Short- and Long-Term Effects of Modified Humic Substances on Soil Evolution and Plant Growth in Gold Mine Tailings
2013
Szczerski, Carl | Naguit, Christian | Markham, John | Goh, Tee Boon | Renault, Sylvie
Mining creates large amounts of processed waste in the form of mine tailings. Sulfide mine tailings are of particular concern due to the biotic and abiotic oxidation of sulfide minerals that release acidity and metals into the environment. Revegetation can be employed to mitigate the spread of tailings in the environment. Revegetation often involves ameliorating tailings with organic materials to promote plant growth and improve tailings physicochemical structure. We amended plots in the Central Manitoba Mine tailings pond with humic substances applied at rates up to 4 g C kg-1 through roto-tilling and seeded with Medicago sativa and Elymus trachycaulus in 2003 and 2004. The humic substances improved tailings fertility by increasing macro aggregation, organic carbon, and macronutrients but also resulted in a short-term increase in electrical conductivity levels. In the first growing season the humic amendment had little effect on plant yield, except in the 2003 experiment where the yield of E. trachycaulus decreased by 84 % with 4 g C kg-1 amendment. After 7 years, the addition of humic amendment resulted in a cover of over 38 % for M. sativa, compared to less than 2 % in control plots. In addition, non-seeded species cover increased with amendment rate in the 2003 experiment but not the 2004 experiment, most likely due to lower pH in the latter. Our results suggest that short-term patterns of plant performance do not reflect longer-term performance or invasion by volunteer plant species. Our long-term data suggest that humic amendments can be effective in establishing plant invasion of mine tailings, although the effects vary depending on the pH of the tailings. © 2013 Springer Science+Business Media Dordrecht.
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