In this study, the concentrations of seven heavy
metals in soils were determined. The normal
levels of metals in soils which are not harmful
are: Cd (1 mg/kg), Cr (34 mg/kg), Cu (20-30
mg/kg), Pb (50 mg/kg) and Zn (50 mg/kg). Their
concentrations in the soils sampled exceeded
normal levels of metals in soils [45,46], thus,
making them to be termed contaminated soils.
Therefore, there is a strong need to remove
heavy metals from the soils to make them safe
for agricultural activities. Phytoextraction with
sunflower has been reported to be very efficient
in removing metals from polluted soil but due to
the low availability of these metals, chelating
agents are applied to soils to enhance their
uptake by plants