Suitability of extractants and response of linseed to sulphur in Vertisols of Madhya Pradesh

A greenhouse study was conducted with twenty Vertisols varying in available sulphur status during 2008–09 and 2009–10 at Jabalpur (Madhya Pradesh), India to assess the suitability of extractants for establishing critical limit of available soil sulphur and response of linseed to sulphur application. All the deficient soils (soils below 10.5 mg kg⁻¹ in 0.15% CaCl₂) responded to sulphur application, while in the sufficient categoryonly 10% soils responded to sulphur application. The critical limit in soil by different extractants, viz. 0.15% CaCl₂.2H₂O, Morgan's reagent, 1% NaCl, and KH₂PO₄ were 10.5, 10.2, 11.2 and 7.0 mg kg⁻¹ for linseed, respectively. The critical level of sulphur in linseed grain was 2.15 g kg-¹. The available sulphur extracted by 0.15% CaCl₂.2H₂O (r=0.848) and Morgan's reagents (r=0.81) showed significant positive correlation with Bray's per cent yield. The degree of suitability of extractants for available sulphur to linseed crop was in the order of 0.15% CaCl₂.2H₂O> Morgan's reagent >1% NaCl >KH₂PO₄.