The development of soil conservation strategies requires knowledge of actual and acceptable rates of soil erosion.
It reveals that the intensification of farming over the past century has increased the rate of soil erosion sixtyfold.
With low rainfall and high rates of soil erosion, the Atlas Mountains are fairly sparsely vegetated.
A primary benefit of the protection and minimal disturbance of topsoil is a decreased rate of soil erosion.
This conclusion is borne out by careful field studies worldwide in which the rate of soil horizon formation is determined.
Broad variation is the rule, but rates of soil loss exceeding 10 metric tons per hectare annually signal accelerated erosion.
According to the UN food and agriculture organisation, at current rates of soil loss we have 60 years of harvests left.
This quantity is defined as the maximum annual rate of soil loss by erosion that will permit high soil productivity for an indefinite period of time.
When climate and topography are fixed and soil cover is varied, the rate of soil loss by water erosion has a predictable and dramatic dependence on vegetation.
The continual ploughing of fields, combined with heavy use of fertilizers, has degraded soils across the world, the research found, with erosion occurring at a pace of up to 100 times greater than the rate of soil formation.
