Soil erosion is a major concern in many areas as coastlines or shores along rivers get closer and closer to dwellings or important lands. Soil erosion may also threaten structures, destroy crops or make land unsuitable for some uses. Soil erosion takes place over long periods of time in most cases and it can be caused by a variety of factors. There are five major factors that affect the pace and extent of soil erosion in a given area.
Rainfall is a major contributor to soil erosion. According to the Iowa State University Extension website, during a normal rainfall millions of raindrops ranging from 1 to 7 mm in size will pound the surface and splash soil particles 3 to 5 feet away from where they were before the rain. During heavy downpours the soil movement can equal 90 tons of soil per acre. While much of it doesn't splash out of the area it was already in, it does compact the soil and makes it drain more poorly. This increases the effects of runoff on soil erosion.
Type of Soil
The type of soil in question is a factor in how erosion takes place. Some spoils are simply more apt to erode quickly than others. Soils with a lot of silt content tend to erode the most, while heavy clay soils tend to be the least erosive.
Just as the impact of rain and the runoff of water will affect the rate of erosion of soil, the slope of the land also affects the movement of the water and the soil. Water runs more quickly, having a greater eroding impact on the soil on a steep slope whereas water on a flat surface only sees pooling water. The gravity pulls on soil on a slope as well, making it easier to move.
Vegetation is a major factor in controlling erosion of the soil. Crops, forests or other plant life can reduce erosion in several ways. The foliage of the plants intercepts much of the rainfall, reducing the high-speed impact of the raindrops. They also absorb some of the water. The roots of the plants help the water drain through the soil easier and also act as anchors to keep the soil in place instead of washing away.
A man-made erosion factor has to do with the way a farmer manages his land. If a farmer plants crops using a cross-slope planting method in which he plants rows perpendicular to the slope of the land, then he can help control erosion. Not managing the farm using these or other erosion prevention methods will contribute to accelerated erosion of the soil.