Solubility enhancement: a potent tool for gypsum dose reduction in sodic soil reclamation

Gypsum which provides readily available source of Ca2+ ions to replace Na+ ions from the cation exchange complex of soil has been used as a common chemical amendment in the reclamation of sodic soil. As a non-renewable resource in nature, its dwindling scenario has now become imperative to find either an alternate sources of gypsum or to increase the efficacy of gypsum to reduce its dose in the reclamation of such sodic soils. The present study was undertaken with the aim to enhance the solubility of gypsum using different chemical formulations both in laboratory and pot culture experiment. It was observed that the addition of KNO3, NH4NO3 and NaCl to gypsum, increased the Ca2+ ion to 39.73 %, 60.59 % and 68.05 %, respectively. The maximum increase in the Ca2+ content was noticed in gypsum saturated solution containing NH4NO3 + citric acid and NaCl + citric acid combination which was 94.53 % and 91.22 %, respectively. The increase of Ca2+ ion due to the increased dissolution of gypsum resulted in saving of 75% and 50% of its doses in the reclamation of sodic soil when compared with the quantity required under normal existing reclamation process (50 GR).