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examBoard: Cambridge
examType: IGCSE
lessonTitle: Case Study: Agriculture with Environmental Consequences
Agriculture feeds the world's growing population but often at a significant environmental cost. Modern farming methods have dramatically increased food production but have also led to serious environmental problems including soil degradation, water pollution, habitat destruction and biodiversity loss.
Key Definitions:
Modern agricultural practices often prioritise high yields and short-term profits over environmental sustainability. This approach has led to serious environmental degradation worldwide, threatening the very ecosystems that agriculture depends on.
The challenge facing global agriculture is how to produce enough food for a growing population while protecting natural resources and ecosystems for future generations. This requires a shift towards more sustainable farming methods.
Soil is a precious resource that forms very slowly but can be damaged or lost quickly through poor agricultural practices. Globally, about 33% of the world's soil is moderately to highly degraded due to erosion, salinisation, compaction, acidification and chemical pollution.
Excessive tillage breaks down soil structure, leading to compaction and increased vulnerability to erosion. In the US Great Plains, this contributed to the 1930s Dust Bowl disaster.
Too many livestock on limited land destroys vegetation cover, compacts soil and increases erosion. This is a major cause of desertification in parts of Africa and Asia.
Clearing forests for agriculture removes the protective tree cover, exposing soil to erosion by wind and rain. This is particularly damaging on hillsides and in tropical regions.
Once the fourth-largest lake in the world, the Aral Sea in Central Asia has shrunk to just 10% of its original size due to irrigation for cotton farming. Starting in the 1960s, Soviet planners diverted water from the rivers that fed the Aral Sea to irrigate cotton fields in Kazakhstan and Uzbekistan. This caused:
This environmental catastrophe shows how agricultural decisions can have far-reaching consequences beyond the farm.
Agriculture is the leading source of water pollution in many countries. Fertilisers, pesticides and animal waste can contaminate surface water and groundwater, causing serious environmental and human health problems.
When rain falls on farm fields, it can wash various substances into nearby water bodies:
Nitrogen and phosphorus from fertilisers cause algal blooms in lakes and coastal waters. When these algae die, their decomposition depletes oxygen in the water, creating "dead zones" where fish and other aquatic life cannot survive. The Gulf of Mexico dead zone, which can cover over 22,000 square kilometres, is largely caused by fertiliser runoff from farms in the Mississippi River basin.
Pesticides can kill aquatic plants and animals and accumulate in food chains. They may also contaminate drinking water sources. In the UK, studies have found pesticides in about 15% of groundwater monitoring sites. Some pesticides, like neonicotinoids, are particularly harmful to pollinators such as bees, which are essential for crop production.
Rachel Carson's 1962 book "Silent Spring" highlighted how the pesticide DDT was causing eggshell thinning in birds of prey, leading to population crashes of species like the bald eagle and peregrine falcon. Though DDT was eventually banned in many countries, modern pesticides continue to harm wildlife:
This case shows how chemicals used to protect crops can have unintended consequences throughout ecosystems.
Agriculture is the leading cause of habitat loss worldwide. Converting natural ecosystems to farmland destroys wildlife habitat and reduces biodiversity. Additionally, modern farming practices often create vast monocultures that support far fewer species than natural habitats.
The expansion and intensification of agriculture affects biodiversity in several ways:
Converting forests, grasslands and wetlands to farmland destroys the homes of countless species. Tropical deforestation for soy, palm oil and cattle ranching is particularly devastating for biodiversity.
Large fields of a single crop provide food and habitat for very few species compared to diverse natural ecosystems. In the UK, the loss of hedgerows and field margins has reduced habitat for many farmland species.
Pesticides don't just kill target pests but also beneficial insects and other wildlife. Herbicides eliminate wild plants that many animals depend on for food and habitat.
The expansion of oil palm plantations in Indonesia and Malaysia has led to massive deforestation and biodiversity loss:
This case illustrates how global demand for agricultural products can drive environmental destruction in biodiversity hotspots.
Despite these serious environmental problems, agriculture doesn't have to be destructive. Many farmers around the world are adopting more sustainable practices that protect soil, water and biodiversity while still producing good yields.
These approaches can help reduce agriculture's environmental footprint:
This approach includes minimal soil disturbance (no-till farming), permanent soil cover with cover crops or mulch and crop rotation. It helps prevent soil erosion, improves soil health and reduces the need for fertilisers and pesticides. In the UK, no-till farming has increased by 30% in the last decade, helping to reduce soil erosion and improve carbon sequestration.
IPM combines biological controls (like beneficial insects), cultural practices (like crop rotation) and careful monitoring to manage pests with minimal pesticide use. This approach protects beneficial insects and reduces water pollution. Studies show IPM can reduce pesticide use by 50-90% while maintaining yields.
Gabe Brown's farm in North Dakota, USA, demonstrates how regenerative agriculture can restore degraded land:
This case shows that farming can actually restore ecosystems while remaining productive and profitable.
Agriculture faces the enormous challenge of feeding a growing global population while reducing its environmental impact. The case studies we've examined show both the severe consequences of unsustainable practices and the promise of more ecological approaches.
As consumers, we can support sustainable agriculture through our food choices. As citizens, we can advocate for policies that encourage environmental protection in farming. And as students of environmental management, we can help develop and promote solutions that balance food production with conservation.
The future of agriculture must be one that works with nature rather than against it producing abundant food while protecting the soil, water and biodiversity that all life depends on.
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