Premium
Carbon Cycling During Sewage Sludge Decomposition in Soils
Author(s) -
Terry R. E.,
Nelson D. W.,
Sommers L. E.
Publication year - 1979
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1979.03615995004300030013x
Subject(s) - organic matter , sewage sludge , decomposition , soil water , incubation , chemistry , environmental chemistry , soil organic matter , dissolved organic carbon , sewage , environmental science , environmental engineering , soil science , organic chemistry , biochemistry
The objectives of this study were to determine the extent and kinetics of sludge decomposition in soil, to evaluate the effects of sludge addition on microbial degradation of soil organic matter, and to determine the distribution of residual sludge organic C in soil organic matter fractions. Synthetic sewage sludge was prepared by anaerobically digesting a mixture of 14 C‐labelled Candida utilis cells and inorganic salts. The prepared sludge had a composition which was similar to that of many anaerobically‐digested municipal sludges. Synthetic sludge was added to soils and 14 CO 3 activity and CO 2 production were measured periodically during 336 days of incubation. At the end of incubation, the distribution of residual 14 C in soil organic matter fractions was determined. Sludge decomposition was rapid during the first 28 days of incubation and then decreased to a slower, nearly constant rate for the remainder of the period. At the end of 336 days of incubation, 46% of synthetic sludge organic 14 C was evolved as CO 2 . In comparison, 26 to 42% of added organic C was apparently evolved as CO 2 from soils treated with municipal sludges and incubated for 130 days. These findings suggest that a fraction of anaerobically‐digested sludge was readily decompossible when added to an aerobic soil; however, the major portion of sludge organic matter (55 to 80%) was resistant to decomposition. There was a linear relationship between cumulative 14 CO 2 evolution and the log of incubation time. From this relationship the turnover time of synthetic sludge in soil was calculated to range from 343 to 890 years. Decomposition of sludge in soil increased the degradation of native soil organic matter by approximately 100% over a period of 336 days. At the end of 168 days of incubation, 62% of the residual sludge organic 14 C added in sludge was recovered from soils as humic and fulvic acids.