Effect of long-term use of organic and inorganic fertilizers on nitrogen forms were studied under maize-wheat (41 years) cropping systems by conducting both field and laboratory studies. Soil pH decreased with the continuous application of inorganic fertilizers and organic manure under maize-wheat cropping system. Soil pH decreased however, SOC, available N, available P and available K improved with continuous application of organic and inorganic fertilizers under maize-wheat and systems. Continuous application of inorganic fertilizers, alone or in combination with organic manure led to marked increase in the total soil N, total hydrolysable- N (THN) (amino acid-N, ammonia-N, amino sugar-N, hydrolysable unknown-N) and non-hydrolysable-N. The effect of FYM with 100% NPK in maize-wheat was more pronounced in increasing the total soil N and THN. Maximum grain, straw yield and N, P, K uptake in the maize-wheat cropping systems were observed with an application of 100% NPK+FYM. Soil organic carbon and EC correlated significantly and positively with different fractions of N and pH correlated negatively and significantly with these fractions. Maximum grain, straw yield and N, P and K uptake in the both maize-wheat cropping systems were observed with an application of 100% NPK+FYM. Total hydrolysable N, ammonia-N, amino acid N, amino sugar N, non-hydrolysable N and hydrolysable unknown nitrogen were correlated significantly and positively with the grain yield and N uptake by maize, under maize-wheat cropping systems. The fraction of N correlated significantly and positively with soil organic carbon and negatively significant with soil pH.