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There is little information available on the impact of superphosphate and compost on the uptake of metals by okra (Abelmoschus esculentus L. Moench). The objective of this study is to evaluate the efficiency of superphosphate and compost in reducing metals uptake by okra to healthy acceptable levels. A field experiment in randomized complete block design (RCBD) was conducted to investigate the effect of superphosphate (SP) and compost (C) on the availability and uptake of heavy metals by okra cultivated on a metals contaminated soil. The application of SP or C significantly (P 0.05) reduced the availability and uptake of Cu, Pb, and Cd by okra. The C+SP treatment reduced the concentrations of Zn, Pb, and Cd in the edible portion of okra by 14, 35, and 38%. The combined application of C and SP was more effective in reducing the Zn, Pb, and Cd concentrations compared to the sole application of each amendment. The edible portion of okra collected from the unfertilized contaminated soil or that which received only C or SP contained toxic levels of Pb and Cd, while the concentrations of the two metals were below the safe limits when the two amendments were applied together. The result of the current study clearly indicated that it is feasible to apply P fertilizer and compost together to alleviate root-to-shoot transfer of Zn, Cu, Pb, and Cd in okra.

Phytostabilization of heavy metals in contaminated soils should be subject to two conditions, the first is the choice plant must be able to stabilize heavy metals in soil, the second is the plant material which produced from the phytostabilization process must be safe and useful to avoid overload on environmental system. A field experiment was conducted out to evaluate the phytostabilization potential of two halophytes species (Atriplex lentiformis and Atriplex undulata). Compost at rates of 0, 15 and 30 ton ha-1 was used to examine its role in plant growth and heavy metals uptake. The high rate of compost (30 ton ha-1) decreased zinc (Zn) concentrations in the leaves of A. lentiformis and A. undulata by 15.8 and 13.0%, while lead (Pb) in the leaves decreased by 37.6 and 35.2% respectively. Despite the extremely high total heavy metals concentrations in the studied soil, plants of Atriplex were able grow and maintain shoots metals content below the toxic level and the produced plant materials had a high nutritive value compared to the conventional forage crops. Phosphorus (P) and chloride (Cl) in the roots of Atriplex plants play important function in heavy metals phytostabilization mechanism by the two halophyte plants.