ABSTRACT
Soil degradation is a problem that has faced mankind for millennia. For many years, local assessments on a large scale have been used as an aid to farmers and land managers trying to ensure productivity and profitability of their soils. Parametric methods and simulation modeling offer the most promise for extrapolating knowledge of rates and processes of soil degradation to broad areas. The most direct extrapolation in assessments of soil degradation is the extrapolation of process descriptions and parameter values derived from small field plots or laboratory experiments to fields and small catchments. The most common source of soil data for degradation assessments is a soil survey. The scale of the assessment or size of area to be assessed must be considered when selecting a model for simulations of soil degradation.
