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

Abstract

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.

Keywords:

• Phytoextraction
• Industrial waste
• Municipal wastes
• Indigenous species
• Ethiopia

Acknowledgments

We acknowledge the ESTC (Ethiopian Science and Technology Commission) and ENDA (Environment Development Action) Ethiopia, for covering the field expenses in Ethiopia. The interest, cooperation and support given by Mr. Camille de Stoop, the country coordinator of ENDA, made the field work a success. Special thanks goes to W/o Amakelech Bogale, from ENDA Ethiopia, for providing unreserved technical assistance during the field work. We are very thankful to Mrs. Gisele Morin-Labatut, who facilitated support from IDRC to cover travel cost and part of the laboratory expenses. The ILRI is acknowledged for supplying the planting materials and for the weather data. We are also very grateful for access to facilities, and excellent cooperation by the Forage Crops Section of the Saskatoon Research Centre of Agriculture and Agri-Food Canada. The Department of Soil Science of the University of Saskatchewan is acknowledged for its support in some of the laboratory analyses and Mr. Barry Goetz for the analytical work.