section_path: Environmental issues/Soil degradation
section_name: Soil degradation
paragraph_text: Soil degradation
  
  Human land use can cause soil to degrade, both in quality and in quantity. Soil degradation can be caused by agrochemicals (such as fertilizers, pesticides, and herbicides), infrastructure development, and mining among other activities. There are several different processes that lead to soil degradation. Physical processes, such as erosion, sealing, and crusting, lead to the structural breakdown of the soil. This means water cannot penetrate the soil surface, causing surface runoff. Chemical processes, such as salinization, acidification, and toxication, lead to chemical imbalances in the soil. Salinization in particular is detrimental, as it makes land less productive for agriculture and affects at least 20% of all irrigated lands. Deliberate disruption of soil in the form of tillage can also alter biological processes in the soil, which leads to excessive mineralization and the loss of nutrients.
  
  Desertification is a type of land degradation in drylands in which fertile areas become increasingly arid as a result of natural processes or human activities, resulting in loss of biological productivity. This spread of arid areas can be influenced by a variety of human factors, such as deforestation, improper land management, overgrazing, anthropogenic climate change, and overexploitation of soil. Throughout geological history, desertification has occurred naturally, though in recent times it is greatly accelerated by human activity.