Author(s)

Xiangzheng Kong^1,2, Decheng Li^1*, Xiaodong Song¹, Ganlin Zhang¹

¹State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China.
²University of Chinese Academy of Sciences, Beijing, China.

Cation exchange capacity (CEC) is one of the most important properties of soils. The NH₄OAc (pH = 7.0) exchange method is usually recommended to determine CEC (CEC₁) of all soils with different pH values, particularly for studies on soil taxonomy. But comparatively the BaCl₂-MgSO₄ forced-exchange method is more authentic in determining CEC (CEC₂) of tropical and subtropical highly-weathered acid soils. But so far little is known about the difference between CEC₁ and CEC₂. In this study, the physiochemical data of 114 acid B horizon soils from 112 soil series of tropical and subtropical China were used, CEC₁ and CEC₂ were determined and compared, the influencing factors were analyzed for the difference between CEC₁ and CEC₂, and then a regression model was established between CEC₁ and CEC₂. The results showed that CEC₂ was significantly lower than CEC₁ (p < 0.01), CEC₂ was 14.76% - 63.31% with a mean of 36.32% of CEC₁. In view of the contribution to CEC from other properties, CEC₂ was mainly determined by pH (45.92%), followed by silt (21.05%), free Fe₂O₃ (17.35%) and clay contents (12.76%), CEC₁ was mainly decided by free Fe₂O₃ content (40.38%), followed by pH (28.39%) and silt content (27.29%; and the difference between CEC₁ and CEC₂ was mainly affected by free Fe₂O₃ (50.92%), followed by silt content (26.46%) and pH (21.80%). The acceptable optimal regression model between CEC₂ and CEC₁ was established as CEC₂ = 2.3114 × CEC₁^1.1496 (R² = 0.410, P < 0.001, RMSE = 0.15). For the studies on soil taxonomy, the BaCl₂-MgSO₄ forced-exchange method is recommended in determining CEC of the highly-weathered acid soils in the tropical and subtropical regions.

Acid Soil, CEC Determination, NH₄OAc (pH = 7.0) Exchange Method, BaCl₂-MgSO₄ Forced-Exchange Method

Kong, X. , Li, D. , Song, X. and Zhang, G. (2021) Comparison of Highly-Weathered Acid Soil CEC Determined by NH₄OAc (pH = 7.0) Exchange Method and BaCl₂-MgSO₄ Forced-Exchange Method. Agricultural Sciences, 12, 917-927. doi: 10.4236/as.2021.129059.