Effect of Arak Municipal Sewage Sludge Application on Corn Cd Uptake in a Loamy Soil

Emission of heavy metals pollutants caused by human activities is one of the most important issues in today’s society. The management and application of organic wastes in agricultural lands decreases environmental risks and increases utilization of these materials. A greenhouse factorial experiment was conducted to investigate the effect of Arak municipal sewage sludge on corn Cd uptake in a loamy soil, using a randomized complete block design. Treatments consisted of applying sewage sludge (0, 15 and 30 t ha-1) polluted with cadmium at the rates of 0, 5, 10 and 15 mg kg-1 and DTPA at the rates of 0 and 1.5 mmol kg-1 soil. Sixty days after corn sowing, soil physico-chemical properties and soil and corn Cd concentrations were measured. Increasing the loading rates of sewage sludge from 0 to 30 t ha-1 caused a significant increase in cation exchange capacity (3.5 units) and a significant decreasing in soil pH (0.3 units), respectively. Applying 1.5 mmol DTPA chelate in a soil treated with 15 and 30 t ha-1 polluted sewage sludge (15 mg Cd) increased the plant Cd availability by 8.2% and 15 percent, respectively, and decreased phosphorous availability by 4% and 14 percent, respectively. Almost 79 % of Cd uptake changes were estimated by shoot Cd concentration. The result of this study showed that applying DTPA chelate can increase corn Cd uptake and its phytoremediation efficiency.