Methane Emissions from Our Animal Industry in Abbotsford

Based on previous estimates of methane emission from enteric fermentation and from dairy cattle manure, the total agricultural methane emission from animals in Abbotsford can be estimated. It is also important to include estimates of methane emission from hog manure and from poultry manure.

Although hog manure is also stored anaerobically and may produce methane similar to dairy cattle manure, the hog industry has declined significantly in Abbotsford, and the potential methane emission is small.

Estimated methane emission from hog manure management in Abbotsford

The poultry industry produces a significant amount of manure in Abbotsford, however, most of this manure is drier, and is managed as a solid, which is not as likely to produce methane. In addition, a significant quantity of poultry manure goes directly for mushroom substrate production, or is exported from Abbotsford and applied on land elsewhere in British Columbia.

Estimate of methane emissions from poultry manure in Abbotsford

The total amount of methane produced in agriculture in Abbotsford is 66,675 tonnes CO₂ equivalent, with only 12.4% originating from dairy cattle manure. The largest percentage of methane produced from the animal industry in Abbotsford is enteric methane (from the cow’s stomach), which makes up 77% of the total methane emission.

Estimate of total methane emissions from animal agriculture in Abbotsford

There has been considerable debate about the actual baseline emissions of methane, particularly from dairy cattle manure. Previous methane emission factors (MCF) have been reviewed, and concluded to be overestimates of actual methane emission rates. If we considered the previously estimated MCF of 25.8%, the total emissions from Abbotsford increase considerably to 101,094 tonnes of CO2 equivalent, with 42% coming from dairy cattle manure. Based on substantial research and our own experience, we believe the current estimates to be more accurate.

Owen and Silver (2014) developed a model of greenhouse gas emissions from dairy manure management. They suggested that the methane conversion factors used in Europe, which were similar to what was used in the Abbotsford estimates, may be underestimating the baseline methane emission. The primary focus of this study was on methane emissions from manure storage lagoons in warmer climates, which undoubtedly has significantly higher methane emission than short term storages in colder climates. What was particularly interesting about this research was the inclusion of nitrous oxide in the emission estimates. It appears that nitrous oxide has been underestimated or ignored in some areas, which may lead to agricultural policy development that may not necessarily reduce overall greenhouse gas emissions.

 References

Owen, J.J., and W.L. Silver. 2014. Greenhouse gas emissions from dairy manure management: a review of field-based studies. Global Change Biology, doi: 10:1111/gcb.12687