Soil acid buffering capacity is an intrinsic factor that determines the rate of soil acidification; however, the mechanism by which clay influences soil acid buffering capacity remains unclear. This study examines three different types of clay (kaolin, montmorillonite and alumina) to compare the difference between linear and nonlinear fitting of acid buffer capacity. Our findings reveal a significant positive correlation between the estimation results of both methods. However, linear fitting may overestimate acid buffer capacity compared with nonlinear fitting. Further analysis of the effect of clay type and content on acid buffering capacity showed that kaolin (1∶1 type) exhibited the lowest acid buffering capacity with no observable dose effect. In contrast, montmorillonite (2∶1 type) demonstrated the highest acid buffering capacity and a significant dose effect. The acid buffering capacity of montmorillonite was positively correlated with cation exchange capacity (R2=0.99), indicating that montmorillonite primarily contributes to acid buffering capacity by providing exchangeable cations. Although the acid buffering capacity of alumina is greater than that of kaolin, it is still less than that of montmorillonite and increases significantly with higher clay content. The acid buffering capacity of alumina is significantly correlated with cation exchange capacity, but the increase is significantly lower than that of montmorillonite. These findings indicate that the type of clay plays a crucial role in determining the magnitude of its acid buffering capacity. The results provide a scientific basis for revealing the impact of soil acid buffering capacity and offer data support for mitigating soil acidification and implementing acid soil remediation practices.
WEN et al. (Thu,) studied this question.