Potentiality of Miscanthus Production in Zn Contaminated Soils

The increasing demand for biomass for the production of bioenergy is generating land-use conflicts which might be avoided through the establishment of dedicated energy crops on marginal land. But assessment of bioenergy from marginal land should take into account constraining factors, such as productivity and biomass quality, as well as environmental and social aspects. In this context, this research work aims to study the potentiality of Miscanthus production in Zn contaminated soils. During three consecutive growing cycles, the response of three Miscanthus genotypes (two species - Miscanthus sinensis and Miscanthus floridulus, and a hybrid – Miscanthus × giganteus) to Zn contaminated soils (450 and 900 mg Zn.kg-1 dry matter) under different water regimes (950 mm and 475 mm) was evaluated in terms of growth and biomass productivity. Results obtained and modelled show that at higher water regimes (950mm) growth and biomass productivity of Miscanthus was not affected by zinc contamination. At a lower water regime (475 mm), growth and biomass productivity of M. x giganteus, but not of M. floridulus and of M. sinensis, were negatively affected by the zinc contamination. Reducing the water application affects significantly the production of M. x giganteus and M. floridulus but not so significantly M. sinensis. M. x giganteus was also significantly more productive than the other two Miscanthus species. Zinc removal percentages by Miscanthus accumulation are not significant after three consecutive years, towards the Zn soil total fraction, yet, the establishment of a Miscanthus cover represent an approach to attenuate and stabilize contaminated sites with additional revenue to owners. Biomass obtained in Zn contaminated soils presented no effects in terms of ash content, thus showing potential to be used for energy production, even if the Zn content increased with Zn contamination