Soil erosion is an entirely natural process. In nature, soil erosion typically occurs at roughly the same slow rate as soil formation. That's because plants help to anchor soil in place with their roots, preventing it from being eroded quickly. Humans, however, often clear away existing growth to make way for farms or suburbs, sometimes leaving soil exposed in the process. This exposed soil is highly vulnerable to erosion. SInce healthy soil forms very slowly and is vital to good plant growth, soil erosion can deplete a valuable natural resource that's tough to replace.
The process that wears away the Earth's surface, removes soil and deposits it elsewhere is called soil erosion. Wind and water are the primary culprits; wind is a common problem on flat or hilly terrain, while water erosion is most severe on slopes. Farmers and landowners struggling with soil erosion have several different options available.
When strong winds blow across loose soil, they can blow some of the topsoil away, directly removing part of the soil's most fertile layer. Because moisture helps clump the soil and hold it together, wind erosion is worst in dry or arid regions. Moreover, wind erosion kicks up large amounts of dust, which can clog machinery, pollute air and water, and adversely affect human or animal health. Common symptoms of wind erosion include dust clouds, accumulation of loose dirt along fences and a windblown appearance of the soil surface, as if the dirt has been blown or drifted. In the midwestern United States, one of the country's most productive agricultural regions, wind erosion is a common problem in the wintertime.
When raindrops land on dirt or mud with sufficient force, they can scatter some of the dirt; this effect is called rainsplash. It doesn't actually transport the soil away, however. More serious are rill and gully erosion. As the water accumulates and the soil becomes waterlogged, excess water starts to flow downhill, carving out tiny channels called rills and larger channels called gullies. As it flows, it carries away an increasing load of soil, which will eventually be deposited into local streams, lakes and rivers. Not only does water erosion rapidly denude the land of topsoil, but it also pollutes bodies of water downstream. Common symptoms include plants or rocks on pedestals carved out by rainwater, surface crusts on bare soil, a network of rills or gullies crossing a field, decreased soil thickness, exposed subsoil and poor plant growth.
Soil erosion can badly damage agricultural productivity and cause pollution, so it's highly desirable to prevent it. Planting windbreaks made of trees or planting crops on terraces that follow natural contours can help protect fields from the full fury of the wind; making the slope shorter or shallower can help minimize water erosion. Plants anchor soil against the forces of wind and water, so maintaining cover is critical. Planting winter crops or growing crops in rotation helps reduce erosion, as does protecting the surface with crop residue like straw.
- Michigan State University: Soil Erosion in Agricultural Systems
- Maine Department of Environmental Protection; Soil Erosion; 2005
- Soil Erosion Site; What Is Soil Erosion?; Dave Favis-Mortlock; 2007
- University of California; Understanding Soil Erosion; Anthony O'Geen & Lawrence Schwanki; 2006
- Kansas State University Extension: Wind Erosion
- Photo Credit Dynamic Graphics Group/Dynamic Graphics Group/Getty Images
How to Prevent Soil Erosion
Soil erosion can be a major problem for you if you have a garden, plant beds or a farm. Preventing soil erosion...