An incubation experiment was conducted under laboratory conditions to study the effect of heavy metals (Cd, Cr and Pb), soil types (sandy, loam and clay) and incubation periods (7, 15, 30, 60, 90 and 120 days) with respect to their impact on soil invertase enzyme activity. The heavy metals decreased soil invertase activity, and the order of decrease varied when compared at 0, 10, 50,100 and 1000 ug g–1 soil. Increasing the concentration of heavy metals and incubation periods adversely affected the soil invertase activity. The largest decrease (40%) in invertase activity was recorded for Cd at 1000 ug g–1 soil contamination, followed by Cr (38%) and Pb (36%), compared to the control. Maximum soil invertase activity was found after seven days of incubation. Clay soil had the highest invertase activity, followed by loam and sandy soil. Heavy metals reduced soil invertase activity in the order Cd > Cr > Pb.

Key words: heavy metals, incubation periods, invertase enzyme activity, soil types

Land Contamination & Reclamation, 18 (2), 175-180 (2010)