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6 Cards in this Set

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geological erosion

- natural, not human induced


accelerated erosion

- not natural, induced by human activities


- 10 to 1000 times as destructive as geological erosion

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



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

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

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