Effect of Organic and Inorganic Iron Sources on Pb Concentration of the Plants Grown in the Soil Treated with the Biochar of Arak Municipal Sewage Sludge

Background: This study investigated the effect of inorganic and organic sources of iron on Pb availability in soil. Methods: The treatments involved applying organic and inorganic Fe sources at the rate of 0, 30, and 60 kg/ha pure Fe from different sources in the Pb-polluted soil treated with municipal sewage sludge biochar (MSSB). Corn was chosen as the tested plant in this experiment. The plants were collected after 90 days, and the Pb concentration in the soil and plants was determined using atomic absorption spectroscopy (AAS). Further, the plant enzyme activity was determined. Results: Soil application of ethylenediamine Di-2-Hydroxyphenyl Acetate Ferric (Fe-EDDHA) had the greatest efficiency in reducing the soil and plant concentration. Using 30 kg Fe/ha from Fe-EDDHA relative to iron slag and FeSo4 source significantly decreased the plant Pb concentration by 11.6 and 9.8%, respectively. For ascorbate peroxidase (APX) and peroxidases (POX) enzyme activity, it was decreased by 17.2 and 15.4%, respectively. Conclusion: Considering the results of this research, using inorganic and organic Fe sources in soil treated with MSSB had a substantial impact in reducing the soil and plant Pb concentration which is an advantage of environmental studies.