Kristin Ohlson, author of The Soil Will Save Us, shares the story of the remarkable partnership between plants and creatures in the soil. Discover the unsung heroes in the dirt beneath our feet and the role that they can play, together with plants, to shift the carbon balance in our favor.
Take heart! If we focus on tending the Earth instead of exploiting it, we can mitigate the warming of our planet. But we need to respond to the climate crisis now and we need to empower our neighbors to do the same.
This Sunday, Kristin Ohlson will be holding a presentation and conversation at St. Andrew Lutheran in Beaverton, OR. Join us at 9:45 am in the Fellowship Hall Sun, Nov 24th to learn what we can do and the hope available to us. RSVP if we’ll see you there.
An Excerpt from The Soil Will Save Us, from Science Friday
It’s tempting to think that the loss of soil carbon is a relatively modern curse, the result of surging populations in poor countries and industrial farming in rich ones. But this is not the case. As soon as humans segued from a hunter-gatherer lifestyle to an agricultural one, they began to alter the natural balance of carbon dioxide in the soil and the atmosphere. Settled agriculture began in the world’s great river valleys–those of the Tigris, Euphrates, Indus, and Yangtze rivers–some 10,000 to 13,000 years ago. By around 5000 BC, people began to develop simple tools to plant and harvest. The earliest of these were mere digging sticks, but by 2500 BC, people were using animals to pull plows in the Indus Valley.
Plowing seems so harmless and soothingly bucolic, especially when the plows are pulled by oxen or horses. But as [Rattan] Lal [director of the Ohio State University’s Carbon Management and Sequestration Center] pointed out in a speech given in 2000, “nothing in nature repeatedly and regularly turns over the soil to the specified plow depth of 15 to 20 centimeters. Therefore, neither plants nor soil organisms have evolved or adapted to this drastic perturbation.” Modern mechanized farming makes the problem even worse: The heavy machinery compacts the soil further, requiring deeper plowing to loosen the soil. As greater volumes of soil are churned up and exposed to the air, the soil carbon–which may have been lying in place under the soil line for hundreds or thousands of years–meets oxygen, combines with it to form CO2, and departs for the upper atmosphere.
But allowing the animals to reduce grassy plains to bare ground halted the great biological process that had created vast underground stores of carbon in the first place: photosynthesis. 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—Lal points out that “humus” and “human” share the same root word—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: When there is rainfall, the soil absorbs and holds water instead of letting it puddle and run off. Healthy soil is also rich with tiny organisms—an amazing 6 billion in a tablespoon—that can disarm toxins and pollutants that soak into the soil through the rain. Lal believes farmers should be compensated not just for their crops; they should also be compensated for growing healthy soil because of its many environmental benefits.
No other natural process steadily removes such vast amounts of carbon dioxide from the atmosphere as photosynthesis, and no human scheme to remove it can do so on such a vast scale with any guarantee of safety or without great expense. Photosynthesis is the most essential natural process for life on our planet, as it regulates the steady cycling of life-giving carbon into our soil and creates that other gas on which so many of us depend: oxygen.
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