STUDY ABOUT THE LEAD TRANSFER FROM SEWAGE SLUDGE INTO AGROECOSYSTEMS

In order to study the evolution of Pb contents both in soil and plants, progressive sludge doses were spread: 0 t.ha-1, 5 t.ha-1, 10 t.ha-1, 25 t.ha-1 and 50 t.ha-1 together with the chemical fertilizers (NP type) in levels 0, ½ and 1/1 from doses indicated for: maize, winter wheat and soybeans. The three plants absorbed Pb2+ ions or not, in quantities considered unnecessary. Thus, the maize and soybean didn`t absorbed Pb , wheat second year containing in leaves 4-6 mg.kg-1 and in fourth year around 5 mg.kg-1d.w. Pb was deposited only in wheat grains (year 2), between 3 and 2 mg.kg-1, in a negative correlation with grain yields. The sewage sludge seems to be un organic fertilizer with an-dangerous concentrations of this heavy metal, the lead (Pb), for agricultural medium