Soil organic carbon (SOC) of soil series is necessary to calculate soil C sequestration due to IPCC default categorized by climate regions and by soil types. The 3,400 thousand data were downloaded from agricultural soil information system and analyzed to get averages of soil order, soil series, and textual family for the three different soil management practices in Korea. The SOC content was $13.3{pm}5.38g;kg^{-1}$ in paddy field, $13.7{pm}7.19g;kg^{-1}$ in upland field, and $15.2{pm}8.22g;kg^{-1}$ in orchard soil, respectively. As SOC in orchard was 10% greater than that in upland, orchard must be managed with applying compost. The SOCs of inceptisols, which was largely distributed in Korea, were $13.6{pm}5.48g;kg^{-1}$ in paddy field, $14.1{pm}7.38g;kg^{-1}$ in upland field, and $15.3{pm}8.20g;kg^{-1}$ in orchard soil, respectively. The SOCs of alfisols were $13.6{pm}4.96g;kg^{-1}$ in paddy field, $13.7{pm}6.99g;kg^{-1}$ in upland field, and $15.6{pm}8.59g;kg^{-1}$ in orchard soil, respectively. The SOCs of entisols were $11.7{pm}5.16g;kg^{-1}$ in paddy field, $12.8{pm}7.05g;kg^{-1}$ in upland field, and $13.7{pm}7.81g;kg^{-1}$ in orchard soil, respectively. The SOCs of ultisols were $12.7{pm}4.79g;kg^{-1}$ in paddy field, $12.7{pm}6.22g;kg^{-1}$ in upland field, and $16.3{pm}8.49g;kg^{-1}$ in orchard soil, respectively. The fact that soils containing greater clay content in textual family had also more SOC content revealed that SOC could be also dependent on some soil properties as well as soil order. Because SOC differences among soil series representing same textual family were greater than those among textual family, SOC differences should be mainly affected by management practices such as compost application.