Effects of agronomic treatments on functional diversity of soil microbial community and microbial activity in a revegetated coal mine spoil

Successful restoration of coal mine spoil requires functional microbial community for soil development and biogeochemical cycling to ensure long term sustainability of established plants. The current study investigated functional diversity of the soil microbial community, microbial activities, and physico-chemical properties of a revegetated coal mine spoil that was exposed to different agronomic practices. Treatments included Control (conventional revegetation practice), selective herbicide (SH), mulching (M), succession planting (SP), and green manure (GM) crops. Fluorescein diacetate (FDA) hydrolysis revealed significantly (P < 0.05) higher microbial activity in the GM treatment compared to the Control and all other treatments. Patterns of microbial biomass C (MBC), determined by the chloroform fumigation extraction method, also showed significant (P < 0.05) differences between treatments, with the SH treatment showing the lowest MBC. Basal respiration (BR) and substrate induced respiration (SIR) did not differ amongst the treatments. Principal component analysis of community level physiological profiles data based on Biolog® Ecoplate data revealed differing bacterial functional (metabolic) diversity amongst the treatments. Overall, the study demonstrated significantly (P < 0.05) higher average well color development (AWCD), indicating high metabolic activity, and substrate richness (R) and Shannon's index (H) showed greater functional diversity of the bacterial community in the SP treatment, as compared to other treatments. These results demonstrate that the agronomic treatments such as SP will not only boost microbial activity, but they also play a constructive role in increasing functional diversity of soil microbial communities. Based on these results, we recommend that agronomic practices such as SP should be used as an important component in mine site revegetation programs. © 2018 Elsevier B.V.