Availability and Uptake of Cadmium, Copper, and Zinc by Radish Plant Grown on Contaminated Soils as Affected by Compost Amendment

The study was conducted to elucidate the effect of three levels of compost amended soils (0, 3, and 6%, w/w) on Cd, Cu, and Zn extractability and uptake by radish plant (Raphanus sativus) grown in calcareous and sandy soils contaminated with 0, 40, 80 or 160 mg metal kg^-1 soil. DTPA extraction and greenhouse experiments were designed. The study revealed that the addition of compost treatments improved the plant biomass in both uncontaminated/contaminated two soils since the dry weight of shoots and roots for the two compost treatments was higher than that of the control (0 compost addition) even in high contamination level. Also, For Cu and Zn, the plants cultivated in metals levels (40-160 mg kg^-1) showed a significant increase in the dry weight in both radish shoots and roots grown in the both soils; whereas increase Cd levels from 40 to 160 mg kg^-1 decreased the dry weight of both radish shoots and roots. DTPA extractable Cd and Cu in addition to their concentrations in radish shoots/roots grown in the soils were decreased as a result of compost amendments with more pronounced at high compost level; whereas the opposite results were obtained for Zn. Good correlations were obtained in most cases between DTPA extractable metals and absorbed by radish plant indicated by correlation coefficients. These findings highlight the applicable of compost to ameliorate Cd and Cu risks in high contaminated soils.