Soil erosion is the loss of the top layers of soil by the action of water, wind, plants, animals, snow, and humans. It is to some extent a natural process in which the soil that is slowly lost is gradually replaced with new soil created by geological and biological activity. However, human activity has greatly intensified soil erosion, with estimates ranging from ten to 50 times the natural rate, and on much of the world’s most productive agricultural land and nearly half of the best topsoil has been lost over the past 150 years.
Human activities that have contributed to this massive soil loss include deforestation, intensive agriculture, road construction, urban sprawl and human-caused climate change.