Fertilisers
A nutrient added to the soil to increase the soil fertility. provide Naturally occurring, inorganic chemical substances. Minerals are necessary for both plant and animal health. Electrically charged particle, formed when an atom or molecule gains or loses electrons. needed for healthy growth in plants. As plants grow, they absorb mineral ions from the water in the soil through their A specialised cell that increases the surface area of the root epidermis to improve the uptake of water and minerals.. Over time, the The concentration of a solution tells us how much of a substance is dissolved in water. The higher the concentration, the more particles of the substance are present. of these ions decreases, so farmers and gardeners add fertilisers to the soil.
Nitrogen, phosphorus and potassium
Fertilisers may contain nitrogen, phosphorus and potassium A substance formed by the chemical union of two or more elements. to promote plant growth. Fertilisers that supply all three A substance made of one type of atom only. are often called NPK fertilisers, after the chemical symbols for these three elements.
Fertiliser compounds must be Able to dissolve in solvent. For example, sugar is soluble in water because it dissolves to form sugar solution. 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 When a substance breaks up and mixes completely with a solvent to produce a solution. in water to produce potassium ions, K+
The table shows some examples of fertilisers, their A combination of symbols that indicates the chemical composition of a substance. and the essential elements they provide.
| Fertiliser | Formula | Essential element(s) |
| Ammonium nitrate | NH4NO3 | Nitrogen |
| Ammonium sulfate | (NH4)2SO4 | Nitrogen |
| Ammonium phosphate | (NH4)3PO4 | Nitrogen, phosphorus |
| Potassium nitrate | KNO3 | Potassium, nitrogen |
| Fertiliser | Ammonium nitrate |
|---|---|
| Formula | NH4NO3 |
| Essential element(s) | Nitrogen |
| Fertiliser | Ammonium sulfate |
|---|---|
| Formula | (NH4)2SO4 |
| Essential element(s) | Nitrogen |
| Fertiliser | Ammonium phosphate |
|---|---|
| Formula | (NH4)3PO4 |
| Essential element(s) | Nitrogen, phosphorus |
| Fertiliser | Potassium nitrate |
|---|---|
| Formula | KNO3 |
| Essential element(s) | Potassium, nitrogen |
Question
Urea, (NH2)2CO, is used as a fertiliser. Name the essential element it provides.
Nitrogen.