Study on Exchangeable Cation Determining Base Saturation Percentage of Soil in South China
Base saturation percentage (BSP) is an important soil chemical index in soil fertility and soil taxonomy. However, it is still unclear what exchangeable cation dominates BSP of soil in south China. Therefore, in this study, the data of BSPs and exchangeable H + , Al 3+ , Ca 2+ , Mg 2+ , K + and Na + of 109 and 45 horizon samples of 50 and 28 soil species in red soil and yellow soil groups in the Database of Chinese Soil Species were used to explore further the characteristics of BSPs and
... of BSPs and exchangeable cations as well as the correlation between BSPs and exchangeable cations. The results showed that the concentrations of exchangeable cations in both red soil and yellow soil groups were in an order of Al 3+ (4.55 ± 1.47 and 4.22 ± 1.2 cmol(+)/kg) > Ca 2+ (0.32 ± 0.21 and 0.36 ± 0.24 cmol(+)/kg) > H + (0.23 ± 0.13 and 0.19 ± 0.10 cmol(+)/kg) > K + (0.16 ± 0.09 and 0.16 ± 0.11 cmol(+)/kg) > Mg 2+ (0.13 ± 0.09 and 0.11 ± 0.08 cmol(+)/kg) > Na + (0.08 ± 0.06 and 0.11 ± 0.06 cmol(+)/kg). For red soil group, Al 3+ concentration was significantly higher than those of other exchangeable cations, Ca 2+ and H + concentrations were significantly higher than those of K + , Mg 2+ and Na + ; while for yellow soil group, Ca 2+ , H + and K + concentrations were significantly higher than those of Mg 2+ and K + . BSP of red soil group was codetermined by Ca 2+ , Al 3+ , Mg 2+ and Na + , with the contributions of 33.81%, 19.82% and 14.49%, respectively; while BSP of yellow soil group was codetermined by Al 3+ , Ca 2+ , Mg 2+ , K + and Na + , with the contributions of 24.91%, 21.55%, 19.91% and 14.21%, respectively. A higher concentration of exchangeable cation does not mean the higher importance of the cation to soil BSP. According to the available historical records, the sampling and measurement of soil samples were as follows: 1) the location of each typical soil profile was mainly decided by the comprehensive consideration of the representation of topography, parent material, land use type, and etc.; 2) a standard soil profile A. Q. Wang et al.