Amelioration potential of spent mushroom compost on physiochemical properties of heavy metal polluted soils in Uganda

Abstract

Heavy metal pollution of soils due to wastes from mining activities remains a global challenge. In Uganda, mining activity in Kasese has led to extensive land being left unutilized due to the poor quality of soils. Several studies have been undertaken to establish affordable methods of remediating the soils including addition of organic amendments to soil, in place of the conventional ones that are more expensive and impractical in large scale remediation efforts. This research was conducted to study the potential of spent mushroom compost to ameliorate the physiochemical properties of heavy metal polluted soil from the tailings in Kasese. Bidens pilosa was used as a test plant to observe plant response. Heavy metal polluted soil was obtained from Kasese tailings. 4kg of soil and SMC of concentrations 5%, 15% and 30% were added to pots respectively, in triplicates. Negative and positive controls inclusive. These were used to grow the test plant for 30 days. The effect of SMC on the physiochemical properties of the soil was determined through soil analysis before and after the experiment. Changes in microbial diversity were determined using the Total Plate count method and plant response by determining percentage germination, plant height and leaf area. The results of this study suggest SMC had a significant effect on the soil, that increased with increasing SMC concentration however, the changes were not effective enough to allow seedling establishment. The pH of the soil remained <2. Concentrations of Iron, Copper, Nickel and Cobalt reduced significantly. There was no germination in the treated pots, including the negative control. The microbial diversity changed but with minimal variance across the treatments. The research established that SMC does not efficiently ameliorate the physiochemical characteristics of heavy metal polluted soils from Kasese and would not be recommended for remediation processes.