Three types of acidic paddy soils from Hechi, Xiangtan, and Shaoguan were selected, and a 308 day soil cultivation experiment was performed in a greenhouse to reveal the effects of the aging of immobilization materials on the stability of soil cadmium(Cd) immobilization. Each experiment site was equipped with a control treatment and two treatments with sepiolite and biochar. The experiment was performed to study the changes in soil Cd fractions in the paddy soils of Hechi, Xiangtan, and

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... and the Pearson correlation between the forms of soil Cd, iron(Fe), manganese(Mn), copper(Cu), and zinc(Zn). Results showed that after the application of sepiolite, the content of acid-extractable Cd in the Hechi, Xiangtan, and Shaoguan soils showed downward and upward trends in the early and late stages of soil cultivation, respectively. Specifically, the ratio of acid-extracted Cd to total Cd in the Hechi soil decreased by 9.0 percentage points from 0 to 28 days and increased by 13.8 percentage points from 28 to 308 days. Similarly, the percentage of acid-extracted Cd in the Xiangtan and Shaoguan soils decreased by 3.2 percentage points and 4.4 percentage points from 0 to 7 days, respectively, and increased by 2.0 percentage points and 3.5 percentage points from 7 to 308 days, respectively. The content of acid-extracted Cd in the Hechi, Xiangtan, and Shaoguan soils increased and then decreased similar to that of soil treated with biochar. In 0~7 days, the ratio of soil acid-extracted Cd to total Cd at the three test sites decreased by 5.5~8.1 percentage points and increased by 3.4~6.6 percentage points in 7~308 days. Additionally, compared with the application of sepiolite, the application of biochar was strongly correlated with of Cd, Fe, Mn morphology in the soil. The conclusions were the following:after the application of sepiolite or biochar, Cd in the paddy soils of Hechi, Xiangtan, and Shaoguan was gradually reactivated and re-released; the aging of sepiolite and biochar significantly affected the morphological ch [...]