Department of Soil Science and Agricultural Chemistry, Orissa University of Agriculture and Technology, Bhubaneswar, Orissa, 751003.
1Present address: Orissa University of Agriculture and Technology, Krishi Vigyan Kendra, Kalahandi, Orissa.
Sulphate release characteristics of the surface soils and subsoils of five Alfisols of Orissa were studied by repeated extractions with 0.016 M KCl and 0.016 M KH2PO4. The amount of SO42−-S extracted by both the extractants was maximum in the 1st extraction with a drastic reduction in the 2nd extraction and slow decrease after the 3rd extraction. Total KH2PO4 extractable SO42−-S (total KH2PO4-SO42−) was higher in the subsoils than in the surface soils except in Mahisapat. Both total KCl extractable SO42−-S (total KCl- SO42− and total KH2PO4-SO42− were positively correlated with clay, exchangeable Ca2++Mg2+ and Fe2O3 of free, crystalline and amorphous forms. Positive correlation existed between total KCl – SO42− and total KH2PO4-SO42− (r = 0.91**). Clay, exchangeable Ca2++Mg2+, free Fe2O3, free Al2O3, pHw and organic carbon combinedly accounted for 92.5% of variations in total KCl – SO42− and 99.6% of variations in total KH2PO4-SO42−.
Alfisols, 0.016 M KCl extractable SO42− – S, 0.016 M KH2PO4 extractable SO42−–S
