Effect of municipal solid waste compost and application time on accumulation of lead, nickel and cadmium in soil and corn plant

To evaluate the effect of application of municipal solid waste compost (MSWC) on the accumulation of heavy metals of lead, nickel and cadmium in the soil under maize cultivation, a factorial experiment in base randomized complete block design (RCBD) with four different amounts of municipal solid waste compost (zero, 15, 30 and 60 tons ha-1) and time (compost applied once or twice) was performed with three replications. The results showed that (MSWC) significantly increased total and DTPA extractable lead and nickel in soil in all treatments (P≤0.01), so that the concentrations of total and DTPA extractable lead in the treatment of 60 tons ha-1 was increased 1.38 and 1.89 times in compared to control. These increasing for nickel were obtained 1.27 and 4.21 times respectively. In all treatments the amount of cadmium was less than atomic absorption detection limit. The effects of (MSWC) apply replication times on accumulation of total lead and nickel in soil also was significant (P≤0.01), so that as compared with control for total Ni 4.4 and total Pb 2.7 percent was increased. In relevance with the accumulation of metals in maize, the results indicated that root uptake higher concentrations of these metals than shoots. This accumulation for nickel was more than lead (P≤0.01).So that concentration of lead and nickel root was increased 1.9 and 2.9 times in 60 tons ha-1 second year treatment in compared to control. Transfer factor was obtained 0.302 for Pb and 0.284 for Ni.