NPK Fertilisers

What are fertilisers?

• Fertilisers provide mineral ions needed for healthy growth in plants.
• As plants grow, they absorb mineral ions from the water in the soil through their root hair cells.
• Over time, the concentration of these ions decreases, so farmers and gardeners add fertilisers to the soil.

Nitrogen, Phosphorous and Potassium

• Fertilisers are formulations which may contain nitrogen, phosphorus and potassium compounds to promote plant growth.

• Fertilisers that supply all three elements are often called NPK fertilisers, after the chemical symbols for these three elements.

• Fertiliser compounds must be soluble in water so they can be absorbed by the root hair cells:

  • ammonium ions, NH4+, and nitrate ions, NO3-, are sources of soluble nitrogen
  • phosphate ions, PO43-, are a source of soluble phosphorus

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