INFLUENCE OF THE URBAN SLUDGE USED AS FERTILIZER ON THE CHEMICAL COMPONENTS OF SOIL AND LEAVES OF IDARED APPLE.

It is known that the urban sludge resulted from clearing of the waste waters has a complex and various composition due to several factors. The utilization of sludge as fertilizer in agriculture has to prevent the pollution of environment which is primarily caused by some pathogens infestation or by the increased content in chemicals beyond the maximum limits admitted by the legislation. To determine the effects of such sludge on the chemical compounds in soil and plant some investigations were carried out at the RIFG Pitesti in 2006. The experiment involved Idared apple grown in large pots (0.785 m 3 ). The following experimental scheme was organized: A factor = depth of planting substrate for applying the organic matter on it, with two graduations: a1 = 0 - 30 cm; a2 = 0 - 60 cm; B factor = type and amount of organic matter applied (g/l substrate), with the following graduations: b1 = 0; b2 = manure 340 g/l; b3 = sludge 170 g/l; b4 = sludge 340 g/l; b5 = sludge 510 g/l; b6 = sludge 680 g/l; C factor = soil sampling depth with two graduations: c1 = 0 -30 cm; c2 = 30 – 60 cm. The soil samples were collected from pots in abo ut 5 months after tree planting to determine the contents of organic matter and of major macro and microelements. The same macro and microelements as well as some heavy metals were found in the water samples drained at the pot bottom. From the leaves collected from the middle of annual shoots, the macro and microelements were also determined. The chemical compounds, except the total soluble salts from the soil samples showed no significant differences. In the case of a2 = (0 - 60 cm - planting substrate), the total soluble salts were significantly higher by 126% vs. a1 = (0 - 30 cm - planting substrate. The manure application (340 g/l) did not show a significant increase in total salts versus the unfertilized control, but the sludge rates (b4-b6) led to a significant raise by 172-238% vs. unfertilized control (b1). In case of waters drained at the pots bottom and also of leaves, the chemical compounds did not significantly vary. Of the total chemicals from the waste waters (Fe, Ca, N, B, Zn, Cd, Cr) only the Zn content of 4 samples had higher values than those stipulated in NTPA 001 regulation. At the c2 = (30 – 60 cm) soil depth. the total salts content was significantly higher by 132% versus c1 = (0 -30 cm).