In many regions salinity control can be a major issue. Salinity in the soil is the measure of salt in your soil. Sodium chloride or table salt is the most common salt overtaking soil.
Over salted soils are an issue in lands that have been irrigated over a long period of time. This tends to happen in arid and semi-arid regions the most.
Lack of precipitation and natural water infusion forces people to manually water their crops and those waters, generally from rivers and groundwater, have a higher salt content.