A long-term field experiment on Studies on nitrogen dynamics under different nutrient management practices and cropping systems was initiated in 2004-05 at MARS, IOF, UAS, Dharwad. Application of organic manure continuously for eight years increased all the fractions of nitrogen. NH4-N (28.7 mg/kg), NO3-N (9.6 mg/kg) and total-N (664.1 mg/kg) showed statistically higher values in organic nutrient management practice than inorganic nutrient management practice which recorded 21.1 mg per kg of NH4-N, 6.4 mg per kg of NO3-N and 520.8 mg per kg of total-N content in soil at surface layer. Similarly, at sub surface layer treatment receiving organic manure application recorded significantly higher values followed other management practice. All the forms of nitrogen were significantly and positively correlated with each other. Hundred percent organic nutrient management practice increased the soil microbial biomass carbon (79.0 mg/kg) and nitrogen (21.7 mg/kg) when compared to other nutrient management practices.