Lime and pig manure as ameliorants for revegetating lead/zinc mine tailings: a greenhouse study

The Lechang lead/zinc mine is located at the north of Guangdong Province in southern China. The residual tailings from the extraction of lead/zinc ore s were permanently stored in tailings ponds which required revegetation to reduce their impact on the environment. Therefore, a greenhouse study was c onducted to evaluate the effects of lime (0.5, 1.0, 2.0 and 4.0 t ha(-1)) a nd pig manure (12.6, 25.2, 37.8, 50.3 and 75.5 t ha(-1)) amendment on the r evegetation of the Pb/Zn mine tailings using Agropyron elongatum (tall whea tgrass) and Trifolium repens (clover). The results showed that the applicat ions of lime or pig manure increased pH, reduced electrical conductivity (E C) and DTPA-extractable concentrations of Zn, Pb and Cd in the tailings. Co mpared with tailings without amendment, application of lime alone (2 t ha(- 1)) did not improve growth of either species. However, using lime with supp lemental fertilizer (150 kg ha(-1) of N) improved shoot growth of A. elonga tum, especially at lime amendment rates of 0.5 and 4.0 t ha(-1) + 150 kg ha (-1) of N, but it did not improve root growth of either plant species. When compared with the tailings amended with lime (2 t ha(-1)) only, tailings r eceiving pig manure (25.2-50.3 t ha-(1)) and 2 t ha(-1) of lime effectively improved shoot and root growth and reduced tailings toxicity to seedlings of T. repens, especially at 50.3 t ha(-1) of pig manure. However, only tail ings receiving 37.8 t ha(-1) of pig manure and 2 t ha(-1) of lime significa ntly increased shoot and root dry weight of A. elongatum. Plant tissue anal ysis showed that applications of lime and pig manure did not significantly reduce Zn, ph and Cd uptake and accumulation in A. elongatum. However, high er pig manure amendment rates ( > 25.2 t ha(-1)) significantly reduced Ph c ontent in shoots of T. repens. (C) 1999 Elsevier Science Ltd. All rights re served.