ABSTRACT
An excess amount of salts in soil adversely affects plant growth and development. Nearly 20% of the world’s cultivated area and nearly half of the world’s irrigated lands are affected by salinity [1]. Salinity stress threatens agricultural productivity in 77 million hectares of agricultural land, 45 million hectares of which (20% of irrigated area) are irrigated and 32 million hectares (2.1% of dry land) are unirrigated land [2]. Salinization is further spreading in irrigated land due to improper management of irrigation and drainage. Rain, tornadoes, and wind also add salts to coastal agricultural land. Soil salinity often leads to development of other problem soils such as soil sodicity and alkalinity. Soil sodicity is the result of binding of Na
to negatively charged clay particles leading to clay swelling and clay dispersal. Hydrolysis of the Na-clay complex results in soil alkalinity. The USDA Salinity Laboratory standards define a saline soil as a soil having the electrical conductivity of a saturated paste extract (EC
) of 4 deci Siemens per meter (dS m
) or more. High concentrations of soluble salts such as chlorides of sodium, calcium, and magnesium contribute to the high electrical conductivity of saline soils. NaCl contributes most of the soluble salts in saline soils.
