Effect of sodic irrigation and gypsum on the reclamation of sodic soil and growth of rice and wheat plants

Abstract

Effect of gypsum and sodic irrigation on the precipitation of Ca and removal of Na from a sodic soil reclaimed with different levels of gypsum (33, 67 and 100% of the total gypsum requirement of the soil) and growth of rice was investigated in a greenhouse experiment. Precipitation of Ca and carbonates and soil Na saturation increased with increase in sodicity of irrigation water. Application of gypsum for initial sodic soil reclamation or at each irrigation (G ei) during growth of rice and wheat increased the removal of Na from the soil and decreased exchangeable sodium percentage (ESP) and pH. Under sodic irrigation treatments, even the high levels of gypsum applied for initial sodic soil reclamation did not control the build-up of ESP to below the levels at which rice and wheat could produce normal growth. But under G ei treatments, soil pH and ESP values observed under sodic irrigation treatments were similar to those recorded under good water irrigation. When sodic irrigation water has to be used for reclamation of sodic soils, additional gypsum (more than was used for initial reclamation) should be applied to decrease SAR and alkalinity of water and control the build up of Na in soil and improve crop production.