Effect of Poultry Manure Amendment on the Distribution and Mobility of Heavy Metals in Naturally Contaminated Dump Soil

In this study, the effect of poultry manure amendment on the availability of some heavy metals, (Cu, Cr, Mn and Zn) was evaluated. The uptake of the metals by Ricinus communis (castor oil) with and without amendment was conducted in a green house. Soil sample was treated with 5%, 10% and 20% of poultry manure in a pot experiment. There was an increase in physicochemical properties of the soil such as pH, organic matter content and ECEC on treatment. Chemical speciation of the parent soil indicated that there was appreciable concentration of the metals in the extractable fraction. After three months of planting, the results showed that the extractability of the metals decreased significantly mostly with increase in percentage amendment. Residual fractionsgave the highest concentration of the metals and extractable having the least. 20% amendment has the best immobilization potential for Cu (7.07%), Cr (9.68%) and Mn (15.17%). The results also showed that amendment decreased plant metal uptake, generally decreasing as percentage amendment increased. These findings will be useful in the assessment and remediation of heavy metal-contaminated soils.