How bedding materials used in dairy farms impact greenhouse gas emissions

What is it about?

Greenhouse gases (GHGs) trap heat in the atmosphere and lead to global warming. In Canada, 95% of the total GHGs released contain methane and nitrous oxide. It is, therefore, important to reduce the emissions of these gases to lower air pollution. Liquid manure from dairy farms is a major contributor of global GHG levels. These levels are measured based on methane release and volatile solid content in the manure. Research shows that the bedding of farm animals plays a key role in the release of the latter. But climate change panels fail to consider the effect of bedding while measuring GHG levels. In Canada, most dairy farms use beds made of straw, while a few use beds made of sand. This study’s authors measured GHG levels from liquid manure generated from wood-based and sand-based bedding in a Canadian dairy farm for 207 days in warm storage conditions. They found that the release of ammonia was much higher from manure generated from sand bedding. However, wood bedding manure generated 51% more methane, 8 times more nitrous oxide, and 53% more total GHGs in the first 123 days than sand bedding.

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Photo by Mitch Fox on Unsplash

Photo by Mitch Fox on Unsplash

Why is it important?

Emissions from wood bedding reduced after 123 days and were similar to those from sand bedding, due to slower degradation. The delayed breakdown of wood-based manure also produced higher amounts of volatile solids. Also, since wood bedding manure has higher organic matter, it generated high quantities of total solids (TS). Higher TS quantity resulted in more crusting, i.e., degradation of the material, which promoted bacterial growth. Inorganic sand bedding resulted in minimal crusting, harbored fewer bacteria, and is known to improve herd health over wood bedding. Hence, choosing the type of bedding for dairy farms requires a greater understanding of its effects on GHG levels, and on methane and volatile solid release, depending on different storage conditions. KEY TAKEAWAY: Choosing environmentally friendly farm bedding should account for its effect on GHG emissions, and on methane and volatile solid release in different storage and temperature conditions.