Objectives of this study were to investigate changes of soil carbon contents and to evaluate N mineralization and nitrification rates in soils cooperated with organic composts and bio-char during 2nd year corn cultivation. For the experiment, the soil texture used in this study was clay loam, and application rates of chemical fertilizer were 480-150-260 kg ha-1(N-P2O5-K2O) as recommended amount after soil test, and biochar application was 0.2% to soil weight. The soil samples were periodically taken at every 15day intervals during corn cultivation periods. The treatments were consisted of cow compost(CC), pig compost(PC), swine digestate from aerobic digestion system(AD), and their bio-char cooperation. TC contents in treatments cooperated with bio-char at harvesting stages were ranged from 0.96% to 1.24%, and its CC applied plot was highest at 1.24%. It was observed that TC contents with biochar treatments were higher than the compost treatment only. Therefore, it was observed to be carbon sequestration into corn field cooperated with biochar. For nitrogen transformation in soil cooperated with organic composts and bio-char, net mineralization rates were dramatically decreased at 44 days after sowing, but nitrification rates were abruptly increased at 73 days after sowing. For N mineralization and nitrification rates, it was shown that there were generally low in the soil cooperated with biochar as compared to the only application plots of different organic composts. Also, it was observed to be highest in the application plot of pig compost manure. Overall, Application of biochar in the cropland could be important role for mitigation of greenhouse gas as well as carbon sequestration.