Nitrogen fertilisers

Ammonium salts and nitrates are used as fertilisers because they supply nitrogen in forms plants can absorb. Nitrogen supports amino-acid and protein production and vigorous growth.

NPK fertilisers

NPK fertilisers provide nitrogen, phosphorus and potassium. Phosphorus supports roots and energy-transfer compounds, while potassium supports enzyme activity and general plant health.

Balanced use

The correct formulation depends on crop and soil. Too little nutrient limits yield, but excessive use wastes resources and increases runoff or leaching.

Environmental trade-off

Fertilisers increase food production but can contribute to nitrate and phosphate pollution. Application rate, timing and placement help reduce loss to water.

High-value recall and connections

Essential recall: Name two nitrogen fertiliser types. Ammonium salts and nitrates. What elements are supplied by NPK? Nitrogen, phosphorus and potassium. Why avoid over-application? It wastes fertiliser and increases water pollution. Practical connection: Compare three fertiliser labels and identify which is most suitable for leafy growth, root establishment or potassium-demanding crops. Examination connection: NPK letters name elements, not the exact compounds present.

Review questions and suggested answers