My pile is a homegrown solution to a global problem — climate change caused by man-made increases in greenhouse gas emissions.
True, the vapors ever-rising from its midst are proof that my pile passes a lot of gas of its own making.
My pile is, after all, a hot mess of carbon-laden leaves spiked with nitrogen-rich combustibles. Its main purpose in life (and death) is to break down complex molecules into more elemental, reusable parts, as quickly and robustly as my meddling efforts make possible. A byproduct of that energetic process is greenhouse gases, mostly in the form of carbon dioxide and no doubt some methane as well.
Ever-increasing levels of those noxious fumes are now playing havoc with what has been a very human-friendly climate these past few millennia, give or take an ice age or two, or even this long slog of a snowbound winter.
But here’s some research from an EPA report from 2010 that supports the value of a compost pile as a way to lock up some of that excess carbon dioxide or otherwise offset its potentially ghastly effects on our environment. Living as I do in a fully four-season climate, hard by the intricate meeting of saltwater and shore, the weather forecast is a constant reminder of how delicate the balance is between comfort and crisis, near term and long.
I’ve extracted a few relevant bits from the footnote-laden report, but the conclusion to me is that my pile saves more energy and stashes away more carbon than it gives off in excess greenhouse gases.
“This guidance document describes the development of composting emission factors for EPA’s Waste Reduction Model (WARM). Included are estimates of the net greenhouse gas (GHG) emissions from composting of yard trimmings and food scraps, as well as mixed organics.
…. During this decomposition, approximately 80 percent of the initial organic matter is emitted as CO2. The remainder of the organic compounds eventually stabilize and become resistant to further rapid microbial decomposition (i.e., recalcitrant).
…. Significant evidence exists that compost contains stable compounds, such as humus, and that the carbon stored in that humus should be considered passive when added to the soil because it breaks down much more slowly than crop residues.
…. Although EPA understands that generally compost is applied for its soil amendment properties rather than for pest control, compost has been effective in reducing the need for harmful or toxic pesticides and fungicides.
…. Manufacturing those agricultural products requires energy. To the extent that compost may replace or reduce the need for these substances, composting may result in reduced energy‐related GHG emissions.”
On a modest backyard scale, my pile is a farm factory. Its end product (more like a beginning) is humus, loaded with stable carbon molecules and other nice-to-have nutrients. These reconstituted elements are bound up in a loamy matrix of organics, teeming with life. This rich mix of newly made earth has a multiplier effect when spread across the land, leading to other eco-friendly results with lasting benefits, like more plant growth (photosynthesis = oxygen ), less water use and reduced need for chemical fertilizers and pesticides.
In “The Soil Will Save Us,” Kristin Ohlson writes of reclaiming her worn-out suburban lawn through the use of leaf mold and compost, then uses the experience to tell the larger story of “How Scientists, Farmers, and Foodies are Healing the Soil to Save the Planet.”
She reports: “Carbon Farming. That’s the new thing.”
… Sometimes they called themselves microbe farmers, aware of the billions of tiny creatures that they couldn’t see but that scientists told them were at work in the soil. Sometimes they called themselves carbon farmers, knowing that it was the carbon that was making their soils richer, moister and darker. Some had been following the work of scientists who said that this kind of farming accelerated the removal of carbon dioxide from the atmosphere via photosynthesis and could slow and maybe even turn back global warming.”
I am a compost farmer as much as I am a suburban dad who keeps a nice lawn for the kids to play on and a garden with fresh organic vegetables to put on the table.
My pile is my back 40, and its yearly crop of rich dark compost, teeming with life and recycled nutrients, chief among them repurposed carbon, is what makes my garden and lawn so prolific in the six months of the year when our world is green and growing.
Ohlson provides more of a global view, from the ground up:
“Plants remove carbon dioxide from the air and, combined with sunlight, convert it to carbon sugars that the plant uses for energy. Not all the carbon is consumed by the plants. Some is stored in the soil as humus … a stable network of carbon molecules that can remain in the soil for centuries. There in the soil, the carbon confers many benefits. It makes the soil more fertile. It gives the soil a cakelike texture, structured with tiny air pockets. Soils rich in carbon buffer against both drought and flood soil is also rich with microorganisms – an amazing 6 billion in a tablespoon – that can disarm toxins and pollutants that soak into the soil through the rain.”
Ohlson makes the case that composting on a scale both large and small is one of the most effective, scalable ways to reduce the amount of carbon emissions entering the atmosphere.
Other scientist writers, such as David R. Montgomery in Dirt: The Erosion of Civilizations, and Jared Diamond in Collapse: How Societies Choose to Fail or Succeed, have made similarly convincing arguments that when a civilization’s soil goes bust, that culture is toast.
“Ohio has lost 50 percent of its soil carbon in the last 200 years. But in areas of the world where cultivation has been going on for millennia, soil carbon depletion is much higher – up to 80 percent or more. Altogether, the world’s soils have lost up to 80 billion tons of carbon…. Even now, land misuse accounts for 30 percent of the carbon emissions entering the atmosphere,” writes Ohlson.
“With good soil practices, we could reverse global warming.”
To shift from thinking globally to acting locally, so about how much does a backyard compost pile contribute to carbon sequestration? The best account I can find is an article on The Global Citizen website by Donella H. Meadows, an adjunct professor of environmental studies at Dartmouth College and director of the Sustainability Institute.
In “How Much Greenhouse Gas Does Your Garden Cut,” she relates relates some number-crunching done by Dr. Jonathan Foley, an environmental scientist at the University of Wisconsin, for his brother David’s .4 acre organic garden — a plot about the size of my backyard.
Over 10 years of composting and other sustainable gardening practices, David and his wife, Judy, have increased the the percentage of organic matter in their communal garden in Maine from 1 percent to 7.7 percent.
That impressive boost translates to an increase of 2.2 pounds of carbon in every square foot of their garden. Add it all up and, according to Jon Foley’s back-of-the-envelope calculations, his brother has removed over 38,000 pounds of carbon from the atmosphere — 19 tons — over the past 10 years.
“The average American releases 6 to 6.5 tons of carbon into the atmosphere each year,” Foley reports, “So you have offset about three years of an average American’s emissions.”
My pile and backyard garden are surely of a more modest scale than the Foleys’ communal efforts, but composting surely reduces my carbon footprint in similar ways, and that’s a good step in the right direction.