What Are the Causes of Soil Erosion Besides Grazing?

Water

• When rainwater hits dry soil at speeds up to 30 mph, it loosens the soil so that it becomes airborne. On sloped land, rainwater pushes the soil downhill, eroding the soil and its underlying structure. When soil erodes in thin layers, the process is referred to as sheet erosion. However, soil rarely erodes this uniformly.

  Rill erosion occurs when water passes through areas where surface water from streamlets collects instead of percolating into the land. Water loosens the soil, pulling it away from the land and causing erosion. Typically, rills are located between crop rows. While its consequences can be neutralized through tillage, rill erosion is often ignored and it continues to be the most common type of erosion.

  Gully erosion occurs when rills expand in size so that vehicles cannot access them. Once they become gullies, they cannot be repaired through tillage. Because of their size, gullies are capable of hosting large quantities of water that move at faster speeds, displacing more soil than rill and sheet erosion.

Wind

• Wind erosion occurs when high-speed winds displace particles of soil. It is most common to areas that are flat and dry, like deserts, but also affects soil along water bodies. Suspension occurs when the smallest particles of soil detach from land and become airborne, resulting in sandstorms. Saltation occurs when wind pushes particles of soil into an erratic, bouncing fashion. Soil creep occurs when wind pushes larger particles of soil by rolling them away from land. These methods of wind erosion divide particles according to size, displacing finer particles and leaving behind soil that is heavy, coarse and potentially infertile. Eventually, wind erosion strips away the surface layer, exposing the subsoil.

Gravity

• Gravitical erosion occurs when the land mass cannot support the weight of the surface material. As a result, the surface layer separates from the land mass beneath it. Mass movement refers to soil erosion from gravity. Earthflows occur when masses of soil liquefy and run downhill. Slumps and landslips occur when subsoil cannot rotate. Rock structures collapse, causing rock avalanches. Soil creeps occur when soil particles gradually roll downhill.

Freezing and Melting

• Some areas of the world, including the Arctic, experience periods of extreme freezing and melting. During warmer months, water seeps into land and rocks. During colder months, that water freezes and expands. The water increases in size and density with such strength that it can cause breakage. As a result, pieces of land and rocks break away from the original land mass, stripping the soil away over time. This process occurs frequently in snowcapped mountains, breaking up the land into steep cliffs.