Shifting cultivation - Degradation of Ecosystem
This method of cultivation is practised all over the globe, but is more prevalent in the tropical countries. In this practice a patch of land is cleared, vegetation is burned and the ash is mixed with the soil thus adding nutrients to the soil.
This patch of land is used for raising crops for two to three years, and the yield is modest. Then this area is abandoned and is left to recover its fertility, and the same practice is repeated elsewhere on a fresh piece of land.