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Becoming the Good Soil: Other Ways That Compost Helps Mitigate Climate Change

To make compost, organic materials are necessary, like yard waste, food waste, wastewater treatment plant residuals, animal manures, or others. Currently, some organic wastes are finding their way to the landfill, where they decompose anaerobically (without oxygen) and methane is emitted—a greenhouse gas contributing to climate change. Landfills contribute 20% of the total methane emissions generated in the US (https://www.epa.gov/ghgemissions/overview-greenhouse-gases). The EPA estimated that in 2014 the trash contained approximately 22% food by weight (https://www.epa.gov/smm/advancing-sustainable-materials-management-facts-and-figures-report ). In North Carolina alone, it is estimated that just over 8% of the excess food generated is recovered from the landfill through composting, anaerobic digestion, food donations, and animal feeding (NCDEQ 2012 and 2016 reports — http://deq.nc.gov/conservation/recycling/composting/composting-resources). Composting itself produces carbon dioxide as a byproduct of the respiration of the composting microorganisms, and it could produce methane and nitrous oxide if the pile is not managed correctly; however, when compared to the traditional method of organic waste disposal—landfilling—composting is regarded as a way to avoid the generation of methane (http://faculty.washington.edu/slb/docs/CCAR_Composting_issue_paper.pdf). Therefore, just the act of diverting organic waste from the landfill can prevent significant quantities of methane from being generated, helping to mitigate climate change in its own way.