A long-term field experiment on the transformations of carbon under different nutrient management practices and cropping systems in Vertisol (Typic Haplustert) of Northern Transition Zone of Karnataka was initiated during 2004-05 at the Institute of Organic Farming, Main Agricultural Research Station Farm, UAS, Dharwad. Hundred per cent organic nutrient management practice recorded statistically higher organic and total carbon (TC) at surface (6.7 and 20.6 g/kg, respectively) and subsurface (4.8 and 15.3 g/kg, respectively) than inorganic, integrated and RDF+FYM. Similarly, water-soluble carbon (WSC) and labile carbon (LC) contents were significantly higher in 100 per cent organic nutrient management practice both at surface (56.7 and 960.5 mg/kg, respectively) and subsurface (42.3 and 818.5 mg/kg, respectively) soil layers than other nutrient management practices. Noticeable improvement was seen in all the forms of carbon content in the soil under organic nutrient management practice.