Advanced

Influence of initial C/N ratio on chemical and microbial composition during long term composting of straw

Eiland, F; Klamer, Morten LU ; Lind, A M; Leth, M and Bååth, Erland LU (2001) In Microbial Ecology 41(3). p.272-280
Abstract
Shredded straw of Miscanthus was composted in 800-L boxes with different amounts of pig slurry added as nitrogen source. The impact of the different initial CIN ratios (11, 35, 47, 50, and 54) on the composting process and the end product was evaluated by examining chemical and microbiological parameters during 12 months of composting. Low initial C/N ratios caused a fast degradation of fibers during the first three months of composting (hemicellulose: 50-80%, cellulose: 40-60%), while high initial C/N ratios resulted in 10-20% degradation of both hemicellulose and cellulose. These differences were reflected in the microbial biomass and respiration, which initially were higher in low C/N treatments than in high C/N treatments. After 12... (More)
Shredded straw of Miscanthus was composted in 800-L boxes with different amounts of pig slurry added as nitrogen source. The impact of the different initial CIN ratios (11, 35, 47, 50, and 54) on the composting process and the end product was evaluated by examining chemical and microbiological parameters during 12 months of composting. Low initial C/N ratios caused a fast degradation of fibers during the first three months of composting (hemicellulose: 50-80%, cellulose: 40-60%), while high initial C/N ratios resulted in 10-20% degradation of both hemicellulose and cellulose. These differences were reflected in the microbial biomass and respiration, which initially were higher in low C/N treatments than in high C/N treatments. After 12 months of composting, this situation was reversed. Composts with high initial CIN ratios had high microbial biomass (15-20 mug ATP g(-1) OM) and respiration rates (200 mug CO, h(-1) g(-1) OM) compared to treatments with low initial C/N ratios (less than 10 mug ATP g(-1) OM and 25 mug CO2 h(-1) g(-1) OM). This could be explained by the microorganisms being nitrogen limited in the high C/N ratio treatments. In the low C/N ratio treatments, without nitrogen limitation, the high activity in the beginning decreased with time because of exhaustion of easily available carbon. Different nitrogen availability was also seen in the nitrification patterns, since nitrate was only measured in significant amounts in the treatments with initial C/N ratios of 11 and 35. The microbial community structure (measured as phospholipid fatty acid, PLFA, profile) was also affected by the initial C/N ratios, with lower fungal/bacterial ratios in the low compared to the high C/N treatments after 12 months of composting. However, in the low C/N treatments higher levels of PLFAs indicative of thermophilic gram-positive bacteria were found compared to the high C/N treatments. This was caused by the initial heating phase being longer in the low than in the high C/N treatments. The different fungal/bacterial ratios could also be explained by the initial heating phase, since a significant correlation between this ratio and heat generated during the initial composting phase was found. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Microbial Ecology
volume
41
issue
3
pages
272 - 280
publisher
Springer
external identifiers
  • scopus:0034964844
ISSN
1432-184X
DOI
10.1007/s002480000071
language
English
LU publication?
yes
id
41fe48ca-3b49-4f67-8c37-1a4b39edc4bb (old id 146956)
date added to LUP
2007-06-29 09:34:36
date last changed
2018-10-03 10:07:17
@article{41fe48ca-3b49-4f67-8c37-1a4b39edc4bb,
  abstract     = {Shredded straw of Miscanthus was composted in 800-L boxes with different amounts of pig slurry added as nitrogen source. The impact of the different initial CIN ratios (11, 35, 47, 50, and 54) on the composting process and the end product was evaluated by examining chemical and microbiological parameters during 12 months of composting. Low initial C/N ratios caused a fast degradation of fibers during the first three months of composting (hemicellulose: 50-80%, cellulose: 40-60%), while high initial C/N ratios resulted in 10-20% degradation of both hemicellulose and cellulose. These differences were reflected in the microbial biomass and respiration, which initially were higher in low C/N treatments than in high C/N treatments. After 12 months of composting, this situation was reversed. Composts with high initial CIN ratios had high microbial biomass (15-20 mug ATP g(-1) OM) and respiration rates (200 mug CO, h(-1) g(-1) OM) compared to treatments with low initial C/N ratios (less than 10 mug ATP g(-1) OM and 25 mug CO2 h(-1) g(-1) OM). This could be explained by the microorganisms being nitrogen limited in the high C/N ratio treatments. In the low C/N ratio treatments, without nitrogen limitation, the high activity in the beginning decreased with time because of exhaustion of easily available carbon. Different nitrogen availability was also seen in the nitrification patterns, since nitrate was only measured in significant amounts in the treatments with initial C/N ratios of 11 and 35. The microbial community structure (measured as phospholipid fatty acid, PLFA, profile) was also affected by the initial C/N ratios, with lower fungal/bacterial ratios in the low compared to the high C/N treatments after 12 months of composting. However, in the low C/N treatments higher levels of PLFAs indicative of thermophilic gram-positive bacteria were found compared to the high C/N treatments. This was caused by the initial heating phase being longer in the low than in the high C/N treatments. The different fungal/bacterial ratios could also be explained by the initial heating phase, since a significant correlation between this ratio and heat generated during the initial composting phase was found.},
  author       = {Eiland, F and Klamer, Morten and Lind, A M and Leth, M and Bååth, Erland},
  issn         = {1432-184X},
  language     = {eng},
  number       = {3},
  pages        = {272--280},
  publisher    = {Springer},
  series       = {Microbial Ecology},
  title        = {Influence of initial C/N ratio on chemical and microbial composition during long term composting of straw},
  url          = {http://dx.doi.org/10.1007/s002480000071},
  volume       = {41},
  year         = {2001},
}