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.
Fertilisers 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:
The table shows some examples of fertilisers, their formulae and the essential elements they provide.
|Ammonium phosphate||(NH4)3PO4||Nitrogen, phosphorus|
|Potassium nitrate||KNO3||Potassium, nitrogen|
Urea, (NH2)2CO, is used as a fertiliser. Name the essential element it provides.