Study on the soil improvement of waste dump in open-pit mining areas using plant waste fermentation substrates

With China’s rapid economic growth, substantial mineral resources have been harnessed, especially the waste dump formed by the screening of concentrate during the mining process, resulting in the occupation and destruction of existing land resources. The newly formed waste dump has an imperfect soil structure and poor nutrient supply, resulting in an abandoned area where a large number of plants are difficult to grow. Guided by the philosophy of “integrated management of mountains, rivers, forests, fields, lakes, grasslands, and deserts, promoting harmonious coexistence between humans and nature”, the approach involves utilizing the plant waste in the original mining area and surrounding farmland as a soil substrate, employing various mixtures of plant waste to amend and enhance the soil in the waste dump. This study uses tall fescue （Festuca arundinacea “Cannavaro”） as plant materials. The effects of five substrate treatments （original soil, unfermented garden waste, unfermented garden waste∶original soil =7∶3, fermented garden waste∶original soil=7∶3 and fermented garden waste） on the turf quality, turf grass growth and soil physicochemical properties are compared. The most suitable substrate type for the growth of Festuca arundinacea is selected by TOPSIS comprehensive evaluation. The results show that the substrate of fermented garden waste∶original soil=7∶3 treatment has a certain promoting effect on the performance quality. The turf biomass of substrate after fermentation treatment has no significant difference with the original soil treatment, but it is significantly higher than that of the two treatments without fermentation. The two treatments of substrates after fermentation show the soil dry density suitable for turfgrass growth, which improves soil aeration and significantly increased the supply of nitrogen, phosphorus and potassium. The comprehensive quality index of fermented garden waste∶original soil= 7∶3 treatment is the best, which is 0.82, higher than 0.49 of the original soil treatment. While the comprehensive quality evaluation of garden waste without fermentation treatment is the worst, which is only 0.38. Therefore, mixing the fermented garden waste and original soil according to the proportion of 7∶3 as the growth substrate for Festuca arundinacea is a reasonable plant waste treatment method and mixing ratio, which can significantly improve and enhance the disturbed soil in mining area’s waste dump.