Environmental impacts of agriculture
Big idea: Agriculture is essential for feeding 8 billion people, but it has massive environmental costs: habitat destruction, water pollution, soil degradation, biodiversity loss, and climate change contributions.
Impacts on water
- Eutrophication — fertilizer runoff causes algal blooms, dead zones
- Water scarcity — irrigation depletes rivers, lakes, aquifers
- Salinization — irrigation in dry areas leaves salt deposits
- Pesticide contamination — chemicals enter groundwater and streams
Impacts on soil
- Erosion — bare fields lose topsoil to wind and rain
- Nutrient depletion — continuous cropping removes N, P, K
- Compaction — heavy machinery crushes soil structure
- Loss of organic matter — tillage accelerates decomposition
Impacts on biodiversity and climate
- Habitat destruction — land cleared for farming is #1 cause of biodiversity loss
- Monoculture — single-crop fields eliminate habitat diversity
- Pesticides — kill non-target species, disrupt food webs
- GHG emissions — CO2 from machinery, N2O from fertilizers, CH4 from livestock
PAST PAPER FAVOURITE (7 marks): "Explain impacts of agricultural pollution on ecosystems." Focus on: nutrient runoff → eutrophication → oxygen depletion → biodiversity loss → downstream impacts. Make clear cause-effect chains!
IB-style question — impacts of intensive farming
Explain two environmental impacts of intensive livestock farming. [4]
How the marks are earned
- Impact 1 — greenhouse gases
• cattle produce methane (digestion + manure)
• → contributes to climate change - Impact 2 — water pollution
• manure / fertiliser runoff adds nutrients to rivers
• → eutrophication, oxygen depletion, loss of aquatic life
Final answer
Each impact needs a cause→effect chain: the farming activity → the environmental consequence.
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