One heavy rain on a sloping field that has just been tilled can remove the equivalent of 50 tons of topsoil per acre. In just a matter of minutes, the work of hundreds of years of natural soil formation can be totally wiped out. That land's productivity would not likely be restored within the life span of anyone living at the time.
Topsoil lost by erosion is not only a loss to the land owner; it also creates problems where it is deposited. It covers crops in low areas, fills road ditches, clogs drains and covers roads. It muddies streams and leaves a slimy layer of silt on the stream bed. Gravel beds and rocks which serve as habitat for many of the water-dwelling organisms are covered with mud and the habitats destroyed.
Rasnake, Monroe, "Tillage and Crop Residue Management" (1983). Agriculture and Natural Resources Publications. Paper 28.