Recovering a copper mine soil using organic amendments and phytomanagement with Brassica juncea L.

•A mine soil was treated by planting mustards and amending with technosol and biochar.•The added amendments improved the soil conditions for the establishment of mustards.•The combined use of both treatments is the best to improve the soil quality.•Mustards and the added wastes reduced the CaCl2-extractable concentration of metals.•Brassica juncea is a good candidate for phytostabilization of mine soils.

A 3-month greenhouse experiment was carried out for evaluating the effect of an amendment mixture and mustards on the chemical characteristics of a mine soil and the metal uptake by plants. A settling pond soil was amended with increasing percentages of a technosol and biochar mixture and vegetated with Brassica juncea L. Adding amendments and planting mustards increased the soil pH from 2.83 to 6.18 and the TSC from u.l to 131 g kg−1 and generally reduced the CaCl2-extractable metal concentrations in the soil. However, the amendments increased the pseudo-total soil concentration of Ni from 9.27 to 31.9 mg kg−1, Pb from 27.9 to 91.6 mg kg−1 and Zn from 46.5 to 577 mg kg−1. The technosol and biochar mixture increased the shoot biomass from 0.74 to 2.95 g and generally reduced the metal concentrations in plants, meaning B. juncea as a potential candidate for phytostabilization of mine soils.