Climate change-induced drought and erratic rainfall intensify soil erosion in semi-arid sloped regions, threatening long-term agricultural sustainability. Although plastic mulching in RFRH systems reduces erosion and water loss, increasing concerns about soil microplastic accumulation justify the evaluation of chopped straw as a biodegradable and eco-friendly alternative for sustainable crop cultivation. To enhance resource efficiency and sustainability, this study employed structural equation modelling to (i) assess the combined effects of RFRH and chopped straw application on runoff, sediment yield, soil water storage (SWS), organic matter, nutrients, soil temperature, evapotranspiration, fodder yield, and water use efficiency (WUE) of sainfoin; and (ii) identify optimal RFRH and chopped straw integration for sustainable crop-soil-water management in sloped landscapes. A two-year (2022-2023) field experiment with sainfoin (Onobrychis viciifolia) as the test crop used a split-plot design with chopped straw application patterns (0 and 4 & times; 10(3) kg ha(-)(1)) as main plots and RFRH methods (flat planting (FP, control), open-ridging (OR), and tied-ridging (TR)) as subplots. The results showed treatment effectiveness followed TR > OR > FP, and integration with chopped straw significantly enhanced soil conditions, WUE and sainfoin fodder yield. Compared to FP under no chopped straw, OR and TR reduced runoff by 28.6% and 44.4%, increased SWS by 8.77 and 28.13 mm, enhanced WUE to 1.86 and 2.83 kg ha(-)(1) mm(-)(1), and improved fodder yield by 9.9% and 16.9%, respectively. Under chopped straw application, OR and TR further reduced runoff by 31.4% and 52.6%, increased SWS by 16.70 and 32.28 mm, enhanced WUE to 3.53 and 6.71 kg ha(-)(1) mm(-)(1), and improved fodder yield by 13.1% and 18.3%, respectively. Chopped straw application improved total nitrogen (29.49%), phosphorus (16.40%), potassium (7.49%), and organic matter (19.85%), leading to an increased soil health index (0.29) and fodder yield compared to no chopped straw application. Structural equation modelling revealed that chopped straw application and RFRH had significant indirect positive effects (0.41) and (0.49) on sainfoin fodder yield, respectively. Tied-ridging combined with chopped straw proved most effective in optimizing soil quality and water use while enhancing sainfoin productivity. These findings offer practical strategies for sustainable soil-crop-water management in erosion-prone, water-scarce sloped areas.