Release of Metals from Sludge Amended Acid and Alkaline Soils Under Different Levels of Moisture and Temperature

In an incubation experiment, effect of ten levels of sludge (0, 1.12, 2.24, 4.48, 8.96, 17.9, 35.8, 71.6, 142, 285 g kg −1 ), two levels of moisture (field capacity and 2.5 cm standing water) and two levels of temperature (20 and 35 °C) on the release of copper (Cu), iron (Fe), manganese (Mn), nickel (Ni) and lead (Pb) was evaluated in acid and alkaline soils. Application of sludge was more effective in enhancing ethylene diamine tetraacetic acid (EDTA) extractable metals in acid soil than alkaline soil. On an average, maximum increase in the release of EDTA extractable Cu, Fe, Mn, Ni and Pb were 2.5, 2.6, 3.8, 4.7, 1.7 fold in sludge treated soil over control. There was a decrease in EDTA extractable Cu, Ni, and Pb by 64.4, 23.0, and 14.0 %, respectively under submergence as compared to that under field capacity. On the contrary, EDTA extractable Fe and Mn increased by 14.1 and 13.7 %, respectively under submergence. On an average, amount of EDTA extractable Cu, Fe, Mn, Ni, and Pb increased by 52.5, 80.8, 40.9, 27.3, and 55.1 %, respectively at 35 °C than that at 20 °C.