Preventing Methane Gas while Composting

Turning a compost pile for viticulture

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Guest Post by Anthony Garcia

Composting, the process of consciously collecting waste to decompose and use as a soil amendment, offers many benefits. Gardeners, whether they are going green as a stress relief from online graduate programs or working outside in professional landscaping, are keenly aware of the nutrients and soil-improving qualities of compost in the vegetable or flower garden. Many people compost to be more environmentally friendly. However, compost does release some amount of methane during decomposition, which can sometimes lead to accidental pollution.

By understanding the natural processes that occur during composting, and promoting good management practices, you can diminish the chance of your compost releasing too much methane gas.

Carbon dioxide is often cited as the main greenhouse gas regarding climate change, but methane is another gas that greatly contributes to the issue, according to research at the University of Guelph in Canada. Methane is expelled from volcanoes naturally, although animal manure decomposition also contribute to the amount of methane in our atmosphere. When decomposing matter is deprived of oxygen, methane is created in large amounts. Instead of the matter decomposing into stable carbon and water, methane gas is actually released to the air. For example, disposing of biodegradable debris – such as garden debris, paper and old food –in plastic bags that are buried in oxygen-depleted landfills results in the undesirable, large production of methane, which is one of the reasons that compost has traditionally been encouraged by those concerned with the environment.

Poorly managed compost piles may still create unnecessary amounts of methane. There’s more to composting than just tossing grass clippings, dead leaves and food scraps onto a heap and walking away. The proper balance of air, moisture and organic debris called feedstock ensures thorough decomposition without production of methane gas.

Aeration

Without oxygen, bacterial and fungal microorganisms in the compost pile die out and decomposition slows and often releases offensive odors and gases like methane. These microbes need some air to flourish and efficiently break down the compost debris into carbon and water. Mixing and turning the contents of the compost pile or bin helps move air into the spaces around the debris. Once or twice a month is sufficient, according to the Purdue University Cooperative Extension Service.

Composition

A mix of variably sized debris in a compost pile helps insure good aeration and faster and more complete decomposition. Fine-particle leaf clippings and handfuls of soil blended with coarse leaves or vegetable scraps provide an ideal environment for microbes to produce compost without making any methane.

Avoid adding any feces or meat into your compost pile. When it comes to meaty bone and food scraps, the oils can limit the penetration of oxygen to microbes, increasing methane and other gases. If you are an accomplished compost-maker, strive for no more than 5% composition of feedstock of meat scraps and bone into the entire compost pile.

For the highest-quality compost pile and end product, incorporate waste paper pieces into the compost pile. Paper helps with aeration to prevent methane production, but paper also is naturally high in carbon. A compost pile of half carbon and half nitrogen components is ideal. Fresh, green feedstock, such as old vegetables and grass clippings, are high in nitrogen. The U.S. Composting Council encourages including some paper, as it balances the nitrogen-rich vegetation waste commonly heaped into the compost pile. Porous paper also helps retain moisture and nutrients within the compost and can hold gases from being released into the air.

Management

By aerating and adding the appropriate mix of biodegradable debris into the compost heap, you likely create an ideal decomposition system that does not produce any methane. A healthy or “cooking” compost pile creates and maintains its own heat, around 130 to 160 F. The compost also is evenly moist, never dry or soggy wet. The combination of air, feedstock, heat and moisture in balance promotes the microbes and natural decomposition without the worry of producing methane, keeping the mixture and the air safe.

About the Author

Anthony recently completed his graduate education in English Literature. A New Mexico native, he currently resides and writes in Seattle, Washington. He writes primarily about education, travel, literature and American culture.

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