Growth response of Sesbania rostrata and S-cannabina to sludge-amended lead/zinc mine tailings - A greenhouse study

Legumes are ideal for revegetation of metal-mined wastelands which lack nit rogen (N). A greenhouse study was conducted to investigate the feasibility of using Sesbania rostrata and S. cannabina for the reclamation of lead/zin c (Pb/Zn) mine tailings and to evaluate the effects of organic amendment us ing sewage sludge (0%, 25%, 50%, and 75%, v/v). The results showed that bot h species could continue to grow on the highly toxic tailings substrata for at least 80 days, although their growth suffered from adverse effects. Tha t S. rostrata with stem and root nodules had better growth (biomass, growth rates, and biomass of nodules) than S. cannabina suggested that S, rostrat a is a better choice as a pioneer species for revegetation of the mine tail ings. Stem nodules had less obvious adverse effects imposed by tailings tha n root nodules. Application of sewage sludge increased contents of total ca rbon (C), N, phosphorus (P), and potassium (K), and reduced total Zn, Pb, C d, and DTPA-extractable Pb and Cd in tailings substrata. These, in turn, re duced metal (Zn, Pb, and Cd) uptake and accumulation in plant tissues, and improved plant growth performance, including biomass, growth rates, stem no dulation. Fifty percent (v/v) of sludge application rate was the best loadi ng rate for plant growth. (C) 2001 Elsevier Science Ltd. All rights reserve d.