Effect of Compost and Phosphate Applications on the Growth, Cadmium and Lead Uptake by Maize Plants Grown on Contaminated Soils

A pot experiment with maize (single cross-2030) was conducted to study the influence of phosphorus sources and levels and compost additions on growth, cadmium (Cd) and lead (Pb) contents of maize, as well as the availability of cadmium and lead in rhizosphere soil after the harvest of maize plants in three contaminated soils. It was observed in the three soils used in this study that compost addition increased significantly shoots and roots dry weight of maize plants and performed better than phosphate. With the three soils used in the study, results indicated that plants grown in soils amended with compost and supplied with rock phosphate (RP) at the high phosphate level, recorded the highest shoots & roots dry weight. Cadmium & lead contents of the both shoots & roots of maize plants were significantly reduced as a result of compost treatment. Rock phosphate addition significantly reduced Cd and Pb contents of both shoots and roots compared to single supper phosphate (SSP) for all soils examined. Increasing phosphate levels markedly reduced Cd and Pb contents of both shoots and roots with all soils studied. Also, the results revealed that plants grown in soils amended with compost and supplied with RP at high phosphate level recorded the lowest cadmium and lead contents of shoots and roots for the three soils used in this study. The availability of cadmium and lead in rhizosphere area after the harvest of maize plants were significantly decreased in all soils studied as a result of compost treatments. RP treatments significantly decreased the availability Cd and Pb in rhizosphere area of all soils studied compared to SSP addition. The available Cd and Pb in rhizosphere area were reduced as a result of increasing phosphate levels. The lowest value of available cadmium and lead in rhizosphere area of all studied soils were recorded for soils amended with compost and treated with RP at the high phosphate level.