

Nitrous oxide Sources - Livestock and Feed

grazing sheepGlobally, livestock related nitrous oxide emissions are estimated to total between 1 and 2 million tonnes of nitrous oxide-N each year. Livestock themselves produce only relatively minor amounts of nitrous oxide directly.

Though some nitrous oxide can be produced in ruminant guts via the reduction of nitrate in livestock feed to ammonia and ammonium, the very anoxic conditions in the gut mean that actual nitrous oxide production is likely to be very low.

Where livestock do have a large impact on nitrous oxide emissions is through initial production of their feed, and through subsequent management of their waste. Livestock feed production, like human food production, often involves large applications of nitrogen based fertilizer to agricultural soils. This in-turn results in nitrification and denitrification in the soil and the release of nitrous oxide to the atmosphere.

Nitrous oxide arises from animal wastes occurs during both storage and treatment, again by the processes of nitrification and denitrification. Additionally, nitrous oxide is indirectly produced via the volatilization and atmospheric oxidation or deposition of nitrogenous compounds, such as ammonia and nitrogen oxides.

Human Impact

As humans are directly responsible for livestock rearing, we are also responsible for livestock related nitrous oxide production. Increased global demand for meat and diary products has led to increases in animal wastes. Additionally, the more intensive livestock rearing practices now common throughout the world have necessitated more intensive livestock feed cultivation, with the inevitable increase in N fertilizer use and nitrous oxide emissions.

Potential for control

The demand for livestock feed with a high nitrogen content makes the potential for reductions in livestock related emissions through feed cultivation practices limited. As with agriculture as a whole, better targeted fertilizer application and properly informed land-use practice may go some way to reducing nitrous oxide emissions from this source.

The various livestock waste management strategies provide further ways in which emissions can be reduced. The use of subsurface injection of liquid waste for instance can result in a much lower emission of nitrous oxide than that from its surface application to open pasture.

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