Answer: farming, overgrazing, population growth
Desertification is a process that occurs naturally or by human induce causes, the water body of the region gets dried up and the region acquires desert like conditions such as soil looses it's moisture and becomes compact, limited vegetation cover and dry climate.
Farming is the agricultural practice which involves the growth of commercially valuable crops. The excess use of land for agricultural purpose can result in the loss of the minerals and organic matter necessary for growth of plants. The land will loose it's fertility and will become barren land. The barren land will acquire desert like conditions.
Overgrazing can be responsible for desertification, as the herbivorous animals sometimes consume plants down the ground, which means they consume entire plant along with the roots. The soil gets loosen and eroded by wind. This way soil looses it's fertility and no more plants can be grown on such soils. This results in desertification.
Increase in population will result in increase in demand of water. This may result in depletion of water body for human use. Hence, population growth may lead to desertification.
