Quirks & Quarks

Do cows produce more methane than rotting grass?

Decomposing plants also release methane but no more or less than cows

Posted: March 01, 2019

Cows release methane faster, but no more or less than decomposing plants. (Getty Images)

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Bacteria produce the methane in both examples  2:22

This weeks question comes from Cheri Harris in Edmonton, Alberta. Cheri asks:

There's a lot of discussion around the amount of methane that cattle produce by digesting their food. But what if the pasture was just left to decompose? How would the amount of methane produced by the two compare?  

We went to Christine Baes, associate professor in the department of animal biosciences at the university of Guelph, for the answer.


She said that it's important to note that methane is not released by the cows themselves, but the bacteria in their gut. Similar bacteria also exist in the environment and produce methane in wetlands, rice fields and landfills.

The actual amount of methane released from a single blade of grass wouldn't change if it was just left to decompose, or if it was eaten by a cow and then digested by the bacteria in their gut.

The only difference is that the methane would be released more quickly by a cow or other ruminants (animals that acquire nutrients from plant-based foods with the help of microorganisms).

The amount of methane that different bacteria release (whether in a cow's gut or in the field) is still unknown at this point, but is an area of ongoing research.