📖 In-Depth Theory
Food Production and Land Use
The human population has grown rapidly — we now need to produce more food than ever before from a finite amount of land.
FARMING LAND USE:
Approximately 50% of the Earth's habitable land is used for agriculture.
This has dramatically reduced natural habitats — particularly forests and wetlands.
Large-scale agriculture often involves MONOCULTURES — growing one crop species over vast areas.
Consequences of modern intensive farming:
HABITAT LOSS — natural ecosystems cleared for cropland or pasture → biodiversity loss.
SOIL DEGRADATION — intensive tilling, removal of hedgerows and chemical use reduce soil quality.
WATER POLLUTION — nitrate and pesticide runoff into rivers and groundwater (eutrophication).
GREENHOUSE GAS EMISSIONS — livestock (methane), deforestation (CO₂), nitrogen fertilisers (N₂O).
FARMING TECHNIQUES TO INCREASE YIELD:
FERTILISERS — provide nitrogen, phosphorus, potassium for plant growth.
PESTICIDES — kill insects, fungi, weeds that reduce crop yield.
SELECTIVE BREEDING — developing high-yield, disease-resistant varieties.
GENETIC MODIFICATION — herbicide-resistant and pest-resistant crops.
GREENHOUSES — controlled conditions maximise growth year-round.
The Cost of Raising Livestock
Producing meat and dairy requires significantly more land, water and energy than producing equivalent plant-based food.
WHY ANIMAL PRODUCTS ARE LESS EFFICIENT:
Cattle, pigs and chickens are at trophic level 2 or above — they eat plant material.
As we've seen, only ~10% of energy at one trophic level passes to the next.
The grain fed to livestock contains far more energy than the meat produced from it.
To produce 1 kg of beef, approximately 8–10 kg of grain is needed.
IMPACTS:
MORE LAND needed to grow feed crops AND for grazing.
MORE WATER — livestock production is a major consumer of freshwater globally.
METHANE — cattle and sheep produce large amounts of methane (a potent greenhouse gas) during digestion.
DEFORESTATION — particularly in South America, forest is cleared for cattle ranching and soy production (livestock feed).
IMPLICATION:
Reducing meat consumption — particularly beef — is one of the most effective individual actions for reducing environmental impact.
Plant-based diets require less land, less water and produce fewer greenhouse gases.
Sustainable Fishing
Many of the world's fisheries are being OVERFISHED — fish are being caught faster than populations can reproduce and recover.
Consequences of overfishing:
Fish populations collapse — some fisheries have been effectively destroyed (e.g. Grand Banks cod fishery, Canada).
Food security threatened — billions of people depend on fish as a primary protein source.
Ecosystem damage — removing key fish species disrupts food webs.
METHODS TO ACHIEVE SUSTAINABLE FISHING:
FISHING QUOTAS:
Governments and international bodies set limits on how much of each species can be caught per year.
Gives populations time to recover.
Controversial — difficult to enforce and quota-setting is politically contentious.
FISH SIZE LIMITS:
Fish below a minimum size cannot be landed.
Allows young fish to reach breeding age — ensuring population reproduction.
NET MESH SIZE REGULATIONS:
Larger mesh sizes allow juvenile fish to escape and grow.
Reduces bycatch (accidentally caught non-target species).
FISHING BANS (closed seasons and marine protected areas):
Banning fishing in certain areas or at certain times allows populations to recover.
Marine reserves where fishing is completely prohibited can act as breeding refuges.
SUSTAINABLE AQUACULTURE (fish farming):
Farming fish in controlled conditions reduces pressure on wild populations.
Environmental concerns: waste, disease spread to wild fish, feed requirements.
⚠️ Common Mistake
Sustainable fishing is not about stopping fishing — it is about fishing at rates that allow fish populations to maintain their numbers. Quotas, size limits and protected areas allow fish to breed before being caught. Aquaculture (fish farming) can reduce pressure on wild stocks but has its own environmental impacts.