Land degradation is a process in which the value of the biophysical environment is affected by one or more combination of human-induced processes acting on the land. It is also the gradual destruction or reduction of the quality and quantity of human activities, animal activities or natural means. It is viewed as any change or disturbance to the land perceived to be deleterious or unwanted. Natural hazards are not included in the causes; however, human activities can indirectly affect phenomena such as bush fires and floods.
Various causes include land clearance, agricultural depletion of soil nutrients through poor farming practices, livestock including overgrazing and overdrafting, inappropriate irrigation, urban sprawl and commercial development, soil contamination including vehicle off-roading, quarrying of stone, ore, minerals and sand, increase in field size, exposure of naked soil, monoculture, and dumping of non-biodegradable trash.
The main outcome of land degradation is a considerable decrease in the productivity of the land. The major pressures on vulnerable land include accelerated soil erosion by wind and water, soil acidification and the creation of acid sulfate soil resulting in barren soil, soil alkalinisation owing to irrigation with water holding sodium bicarbonate leading to poor soil structure and reduced crop yields, soil salination in irrigated land that requires soil salinity control to reclaim the land, soil water logging in irrigated land which calls for some type of subsurface land drainage to remediate the negative effects, and destruction of soil structure including some loss of organic matter.