Abstract: The effect of fertilization on soil organic carbon and nitrogen was conducted in a long-term experiment, with monoculture of corn (Zea mays L.), established in 1980 at Gongzhuling, Jilin province of China. Six treatments, i.e., CK, N, NP, NK, NPK and MNPK, were established with 165 kg N ha 1, 36 kg P ha 1 and 68.5 kg K ha 1 for chemical N, P and K fertilizer input, respectively, with 60 Mg farmyard manure ha 1 containing 150 kg N ha 1 for M and no fertilization for CK. The results showed that soil organic C, total N and alkali N were significantly greater in the MNPK treatment than in the other 5 treatments (p<0.05). Soil NH4+-N was significantly greater in the NPK and NK treatments than in the CK and N treatments (p<0.05). Soil NO3--N content was about 6 times as much in the MNPK treatment and 3-4 times as much in the chemical fertilizer treatments as in the CK treatment. Chemical N application alone or together with chemical P or K could not significantly improve the soil organic C or total N content, but chemical fertilizer NPK along with farmyard manure could substantially increase soil organic C and N contents in topsoil layer in the study site.