In the United States, we use our soil intensively to grow crops. Our fertile soil has played an important role in America’s history and contributed much to our prosperity. But, in agriculture and many other ways that our land is used, we have not treated our soil resources with the care needed to make sure the soil stays productive.

Historically, land was considered a limitless resource in the U.S. and many other countries. Settlers cleared patches of forests for small farms, then moved on when the land became barren from overuse. In the 1800s, settlers moved westward., setting up homesteads and farms. The rich prairie soil seemed inexhaustible, able to support huge fields of crops and herds of cattle and sheep. Few people saw the importance of soil conservation, and the consequently tremendous amounts of soil that were lost to erosion.

Erosion, what is it? It is the loosening of and movement of soil by wind, moving water, ice, and landslides. Without human activities, losses of soil through erosion would in most areas probably be balanced by the formation of new soil. On virgin land the soil is protected by a mantle of vegetation. When rain falls on a surface of grass or on the leaves of trees, some of the moisture evaporates before it can reach the ground. Trees and grass serve as windbreaks, and a network of roots helps to hold the soil in place against the action of both rain and wind. Agriculture and lumbering, as well as housing, industrial development, and highway construction, however, partially or wholly destroy the protective canopy of vegetation and greatly speed up erosion of certain kinds of soils. Erosion is less severe with crops such as wheat, which cover the ground evenly, than with crops such as corn and tobacco, grown in rows.

Overgrazing, which in time can change grassland to desert, and careless cultivation have had disastrous effects in certain parts of the U.S. Some historians believe that soil erosion has been a determinant in the complex of causes underlying various population shifts and the fall of certain civilizations. Ruins of towns and cities have been found in arid regions such as the deserts of Mesopotamia, indicating that agriculture was once widespread in the surrounding territory.

There are many different types of erosion. One type is sheet erosion. Sheet erosion is a type of erosion that gradually wears away thin, uniform layers of soil. Rill erosion is another type. This type is the removal of soil on slopes where water runoff and soil accumulates into small channels. Another type of erosion is splash erosion. In splash erosion, raindrops break the bonds between soil particles and splash them a short distance. These particles are much more vulnerable to erosion by water flowing over the surface. Concentrated flow erosion is erosion by water flowing in channels that may range from a large rill to a small gully. Rills are erased by tillage, but channels eroded by concentrated flow tend to reform in the same location each year. If allowed to continue, erocsion by concentrated flow can form a gully. Mass erosion is another type of erosion. It is a form of erosion in which a hillside becomes so saturated with water that large areas of soil slide or creep downhill. Gullies can be formed rapidly in these slide areas.

Preventing Erosion
Terracing is a grass waterway to prevent erosion. A grassed waterway is an ideal way to prevent erosion. A grassed waterway is a waterway made out of grass. The roots of the grass holds the soil particles in place. Contour farming is also good for preventing erosion. In contour plowing, you plant crops around a hill instead of up and up and down a hill. Some people may leave crop residue on top of the soil. This layer is like a coat that protects the soil. As I told you, grass holds the soil, but overgrazing can cause the grass to be eaten away, along with the roots which hold the soil.