Abstract Enhancing crop tolerance to water stress in acidic soils presents a significant problem for sustainable wheat production. This research investigates the combined application of lignin‐based supplements and deficit irrigation techniques to improve soil quality, physiological performance, and water use efficiency (WUE) in wheat cultivation. This study systematically assessed the effects of five soil amendment treatments—no amendment (CO), calcium lignosulfonate (CL), CL combined with biochar (CL + B), CL combined with bioorganic fertilizer (CL + BOF), and a triple combination (CL + B + BOF)—applied under two regulated deficit irrigation regimes: DI90 (deficit irrigation at 90% field capacity, moderate stress) and DI60 (deficit irrigation at 60% field capacity, severe stress) on soil properties, root morphology, shoot physiology, and WUE in winter wheat. The results indicated that various soil amendment treatments (CL, CL + B, CL + BOF, and CL + B + BOF) can improve the soil properties and crop growth under both DI90 and DI60 regimes. Specifically, the integrated CL + B + BOF treatment produced the most significant improvements across a range of indicators. Under DI90, this treatment increased soil pH from 5.10 to 6.54, improved water‐stable aggregates by 41%, and raised available nitrogen and phosphorus to 38.78 and 49.23 mg/kg, respectively. The root surface area and photosynthetic rate increased by 56% and more than threefold, while shoot biomass and WUE doubled compared to the control. Although the effects were less pronounced under DI60, CL + B + BOF still enhanced soil pH, aggregate stability, and root development, and increased grain yield, shoot biomass, and WUE by 163%, 113%, and 43%, respectively, over the control. These findings highlight that combining lignin‐based amendments with regulated deficit irrigation offers a robust, sustainable strategy to improve soil health, optimize water use, and enhance wheat productivity in water‐limited, acidic soils.
Chang et al. (2026) studied this question.