Grassland: Selecting indicators of success for grassland enhancement (TIN050)

Soil pH

This is an optional indicator. It should always be used on neutral and acid grassland and can sometimes be useful on other sites. The aim is to put the onus on the agreement-holder to maintain pH in the appropriate range. The pH of the site should be known and recorded at the start of the agreement.

Most soils in the UK are naturally acidic except those derived from chalk, limestone or calcareous clays. Under agricultural production the pH has usually been raised by liming to between 6.0 and 6.5. Where liming has been done regularly in the past it should usually be allowed to continue. Otherwise it should be done only after taking advice or if there is an issue with falling pH.

For practical purposes, and to maintain and encourage indicator species, neutral grasslands should have a pH of between 5.0 and 6.5. Without lime application the pH of neutral grassland sites will tend to fall at varying rates depending on soil type. If the pH of neutral grassland is at risk of falling below 5.0 you should consider allowing the application of lime with the aim of raising the pH to about 6.0. Consult an ecologist if you are considering this.

For acid grassland you should set the upper limit as 5.0 (or lower if the current pH is lower) to guard against application of liming agents. You would not normally need to set a lower limit of pH for acid grassland, though the current wording of the indicator means you do have to!

Guidance on pH is included in TIN036, Soils and agri-environment schemes: interpretation of soil analysis and TIN045 The use of lime on semi-natural grassland in agri-environment schemes.

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