Extractability and availability index of sulphur in selected soils of Odisha

Abstract

We aimed to evaluate the extractability of two reagents viz.0.15% CaCl2 & 0.01M Ca (H2PO4) for sulphur along with the sulphur availability index of mixed red and black soils. For this 86 soil samples were collected from mixed red and black soil regions and extracted with these solutions. Results showed that both these solutions ex-tracted nearly similar amount of sulphur in black soils while the Ca phosphate solution extracted higher amount (13.9mgkg-1) compared to Ca chloride solution (11.5mgkg-1) in red soil regions. Considering all the 86 soil samples tested, there was an excellent correlation between the extractable sulphur, the highest correlation being reported from black soils (R2= 0.97). Sulphur availability index was found to be higher in black soils (mean 6.6) compared to red soils (mean 5.1). Also the content of adsorbed sulphur was found to be high in red soils (2.4mgkg-1) compared to black soils (1.5mgkg-1). Correlation matrix and regression equations (Ca phosphate S= 5.00+ 0.77 Ca chloride S) were worked out between the extractable sulphur and soil properties to justify the results.