We thought we were smarter than nature, but we’re not. We forgot that life itself is a miracle. We forgot that we are dependent on complex systems that we don’t control and can only partly understand.
Now, the crisis of climate change gives us an opportunity to reconsider our assumptions and change our ways. As we look beyond reduction of greenhouse gas emissions to drawing down the excess carbon in the atmosphere, the question is: How might we safely do this and not end up with unintended consequences from some high-tech solution like pumping sulfur particles into the stratosphere?
Soil scientists, permaculturists and carbon farmers are suggesting that we learn from and imitate nature. In the first post in this series, I suggested that regenerative agriculture and carbon-conscious land-use policies can reverse carbon buildup by putting the carbon back where it belongs, in the soil.
To do this, farmers, gardeners, consumers and policy makers need to understand a little about plant and soil biology. The bodies of all living beings, animals and plants alike, are made up of carbon molecules. Plants take in carbon dioxide from the air, and through photosynthesis, separate the carbon and oxygen atoms and release the oxygen back into the atmosphere.
But plants can’t live by CO2 alone. They need lots of other nutrients, most present in rocks, stones, sand and clay, the base materials in soil around the world. But in nature’s plan, plants can’t access these mineral nutrients without the help of the microbial populations that make up healthy soil. There are more individual organisms in a teaspoon of healthy soil than there are people on earth, according to the Department of Agriculture.
Plants and soil microbes have co-evolved an amazing system. Plants exude sweet carbon juice from their roots, which soil scientist Elaine Ingham calls “cake and cookies,” attracting and feeding microbes like soil bacteria and fungi. Meanwhile, other microbes have been dissolving the basic materials of the earth (rocks, sand and clay) with acid enzymes and have all these minerals incorporated into their bodies. The abundance of bacteria and fungi in the soil around plant roots attracts predators like nematodes and protozoa, who eat and then excrete these nutrients in a form accessible to plants.
This mutually beneficial relationship between plants and soil life results in the thriving and abundant earth community that is the context in which we humans evolved.
But how can healthy soils and plants capture and then sequester excess carbon from the atmosphere? How can carbon be fixed in the soil in a form that won’t just be consumed, excreted and exhaled by soil microorganisms? The Soil Story gives a quick look at this and shows why storing carbon in the soil is so promising.
Healthy soils are made up of soil aggregates, little protected areas in the soil around plant roots where bacteria and fungi and other microorganisms hang out, do their biochemical thing and trade nutrients with plants. Under the conditions that nature developed, soil microorganisms in aggregates transform liquid carbon exuded from plant roots into humus, an organo-mineral complex composed of about 60 percent carbon, and not easily broken down by microbes.
Scientists are still trying to understand the exact way that stable soil carbon or humus is formed, but they do know that soils can hold up to 6 to 20 percent organic matter that is not consumed and emitted, but just serves as a reservoir of carbon. What is known is how to build deep and healthy soil and how to fix more carbon in the soil and plants than is released by the biological processes of life.
Amazing! Could it be that the soil will save us? When I think about the intricate dance of all the members of the soil food web, a non-scientific word comes to mind: miracle. Nick can tell you that I’ve been walking around the house singing the chorus of Amherst songwriter Helen Fortier’s “Sweetest Song” which conveys this sense of wonder:
I’m grateful for the life in everything I see,
Seems just like a miracle when you look beneath,
See all the tiny pieces that make this harmony,
Spirit sings the sweetest song through every living thing.
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