Earth worm role on bioremediation of lead and cadmium heavy metals in maize

To investigate the earthworm role in bio-remediation of lead and cadmium heavy metals and changes in their adsorption trend in corn, a pot experiment was carried out as factorial based on randomized completely block design with three replications in 2011. The treated pots received 20 earthworm individuals with 0, 150 and 300 mg/kg of cadmium (Cd) and lead (Pb). The increase of Cd and Pb concentrations led to higher Cd and Pb accumulation in grains. Pb highly accumulated in roots; however, Cd root accumulation was 63% less. Also, an increment of 14% was observed in plant tolerance index in presence of earthworm up-taking considerable amount of Pb and Cd. More tolerated plants against Pb was because of higher Pb translocation to shoots than Cd. Higher concentrations of Pb and Cd in soils severely decreased earthworm population and increased their accumulation in earthworm, indicating the success of the earthworm in the bio-remediation of heavy metals. Furthermore, Pb accumulated in higher levels than Cd in earthworm bodies. Therefore, earthworm application is recommended in bio-remediation of soils contaminated to heavy metals.