Dynamics of extractable cadmium and soil pH as influenced by poultry manure application

The study was conducted using soil samples from different locations and land uses in southwestern Nigeria. This is with a view for evaluating the influence of poultry manure additions on changes in extractable cadmium (Cd) and soil pH. The laboratory incubation experiment was conducted at the National Horticultural Research Institute (7°25”N, 3°52”E), Ibadan, Oyo State, Nigeria, by weighing 200 g each of soil into polythene bags. Cadmium was added as CdCl₂.2H₂O to achieve concentrations of 20 mg kg^‑1 Cd, thoroughly mixed and then incubated. Poultry manure was previously added to each soil at varying proportions (0, 4 and 8% (w/w) basis), corresponding to 0, 112 and 224 g of poultry manure to soil. The samples were kept in field moist condition during the incubation period. Soil samples were taken at intervals of 0, 5, 10, 15, 20 and 30 days and then analyzed for extractable Cd and soil pH. Results showed that soils amended with 8% poultry manure had lower extractable Cd and higher soil pH content. Soil pH increases of up to 2.32 units were obtained.