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6 Cards in this Set
- Front
- Back
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geological erosion |
- natural, not human induced
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accelerated erosion |
- not natural, induced by human activities - 10 to 1000 times as destructive as geological erosion |
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about 4 billion Mg of soil is moved annually by erosion in the United States |
- 2/3 by water, 1/3 by wind
- somewhat more than half occurs on cropland - the remainder from range land, timber harvest, construction sites |
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on-site erosion damage |
- lose topsoil - selective removal of OM, fine particles, nutrients - remaining soil has lower infiltration rates and water holding capacity - gullies make equipment operation difficult, undercut roads, buildings |
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off-site erosion damage |
- nutrient and pesticide transport degrades water quality - sediments - smother crops and low-lying vegetation - fill in drainage ways, causes flooding, reduce reservoir capacity, require dredging - degrade stream beds - causes turbidity |
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T value |
- maximum amount of soil that can be lost annually by erosion on a particular soil without degrading its long term productivity - t-values in most agricultural soils in the USA are 5-11 Mg/ha |
