Chemistry revision for subtopic 4.3, Stage 2 Chemistry, South Australia
| Front | What role do nitrogen-fixing bacteria play in soil? |
| Back | These bacteria convert atmospheric nitrogen (N₂) into ammonium (NH₄⁺₍ₐᵩ₎), increasing soil nitrogen content. |
| Front | What is cation exchange in soils? |
| Back | The process where cations adsorbed onto clay surfaces are exchanged with those in soil water, making them available to plants. |
| Front | Why might sandy soils require more frequent fertilisation? |
| Back | Their low CEC and poor water retention lead to rapid nutrient loss via leaching. |