Organic amendments impact the availability of heavy metal(loid)s in mine-impacted soil and their phytoremediation by Penisitum americanum and Sorghum bicolor.

The amendment of contaminated soil with organic materials is considered to be an environmentally friendly technique to immobilize heavy metal(loid)s and minimize their subsequent bioaccumulation in plants. This study focuses on the effects of different amendment techniques, such as the use of activated carbons (granulated or powder) and farmyard manure at various application rates (2 and 5 %). These techniques were applied on heavy metal(loid)s such as Ni, Cr, Cd, Pb, Mn, Cu, Zn, Fe, Co, and Al that were present in mine-impacted soil and caused bioaccumulation in cultivated plants. The results showed that, compared with the control, almost all the techniques significantly (P ≤ 0.01) reduced the bioavailability of heavy metal(loid)s in the amended soil. The bioaccumulation of heavy metal(loid)s in Penisitum americanum and Sorghum bicolor was significantly (P ≤ 0.01) reduced with all techniques, while Zn and Cd concentrations increased with the use of farmyard manure. Also compared with the control, plant growth was significantly decreased with the use of activated carbons, particularly with powder activated carbons, while farmyard manure (at 5 %) significantly (P ≤ 0.01) increased plant growth. Among the amendment techniques, powdered activated carbons (at 5 %) were best at reducing the bioavailability of heavy metal(loid)s in soil and plant accumulation. However, it negatively affected the growth of selected plant species.