Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/9/2000
Publication Date: N/A
Technical Abstract: Use of metal-enriched sewage sludge as soil fertilizer may result in trace metal contamination of soils. This study was conducted to evaluate the effects of long-term sludge application on trace metal (Zn, Cu, Pb, and Ni) distribution and potential bioavailability in a Nigerian Ultisol. Total metal analyses, sequential chemical fractionation, and DTPA extractions were conducted on samples of control and sludge-amended pedons (a Rhodic Kandiustult and two Rhodic Kandiustalfs). Soil enrichment factors (EF) were calculated for each metal. The sewage sludge contained high levels of Zn and Cu but low levels of Pd and Ni. The control soil, contained low levels of all four metals. Compared with the control soil, the sludge-amended soils had elevated levels of Zn and Cu, reflecting the trace metal composition of the sewage sludge. Zn and Cu in the sludge- amended soils were enriched to a depth of about 2 m, indicating that they had moved from the soil surface where sludge had been applied. The sequential extraction and DTPA analyses indicated that the sludge-amended soils contained more readily extractable and plant available metals ions than did the unamended soil.