Characterization and identification of elemental sulphur, iron pyrite, mineral gypsum, phospho gypsum and marine gypsum using SEM-EDAX

India has 6.73 million ha of salt-affected soils, of which 3.77 million ha is sodic soil. Sodicity is a serious issue in agriculture, and it prevents to meet the properties of fertile soil. Sodicity alters its physical and chemical properties, including soil structure and hydraulic conductivity. High exchangeable sodium and pH decrease soil permeability, available water capacity and infiltration rates through swelling and dispersion of clays as well as slaking of soil aggregates. Gypsum is one of the sources used for sodic soil reclamation, and the cheaper and alternative source is marine gypsum which is recovered from salt pans during production of common salt in coastal region, particularly in Gujarat and Tamil Nadu. The recovery of by-product gypsum and marine gypsum together is substantial and is comparable with the production of mineral gypsum.The amendments generally used for sodic soil reclamation should be a source of sulphates such as elemental sulphur, iron pyrite, mineral gypsum, phospho gypsum and marine gypsum. Characterization of sources by SEM–EDAX is rapid and elementary. The elemental composition revealed by the spectra of the bentonite sulphur for weight percentage and atomic percentage of sulphur is quantified as 34.04% and 18.59%, respectively, in the ZAF matrix. In iron pyrite spectra the weight percentage and atomic percentage of sulphur are 4.89% and 2.31%,respectively, in the ZAF matrix, while in mineral gypsum, the calcium weight percentage is 10.14% and atomic percentage is 04.04% while sulphur weight percentage is 6.52%, atomic percentage is 3.50%. The calcium composition in phosphogypsum is weight percentage is 14.69%; Atomic percentage is 34%, and the sulphur composition in phosphogypsum is weight percentage 10.40%, atomic percentage 5.60%, whereas in marine gypsum the calcium (weight percentage 09.10%, atomic percentage 03.58%) and sulphur (weight percentage 06.28%, atomic percentage 03.09%) proportions dominate as like two other above-mentioned gypsums, the element which makes difference in the marine gypsum from others is sodium (Weight percentage 00.18%, atomic percentage 00.12%). This helps to confirm that marine gypsum is an economic and alternate source available for sodic soil reclamation.