What you should know about fertilisers

Ashes in pots

For centuries farmers have recognised the benefits to plant growth of wood ash remaining after fires and this is because it is a rich source of potassium. The collection of this material in iron pots resulted in the common name of potash being adopted for materials containing this plant food.

Natural Potash Rock Salt

Nowadays potash is obtained mainly from very extensive rock salt deposits throughout the world which contain the crystallised minerals derived from the evaporation of sea-water. This process occurred naturally and on a very wide scale some 230m years ago - a few million years before the Dinosaurs. It still continues today in regions like the Dead Sea where the mineral rich water is evaporated by the sun to produce potash and common salt (sodium). The salts produced in this way are used for many purposes including soap manufacture and de-icing roads as well as fertiliser.

Potash production

The potash for plant food is prepared from the rock salt by washing away the sodium because plants do not require as much sodium as potassium. (no chemical process is involved). It can be used on its own as a "straight" fertiliser or combined with other important plant foods - principally nitrogen and phosphorus to produce compound fertilisers.

All potash salts are naturally soluble in water and therefore freely available for plant uptake by the roots.

Functions of potash

Potash is a vital "regulator" in plant growth. It controls water content and the movement of other plant foods from roots to leaves and the formation of grains, fruits, flowers etc. Many aspects of quality are thus controlled by potash. Adequate supplies are essential to balance other plant foods and to create vigorous, healthy growth with natural resistance to pests, diseases and adverse climatic conditions such as cold, wet, drought etc.