Dynamics of Sulphur Fractions in a Calcareous Vertic Haplustepts Under AICRP-LTFE Soils

In case of sulphur status of LTFE soils, FYM played a vital role. It maintained availability of sulphur in soils, but more increment after a long run was observed in T₁₁, where P source was SSP which contains 13% S. Total-S content of LTFE soils increased after a span of 8 years, but it was reversed in case of heat soluble-S, that was decreased after 8 years, except in treatments which received FYM and inorganic-P as a SSP (13% S). It was required to apply S fertilization every year and application of FYM for maintaining available status of soils at long run. Water soluble fraction of sulphur declined very much after 8 years of groundnut-wheat cropping sequence as compared to initial status, but it remained stable in treatments T₄ and T₁₁ which received sulphur from outside sources like ZnSO₄ and SSP. Whereas organic-S status of LTFE soils increased after a span of 8 years, it might be due to incorporation of plant residues to the soils from crop ischolar_mains and stubbles. Sulphate-S in LTFE soils increased after 4^th year and then remained stable except in T₂ and T₃ where depletion in this fraction was noticed perhaps due to the interaction with phosphorus. Non-sulphate-S fraction found significantly the highest in the treatments which received sulphur from outside as ZnSO₄ and SSP (T₄ and T₁₁). In case of heat soluble-S, there was overall decrease in soil status after 4^th year as compared to initial status and after word it maintained level with initial status, but in treatments of FYM and SSP it was increased as compared to initial status after 8^th year of experiment. Whereas total-S status of LTFE soil increased after a span of 8 years. The increment was more in treatments which were received sulphur from fertilizer sources i.e. T₄ and T₁₁. It was required to apply S fertilization every year and application of FYM for maintaining available status of soils at long run. Depletion per cent of sulphur noted positive in case of water soluble-S and it was negative or very low in treatments which received sulphur from fertilizers i. e. T₁₁ and T₄. Most of the other fractions of sulphur were not depleted in most of the treatments.