Efficacy of biochar on the phytoremediation potential of Tithonia diversifolia on spent oil-contaminated soil

The application of biochar has gained attention as a simple, affordable and sustainable strategy for the remediation of contaminated soils. However, the phytoremediating potential of certain plants and interactions with biochar are necessary to achieve effective environmental clean-up. This study evaluated the influence of biochar on the remediation potential of Tithonia diversifolia grown in spent oil-contaminated soil. T. diversifolia was grown in spent oil-contaminated soil amended with rice biochar and sorghum biochar at four different application rates (1, 2 and 3% w/w) for 6 weeks. The heavy metals studied included copper (Cu), zinc (Zn), lead (Pb), cadmium (Cd) and chromium (Cr). The results of this study showed that compared with the other treatments, rice biochar strongly enhanced the growth of T. diversifolia. RB3% influenced the phytostabilization potential of T. diversifolia for Cu. However, StB3% and SB3% enhanced T. diversifolia’s potential capacity for the phytoextraction of Cr and Pb, respectively. Generally, the response of T. diversifolia to phytoextraction and phytostabilization is dependent on the biochar and application rate used. Hence, there is a need for further research on the use of T. diversifolia for remediation purposes under the influence of specific biochar types and application rates.