The human population keeps growing, and farmers have found ways to grow far more food on each hectare: machines, fertilisers, pesticides and selectively bred crops and animals. Growing one crop over a huge area, or keeping animals indoors in large numbers, produces cheap food but changes the ecosystem around the farm.
Humans have increased food production by using agricultural machinery to farm larger areas efficiently, chemical fertilisers to improve yields, insecticides to improve quality and yield, herbicides to reduce competition with weeds and selective breeding to improve production by crop plants and livestock. Large-scale monocultures and intensive livestock production give high yields at low cost, but reduce biodiversity, spread disease and pollute the environment.
In the sim a wheat field starts with no help at all: weeds (purple) grow between the crop and insect pests (black) swarm over it. Tick each method in turn and watch the yield bar, then tick them all.
| Method | What it does | Why the yield rises |
|---|---|---|
| Agricultural machinery | tractors, combine harvesters, irrigation | one farmer can work a much larger area of land quickly and efficiently |
| Chemical fertilisers | add nitrate, phosphate and potassium ions to the soil | plants get the mineral ions they need, e.g. nitrate to make amino acids and proteins |
| Insecticides | kill insect pests | less of the crop is eaten or damaged, improving quality and yield |
| Herbicides | kill weeds | less competition for light, water and mineral ions |
| Selective breeding | humans choose parents with useful features to breed | varieties and breeds with higher yields, disease resistance or faster growth |
Insecticides kill insects; herbicides kill weeds (plants). Both are pesticides. Do not mix them up, and remember fertilisers supply mineral ions, not "food" for the plant: plants make their own food by photosynthesis.
Switch the sim from crop field to intensive livestock. Both systems are designed to produce as much food as possible at the lowest cost, but both have drawbacks.
| Advantages | Disadvantages | |
|---|---|---|
| Large-scale monoculture (one crop over a huge area) | easy to use machinery; efficient planting, spraying and harvesting; high yield at low cost; crop of uniform quality | low biodiversity (hedgerows and habitats removed); pests and diseases of that crop spread easily; heavy use of pesticides and fertilisers that can pollute water; soil loses the same ions year after year |
| Intensive livestock (many animals kept close together indoors) | more meat, milk or eggs from less land; cheaper food; animals use less energy moving and keeping warm, so more of their food becomes growth | diseases spread easily, so antibiotics are often used; poor animal welfare; large amounts of waste can pollute water; land is used to grow their feed |
"Higher profit" on its own is a weak answer. Say why: higher yield per hectare, less labour per tonne, or less energy wasted by the animals.
Four quick checks. Each correct answer earns XP and records this skill on your profile.
In the food production sim, what disappears from the field when herbicide is switched on?
Which single method gives the biggest rise in the yield bar in the sim?
Why does switching on insecticide improve the yield?
In the intensive livestock view, why do diseases spread easily?
Unlocks once the four checks above are done. Worth more XP, written to IGCSE Paper 2 and Paper 4 standard.
Which method of increasing food production works by reducing competition between plants?
Which is a disadvantage of a large-scale monoculture?
A farmer selectively breeds a variety of wheat. Which feature would most improve production?
Why do chickens kept indoors in warm sheds grow faster on the same food than free-range chickens?
This skill is now recorded on your profile. Keep the chain going.