Soil test (pH)

Why pH matters

Soil pH decides how easily grass roots can take up nutrients. In acidic soil (below about 6.0) nitrogen, phosphorus and potassium become harder to use and moss gains an advantage. In alkaline soil (above about 7.0) iron and other trace nutrients become locked up and the grass yellows. Fertilizer cannot fully make up for the wrong pH.

How to take a sample

1. Take five or six plugs of soil from across the area, each about 8 cm (3 in) deep, avoiding spots that are obviously different, such as old bonfire sites.
2. Mix them in a clean bucket and let the soil dry.
3. Test it with a home kit, or send it to a soil lab for a fuller result that includes nutrients.
4. Write the result down; feeding and lime decisions for years to come depend on it.

Reading the result

• 6.0–7.0: ideal, nothing to do.
• Below 6.0: acidic; work garden lime into the topsoil.
• Above 7.0: alkaline; elemental sulfur lowers it, slowly.

Follow the product or lab recommendation for the amount, as it depends on how far off the reading is and on your soil type. Correcting pH is most effective while the soil is open, before sowing; on an established lawn changes are slow and done in small doses over seasons. Retest every few years.

Next comes leveling the ground, then sowing.