Abstract: 【Objective】The soil will be saturated by the ions of H⁺ and Al³⁺ under the process of electrodialysis. Theoretically, the acidification characteristic of soil can be studied with the method of electrodialysis. 【Method】Purple soil, Yellow soil and Latosol were selected to undergo the electrodialysis at a potential gradient of 15 V·cm^-1. The electrodialytic times were 30 times and the duration of each electrodialytic time was 8 hours. The acidification characteristics of three kinds of soil were characterized by the measurements of soil exchangeable acidity, base cations before and after the electrodialysis and the release regulation of base cations in the process of electrodialysis. 【Result】The results showed that the tested soils could be acidified quickly with electrodialysis in short time. The pH value of each soil was less than 4.5, which meant the soils were strongly acidified. After electrodialysis, the contents of exchangeable acidity, exchangeable H⁺ and exchangeable Al³⁺ increased significantly. The contents of exchangeable acidities of Purple soil, Yellow soil and Latosol increased from 3.35, 0.23 and 0.76 cmol(+)·kg^-1 to 18.9, 7.0 and 5.8 cmol(+)·kg^-1，respectively. On the contrary, the content of water soluble and exchangeable base cations, especially Ca²⁺ and Mg²⁺, base exchange capacity and base saturation decreased. For example, the contents of base saturation of Purple soil, Yellow soil and Latosol decreased from 96.8%, 82.6% and 47.3% to 20.5%, 11.8% and 12.2%，respectively. The acidified Purple soil had higher content in soil exchangeable acidity and base saturation. Because the contents of Ca²⁺ and Mg²⁺ were higher than K⁺ and Na⁺ and the electrostatic force between Ca²⁺/Mg²⁺ and negatively charged soil surface is strong. In the process of electrodialysis, the monovalent base cations K⁺ and Na^＋ were released from the soil very quickly. However, the divalent base cations Ca²⁺ and Mg²⁺ were released from the soil slowly and wavily. The exchangeable acidity content of Purple soil was significantly higher than that of Yellow soil and Latosol because of the high content of cation exchange capacity (CEC), which increased the risk of Al³⁺ toxicity of plant in the acidified Purple soil. Meanwhile, the contents of base cations and base saturation of Purple soil were higher than that of Yellow soil and Latosol, because the cations in Purple soil could be supplied from the decomposition of soil minerals. The high content of base cations in the Purple soil ensured the demand of base cation for plant growth and alleviated the further acidification of soil. 【Conclusion】Therefore, the electrodialysis could be as an useful tool to research the acidification characteristics of soil. The acidification characteristic of soil was affected by the content of negative charge on the surface of soil and the soil’s renewed ability of base cations. Compared to Yellow soil and Latosol, the Purple soil had a dual effect on the process of acidification.

Key words: electrodialysis, acidification characteristic, Purple soil, Yellow soil, Latosol