Salt-Affected Soils: Their Reclamation and Management for Crop Production

Abstract

Agricultural production in the arid and semiarid regions of the world is limited by poor water resources, limited rainfall, and the detrimental effects associated with an excess of soluble salts, constrained to a localized area or sometimes extending over the whole of the basin. In order to minimize vagaries of arid weather, bring more land under irrigation, and produce and stabilize greater yields per unit area, numerous water development projects have been commissioned all over the world. Extension of irrigation to the arid regions, however, usually had led to an increase in the area affected by shallow water tables and to intensifying and expanding the hazards of salinity. This is because irrigation water brings in additional salts and releases immobilized salts in the soil through mineral dissolution and weathering, and losing water volumes through evapotranspiration and concentrating the dissolved salts in soil solution. Fertilizers and decaying organic matter also serve as additional salt sources. Atmospheric salt depositions, though varying with location, may be an important source along the coasts. The relative significance of each source in contributing soluble salts depends on the natural drainage conditions, soil properties, water quality, soil water, and agronomic management practices followed for crop production.