All the nutrients contained in different fertilizers are found in nature.
The most common sources of nutrients in mineral fertilizers are nitrogen, potassium and phosphate.
Nitrogen originates from the air. The most common process in nitrogen fertilizer manufacturing is to create ammonia from a mixture of nitrogen from the air and hydrogen from natural gas.
Air consists of 78 percent nitrogen, but plants cannot get the nitrogen needed directly from the air – they need to take it up through their roots from the soil.
Potassium is sourced from old sea and lake beds formed millions of years ago.
Potassium fertilizers are based on naturally occurring potassium chloride. This is somewhat similar to table salt – sodium chloride.
The ash from burning wood or straw is high in potassium, this is where the name ‘potash’ originates.
Since potassium sources are often located far below the soil surface (1-2km depth), plant roots are unable to reach them naturally.
The world´s biggest potassium producers are Canada, Russia, Belarus and China.
Phosphate is sourced from insoluble calcium phosphate rocks – often referred to as “rock phosphate”. In this form it is not available to plants. Rock phosphate is made available for the plant usually through a chemical process to create plant friendly fertilizers.
China, Russia and Morocco have some of the world´s largest deposits of phosphate rock.
Nitrogen (N), phosphate (P), and potassium (K) can also be combined to form NPK compound fertilizers, that provides the crop with the 3 major nutrients at the same time.
The alternative to mineral fertilizers is organic fertilizers which are based on materials with a biological origin. These include animal wastes, crop residues, compost, biosolids and more.
Without fertilizers, the soil would be depleted and therefore plants would be particularly difficult to grow. They cannot survive on water alone, and nor can we.
Barry Bull, Plant Nutrition Consultant