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Study Shows that Grazing Helps Cut Greenhouse Gases

Goats grazing on grass.

A new study published in Nature this week found that grazing animals on grasslands reduced the amount of nitrous oxide released by those grasslands. Nitrous oxide is the third most important greenhouse gas after carbon dioxide and methane. It contributes to the destruction of ozone in the atmosphere and accounts for roughly 6% of the heating effect of greenhouse gases. About a third of the nitrous oxide produced in the U.S. anthropogenically comes from lands used for grazing; the rest comes from crop lands and from industrial sources.

Nitrous oxide is produced by soil organisms when the soil warms in the spring. When grass has been cut low by cattle or sheep, the soil freezes in the winter and many of the soil organisms die off. When the grass is not cut, snow covers the vegetation, providing warmth over the winter and moisture in the spring, and more of the soil organisms survive.

Prevailing wisdom has been that more animals on grasslands would increase the amount of nitrogen available (from manure, for example) to be transformed into nitrous oxide. Instead, it seems that the animals’ grazing reduces the impact of the increased nitrogen.

The study did not take into account methane or carbon dioxide produced by the animals or by grassland management. The study also did not consider effects of improperly managing grazing land, such as erosion from overgrazing or compaction of soil from too many animals on the land. It does give scientists and ultimately farmers more information on grassland management and help give insights into climate change.

Source: Nature 464, 881-884 (8 April 2010), β€œGrazing-induced reduction of natural nitrous oxide release from continental steppe”
doi:10.1038/nature08931

One comment
  1. Greg

    The study (and your post) also failed to take into account the most important and largest source of toxic gases in the production of grazing animals as a food source.

    The major pollution isn’t from the cows or the effects on the grass. The major pollution is from the corn they are fed for months prior to slaughter at the Concentrated Animal Feed Operation, and all of the petroleum used in the production, transportation, and consumption of corn by these “grazing animals”. I often post about this on http://www.thecasualvegan.com, because its so amazing how many people don’t even think about the amount of resources we are wasting feeding corn to cows.

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