A pot experiment was carried out, over a period of three years, based on the completely randomised model with three replications. The aim of the investigation was estimation of changes in the content of cobalt, lithium and aluminium in organic materials, in soil and in the dry mass of Lolium multiflorum Lam. under the influence of brown coal, waste activated sludges, their mixtures and mineral fertiliza-tion. The total content of Co, Li and Al in organic materials, soil and in dry mass of grass after dry combustion of samples was determined by ICP-AES method on the spectrometer Optima 3200 RL manufactured by Perkins-Elmer. The mean content of cobalt in tested plants reached 1.39 mg kg-1 , lithium 53,97 mg. kg-1 and aluminium 402,6 mg kg-1. The highest content of cobalt in dry matter of the tested plant, Italian ryegrass, was reached on the control object, while the highest levels of lithium and aluminium were recorded in dry mass of grasses from the objects where mixtures of waste brown coal from Konin and waste activated sludge from Łuków were applied.