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In response to the low permeability of sodic saline soils and the limited adaptability of conventional reclamation equipment, a specialized machine was designed for saline-alkali soil improvement based on deep straw incorporation. Soil column experiments revealed that filling the 20~40cm soil layer with straw increased permeability by 59.52%. A stepped drag-reduction optimization of the trenching device was conducted by using the discrete element method (DEM) and central composite design (CCD). The results showed that at subsoiler shovel working depth of 38.4cm, penetration angle of 24.7°, and blade angle of 60.1°, the trenching shovel resistance reached 9752.5N, while the total system resistance was 12401.9N, representing decreases of 27.7% and 0.4% compared with that of the control, respectively. Field validation of the optimized parameter combination revealed that the total system resistance reached 14500.5N, a 2.6% increase compared with that of the control, whereas the trenching shovel resistance dropped by 16.5% to 11801.8N. The average trenching depth was 39.1cm (coefficient of variation 5.06%), and the average trenching width was 9.4cm (coefficient of variation 5.16%), demonstrating a high degree of operational consistency. The straw burial qualification rate was 80%, indicating that the equipment was capable of effectively accomplishing the deep burial task. Through structural innovation and parameter optimization, the research can effectively address the high-resistance, low-efficiency issues inherent to trenching in sodic saline soils, providing a reliable technical and equipment solution for saline-alkali land improvement.