Farming Methods (SQA National 5 Biology): Revision Note
Exam code: X807 75
Human population growth
The human population has increased in size rapidly due to factors such as improved healthcare and better nutrition
As global populations continue to grow, so does the need for improved food yield from the world's farmers
Fertilisers & pesticides
To meet the food needs of a growing global population, agricultural processes have changed
Agriculture has intensified by, e.g.:
growing a small selection of high-yield crop varieties
increasing the use of farm machinery and technology
growing crops under cover in a controlled environment
increasing the use of chemicals, such as fertilisers and pesticides
Fertilisers
Fertilisers are substances added to soil to supply mineral ions that are required by plants, e.g. nitrates (N), phosphates (P) and potassium (K)
Fertilisers therefore, increase crop yield by preventing mineral deficiency
Type | Description | Benefit | Concern |
|---|---|---|---|
Chemical fertilisers | Industrially manufactured mineral salts | Release minerals quickly Have precise NPK ratios, so are easy to dose | Can leach into soil Don’t build up soil structure |
Organic fertilisers | Formed from decomposing organic matter, e.g. manure and compost | Improve soil structure They are less likely to leach due to their slow-release nature | Release minerals more slowly as they decompose Have variable nutrient content |
Pesticides
Pesticides are substances applied to crops to kill or control plants and animals that reduce yield, e.g. insects and weeds
Type | Description | Benefit | Concern |
|---|---|---|---|
Herbicides | Chemicals that kill unwanted plants, i.e. weedkillers | Removing weeds reduces competition for light, water and mineral ions | Overuse can lead to water pollution and the evolution of herbicide-resistant weeds |
Insecticides | Chemicals that kill insects | Reduces feeding damage due to herbivory Reduces the spread of insect-borne diseases | Can kill beneficial insects such as pollinators Can persist in the environment for long periods |
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