Effect of an artificial soil mix from coal fly ash and sewage sludge on soil microbial activity

Jonathan W C WONG*, Ka Man LAI

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

37 Citations (Scopus)


An artificial soil mix was prepared from coal fly ash and sewage sludge and an experiment was performed to evaluate their effects on soil microbial respiration. Coal fly ash at 0%, 5%, 10%, 35%, and 50% w/w was mixed with dewatered sewage sludge and then each ash-sludge mixture was incubated with a sandy soil at 1:1 v/v at 28°C for 42 days. All treatments showed the same carbon dioxide production pattern with a peak production at day 7 to day 14. Addition of ash-sludge mixtures to soil resulted in an increase in carbon dioxide production but the production rate decreased according to the ash amendment rate. The high pH of coal fly ash and the dilution effect of the sludge were the major reasons for the decrease. However, the ecological dose 50% values sharply in creased from 26% at day 3 to 39% ash at day 14. This indicates the rapid acclimatization of microorganisms to the fly ash-sludge mixtures. Therefore, a brief stabilization period may be required for the establishment of soil microbial populations in soil amended with ash-sludge mixtures.

Original languageEnglish
Pages (from-to)420-424
Number of pages5
JournalBiology and Fertility of Soils
Issue number4
Publication statusPublished - Nov 1996

Scopus Subject Areas

  • Microbiology
  • Agronomy and Crop Science
  • Soil Science

User-Defined Keywords

  • Artificial soil mix
  • Coal fly ash
  • EcD
  • Sewage sludge
  • Soil respiration


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