Soil retrogression and degradation

Soil retrogression and degradation are two regressive evolution processes associated with the loss of equilibrium of a stable soil. Retrogression is primarily due to soil erosion and corresponds to a phenomenon where succession reverts the land to its natural physical state. Degradation is an evolution, different from natural evolution, related to the local climate and vegetation.^[1] It is due to the replacement of primary plant communities (known as climax vegetation) by the secondary communities. This replacement modifies the humus composition and amount, and affects the formation of the soil. It is directly related to human activity. Soil degradation may also be viewed as any change or ecological disturbance to the soil perceived to be deleterious or undesirable.^[2]

According to the Center for Development Research at the University of Bonn and the International Food Policy Research Institute in Washington, the quality of 33% of pastureland, 25% of arable land and 23% of forests has deteriorated globally over the last 30 years. 3.2 billion people are dependent on this land.^[3]