Effects of Different Ecological Measures on Water Use Characteristics of Amorpha fruticosa in Open Pit Coal Mine Areas

[Objective] To explore the water use characteristics of typical plants under different ecological measures at the waste dump, improve plant water use efficiency, and accelerate the ecological restoration process in mining areas. [Methods] Six ecological measures (control, inoculation, green fertilizer, inoculation+green fertilizer, inoculation+weathered coal, inoculation+green fertilizer+weathered coal) were implemented at the waste dump of the Heidaigou Coal Mine to treat Amorpha fruticosa. Stable isotopes of hydrogen and oxygen in water were combined with other techniques. [Results] (1) The soil moisture content of the waste dump was 3% to 9%, which was lower in the 0-30 cm and 70-100 cm soil layers, and higher in 30-70 cm soil layer. (2) Amorpha fruticosa obtained water from precipitation and soil. The soil water undergoes significant fractionation processed in the 0-30 cm soil layer, and exhibited significant differences among different ecological measures, with the green fertilizer treatment showing the highest and inoculation+green fertilizer treatment being the lowest. (3) Significant differences existed in the water use characteristics of Amorpha fruticosa under various ecological measures. The inoculation treatment exhibited a higher water use ratio of 53.4% in the 50-100 cm soil layer; The green fertilizer treatment mainly utilized the soil water in the surface layer (0-20 cm), which was 42.6%; The treatment of inoculation and green fertilizer had a relatively uniform proportion of soil water use in each layer. [Conclusion] The inoculation + green fertilizer treatment optimized the water use characteristics of Amorpha fruticose plants, increased the utilization ratio of surface and deep soil water, and can be used as an ecological reclamation measure for waste disposal sites, which promoted the ecological recovery rate and effect of arid mining areas in the western region.