Contribution of Rhizosphere Processes to Acacia Seedlings Adaptation into Polluted Soils of a Municipal Landfill (Cote d'Ivoire)

Abstract

Inadequate urban waste management in Cote d’Ivoire is the heavy metal source in soils used to produce vegetables. This represents a potential risk of food contamination. In order to find an efficient technique for soils depollution before their use in agriculture, an experimental study had demonstrated the ability of species of Acacia (mangium, auriculiformis and crassicarpa) to extract heavy metals from landfill soils. This work was undertaken to determine rhizosphere processes controlling Acacia growth in polluted soil. An experiment was carried out in hydroponic culture and on thin layer of landfill polluted soil during 3 months. During this experiment, growth parameters, soil chemical properties, heavy metal contents in soil (total and various fractions) and in plants were measured at the end of experiment. Results show that plant growth is related to the development of strategies in root zone. Plants released protons in their rhizosphere and lowering the redox potential, especially under Acacia crassicarpa, which stored the most level of heavy metal in in biomass. The other species produce organic acids allowing plants to grow with high biomass in soil with high content of heavy metal. Acacia crassicarpa is therefore the species better suited for depollution of landfill soil.