Fertilisers (Cambridge (CIE) O Level Chemistry): Revision Note

Fertilisers

N, P, K Fertilisers

• Fertilisers contain nitrogen, phosphorus and potassium

  • Nitrogen makes chlorophyll and protein and promotes healthy leaves 

  • Phosphorus promotes healthy roots

  • Potassium promotes growth and healthy fruit and flowers

• Fertiliser compounds contain the following water-soluble ions:

  • Ammonium ions, NH₄⁺ and nitrate ions, NO₃^-, are sources of soluble nitrogen

  • Phosphate ions, PO₄^3- are a source of soluble phosphorus

  • Most common potassium compounds dissolve in water to produce potassium ions, K⁺

• Common fertiliser compounds include:

  • Ammonium nitrate, NH₄NO₃

  • Ammonium phosphate, (NH₄)₃PO₄

  • Potassium sulfate, K₂SO₄

• Ammonium salts and nitrates are commonly used as fertilisers

• Different fertilisers contain different amounts of fertiliser compounds so each contains different proportions of nitrogen, phosphorus and potassium