As already mentioned, there are different types of fertilizer. There are organic fertilizer (such as cow manure, bat guano, bone meal, and organic compost and green manure crop). There are also chemical fertilizers which are referred to as inorganic fertilizers and are made up of different compositions for a variety of specific uses. The most popular types of inorganic fertilizer in Nigeria come in different NPK composition. Recall that N.P.K stands for Nitrogen, Phosphorus and Potassium.
Guano is the excretion of seabirds, bats and seals. Guano consists of ammonia, uric acid, phosphoric acid, oxalic acid and carbonic acid and also has a high concentration of nitrates. The particularly high levels of phosphorus make this an effective phosphorus fertilizer. Guano was mined off the West Coast of South Africa as early as 1666. Since the 1840’s, large scale mining of guano caused the reserves to be depleted and mining was stopped by the turn of the century.