Freeze-thaw processes influence soil water and salt migration in farmlands

As global extreme climates intensify, freeze-thaw dynamics in cold-region agricultural farmland have become increasingly complex, directly regulating soil water-heat-salt migration and salinization. While previous studies focused on 1-D vertical dynamics, 2-D processes remain unclear. Freezing induces water-salt movement from ditches to farmland, and the downward migration of meltwater elevates the groundwater table, thereby inducing drainage from farmland to ditches. Such asymmetric water-salt exchange, characterized by delayed responses to surface temperature, affects salt exclusion efficiency.This study used the SUTRA-MS-FT model to simulate freeze-thaw-affected farmland-ditch systems in salinized areas, exploring 2-D dynamics. Different desalination measures (varying salinity irrigation leaching and subsurface pipe drainage) were tested to analyze their sensitivity. The findings provide scientific support for water-salt regulation in cold-region farmlands.