Figure 1.

Examples of three of the buffering mechanisms in soils: carbonate/bicarbonate buffer in the soil under Broadbalk Wilderness, where acid deposition has been buffered by very large quantities of chalk applied in the 19th century; cation exchange buffer in the Park Grass unlimed ‘Nil’ treatment (no fertilizer or manure applied so acidification only from acid deposition); aluminium/manganese buffer in the Park Grass unlimed, ammonium sulphate fertilizer treatment that has experienced severe acidification.