Natural Causes of Soil Erosion

Water

• Soil erosion is the loss of soil particles due to natural forces such as wind and water. Water flow is the number one cause of soil erosion in many areas of the United States. It occurs when rainfall exceeds the amount that that soil can absorb, leading to soil-surface runoff, according to Iowa State University agronomist Mahdi Al-Kaisi. This not only causes lower soil productivity, but the sediment eventually deposited in other areas like waterways can lead to poor water quality and disruption of the local ecology.

Wind

• In some areas of the world, wind forces can also cause serious soil erosion problems. Winds above 13 miles per hour at one foot above the ground can cause detectable erosion in soils, according to Colorado State University agronomists T.A. James. Wind moves the soil in three ways, by lifting individual particles off the surface, by dislodging them and making them airborne, and by moving sand-sized particles across the surface.

Wildfire

• Those areas of the world prone to wildfires can experience a different kind of erosion from this natural event. The intense heat from the fire forms a gas that can permeate the surface of the soil and make it hydrophobic, that is, it then resists absorbing rainwater. This increases the amount of runoff that dislodges soil particles. Soils with a thick layer of litter or coarse-textured soils are most prone to this problem. Freezing, thawing and the activity of animals helps to break up this hydrophobic layer.

Preventing Soil Erosion

• Planting cover crops is the best way to prevent soil erosion on bare areas. Plants that creep and spread are better for this purpose than upright plants. Planting windbreak trees or erecting structures helps to control wind erosion on crop producing land. Mounding earth in ridges or mounds can also help to limit damage to the soil. Soil that has been damaged by wildfire should be quickly re-seeded by breaking through the hydrophobic layer. Mulching will help to secure the new seed in the ground and prevent further loss from wind and rain.