Soil loss tolerance limits: an environmental management tool

Soil loss tolerance is defined as the maximum acceptable level of soil loss from an area which will allow a high level of productivity to be maintained. Furthermore the criteria which determines soil loss tolerance limits are discussed, and two methods currently in use in Southern Africa, i.e. those proposed by the Department of Agricultural Technical Services (DATS) and Skidmore are discussed. It is concluded that for various reasons the latter approach is more acceptable, and that it is imperative that a different T-value be determined for each soil series.Application of the principle of soil loss tolerance in the Tugela River Basin reveals that various areas are subjected to severe stress. Maps indicating areas with soil loss of more than 10 t/ha/yr; areas with a soil loss higher than its allocated soil loss tolerance limits; and soil loss as a percentage of its T-values are included. These maps reveal startling facts, and emphasize the need for swift action in order to combat the problem of soil erosion in the area.The conclusion is drawn that the technique by which soil loss tolerance limits are determied could be applied to large areas, and its representation on large scale maps could be very useful in environmental planning and management.