What Causes Soil Erosion?

Weather

• Local climate conditions such as rain and wind often lead to soil erosion. Raindrops dislodge surface soil, and excessive rain can lead to runoff, which pulls large amounts of soil from the surface. If left unchecked, this can create rills, or channels in the soil, which can disrupt tilling and prevent farming equipment from moving across the soil. Wind can blow up dry soil and carry it miles away, also reducing the amount of nutrients in surface soil.

Soil Composition

• The precise makeup of a given patch of soil can lead to erosion. Nutrient-rich soil that retains water well is less prone to erosion, while dry, fine soil lends itself more readily to erosion. Patches of soil that have already experienced erosion are usually more vulnerable to additional erosion since they are less able to resist runoff and wind.

Human Action

• The actions of human beings contribute greatly to soil erosion and its attendant impact on the environment. Poor farming methods, over-tilling of the soil, the use of caustic pesticides and a high intensity of crop concentrations all result in soil erosion. In addition, less direct activities such as deforestation and mining can create eroded soil, as can home construction and overgrazing from domesticated animals such as sheep and cattle.

Vegetation

• The presence of vegetation on a given patch of land helps it resist soil erosion. Plants that provide a lot of surface cover help protect the soil from rain and wind, while root systems help the soil retain cohesion in the midst of heavy rains. A tree line or shrub line can stave off wind erosion as well. Stretches of land without vegetation are more vulnerable to the environment, and thus more susceptible to erosion.

Landforms

• The shape and gradient of the land can contribute to soil erosion. The steeper the slope, the more easily water and wind can carry the topsoil away. Also, gravity exerts a greater pull over soil along a steep slope. Flatter slopes may be more vulnerable to wind shear, but being flatter reduces the effects of gravity on soil erosion. Slopes and hillsides can become more vulnerable to erosion through human construction along their length or at their base.