Compounds called fertilisers are added to the soil to help plants to grow well. A compound can be used as a fertiliser if it contains one of the essential elements, nitrogen (N), phosphorus (P) or potassium (K) and if it dissolves in water.
Ammonium compounds (N), potassium compounds (K), nitrate compounds (N) and phosphate compounds (P) are all possible fertilisers because each one contains an essential element.
However, only the ones which are soluble in water will be able to fertilise plants.
The aim of this experiment is to test the solubility in water of some ammonium, potassium, nitrate and phosphate compounds in order to decide if they could be used as fertilisers.
