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Effect Of Substrate Concentration, Soil Moisture, And Organic Materials On Urease Activity Of Soil Contaminated With Lead
Published 2006 · Biology
Abstract A laboratory experiment was carried out in order to study the effect of substrate concentration, soil moisture, and type of organic materials on urease activity of soils containing variable lead (Pb) contents. Various Pb levels ranging from 52.1 – 589.9 mg kg−1 were created by mixing uncontaminated (containing 52.1 mg Pb kg−1 soil) and contaminated (containing 589.9 mg Pb kg−1 soil) soils in different proportions. Microbial biomass and urease activity were inhibited with increasing levels of Pb in soil. Urease activity ranged from 10.1 – 13.2 μg N hydrolyzed g−1 soil h−1 at 37°C. Urease activity was higher in uncontaminated than in Pb-contaminated soil and increased linearly with increasing substrate concentration from 200 – 800 mg N kg−1 soil. Activity was also enhanced with increasing moisture content up to field capacity (0.03 MPa) and reduced at flooding. Addition of organic materials through poultry manure, pressmud, farmyard manure (FYM) and sewage sludge enhanced the urease activity. A successive increase in the pressmud level (0, 0.1, 0.2 and 0.4% C) enhanced the urease activity of soil at all Pb concentrations.