Healthy soil is easily damaged. This GCSE Geography quiz explores how soil erosion and degradation happen, and how careful management can protect land for the future.
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Bare soils can be caused by overgrazing or extreme droughts
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Nomadic populations are being encouraged to settle down in fixed areas by the increase in land ownership and facilities such as stand pipes
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Slash and burn agriculture removes all of the plant life from the surface exposing the soil to erosion
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Since the nutrients come from decaying organic matter, they tend to be concentrated in the top layer of the soil
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Sheet erosion is worse in areas with steep slopes, often removing the soil down to bare rock
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Tropical storms can cut gullies into slopes. These can become deep channels that flood in the wet seasons
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Ploughing leaves behind ridges and furrows. If these are across the slope they trap water and runoff, but if they are down slope they encourage the water to run downhill and carry soil away with it
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Surface runoff causes soil erosion. Soil structure is a delicate balance and can be destroyed by compaction. Protecting the soil structure is a key method of reducing soil erosion
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The roots of plants bind soil together, so, without vegetation, soil is more susceptible to erosion. Goats will even climb trees and strip leaves, thus reducing leaf litter
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Salt is toxic to many plants, so the soil ends up being bare and therefore more easily subjected to erosion. Irrigation can lead to salinisation. As water is brought in, it evaporates, drawing the salt up to the surface and leaving a layer that is dense in salt
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