Incorporation of Sulphur, Nitrogen and Carbon into Soil Organic Matter Following incubation

Incubation of two chernozemic soils (Haploborolls) for nine months resulted in the net immobilization of inorganic sulphate while during the same period, there was appreciable mineralization of nitrogen. Monthly additions of cellulose and nitrogen increased the organic carbon, organic nitrogen and organic sulphur in the Oxbow Black and Bradwell Dark Brown soils. Fractionation of soils before and after incubation, by 0.1 M NaOH-0.1 M Na₄P₂O₇ extraction-separation technique, showed significant differences in the distribution of incorporated sulphur compared to carbon and nitrogen. The results indicated that sulphur followed different pathways than the other two elements in humus formation or transformation and also supported the earlier hypothesis that fulvic acid is a biologically active, labile and transitory storehouse of organically bound nutrients.