ABSTRACT
Soil is a dynamic surface material in which complex biological, chemical and physical activities take place. Substances in solid, liquid and gaseous forms are found in the soil. Soil erosion is a physical phenomenon of the soil surface which has economic affects, both on upstream soil quality and on amounts of waterway sediment. Water erosion has been classified in many different ways. The following four classifications are used: Sheet erosion, rill erosion, gully erosion and stream bank erosion. Economic analysis of soil erosion programs often begins with the establishment of some notion of productivity, commonly crop yields. Erosion alters the characteristics of soils as a medium for plant growth by changing productive capacity. Erosion also affects soil structure by creating areas of surface seal, or crusting -- the nonuniformity makes farming more difficult. The rate of natural erosion under undisturbed natural vegetation will be approximately the rate of soil formation, thus providing an overall soil balance.
