The Acid Buffer Capacity of a Horizons in Young Residual Entisols in Korea

pH buffer capacities (pHBC, $cmol_c\;kg^{-1}\;pH^{-1}$) of 6 residual Entisols derived from granite, granite-gneiss, limestone, sandstone, shale, and basalt in Korea were studied. Soil acidity may become a problem if the soil pH is reduced to critical levels when nutrient cycles are unbalanced (especially N, C and S). The relation between the pHBC and the physico-chemical properties of the 6 soils was also studied. In the A horizons of all the soils except Euiseong series developed from sandstone, the contents of clay, organic matter and cation exchange capacity (CEC) were higher than those of C horizon, but bulk density and pH were lower than C horizon. Clay content of Euiseong series decreased with soil depth, which might be caused by the elluviation. The soils developed from granite, granite-gneiss and sandstone have a higher $SiO_2$ content than those developed from basalt and limestone. The contents of $Fe_2O_3$ and MgO were high in the soils from developed from basalt, limestone and shale comparing with the soils from granite, granite-gneiss and sandstone. The soils from basalt and limestone showed higher values of ignition loss than those from the other parent rocks. The pHBC of the soils was ranged from 1.8 to 3.2 $cmol_c\;kg^{-1}\;pH^{-1}$ showing as follows : basalt, limestone > shale, granite-gneiss > granite sandstone.