Summary
Highlights
Billions of tons of soil are lost annually in the U.S. due to erosion, which diminishes soil productivity, degrades soil and water quality, and creates stream pollution by filling reservoirs with sediment. Erosion initially removes topsoil, exposing less productive subsoil, and can render land unproductive, leading to abandonment.
Soil erosion is a gradual process caused by wind and water. Wind erosion occurs when wind lifts and moves small soil particles, with higher wind speeds greatly increasing the rate of erosion. Water erosion begins with raindrops, which strike the ground with significant force (up to 30 mph), dislodging up to 100 tons of soil per acre in intense storms. These dislodged particles can splash far, especially on slopes, and plug soil pores, preventing water infiltration and leading to runoff and further erosion.
Water erosion is classified into five types. Sheet erosion is subtle but damaging, involving the loss of thin, uniform layers of topsoil across a field. This often goes unnoticed until significant damage has occurred and subsoil is exposed.
Rill erosion is characterized by small channels or rills cut into bare soil on slopes, which can be removed by normal tillage and occur randomly. Ephemeral erosion is similar but forms in the same natural depressions year after year due to concentrated water flow and can also usually be erased by tillage.
Gully erosion involves channels too large for ordinary tillage. If unchecked, the gully's 'head' cuts upslope, threatening soil resources and making farmlands impassable for machinery. Streambank erosion, caused by continuous water flow, cuts away streambanks, a slow process that accelerates during floods, potentially altering river courses.
While natural processes, wind and water erosion have been accelerated by human activities like farming and construction. Farmers and ranchers should be aware of this damage and take measures to reduce the harmful effects of erosion on their land.