3.5.1Unit 3 — Life on Earth
Farming Methods — SQA National 5 Biology Revision Notes & Topical Questions
5 min read 5 parts Lesson 24 of 31
Part 1 of 5Feeding a Growing Population
Population growth
- Better healthcare and nutrition have made the human population grow quickly, so more food is needed.
Intensive farming
- Farmers grow a few high-yield crop varieties and use more machinery and technology to produce more per hectare.
Controlled environments
- Growing crops under cover lets farmers control conditions such as temperature and water.
Chemicals
- Fertilisers and pesticides are used more often to raise yields.
Part 2 of 5Fertilisers
Fertilisers
Purpose
- Fertilisers add mineral ions such as nitrates, phosphates and potassium, preventing mineral deficiency and raising yield.
Chemical fertilisers
- These are manufactured salts that release minerals quickly and have a precise composition, but can leach out of soil.
Organic fertilisers
- Manure and compost improve soil structure and release minerals slowly, but their nutrient content is variable.
Choice
- Farmers balance fast, predictable nutrient supply against slow release and soil improvement.
| Type | Benefit | Concern |
|---|---|---|
| Chemical | Quick release, exact ratios | Leaching, no soil structure |
| Organic | Improves soil, less leaching | Slow, variable content |
Part 3 of 5Pesticides
Pesticides
Purpose
- Pesticides kill or control organisms that reduce yield, such as insects and weeds.
Herbicides
- These weedkillers reduce competition for light, water and minerals, but overuse can pollute water and breed resistant weeds.
Insecticides
- These cut feeding damage and insect-borne disease, but can kill useful pollinators and may persist in the environment.
Overall
- Pesticides raise yield, but non-target organisms and ecosystems may be harmed.
Part 4 of 5Weighing Up the Methods
1
Population growth increases the demand for food.
2
Farmers intensify production using high-yield crops, machines, fertilisers and pesticides.
3
Yields rise, which helps to feed more people.
4
Run-off, loss of beneficial insects and chemical persistence can damage the wider environment.
5
Careful use and alternatives are therefore needed to produce enough food sustainably.
Part 5 of 5Exam Checklist & Tips
3.5.1 – Key Points for the Exam
- Intensive farming Farming that aims for high yield from each area of land.
- Fertiliser A substance that supplies mineral ions to crops.
- Pesticide A chemical that kills pests that reduce crop yield.
- Herbicide A pesticide that kills weeds.
- Yield The amount of crop produced from an area of land.
Common Mistakes
- Saying fertilisers feed plants with food; plants make their own food and fertilisers supply mineral ions.
- Listing only advantages of chemicals, when questions also ask for a concern.
- Confusing herbicides with insecticides; herbicides kill weeds and insecticides kill insects.
- Writing that organic fertilisers are quicker than chemical ones; they release minerals more slowly.
Last updated:
\n