To address the challenges of excessive chemical fertilizer input, degradation of soil physicochemical properties, and low silage maize yield in the Hexi Oasis irrigation area, this study investigated the effects of different tillage methods and various ratios of organic to inorganic fertilizers on soil quality and yield in a silage maize–Lablab bean mixture system. The aim was to provide a scientific basis and theoretical support for soil health management and the sustainable development of agriculture and animal husbandry in this region. The experiment was conducted at the Wuwei Oasis Agricultural Comprehensive Experimental Station from 2023 to 2024 using a split-plot design. Two tillage methods were applied in the main plots: conventional tillage (autumn deep plowing followed by spring harrow mulching, CT) and reduced tillage (autumn no-tillage combined with spring rotary tillage, RT). Four fertilization treatments were assigned to the subplots: 100% chemical fertilizer (F1), 75% chemical + 25% organic fertilizer (F2), 50% chemical + 50% organic fertilizer (F3), and 25% chemical + 75% organic fertilizer (F4). The results showed that, compared with CTF2, RTF2 reduced soil bulk density by 0.2% and pH by 0.5%, while increasing soil organic matter, total nitrogen, total phosphorus, total potassium, nitrate nitrogen, ammonium nitrogen, available phosphorus, and available potassium content by 4.1%, 4.6%, 4.6%, 5.3%, 7.8%, 7.0%, 4.2%, and 3.1%, respectively. Compared to RTF1, RTF2 reduced soil bulk density by 0.4% and pH by 0.6%, while enhancing the aforementioned soil nutrients content by 4.3%, 2.7%, 2.1%, 4.1%, 6.9%, 7.0%, 5.0%, and 8.3%, respectively. Additionally, forage yield and energy yield under RTF2 were 6.4% and 6.7% higher than those under CTF2, and 9.6% and 10.2% higher than those under RTF1, respectively. Mantel test analysis indicated that all soil physicochemical properties—except pH and bulk density—were significantly positively correlated with forage and energy yields. Furthermore, the random forest model identified soil pH, organic matter, total potassium, nitrate nitrogen, ammonium nitrogen, and available phosphorus as the main predictors of forage yield. Structural equation modeling (SEM) revealed that tillage and fertilization systems indirectly influenced available nutrient content by enhancing total soil nutrients, thereby increasing forage yield and, consequently, energy yield. In conclusion, reduced tillage combined with 75% chemical fertilizer and 25% organic fertilizer (RTF2) effectively improved soil quality and enhanced the productivity of the silage maize–Lablab bean mixed cropping system. This integrated approach is recommended as a suitable tillage and fertilization strategy for sustainable intensification of silage maize production in oasis irrigation areas.
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