Key Messages
Soil pH effects generally limit plant growth below pH 5.5 (measured in CaCl2), though this can vary between different plant and crop species
Soil acidification is a natural process caused primarily by the removal of cations and organic matter, and by nitrate leaching. This process can be accelerated in agricultural production systems, for example by the application of acidifying fertilisers and greater removal of cations in hay
Liming is usually required to neutralise acidity associated with agricultural production, although it can also be managed through changed farming practices
Lime can be used to treat surface acidity, usually with rapid results, but subsoil acidity is much harder and more expensive to correct