Abstract:The black soil in Northeast China experiences repeated freezing and thawing cycles, which result in significant effects on soil erosion and agricultural management. Soil freezing characteristics curve (SFCC) represents the change of unfrozen water content with soil temperature during freeze-thaw cycles. SFCC is important for water, heat, and solute transport in frozen soils. This study aimed to evaluate the performance of existing SFCC models for Northeast China soils and develop a new pedotransfer function for modelling SFCC. The SFCC of three typical Northeast soils was measured in the laboratory under different initial water contents, and the dynamic SFCC of a typical black soil profile in Northeast China was monitored in situ. The accuracy of existing SFCC models was evaluated using the measured data, and a new pedotransfer function model suitable for SFCC in Northeast black soils was proposed. The results show that SFCC is significantly influenced by soil type, texture, specific surface area, initial water content, and bulk density. After stable freezing, a relatively high proportion of unfrozen water still exists in clayey soils. The empirical models that consider both initial and residual water contents can accurately simulate the SFCC of Northeast black soils, with root mean square error (RMSE) around 0.018 m3/m3 and negative AIC values. However, such models require measured SFCC data to obtain its parameters. In contrast, pedotransfer function models that predict SFCC based on basic soil physicochemical properties show relatively poor accuracy, with RMSE exceeding 0.08 m3/m3 and positive AIC values. This study developed a new pedotransfer function for SFCC that incorporates soil specific surface area, bulk density, and sand and clay contents. The new model significantly improves the applicability of SFCC model in Northeast black soils. For the four tested soils, the RMSE between modelled and measured SFCC values was 0.025 m3/m3, with an average AIC value of -179. This study enhances the understanding of freezing and thawing processes of black soils, which is valuable for soil erosion and heat and water transport studies of Northeast China.