Author
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WILLIAMS, A - BRAZIL |
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PRUSKI, F - BRAZIL |
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Nearing, Mark |
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Submitted to: Kluwer Academic Publishers Netherlands
Publication Type: Book / Chapter Publication Acceptance Date: 9/1/2002 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Land degradation poses an increasing threat to agricultural production. Under natural conditions, topsoil in the aggregate is renewed at a rate approximately equal to the rate at which degradation occurs. However, much agricultural land degrades at faster than "tolerable rates". Pimental et al. (1976) estimate that more than one third of US cropland topsoil has been lost in the last 200 years. The U.S. Department of Agriculture estimates that combined water and wind erosion from cultivated cropland averages approximately 14 tonnes ha-1 yr-1, while the USDA considers tolerable rates of soil loss on the vast majority of this land to be between 9 and 11 tonnes ha-1 yr-1 (USDA, 1994). The majority of the world's agricultural soils are probably eroding at a faster pace than are soils in the United States. Global climate change threatens to exacerbate erosion problems as well as bring about changes in yields. Climate simulation models indicate that by the year 2050 average annual temperatures in the Midwestern U.S. may increase around 8 degrees F and average annual rainfall may increase, resulting in warmer, wetter conditions. Perhaps more importantly, less predictable weather patterns will emerge, increasing the frequency of extreme weather events such as heavy downpours of precipitation as well as late season frosts and droughts. While increases in temperature associated with climate change may, in some cases, bring about increases in both crop yields and total crop biomass production, heavy downpours may also exacerbate erosion. |
