Use of vetiver and three other grasses for revegetation of Pb/Zn mine tailings: Field experiment

The Lechang Pb/Zn mine is located to the north of the Guangdong Province, South of China. The tailings pond had been abandoned for over 5 years, and revegetation was necessary for stabilizing the bare surface and to reduce its environmental impact. The tailings contained high levels of heavy metals (Pb, Zn, Cu, and Cd) and low levels of major nutrient elements (N, P, and K) and organic matter; therefore, heavy metal toxicity and extreme infertility were the major constraints on revegetation. A field experiment was conducted to compare the growth of Vertiveria zizanioides, Paspalum notatum, Cynodon dactylon, and Imperata cylindrica var. major on the tailings. The tailings were amended with 10 cm domestic refuse + complex fertilizer (NPK) (Treatment A), 10 cm domestic refuse (Treatment B) and complex fertilizer (NPK) (Treatment C), respectively; tailings without any amendment were used as control (Treatment D). Plant growth was improved when either domestic refuse or NPK fertilizer was added to the substrate, but the combination of both amendments gave the best yields. After 6 months' growth, V. zizanioides growing on treatment A had a height of 220 cm, cover of 100% and a yield of 2.1 kg m^-2 (d.w.). The height and biomass of V. zizanioides were significantly greater than the other three grasses growing on the same treatment. Judging from results, V. zizanioides was the best species for tailings revegetation, followed by P. notatum, C. dactylon, and I. cylindrica var. major.