Erosion Brylee Lutman Definitions Erosion The removal of
Erosion Brylee Lutman
Definitions Erosion: The removal of material from one place and its transport toward another by the action of the wind or water Deposition: The arrival of eroded material at its new location
Natural causes of soil erosion Sheet erosion Wind erosion Splash erosion Rill erosion Gully erosion
Unnatural causes of erosion Over cultivating fields through poor planning or excessive tilling Clearing forests on steep slopes or with larger clearcuts Overgrazing rangelands with more livestock than the land can support
Problems Erosion removes top soil, the most valuable soil layers for living things Gradual and hard to detect U. S. farm lands lose 6 tons of soil for every ton of grain harvested Occurs more quickly than soil is formed Soil degradation– loss of more than 10% productivity Dust Bowls
Erosion-control practices Contour farming: plowing furrows sideways across a hillside, perpendicular to its slope • Helps prevent the formation of rills and gullies Crop rotation: alternating the types of crops grown in fields from one season to the next • Returns nutrients to the soil • Breaks cycles of disease associated with continuous cropping • Minimizes erosion that comes from letting fields lie fallow Terraces: level platforms, sometimes with raised edges, that are cut into steep hillsides to contain water from irrigation and precipitation • Cultivate hilly land without losing huge amounts of soil to water erosion
Erosion-control practices (continued) Shelterbelts: rows of trees or other tall, perennial plants that are planted along edges of fields to flow the wind • Reduces erosion from wind Intercropping: planting different types of crops in alternating bands or other spatially mixed arrangements • Provides more ground cover than a single crop • Replenishes soil Reduced tillage: a tractor pulls a “no-till drill” that cuts furrows through the O horizon of dead weeds and crop residue and the upper level of A horizon. It then drops seeds into the furrows, and covers it over • Restores and improves soil quality
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