The effects of fly ash-containing sludge amendment on nitrogen content and urease activity of soils

Topac F. O., Baskaya H. S., Alkan U.

FRESENIUS ENVIRONMENTAL BULLETIN, vol.16, no.5, pp.532-536, 2007 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 16 Issue: 5
  • Publication Date: 2007
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.532-536
  • Keywords: fly ash, nitrogen, soil, urease activity, wastewater sludge, SEWAGE-SLUDGE, STABILIZATION, WASTES
  • Bursa Uludag University Affiliated: Yes


The present study was undertaken to demonstrate the effects of fly-ash addition to sludges on nitrogen content and urease activity of soils. Wastewater sludges added with varying doses of fly-ash (40, 80 and 120%, on dry weight basis) were amended to a clay soil, and the variations in ammonium, nitrate and total nitrogen contents and urease activities were monitored during incubation at 28 degrees C for 360 days. Co-application of fly-ash and wastewater sludge, especially at the dose of 120 % fly-ash, caused an initial decrease in inorganic nitrogen and urease activity levels in contradiction to sludge-only application. However, after the first 3 months of incubation, this adverse effect almost disappeared. Application of fly-ash/sludge mixture to soil with appropriate dosages (< 120%) may not affect the microbiological processes occurring in soil system.