Salinization of soil involves the processes of salt accumulation in the upper rooting zone so that many plants are inhibited or prohibited from normal growth. Salinization occurs primarily in the semi-arid and arid portions of the earth. Salinization is commonly thought to occur only in the hot climatic regions, but may be found in cooler to cold portions of the earth where precipitation is very limited. Where the annual precipitation exceeds about 20 inches (500 mm), there is usually adequate downward movement of salts through leaching to prohibit the development of saline soil. Occasionally salinization of soil will occur where there has been an inundation of land by sea water. Some areas of the world were once under sea water, but due to uplift the land is now many feet above sea level. These lands are common sources of "ancient salts" and may lead to the...