Effect of periodic application of wastewater on chemical forms of zinc and copper in soil depths

The current study was carried out in order to investigate the effect of periodic application of wastewater on some soil chemical properties and distribution and migration of Cu and Zn in soil profile. Application of wastewater on the soil properties showed that, irrigation with wastewater decreased soil pH and CCE, and on the other hand, increased Ec, SAR and OM, compared with non irrigated soils. The change of Zn and Cu fractions with depth for non-irrigated soil showed that Zn and Cu are strongly associated with the residual fraction. Chemical forms of Cu and Zn tendency to decrease with depth. Increased wastewater after 6 and 12 months caused increases in all chemical forms of Zn (except Carbonate form), especially in the surface layer. The mobility factor of Zn was reduced in three layers after 6 months of irrigation. In contrast, after 12 months of irrigating with wastewater resulted in the transformation of metals from the non mobile fraction towards the mobile fraction and finally mobility factor of Zn was increased in three layers. The result showed higher concentrations of chemical forms of Cu in the surface layers than sub surfaces. In irrigated soil, concentration of Chemical forms of Cu tendency to decrease with depth. The mobility factor of Cu was increased in three layers after 6 and 12 months of irrigation. Generally, application of wastewater caused increase in chemical forms of Zn and Cu and finally mobility factor, however, these factors were below of very mobile range.