Effects of Sewage Sludge Composition, Application Rate, and Lime Regime on Plant Availability of Heavy Metals1
- Matt K. John and
- Cornelis J. Van Laerhoven2
Primary digested sludge from the metropolitan Vancouver sewage treatment plant and commercially available Milorganite were applied to unlimed (pH 5.6) and limed (pH 6.4) silt loam at 0, 5, 10, 25, and 100 g/kg in a growth chamber study involving romaine lettuce (Lactuca sativa L. var. longifolia) and beets (Beta vulgaris L.). Concentrations of Cd, Zn, Pb, Cu, Ni, Mn, and Fe in lettuce, beet tops, and beet tubers were not simply or solely dependent upon the resultant sludge-borne heavy metal contamination of the soil but a complexity of factors. Plant availability of the metals was influenced by the nature as well as the rate of sludge applied, lime regime, their interaction, the increase in soil acidity associated with Milorganite application and metal adsorption, and release from organic matter supplied.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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