Application of different soil conditioners to restorate mine tailings with native (Cistus ladanifer L.) and non-native species (Medicago sativa L.)

The present research aims to reclaim a mining area in the Riotinto district combining soil conditioners (composted sewage sludge, commercial fertilizer and lime) and two different plant species: Cistus ladanifer L. and Medicago sativa L. We employed several soil functional parameters (i.e. pH, organic carbon, microbial bio-mass, enzyme activities, soil respiration) and plant indicators (i.e. nutrients, bioaccumulation and transfer factor) to highlight their impact on soil properties and to evaluate the response of plants to the different growth media. Greater organic matter mineralization rates, and consequently higher respiration rates, were recorded in amended and limed soils in comparison with non-limed soils, and were attributed to a reactivation of copyotrophic populations as soil acidification decreased. Compost provided higher C availability and quality, which is partially reflected in a more efficient use of organic substrates (lower qCO(2)) by microbial biomass. Both plant species present an adequate nutritive status except for K deficiency in all cases. Both species contain toxic concentrations of As, Cr and Pb (and Cu also in Medicago) but can be considered as non-accumulators of these elements. In Medicago the concentration of As, Cu and Pb should represent an environmental risk for domestic animals. Liming and adding up to 5% sewage sludge compost effectively assisted soil health and aided plant growth. (C) 2016 Elsevier B.V. All rights reserved.