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Balanced soil pH is very important for a healthy lawn ecosystem. Providing the right pH can vastly improve the health of your lawn. And you know what they say – better lawn, better life!
What is a healthy soil pH?
Soil pH is a measure of the acidity or alkalinity of the soil. Most lawns like it a pH balance between 6–7 for optimum performance. When the soil pH is in this balanced range, it’s as if the grass has its mouth wide open – all the nutrients you provide will be consumed, and no food will go to waste.
Acidic soils can have detrimental effects on your lawn. When the soil pH is too low, it interferes with the availability of essential nutrients that grass needs for healthy growth. Soil acidity can hinder the absorption of nitrogen, phosphorus, and potassium, leading to nutrient deficiencies and resulting in weak, sparse, and discoloured grass.
The increased solubility of aluminium in acidic soil can also become toxic to grass, damaging the roots and inhibiting nutrient uptake. This is why balancing for optimum soil pH is crucial to ensure your grass can grow in the best conditions possible.
Despite this, there are some plant varieties that may require acidic soil to thrive in which case you need to maintain a slightly more acidic pH balance.
Raising soil acidity
Raising soil acidity typically involves lowering the pH level to make the soil more acidic. This process is often necessary for acid-loving plants.
One common method to increase soil acidity is by applying substances like elemental sulphur or ammonium-based fertilisers. These materials undergo chemical reactions in the soil, releasing acids that lower the pH over time. It's crucial to carefully follow recommended application rates and guidelines to prevent over-acidification, which could harm plants and soil organisms.
Using lime to reduce acidity and increase soil pH
If your soil is at risk of being too acidic, lime is a commonly used soil amendment to raise the pH level and make it more alkaline. It consists mainly of calcium and magnesium compounds that react with soil acidity, neutralising it over time. Adding hydrated lime to the lawn can help correct soil acidity issues and create a more favourable environment for grass growth. Lime also provides calcium and magnesium, which are essential nutrients for plants.
Alkaline soils, or high-pH soil, can also negatively affect your lawn if it takes things too far out of balance. When the soil pH is too high, it can lead to nutrient imbalances and deficiencies that adversely affect the health and vigour of your grass. Alkaline conditions can limit the availability of essential nutrients like iron, manganese, and phosphorus, which are crucial for plant nutrients and proper lawn growth.
As a result, the grass may exhibit symptoms such as yellowing or chlorosis, stunted growth, and an overall weakened appearance. Alkaline soil can also impede the absorption of certain herbicides, making it more challenging to control weeds effectively.
Reduce soil alkalinity
Are you wondering how to fix alkaline soil? Reducing soil alkalinity is important for creating a more suitable environment for plants that thrive in slightly acidic to neutral pH levels.
One common method to decrease soil alkalinity involves the application of soil amendments such as elemental sulphur, sphagnum peat moss, or acidifying fertilisers. These materials work to lower the soil pH over time by releasing acids into the soil. It's crucial to follow recommended application rates and guidelines to prevent over-acidification when lowering soil pH, which can be harmful to plants.
How to test lawn soil pH levels
Testing the soil’s pH may seem like some mad scientific operation, but it couldn’t be simpler. Just purchase a soil pH test kit and follow the instructions. Most kits even explain how to adjust the pH if you detect a problem.
To test the pH of your soil, you can follow these steps:
- Obtain a soil testing kit - purchase a soil pH testing kit from a local garden centre or online. These soil test kits typically include pH testing strips or a soil pH meter.
- Collect soil samples - choose several locations across your lawn for sampling. Use a trowel or a small shovel to collect soil samples from a depth of about 10 –15 cm. Take multiple samples and mix them together in a clean container. Avoid sampling areas where fertiliser or lime has recently been applied.
- Prepare the soil samples - remove any debris or stones from the soil sample. Allow the sample to air dry naturally, and then break up any clumps. Crush large soil particles into smaller ones.
- Perform the pH test - follow the instructions provided with your soil testing kit. The most common methods are:
- pH testing strips: moisten the soil sample with distilled water, and then dip the pH testing strip into the mixture. Wait for the recommended amount of time and compare the colour of the strip with the provided colour chart to determine the pH level.
- Soil pH meter: insert the electrode of the pH meter into the soil sample, following the manufacturer's instructions. Allow the reading to stabilise, and then note the soil pH value displayed on the meter.
- Repeat the process - for more accurate results, it's recommended to test multiple areas of your lawn and average the results. Different parts of your lawn may have slightly different pH levels.
- Interpret the results - the pH scale ranges from 0 to 14, with 7 being neutral. pH values below 7 indicate acidic soil, while values above 7 indicate alkaline soil. Most lawns thrive in a slightly acidic to neutral pH range of 6 to 7.
- Adjust the pH if necessary - If the pH of your lawn soil is too acidic or alkaline for optimal grass growth, you can make adjustments to raise or decrease soil pH.
How do I adjust the soil pH?
Adjusting the pH is easier for lighter, sandy soils than heavy clay soils. For sandy or free-draining soil, applying 150 g of liming material (one and a half adult handfuls) per square metre will raise the soil pH by 1.0. For heavy clay soils, you will require at least 250 g per square metre to raise the pH by 1.0. Super-fine lime works quickest and is very affordable.
Established lawns are often lacking in magnesium, so mix 50/50 lime and dolomite to get the right balance of calcium and magnesium.
After applying lime or dolomite, make sure you water well to help it distribute evenly into the soil.
If your soil is alkaline, it means it has a high pH. You can increase the acidity of your soil by adding things like compost and manures, leaf litter and mulch. Iron chelates work too.