Effect of municipal solid wastes on arsenic leaching in soils is a controversial issue. Calcareous soil naturally bearing considerable amount of arsenic samples from Qorveh plain, in western Iran, was applied to assemble nine soil columns including three treatments of 0 (control), 30 and 60 percent of municipal solid wastes compost each triplicated. Four months of leaching experiment using 300ml of 833 mg L-1 ammonium phosphate twice a week showed less arsenic leaching for composted soil columns compared to the controls. The results approved that iron, phosphate, nitrate and arsenic concentration leakage significantly differed between the composted and the control columns as decreasing of arsenic leaching throughout the composted columns was also approved. Additionally, it seems soil water retention capacity influenced by amount of the compost added to the columns affects arsenic leaching intensity.
