Crop Response in Salt-Affected Soils

ABSTRACT Salt-affected soils, those on which plant growth is limited by an excess of salts, are of three types: (i) saline soils in which electrical conductivity is > 4 dSm−1; (ii) sodic soils in which the exchangeable sodium percentage (ESP) is > 15; and (iii) saline-sodic in which the electrical conductivity (EC) is > 4 dSm−1 and ESP is > 15. Salt-affected soils are most common in aridic moisture regimes, and secondary salinization (due to anthropogenic activities such as irrigation) may occur by improper management of irrigation. Estimates of the area of salt-affected soils vary widely, ranging from 6% to 10% of earth's land area, and 77 million hectares (Mha) of irrigated lands. Crop yields are drastically affected due to lack of availability of water, nutrients, and oxygen in the root zone. The magnitude of yield reduction depends on the crop, soil type, and management. The reduction in yield normally ranges from 10% to 90% for wheat, 30% to 50% for rice, 50% to 75% for cotton, and 30% to 90% for sugarcane. Crop yield can be enhanced by nutrient management (especially N), water management (irrigation with good quality water and appropriate drainage), use of soil amendments (manures and gypsum, etc.), and use of salt-tolerant varieties.