pH is not recommended. It causes localised sharp pH drops, but the adjustment is not lasting as the organic acids are eventually broken down by various soil microbes.
The sulfur soil acidification method is the best option as this gives a more steady and longer-term pH reduction.