Microcoleus vaginatus: A novel amendment for constructing artificial soil from tailings

Due to lack of soil structure, the fine-grained tailings were difficult with nutrient retention and eco-restoration. Establishing suitable arable soil structures is crucial for the effective restoration of the ecological environment in tailings stockpiles. In this study, the novel amendment, living Microcoleus vaginatus, was employed to help shaping the soil structure of tailings for promoting vegetation growth on tailings soil. Different dosage of M. vaginatus was added into the tailings in pot experiments, and it was found that microalgae could increase the organic matter content, geometric mean diameter, and improve plant growth under the optimal dosage of 1:15000 (w/w). With the optimized microalgae inoculation dosage in the field trials, the plant height and weight increased by 4.48 % and 14.93 %, respectively. Moreover, the bulk density decreased by 9.23 %, significantly, with the content of macro-aggregates, mean weight diameter and geometric mean diameter in soil increased by 33.81 %, 110 % and 101 %, respectively. The water content increased by 1.57 times, and porosity by 2 times. Furthermore, the organic matter content increased by 20.49 %, with the surge of the ecologically beneficial species Thiobacillus. This study confirms the positive effect of M. vaginatus on the formation of soil structure in fine tailings, effectively improving the nutrients possessing and microbial metabolic functions of tailings, which provides a new technical approach for ecological restoration in mine.