What is the major source of methane emissions related to agriculture?

The major source of methane emissions related to agriculture is associated with rice fields and livestock. Methane is produced during the digestive process of ruminant animals, such as cows and sheep, through a process known as enteric fermentation. This biological process accounts for a significant portion of agricultural methane emissions as these animals digest their food.

In addition to livestock, rice cultivation also contributes to methane emissions. When rice fields are flooded, anaerobic conditions are created, which lead to the production of methane by microbes in the waterlogged soil. The combination of these two agricultural practices makes rice and livestock the primary contributors to methane emissions within the sector.

Other options, while relevant to greenhouse gases, do not specifically align with agricultural sources of methane. For example, combustion of fossil fuels mainly produces carbon dioxide, landfill sites are more associated with the decomposition of organic materials under anaerobic conditions resulting in methane but are not directly tied to agricultural practices, and burning of biomass also primarily releases carbon dioxide rather than methane. Thus, rice fields and livestock represent the most significant agricultural source of methane emissions.