Microbiota of Technosols composed of sludge and recycled bentonite resemble the natural soil microbiota in three years. Technosols Laminoria

Technosols can be used to rehabilitate degraded land and recycle wastes at the same time. Ideally, a Technosol should fulfil the main soil functions, of which microbial communities play a key role. In the present study, we characterised the properties and microbial communities of three different Technosol formulations and their ingredients (soil from a waste recovery plant, recycled bentonite and sewage sludge), thereafter monitoring them when introduced for the rehabilitation of a mining area. Soil properties and communities were also compared to an unaltered and undisturbed reference soil from a forest in the same area. Diversity and composition of prokaryotes and eukaryotes was determined using 16S and 18S rRNA amplicon sequencing. Three years after their establishment, as much as 78.8% and 63.9% of the prokaryotic and eukaryotic orders, respectively, were shared among the Technosols and the reference soil. The three Technosols, showed lower values of properties like CO2 emission, functional diversity (determined by Biolog EcoPlatesTM) and compaction, compared to the reference soil in 2011. However, theyapproached conditions similar to the reference soil by 2014. In conclusion, the microbial communities of the three types of Technosols have developed towards similar characteristics of the climax soil of the area in just three years. The functionality and structure of the Technosols has also been restored to a great extent.