Before soda became available in large quantities, potash was used. This is present in wood ash. For this a lot of wood was needed, leading to deforestation and a scarcity of wood ash.

Potash was made by dissolving wood ash in water and evaporating the filtered solution. The soluble salt that remained was called potash. The name is derived from the words 'pot' (cooking pot) and 'ash'. There is about 1,000 m³ oak or beech neede to obtain 0.43 m³ potash.
Potash is a mixture of salts consisting essentially of potassium carbonate. The name is also used for other potassium salts and potassium-containing minerals.

Potash is now being mined at a depth of 1,200 meters or more. Worldwide production in 2009 was approximately 25 million, was 10 million tonnes less than in 2008. Canada is the largest producer (25%). Belarus, Russia, China, Germany and Israel are also major suppliers. The global reserve is estimated at 8.5 billion tonnes. More than 90% is processed into fertilizer.