How to achieve artificial aging approaching natural aging: Long-term remediation effects of biochar on cadmium contamination in soils

Biochar effectively increases the pH of soils with sub-neutral pH values and immobilizes cadmium (Cd) in agricultural soils. The long-term remediation efficacy of biochar is a critical parameter for determining whether soil application is economically feasible. Various artificial accelerated aging methods have been developed; however, further research is required to better understand the utilization of artificially accelerated aging methods to approximate natural aging. This study innovatively established a quantitative simulation model for artificial aging that approximated natural aging across China’s six major regions on the basis of climate characteristics. The latest TabPFN model achieved superior fitting performance for both artificial and natural aging scenarios in terms of the impact of biochar on soil active Cd and pH. Significant differences were identified between the outcomes of artificial and natural aging. With respect to changes in the Cd immobilization rate of biochar, artificial aging exhibited a pattern of initial significant increase followed by a rapid stabilization (measured in days), whereas natural aging exhibited a continuous decline from high values followed by stabilization pattern (measured in years). In this study, under a precise simulation of Cd immobilization rates and pH changes following biochar application (1%, 2%, and 3% application ratios), the accelerated aging combinations reduced the natural aging scale (10 years) by 77.1%–94.6% in Northeast, South, North, Central, East, and Southwest China.