Acid Rain

Rainfall which is more acidic (typically in the pH range of about 4.0 5.0, although a baseline of less than pH 5.6 is often used to identify the start of acid rain) than would occur as natural rainfall without the polluting emissions from human activity. The addition of sulphur dioxide and nitrogen oxides to the atmosphere from human activities react with water vapour to create even more acidic rainfall: this is due to the creation of sulphuric acid and nitric acid following the atmospheric reactions.

Natural rainfall is a weak carbonic acid (H2CO3), due to the reaction of water and carbon dioxide and typically has a pH of 5.6.

The majority of soils within the UK are on the acidic side due to the continuous acidifying effect of rainfall. This has produced conditions which are generally suitable for the growth and development of turfgrasses, although excessive acidity for different species does exist, so its important to understand the impact soil pH has on these species.

(Main source: UK Air Information, Department for Environment Food & Rural Affairs,