Phyto-extraction of Copper, Iron, Manganese, and Zinc from Environmentally Contaminated Sites in Ethiopia, with Three Grass Species

Rhodegrass (Chloris gayana cv. Kallide) and forage setaria (Setaria sphacelata cv. Kazungula), two indigenous grass species, and oat (Avena sativa L.), a recently introduced forage crop, were grown on contaminated sites in Ethiopia, to determine their potential in removing copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) from the soils. Soil pH influenced the availability and plant uptake of micronutrients; therefore, the grasses grown at the industrial waste site with a high pH, had the lowest micronutrient concentrations. Setaria and rhodesgrass had higher concentrations of all the micronutrient metals than oat. Rhodesgrass and setaria accumulated concentrations of Fe and Mn, normally considered toxic to many crops, without developing chlorotic symptoms and yield suppressions. Iron in setaria and Zn in rhodesgrass declined significantly with advancing maturity. Considering biomass yield and tissue concentration, it was found that setaria removed the greatest quantity of micronutrients per unit area of soil.