Erosion 11/19/08

Soil Erosion  erosion is the removal of material from one place and its transport toward another by the action of wind or water both are natural processes that can result in the long term creation of soil  deposition is the arrival of eroded material at its new location

Desertification A loss of more than 10% productivity due to erosion, soil compaction, forest removal, overgrazing, drought, salinization, climate change, and depletion of water sources Severe desertification can result in the expansion or creation of deserts

Desertification can lead to dust storms Between , cultivated areas in the western United States went from 12 million acres to 100 million acres, removing much of the native grass In the 1930s, a drought exacerbated the ongoing human impacts on the soil Dust storms traveled up to 2000 km Some areas lost 10 cm of topsoil in a few years

The soil conservation act of 1935 Described soil erosion as a threat to the nation’s well-being Established the Soil Conservation Service (SCS) Serves as a model for regions around the world

The soil conservation act of 1935 Goals of the act: –Assess the land’s resources, its problems, and opportunities for conservation –Draw on science to prepare an integrate plan for the property –Work closely with land users to ensure that conservation plans harmonize with the users’ objectives –Implement conservation measures on individual properties to contribute to the overall quality of life in the region

Protecting soil against degradation Crop rotation—the practice of alternating the kind of crop grown in a particular field from one season or year to the next

Protecting soil against degradation Contour Farming—plowing furrows sideways across a hillside to help prevent formation of rills and gullies

Protecting soil against degradation Intercropping—the planting different types of crops in alternating bands or mixed arrangements

Protecting soil against degradation Terracing—transforms slopes into series of steps like a staircase, –enabling farmers to cultivate hilly land

Protecting soil against degradation Shelterbelts—windbreaks; rows of trees that are planted along the edges of fields to slow the wind

Protecting soil against degradation Reduced tillage—low disturbance to topsoil when planting seeds –Uses special machinery –Nearly ½ of US acreage is farmed this way