Effect of municipal solid waste compost and sewage sludge on yield and heavy metal accumulation in soil and black cumin (Nigella sativa L.)

In order to investigate the effect of municipal solid waste (MSw) compost and sewage sludge (SS) on yield and concentration of heavy metals in soil and black cumin (Nigella sativa L.) an experiment with MSW compost at 0, 15, 30 t.ha-1 (C0, C15 and C30) and sewage sludge at 0, 15, 30 t.ha-1 (S0, S15 and S30) in a factorial experiment based on completely randomized design with three replications was conducted in greenhouse of Faculty of Agriculture, Ferdowsi University of Mashhad, Iran. Results showed that MSW compost and SS had significant effects on plant dry matter. Increasing the amounts of SS increased dry matter of plant. But increasing MSW compost from 15 to 30 t.ha-1 was decreased in dry matter. The Effect of MSW compost and SS on concentration of heavy metals (Ni and Pb) in plant except Cd was significant. Addition of MSW compost and sewage sludge increased availability of Pb, Ni and Cd in soil. But effect of MSW compost and sewage sludge on Cd availability was not significant. Results showed that the amounts of Ni exceed the standard limits in dry matter. Therefore in use of organic wastes for medicinal plants we should be careful.