Livestock manure and greenhouse gases

The breaking down of manure by microbes releases the greenhouse gases carbon dioxide, methane and nitrous oxide. Yet of the total methane emissions from livestock in Australia, methane from manure contributes only 3%.¹

Manure stockpile

Almost all of the methane that comes from manure breakdown is from manure management systems which store a large amount of manure from confined animal management operations like feedlots.

These types of agricultural operations are termed intensive agriculture. Manure dropped on fields and pastures by animals grazing under extensive farming systems produces insignificant amounts of methane.²

Although the contribution to greenhouse gases from the breakdown of manure is comparatively low, there are still some opportunities to reduce these emissions, particularly in the management of manure from feedlots, piggeries and poultry farms. By capturing and then using the methane as an energy source, or by flaring the methane to convert it to carbon dioxide (CO₂) before release into the atmosphere - CO₂ traps less heat in the atmosphere than does methane.

The high costs of setting up the infrastructure and ongoing costs to capture or flare the methane from manure is a barrier to more widespread use of these methane reduction techniques.

Above and right - Manure from feedlots, poultry farms and piggeries (i.e. intensive livestock enterprises) can be better managed to reduce methane emissions.

¹Hegarty, R (2007) Greenhouse Gas Emissions from the Australian Livestock Sector; Australian Greenhouse Office.

² Rural Industries Research and Development Corporation (2008) Using methane in intensive livestock industries Publication No 08/050. Canberra, April 2008.