Importance of pH soil testing

April 18, 2023

Why is pH levels important when reseeding grassland?

Soil pH has a big influence on the availability of nutrients in soil. Reseeding provides a perfect opportunity to correct pH imbalances and gives the new ley the best chance of establishment. Over time, grassland soils have a tendency to become more acidic, due to rainfall, decay of organic matter and as a result of numerous fertiliser applications. Data taken from across the UK shows that 57% of grassland soil samples are below pH 6.0, which has knock-on effects on nutrient availability and thus impacts the yield potential of your grassland.

Grass crop yields can be reduced by 20% where soil pH is well below target.

When do I need to apply lime to my grassland?

Lime is important in minimum-till reseeding applications as it neutralises the organic acids released by the old sward as it decays. The application of lime will help raise the pH level in your field and allow the crop to grow at an optimal rate and yield using all available nutrients.

For continuous grassland, pH values between 6.0 and 7.0 are thought to be sufficient to maximise nutrient uptake.

How much lime should I apply?

It is good practice not to apply more than 5t of lime per ha in one dose to grassland soils.

The table below from the Agricultural Lime Association (ALA) shows the recommended liming rates required to bring the soil pH to an optimum level. The quantities shows are tonnes per hectare.

Download the table here.

Typically, clay and organic soils require more lime than sandy soils.

Application of lime will help raise the pH of fields and allow the crop to grow at an optimal rate and yield using all available nutrients.

Guidance from AHDB on how frequently to test your soil pH levels

Helpful tools and information

The Agricultural Lime Association has a online lime calculator tool . This allows you to calculate a recommended liming rate (t/ha) based on cropping, enterprise type, measured soil pH, soil type and liming material to be applied.