Impact of agriculture on the physical environment

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Impact of agriculture on the physical environment

Farming can lead to the loss of natural habitats. One of the most significant natural habitats for the UK's flora and fauna is the hedgerow. However thousands of miles of hedgerow have been removed and the rest is still under threat.

The total amount of hedgerow removed or damaged is 6 x the circumference of the globe. This is destroying natural habitats and changing the very nature and look of our rural landscape.

Loss of natural habitat

Increased mechanisation in agriculture encourages farmers to increase the size of their fields. This they do by removing hedgerows. The UK has lost over 25% of its hedgerows in the last fifty years. The USA is also concerned about the effect of hedgerow loss that is removing the habitat for several butterfly species - the monarch being one example.

In Ireland the importance of hedgerows is now recognised and farmers receive compensation for preserving them.

The following table outlines the arguments for and against hedgerows:

For hedgerow preservation: Against hedgerow preservation:
They are a unique and balanced ecosystem. They may harbour pests but they also harbour the predator of that pest. They can provide homes for pests and weeds which damage crops.
They contain a vast array of wildlife including many endangered species and they increase bio-diversity. They are a hindrance to the large machinery that makes farming efficient and reduces food prices to the consumer.
Evidence to suggest that they act as a natural barrier to the spread of disease. They also act as wind breaks that protect crops and reduce soil erosion. They need to be maintained which is costly.
They are a part of our rural heritage. They were planted by farmers in the first place so are not traditional.

P.S: 39 out of 42 hedgerow birds are beneficial to farmers.

Farmers to increase the available land and reduce the potential disease from stagnant water have drained ponds. This removes another habitat for birds, fish, insects and plants.

The soil itself is an ecosystem and inappropriate farming techniques can lead to soil erosion. Overgrazing, over cultivation and deforestation all damage the soil making it more prone to the effect of erosion. This can be made worse if hedgerow has been removed.

The hedgerow acts as a natural windbreak and the roots help hold the soil together. In East Anglia where much of the hedgerow has been removed soil loss through erosion is twice the global average.

Water will also wash away soil. In some instances this is a consequence of poor farming techniques. If the soil has a low organic content then runoff is increased - as there is less to soak up the moisture. Run-off over the surface leads to erosion especially if the soil is poorly bonded.

Farmers often have to plough up and down slopes so creating channels that increase run-off and erosion.

In the developing world the pressure growing populations and foreign debt repayments has seen the removal of natural vegetation cover to make way for cash cropping. This removes precious habitats and can increase soil erosion - as happened in the Brazilian rainforest.

Whilst in other areas (e.g. Bali) subsistence farmers have to farm very steep slopes because of the population pressures. Whilst terracing reduces erosion Indonesia is still facing major problems.

As farmers attempt to increase yields so they can increase their use of fertiliser, pesticides or slurry. Each of these can have potentially damaging effects on the environment.

Eutrophication

Fertiliser and slurry are used to increase the nitrogen content of the soil so encouraging healthy plant growth. If too much is used then it can be leached into underground water supplies and rivers. This is called eutrophication. It then encourages algal and plant growth in the river or lake.

This algae and other autotrophs ( brainy name for plants) multiply rapidly then die off as oxygen is used up. Bacteria then multiply as the plants decompose.

These bacteria use up any remaining oxygen and produce toxic bi-products. The lack of oxygen and increased toxicity kill fish life. This can encourage even more harmful bacteria.

Pesticides are another problem. Without pesticide crop yields would be drastically reduced but many objectors claim pesticides are harmful to humans.

Indeed in the developing world there are countless examples of pesticide poisoning. In the UK the "Mammal Society" claim there are 24 species in danger of extinction as a consequence of pesticide use.

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