Explanation:

The wearing away of the fertile top layer of soil is termed soil erosion. Although there are various natural factors like wind, water, and climate etc. that causes soil erosion; certain activities by the humans like agriculture related over-cropping, over-manuring, over-grazing and deforestation for the need of urbanization leads to soil erosion. Afforestation or planting of trees in areas that are devoid of trees is a major human activity that helps in soil conservation. This is done mainly to conserve the soil in the areas of afforestation as tree roots help to hold the topsoil firmly and thus preventing from erosion.