Responses of Soil and Vegetation Properties to Chemical Fertilization in Restoring Coal Gangue Hills in an Alpine Mining Area

Abstract

During the coal mining operation, the accumulated soil in coal gangue hills often suffers from nutrient deficiencies, which can be overcome using fertilizer supplementation. The supplementation of exogenous nutrients has proven to be an effective means of enhancing physicochemical conditions of these soils and promoting vegetation reestablishment. This study aimed to investigate the characteristics of plant growth and soil properties in vegetation restoration to a coal gangue hill, focusing on artificially seeded grasslands in a high-altitude mining area as the research subject. Over a period of three consecutive years, varying gradients of nitrogen and phosphorus supplements were applied to the coal gangue hill. Furthermore, the interrelationships between plants and soil factors at different dosages of chemical fertilization were analyzed so as to determine the appropriate fertilization level conducive to the ecological system's restoration in the area. The results of this study revealed significant responses (P < 0.05) in vegetation height, coverage, and biomass to nitrogen and phosphorus dosage, leading to a significant increase in the availability of soil nutrients (P < 0.05). Apart from moss coverage, fertilizer dosage exhibited a significant positive correlation (P< 0.05) with various vegetation characteristics, as well as a highly significant positive correlation (P < 0.05) with soil nutrient availability. Notably, no significant differences (P > 0.05) were observed in soil physical properties with varying nitrogen and phosphorus amendments. In conclusion, nitrogen and phosphorus supplementation is beneficial for promoting vegetation growth and improving soil chemical properties in high-altitude mining areas with coal gangue hills. The recommended minimum dosage is 40g/m² of urea in combination with 30g/m² of diammonium phosphate. This supplement should be applied continuously. Considering the capacity of the mining area's ecosystem to self-repair and the costs of ecological restoration, it is advisable to utilize organic fertilizers and sheep manure in the next phase of restoration.