Effects of fertilization with sewage sludge and sewage sludge-based mixtures of heavy metals mobility

The presented work aimed at evaluating a fertilizing mixture of sewage sludge, brown coal and brown coal ash enriched with potassium mineral fertilizer on mobility of heavy metals. The effects of fertilization were compared with the effects obtained from fertilization with: sewage sludge, mixture of sewage sludge and mineral fertilizer, mixture of brown coal and mineral fertilizers and mineral fertilizers. Soil was slightly contaminated with zinc and cadmium (II°) and showed elevated concentration of lead (I°). The uptake of heavy metals by plants depended on the concentration of bioavailable metal forms determined with 0.01 M CaCl2 and 1 M HC1. Fertilization with the mixture of sewage sludge, brown coal, brown coal ash enriched with potassium mineral fertilizer resulted in the reduction in the concentrations of zinc by 30-38%, cadmium by 28-34% and lead by 11-50% in plant biomass compared to soil with no fertilization.