The Loess Plateau, a worldwide recognized ecologically sensitive region, with slope-gully systems (SGS) serving as primary sediment sources due to their unique erosion dynamics. However, quantifying the partitioning of sediment contributions between slope and gully subsystems remains poorly understood. This study examines erosion mechanisms and sediment budgets in a 26 km2 SGS watershed. We assessed slope erosion contributions using data from multiple sources, including remote sensing, field surveys, and historical records. Concurrently, the sediment-trapping capacities of five check dams were calculated using geotechnical field measurements, allowing gully erosion estimation. The results demonstrated differential erosion partitioning, with annual sediment yields of 10,550 t a-1 (30.8%) from slope systems and 23,735 t a-1 (69.2%) from gully systems, showing gully dominance in sediment production. Results show gully systems dominate sediment production (69.2%), with check dams reducing gully slope lengths by 18-32% and vegetation roots enhancing shear strength biome chanically. Furthermore, biomechanical reinforcement by arboreal vegetation within dam sediments was identified, with root structures that functionally emulate anti-slide pile systems. These findings establish vegetation restoration and strategic dam placement as complementary interventions for slope and gully erosion reduction, respectively, providing insights into soil erosion control strategies in the Loess Plateau's agricultural areas.