The CSE was highest in 150% NPK treatment, while 100% NPK+FYM showed the lowest CSE. By applying the values of humification constant (h) and decay constant (k) in Jenkinson's equation, it is possible to predict SOC level in the year 2003 and the C inputs required to maintain the SOC level in the year 1994 (AE) were calculated from Jenkinson's equation.