Incidence of sewage sludge fertilizer application on Ray Grass (Morocco)

The land application of sewage sludge reveals a significant increase in the dry matter production of Ray Grass. In equivalent dose of liquid mud, we registered a lower production of dry material, which could be the result of a loss though lixiviation of a quantity of nitrogen brought by mud. Besides, neither the dose nor the type of mud seems to have an effect on the Pb, Cd, Cu and Zn contents in the air part of the plant. On the other hand, it noticed that the contribution of mud under dry or liquid forms increases significantly the contents of Cd, Pb and of Zn in roots with regard to the witness without mud. The comparison between the beginning and the end of culture, revealed a decrease of the content in Cd, Zn, Pb and Cu in the ground in particular at the level of the superficial coats (0-40 cm). Besides, this decrease of the contents in Cd, Zn, Pb and Cu in the ground is in no case connected to increase in the air part of the plant but rather, is for an accumulation in the roots, which play the role of a barrier, or a migration of these elements beyond roots.