Purpose To study the synergistic improvement effects of the quicklime-arbuscular mycorrhizal fungi (AMF)-herbs on the acid tin tailings, selecting the suitable dominant plants for the improvement.
Methods A pot experiment was used to study the effects of quicklime and AMF on the growth of plant, accumulation of heavy metal, and rhizosphere physicochemical properties of Heteropogon contortus (L.) Beauv., Chrysopogon zizanioides (L.) Roberty, Cynodon dactylon (L.) Pers., Medicago sativa L., Setaria viridis (L.) Beauv., Lolium perenne L. on tin tailings.
Results Compared with the control treatment, complex addition of quicklime and AMF increased the pH value, organic matter and available nutrient contents of tailings, and significantly increased the biomass of six herbaceous plants, especially the increase of biomass for L. perenne was most. Among complex treatments, under quicklime treatment, the pH value of H. contortus rhizosphere soil was the highest, increased by 0.92 comparing with the test tailing before improvement; under the quicklime-AMF treatment, the organic matter content of C. zizanioides rhizosphere soil was the highest, increased by 7.6 times comparing with the test tailing before improvement, and the content of alkali-hydrolyzed nitrogen and available phosphorus in M. sativa and L. perenne rhizosphere soil was relatively high, increased by about 14 times and 21 times comparing with the test tailing before improvement, respectively. The combination treatments of quicklime-AMF-herbs had a more reduction of available Cu and Pb content in the rhizosphere tailings, reduced by 15.66-17.07 and 1.43-1.48 mg/kg, respectively; but for the available Cd, reduced by 0.58-0.59 mg/kg only under the treatment of quicklime-AMF-S. viridis or L. perenne.
Conclusion Quicklime-AMF-herbs can help to improve the tin tailings. L. perenne, H. contortus, C. zizanioides and M. sativa are recommended as pioneer plants for vegetation restoration in tin tailings under the combination of quicklime-AMF.
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