Soil carbon stock is the major source andlor sink of the atmospheric C and varies with climate, topography, soil type and agricultural management practices, etc. However, a good farming practice can decrease atmosphere ca2 evolution from soil and also enhance soil fertility and productivity. Large part of forest areas in north eastern India was converted to agricultural lands due to increasing population. The indigenous farmer's practice in the field may lead to soil carbon stock depletion. Understanding the soil carbon stock can help in forecasting soil fertility and providing scientific information for good soil carbon management. Therefore, present study was attempted to evaluate soil carbon stock under different land uses based on the differences in topography, climate and agricultural management practices. The results clearly revealed that soils of the study areas fall in the strongly acidic condition ranging from 4.21-5.34. Bulk Density was high in lowland area than the other slope lands (i.e.1.42 and 1.44 glcc at 0-15 cm and 15-30 cm soil depth respectively). The Total Nitrogen (TN) content was highest in Central Potato Research Station (CPRS) where good package of management practices are followed (0.26-0.34% and 0.24-0.26% at 0-15 and 15-30 cm soil depth, respectively). The Cation Exchange Capacity (CEC) was highest in lowlands (10.05 to 13.18 cmol(P+)kg-1) with highest clay content (26.3-35.04%). The Soil organic carbon (SaC) content was also found highest at CPRS (2.92-3.02% and 2.27-2.89% at 0-15 and 15-30 cm soil depth, respectively). It was found that sac and TN content decreased with increased soil depth. The highest sac and Total carbon (TC) stock was found at CPRS with sac stock ranging from 6703.2-7032.8 g/m2 and 5880.0-6820.8 g/m2 at 0-15 and 15-30 cm soil depth, respectively and TC stock ranging from 7378.5-8064.4 g/m2 and 6350-7951.8 g/m2 at 0-15 and 15-30 cm soil depth, respectively. Recently converted agricultural lands from grassland and pasture of Sawkilo also showed high TC stock of 5156.3-7706.3 g/m2 and 4790.6-7607.4 g/m2 at 0-15 and 15-30 cm soil depth, respectively. The CENTURY model was used to simulate sac and TC stock in all sites. From the results it was clear that sac and TC was significantly affected by poor management. Continuous agricultural activities without addition of organic and inorganic plant nutrients may rapidly deplete the sac and TC stock at the slope lands of Sawkilo and Pyllun which was recently converted from grassland and pine forests, respectively. However, lowlands (Bhoirymbong) with Rice-fallow cropping system has low soil carbon content but in the long run more soil carbon stock would be stored than the slope lands under similar type of management (no addition of manures and fertilizers) and the declination of soil carbon stock was also gradual. The addition of organic and inorganic sources of plant nutrients with adoption of good management practices increase sac and TC stock as in CPRS. Therefore, land use with judicious nutrient management may build up soil carbon stock and enhanced soil productivity.