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Sewage sludge application on agricultural land as an organic fertilizer the recycling of valuable components such as many plant nutrients. Sewage sludge is rich in macro and micronutrients. However, high concentrations of heavy metals in sludge may cause pollution of soil, groundwater and the human food chain because of toxic metal uptake by crops. The objective of this research was to investigate the effect of sewage sludge application on concentration of iron and manganese in parsley. This study were carried out in a factorial experiment in a completely randomized design with three replications in greenhouse condition. The amounts of 0, 1, 2, 4, 8 and 16% of the soil dry weight of the sewage sludge were added to the pots having soil of three areas (Baharan, Najvan and Shakrekord). Parsley seeds were planted in the pots and was harvested in five leaf stage. The sewage sludge application did not significantly affect soil pH, but EC was increased by 71-107% in 16% of sewage sludge in the three soils. Also, sewage sludge application significantly increased by 22-54 and 23-27% the concentrations of P and K in soils, respectively. In Shakrekord area, using the sewage sludge had a significant effect on concentration of Fe in parsley and increased by 27% in 16% of sewage sludge. In Najvan area, the application of sewage sludge (with the exception of 16% level) significantly increased by 5-17% the concentrations of Mn in parsley.

The objective of this study is to investigate the effect of three kinds of biosolids usage on soil chemical properties and uptake of heavy metals by Cercis siliquastrum leaves. The experiment was carried out in a completely randomized block design with seven treatments including: no fertilizer as a control (C), sewage sludge (SW), cow manure (CM), municipal solid waste compost (MC), mixture of sewage sludge and cow manure (50% SW + 50% CM), mixture of sewage sludge and municipal solid waste compost (50% SW + 50% MC) and mixture of cow manure and municipal solid waste compost (50% CM + 50% MC) at three levels of 0, 2.5 and 5 kg/shrub and three replicates in calcareous sandy loam soil at the botanical garden of Mobarekeh steel company. After 180 days, soil samples were collected from 30 cm depth and leaves assemblage. Results showed that the treatments had significant effect (P < 0.05) on organic matter content, pH, electrical conductivity and cation exchange capacity of the soil. Total diethylen-triamine pent acetic acid (DTPA) extractable concentrations of Zn, Fe and Pb increased significantly (P < 0.05) in biosolid treatments. Between unwashed and washed metals concentrations of leaves, significant differences were shown, so it appeared that the source of metals on leaves was mainly airborn.