Soil salinity and sodicity are major constraints to sustainable agriculture in arid and semi-arid regions. Despite extensive research on remediation practices, the lack of integrated frameworks for quantifying saline-sodic soil degradation has impeded the translation of site-level findings into operational management tools. We assessed the long-term impacts of irrigation and cultivation on calcareous saline-sodic soils in northwestern Iran and developed a comprehensive soil degradation index (CSDI) using both total dataset (TDS) and minimum dataset (MDS) approaches. Ninety-six soil samples were analyzed from adjacent cultivated (cultivated saline-sodic soil [CSSS]) and uncultivated (uncultivated saline-sodic soil [USSS]) sites to evaluate changes in physical, chemical, and biological indicators. The results showed that conversion to cropland substantially reduced degradation metrics, with bulk density, soil crusting index (SCI), modified clay ratio, and exchangeable sodium percentage (ESP) decreasing by 7%-9%, 28%-49%, 26%-83%, and 130%-188%, respectively. In contrast, soil structural stability index (SSI) and soil organic carbon (SOC) increased by 112%-173% and 130%-154%. The CSDI-TDS and CSDI-MDS values declined by 60%-71% and 37%-94% under cultivation. Principal component analysis identified SOC, ESP, SSI, CROSS, K-factor, and SCI as the most diagnostic indicators for MDS construction. Validation against crop yields indicated that while CSDI explained a modest proportion of yield variability (22%-27%), it reliably distinguished management effects and provided a robust framework for monitoring soil recovery. The findings highlight that long-term agricultural practices, when combined with appropriate amendments, can markedly improve the physicochemical remediation of saline-sodic soils. CSDI offers a practical tool for assessing soil degradation trajectories, guiding reclamation strategies, and supporting sustainable intensification in salt-affected agroecosystems.