On-farm carbon footprint should be determined before reducing greenhouse gas emissions

10-06-2011 | Home | News

Poultry farmers wanting to begin a systematic reduction of their on-farm greenhouse gas (GHG) emissions would benefit from first ascertaining the size – and underlying contributors to – their farm’s carbon footprint. Because so many variables contribute to the footprint, each farm’s GHG profile is likely to be unique and will require a specifically tailored approach to achieve maximum results, said the Poultry Science Association (PSA), citing the results of a recent bulletin.

The bulletin, Global Warming: How Does It Relate to Poultry? (March 2011, The University of Georgia Cooperative Extension), authored by Dr. Claudia S. Dunkley, an extension poultry scientist in the University of Georgia’s Department of Poultry Science, provides a brief overview of the theory of global warming and the extent to which poultry farms are contributing to GHG emissions. While remaining neutral on the controversies surrounding the global warming discussion, the bulletin describes the principal sources of GHG emissions on poultry farms and details steps growers can take to reduce emissions.

Poultry’s Contribution to GHGs
According to a 2008 Environmental Protection Agency (EPA) estimate, only about 6.4% of GHG emissions (i.e. emissions of carbon dioxide, nitrous oxide, methane, and other gaseous emissions relevant to climate change) in the U.S. come from agriculture. Of the 6.4%, beef cattle comprise 37% of GHGs, dairy cattle 11.5%, swine 4.4% and poultry 0.6%. However, even though poultry’s contribution is relatively low, Dr. Dunkley notes that due to increasing public concern over the issue, it remains important for the poultry industry to understand the on-farm sources of GHGs so that specific steps can be taken to reduce them.

In addition to public pressure, Prof. Dunkley noted in an interview that there is also a positive economic incentive to reducing emissions: “While many people do not believe in global warming, at the end of the day it doesn’t matter. One of the leading factors of GHGs produced on farms is energy usage. Hence, reducing energy usage will not only reduce your carbon footprint – it will also boost your farm’s profitability.”

On-farm sources of GHGs – fossil fuels
According to the bulletin, “reducing poultry production’s carbon footprint will require identifying and adopting on-farm management practices and technological changes in production and waste management that can result in positive net changes for producers and the environment.”

A poultry farm’s carbon footprint equates to the sum of GHGs the farm produces – either directly (e.g. through the use of propane for heating poultry houses) or indirectly (e.g. through a farm’s use of electricity produced by coal or other fossil fuels, in which case even though the GHG emissions may have occurred elsewhere, such as the power plant producing the electricity, the emissions are counted against the farm as part of its carbon footprint).

The report notes that about 85% of GHG emissions on breeder farms result from electricity usage; on pullet and broiler grow-out farms, electricity usage accounts for, respectively, 30% and 29% of emissions.

The principal source of GHGs on broiler and pullet farms results from the use of propane gas for heading during brooding and colder times of the year. Propane accounts for about 68% of these farms’ emissions. On breeder farms, propane usage accounts for a negligible amount of total emissions – only about 0.3%.

Reducing fossil fuel usage
The bulletin outlines a number of steps that can be taken to reduce on-farm use of fossil fuels, especially propane. Among others, these include:

· Enclosing and insulating openings in houses without solid walls to reduce heat loss – and hence propane use

· Installing circulatory fans to reduce temperature stratification and using radiant heaters instead of gas heaters for brooding

· Installing energy-efficient generators and incinerators

Dr. Dunkley notes that “it is not uncommon to see projected reductions [for poultry houses] of 40% to 60%” due to implementing such measures to improve heating and electrical usage efficiencies.

Improving manure management

According to the bulletin, manure management practices account for about 8% of the methane (a GHG) produced from animal agriculture. The majority of methane and nitrous oxide that is emitted on the poultry farm comes from manure management. While methane emissions can be generated through decomposition of manure under anaerobic conditions, most poultry production systems handle manure as a solid, where it tends to decompose under aerobic conditions and generates less methane.

The bulletin suggests a number of strategies for better manure management that help reduce GHG emission. These include:

· Handle manure as a solid or spread it on land where it decomposes aerobically and produces little or no methane

· Avoid prolonged litter buildup, which can increase methane emissions

· Add nitrification inhibitors to the poultry litter to reduce nitrous oxide emissions

Importance of learning your farm’s footprint prior to beginning GHG reduction efforts

“Carbon footprints, like human fingerprints, are unique. Each facility will have its own specific footprint generated by its own complex set of GHG emission-producing factors. Therefore, you can’t say, for example, that a 12-house farm has X amount of emissions – unfortunately, it’s not that simple. So, it is imperative that poultry farm owners determine how these factors work together to produce their farm’s GHG profile. The best way to do this is probably to reach out to individuals or organizations that are focused on reducing carbon footprints. Once they help you determine your farm’s GHG profile, they can assist you in the development – and then implementation – of a strategy for reducing emissions and improving profitability,” Dr. Dunkley noted.

A free copy of Dr. Dunkley’s bulletin is available for download here.

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PSA