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ABSTRACT Biological, chemical and bio‐chemical strategies have been tested in the past for reclamation of saline‐sodic and sodic soils. The efficiency of two crop rotations (rice‐wheat and Sesbania ‐wheat) alone or in combination with either gypsum (CaSO 4 .2H 2 O) or sulfuric acid (H 2 SO 4 ) was tested for ionic displacement from four saline‐sodic soils. Pure gypsum was applied at 50 per cent of soil gypsum requirement at the time of planting rice and Sesbania , whereas 95 per cent pure sulfuric acid was added at 50 per cent soil gypsum requirement as one‐third applications by mixing with the first three irrigations. The rice crop biomass decreased at a soil saturation extract electrical conductivity (EC e ) of 8 dS m −1 , whereas wheat and Sesbania were influenced at a sodium adsorption ratio (SAR) of ≥40. Gypsum treatment helped the crops flourish well at these EC e and SAR levels. The infiltrated volume of water dropped with decrease in EC e : SAR ratio of soils and increase in crop biomass production. Crops rotation treatments alone helped leach sodium (Na + ) and other ions successfully at SAR ≤ 21 but were less effective at SAR ≥ 40 at which point plants growth was also curtailed. Gypsum and H 2 SO 4 treatments significantly aided leaching of Na + and other ions with water at SAR ≥ 40 under both the crop rotations. Hence, crops effectively reclaimed soil at low sodicity level, whereas at high SAR, chemical amendments are obligatory in order to reclaim soils. This study also suggests that the required dose of H 2 SO 4 should be applied with pre‐planting irrigation for better yield of the first crop. Copyright © 2011 John Wiley & Sons, Ltd.
Ahmad et al. (Wed,) studied this question.