ABSTRACT
Salinization is a process that results in an increased concentration of salts in soil and water. Of these salts, sodium chloride is the most common. With an increase in concentration of soluble salts, it becomes more difcult for plants to extract water from the soil. Higher salt concentrations can be created by poor soil drainage, improper irrigation, irrigation water with high levels of salts, and excessive use of manure or compost as fertilizer. Salinization affects many irrigated areas mainly due to the use of brackish water. Salt-affected soils cover about 800 million ha of land, which accounts for more than 6% of the total land area in the world. There are two kinds of soil salinity, namely primary (natural) and secondary (due to human activity, i.e., dry land and irrigated land salinity). A majority of saline soils have emerged due to natural causes such as accumulation of salts over long periods of time in arid and semiarid zones (Munns and Tester 2008). This is because of the fact that the parent rock from which it formed contains salts, mainly chlorides of sodium, calcium, and magnesium, and to some extent, also contains sulfates and carbonates. Sea water is another source of salts in low-lying areas along the coast. Besides natural salinity, a signicant proportion of cultivated land has become saline due to land clearing or irrigation.
