Tuesday, June 25, 2024
HomeClimate and GrazingHow Does Carbon Get From the Atmosphere Into the Soil?

How Does Carbon Get From the Atmosphere Into the Soil?

Last week, I shared a video introduction to a discovery that will help farmers and ranchers manage and build their soil to be more successful and to potentially slow and reverse climate change. The solution – a small dusting of compost that can double forage production and increase soil carbon sequestration. In Part 2 of this series, John lays the foundation for understanding why this works.

Some years ago, John Wick finally helped me understand how carbon gets into the soil. He’d learned it himself from the scientists he was working with on a study being done on his ranch. It was this background that helped him, and the researchers he was working with, to decide which practices they should include in the study, and what they would be measuring and looking for as signs of success.

John has shared this explanation with lots of audiences since then, and he does it so well that I wanted to share it with you. So, here’s a video excerpt from a presentation he did in 2013 at Fibershed’s Second Annual Wool and Fiber Symposium. You can see the full video here

I’ve included a transcript for those of you with slow internet connections but I really recommend watching the video as John draws out the full process on his digital tablet for us all to see. Enjoy!



It all actually starts with sunshine, soil, a seed, and a little grass plant. As the grass plant gets rain and sunshine it grows roots down into the soil. This is a pretty simple thing and it actually happens on more land area on earth than any other cover type. There are more acres of grassland than forest or tundra or anything else.

There’s several things involved: there’s air, sunshine, soil and water. And what I wanted to talk to you guys about today is how important this combination of things is. As managers we can start to interact with this system in a way that can actually stop and reverse global warming while producing fiber and food and fuel and flora. And the way it works is really quite simple:

Grass plants, as we all learned in school produce, oxygen and a bit of moisture to the atmosphere. We live in an oxygen-rich environment. CO2 is the fourth most abundant gas in the atmosphere and as a gas it spreads itself evenly throughout the vessel it’s in, and the atmosphere is a vessel. So the moment these little microscopic holes in the bottom of the leaf open to release oxygen and moisture, the CO2 rushes in and fills the leaf.

So now we have a leaf full of CO2 and then under the sun’s energy, the plant pulls in soil  moisture and soil nutrients through the microscopic hairs on the roots and recombines all of that to create carbohydrates, which we represent as C6H12O6. And all the of the carbon in carbohydrates comes from the air and no where else.

I always thought it came out the soil through the roots. Turns out that there is a lot of carbon in the soil and that soil is really important. But the reason it’s important is that the more carbon there is in the soil, the more water that soil holds.

Our research project starting on our ranch looked at that whole process and what’s involved in getting carbon from the air through the plant and into the soil.

In order to understand how that works it’s very important to understand that carbon in the soil represents itself in three fractions.

Labile Fraction

The Labile Fraction is fresh carbon and it’s very temporary. Most of it is in the bodies of microorganisms, plants roots. Most of it is actually going to go back to the atmosphere as CO2. A healthy soil system is very busy. It’s full of micro, trillions of them, and as they’re going through their life processes, they oxidize carbon just we are right now. Every single one of uys is exhaling CO2 into the atmosphere we’re actually recharging the resource base from which all this happen.

Occluded Light Fraction

In that process, some of that labile carbon in the Labile Fraction is consumed and is digested by the microorganisms and some of that carbon enters the Occluded Light Fraction. This is interesting carbon because this carbon actually starts to change the electrical properties of the soil structure and it starts to hold more water in a plant available form. So the more carbon there is in the soil, the more plant there is. This water ordinarily would have passed through the system subjest to gravity and left, recharging our aquifers and things like that. But when you have carbon rich soil, that water now is interested in hanging out.

Heavy Fraction

After more processes some of that carbon enters the heavy fraction. And this can take millions of years. This is fossil carbon. It also stays there for millions of years because this carbon now is chemically bonded inside microsites within the soil structure and not available for microorganisms.

This is really important, good carbon. All human civilization has occurred where we have carbon rich soils like that. The challenge for us in our agricultural practices, the conventional ones. When we plow we actually break up the soil’s structure and allow organisms to digest what have been permanent carbon. They oxidize it into the atmosphere so we’re getting more and more agriculturally produced CO2 to the atmosphere and we’re burning up our fossil carbon.

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Kathy Voth
Kathy Vothhttps://onpasture.com
I am the founder, editor and publisher of On Pasture, now retired. My career spanned 40 years of finding creative solutions to problems, and sharing ideas with people that encouraged them to work together and try new things. From figuring out how to teach livestock to eat weeds, to teaching range management to high schoolers, outdoor ed graduation camping trips with fifty 6th graders at a time, building firebreaks with a 130-goat herd, developing the signs and interpretation for the Storm King Fourteen Memorial trail, receiving the Conservation Service Award for my work building the 150-mile mountain bike trail from Grand Junction, Colorado to Moab, Utah...well, the list is long so I'll stop with, I've had a great time and I'm very grateful.

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