The more people that are migrating to urban areas (urbanization) needs more crops for the citizens which causes more people to grow crops and without crop rotating or methods to prevent soil degradation. More likely answer is that more industry grows in the urbanized areas and they have poor management of the soil which causes soil degradation<span />
In this case it's overexploitation of natural resources, wich is a big problem nowadays. Using resources excessively results in damaged resources, that's called overexploitation.
