Methane production potential (B₀) of swine and cattle manures – A Canadian perspective

Abstract

Canada’s agricultural emissions accounted for 60 Mt or 8% of national greenhouse gas (GHG) emissions in 2007. The estimation of CH₄ emission factor (B₀) from manure management systems in Canada is prone to uncertainty owing to lack of B₀ values for Canadian conditions. Therefore, in this study, manure samples from six Canadian animal farms, two each of swine, beef and dairy cattle, were investigated in order to estimate their methane production potential (B₀). The ultimate anaerobic biodegradability was measured with ISO standard batch fermentation. The extent of biodegradation of the manure samples with or without sodium benzoate was always greater than 60% and hence showed no inhibitory effect on methane production by the manure. The impact of use of antibiotics in the animal feed on methane production was also considered; however, no inhibitory effect on methane production could be observed. The plateau of methane production in all cases was achieved by 63 d of anaerobic digestion process and the final pH was within 6–8. The calculated B₀ were in the range of 0.47−0.42, 0.21−0.19 and 0.35−0.30 for swine, beef cattle and dairy cattle, respectively. The uncertainties associated with B₀ values were ± 9% for swine, ± 3% for beef cattle and, ± 6 and ± 2% for dairy cows.

Keywords:

• anaerobic digestion
• biodegradability
• beef
• dairy
• greenhouse gas
• manure
• methane
• swine

Acknowledgements

The authors would like to extend their gratitude to Environment Canada for granting financial assistance to accomplish the research project. We also thank Mr. Michel Côté and Ms. Diane Dubois of IRDA, for their crucial analytical support.