Phytoavailability of Some Micronutrients (Zn and Cu), Heavy Metals (Pb, Cd), and Yield of Rice Affected by Sewage Sludge Perennial Application

A study was conducted as a split-plot arrangement based on a randomized complete block design with three replications to test sewage sludge (SS) influence on yield and phytoavailability of lead (Pb), cadmium (Cd), zinc (Zn), and copper (Cu) by rice. The results indicated that fertilizer (main factor) and application periods (subfactor) affected studied traits. Three years of application of 40 ton ha(-1) SS + 50% chemical fertilizer (CF) gave the greatest paddy yield. The greatest Cu uptake by grain (10.38 ppm) occurred with 3 years application of 20 ton ha(-1) SS. With application of 40 ton ha(-1) SS + 50% CF, the greatest contents of Cd in root and Pb in shoots were recorded. The greatest accumulations of Cd in shoot and Zn in grain (30.56 and 25.81 ppm, respectively) were determined with the 20 ton ha(-1) SS treatment, as well. The greatest concentrations of Pb and Cd in grain (102.2 and 14.78 ppm, respectively) and Pb in root (552.2 ppm) were obtained with 3 years of application of 40 ton ha(-1) SS + 50% CF.