Doreen Fogle: Two powerful ways soil soaks up carbon dioxide
My previous article discussed the role of carbon dioxide (CO2) in our atmosphere and how it helps maintain a range of temperatures that enable life on Earth.
The amount of CO2 in our atmosphere now is at 414 parts per million (ppm), which is the same as saying 0.0414% of the total atmosphere that we live in. And it’s been rising rapidly since scientists started measuring it in the 1950s.
Many scientists say that a level of 350 ppm is as high as we should get without truly dire consequences. And when you think of the weather-related events happening this summer, we’ve gotten a glimpse what truly dire may mean.
But scientists have found that soil has the ability to soak up a lot of carbon dioxide. It is estimated that by restoring the world’s soils we can get CO2 levels back to 350 ppm within 15 years.
Let me describe exactly what goes on in the soil to soak up CO2.
Microbes in the soil
Plants absorb carbon dioxide from the atmosphere through their leaves. They take up water and minerals from the soil through their roots. The combination of CO2, water and minerals allow the plant to manufacture sugars and carbohydrates, and all the other components of the plant body, including sweet fruits and protein-dense seeds.
But there’s one incredible process that makes it all work. It starts with the roots. Little white hairs on all the roots absorb water and nutrients. They exude some of the plant’s sugars, to form a film around them. This film is composed of the right kind of sugars that attract and encourage the growth of the right kind of soil microorganisms (microbes) that in turn excrete nutrients in the right form for the plant’s root hairs to absorb and use.
Got that? What this means is, the roots of the plant grow their own microbes to supply themselves with the nutrients they need. As though they’re doing their own farming.
The microbes in soil include zillions of bacteria, protozoans, nematodes, algae, archea and others. I’ll talk of fungi in a bit.
After all the microbes have eaten and been eaten, what ends up is a substance called humin. Humin is made of a lot of carbon, doesn’t get eaten, and remains fixed in the soil for very long-term storage. It also improves soil structure to allow air and water to penetrate the soil, keeping microbes healthy and happy.
Unless the soil is damaged.
Fungi, especially mycorrhizal fungi
Like little traveling sales people, filaments of mycorrhizae knock on the doors (roots) of their perfect customers and offer a great exchange.
They offer a plethora of nutrients, harvested from far and wide, even water from distant resources if times get tough.
Once granted an agreement by the roots, the tiny mycorrhizal filaments team up with root hairs and get to work.
The long filaments of the fungus grow and reach out far and wide to keep its plant partners supplied. They have the ability to dissolve rock minerals and decay organic matter and turn these components into nutrients the host plants need.
In exchange, the filaments get the carbon building blocks for building the fungus body, which enables the fungus to grow large. Very large. Some fungi have been observed to grow several miles wide. And they live very long. Some for thousands of years! This makes for a lot of carbon stored in the soil for the long term!
Unless the soil is damaged.
We humans have done a lot of damage to the soil.
Compaction by machinery, building and paving kills off microbes. It reduces the oxygen in the soil and breaks the fungal hyphae.
Tillage exposes the soil microbes to sun and air and kills them off. The humins and microbes get broken down and release CO2 back into the atmosphere.
Even fertilizing takes a toll on microbial life. It replaces the microbe farming the roots do so they don’t need to do that job. The plants become dependent on fertilizers and the microbes lose their food source from the roots, reducing their numbers. Less humin gets made.
Practicing better soil stewardship
Regenerative agriculture is the type of agriculture that maximizes the microbes in the soil to grow more nutritious food, improve the CO2 absorption of the soil, water infiltration, and retention and increase productivity.
Work to improve your own soil in your landscape and garden to increase the microbe population. Add compost to soil and mulch with organic matter to create a steady supply of fodder for microbes to break down and feast on.
Switch to organic fertilizers if you’re not confident in not fertilizing. They supply some nutrients and even microbes to help get things started. Then cover the fertilizer with organic materials like composts or wood chips.
Go to soilfoodweb.com to read more and to watch a number of short videos that explain so much more.
For the more adventurous I highly recommend the book “Teaming with Microbes” by Jeff Lowenfels and Wayne Lewis. It will make you love the beauty of the soil’s microbes!
Coming up on Sept. 22, on Netflix, is the film “Kiss the Ground.” The trailer is on Youtube, and the book by the same name has been out since 2017. They tell all about regenerative agriculture and getting CO2 fixed into the soil.
We all can and must participate in any way we can to reduce CO2 in the atmosphere, now that we’ve had a sampling of what’s to come.
Doreen Fogle is a landscape designer and writer in Nevada County. More of her articles can be found on her website mydelightfulgardens.com and she can be reached at email@example.com.
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