Characterisation of alkaline tailings from a lead/zinc mine in South Africa and evaluation of their revegetation potential using five indigenous grass species

Abstract

Tailings from a lead/zinc (Pb/Zn) mine were characterised and their revegetation potential investigated under glasshouse conditions using five grass species with three rates of inorganic fertiliser. The tailings were alkaline with low nutrient concentrations but high total and extractable Zn. The yield of all grass species increased with an increase in fertiliser rate. The yield of Cenchrus ciliaris  at the full fertiliser application rate was significantly higher than the other species tested, followed by Digitaria eriantha. Cymbopogon plurinodis was the third-highest-yielding species, whereas yields of Eragrostis superba and Fingeruthia africana were similar. Concentrations of Zn in the foliage tended to be over the reported grass foliage ranges, whereas Pb concentrations were within typical norms. It is recommended that C. ciliaris, D. eriantha and E. superba be used for initial revegetation, with other species used to improve biodiversity after initial cover has been established.

Keywords: carbonate-rich, dolomitic tailings, indigenous, low cost, phytorestoration

South African Journal of Plant and Soil 2013, 30(2): 97–105