The accumulation of unusually high concentrations of dissolved sulphates and chlorides of sodium and calcium, often as a result of large-scale irrigation in semi-arid areas; as irrigation water is evaporated or transpired, the salt ions are largely left behind to accumulate in the soil (Saysel and Barlas (2001) Ecol. Model. 139, 2–3). Salinization can reduce plant growth rate and yield, and, in severe cases, cause total crop failure. In certain circumstances, excessive salinity in soils cannot be reduced over time by routine irrigation and crop management practices (Qadir et al. (2000) Land Degrad. & Dev. 11).
In coastal areas, salinization can be associated with the over-extraction of groundwater, which can lower the water table and lead to the invasion of sea water (Cardonna et al. (2004) Env. Geol. 45, 3). Tsunamis can cause severe salinization problems.
http://eusoils.jrc.ec.europa.eu/library/themes/Salinization/ European Land Management and Natural Hazards Unit on soil salinization.