An incubation experiment using three contaminated soils from Helwan, El-Gabal El-Asfar (Cairo governorate) and Arab El-Madabeg (Assiut governorate) was conducted for 16 weeks to evaluate effects of four organic materials including ethylene diamine tetra acetic acid (EDTA) as a synthetic organic material as well as poultry litter extract (PLE), vinase (V) and humic acid (HA) solutions as natural or...