Biochar: Interrupting the Carbon Cycle
The carbon cycle describes the forms that carbon takes as it cycles through various physical forms on the Earth.
Most people don’t know this, but most of the tree you see above ground, or the corn plant in a field, actually comes from carbon in the air. As the plant takes in CO2 from the atmosphere, part of the carbon is synthesized into compounds which create the stem and leaves of the plant.
When the tree dies or the corn plant is harvested, the organic matter decays back into CO2 through fungal and bacterial action on the remains of the plant, and the process begins anew.
How can we interrupt this process to keep more CO2 out of the atmosphere? Enter biochar! If we take the plant material and heat it in the absence of oxygen, the carbon will form those black chunks of carbon we charcoal. If we use the charcoal for fuel, we’ve only interrupted the cycle for the few months the bag sits on the shelf.
But… if we take that charcoal and put it somewhere where it will not burn, such as the soil, we can capture and hold that carbon out of the atmosphere for hundreds if not thousands of years! While fungi and bacteria can operate to break down the structure in wood, no microbes break down charcoal, in fact, they love to live in the nooks and crannies left by the plant cell walls.
Fungi in biochar!
The picture here at the right shows the fungal hyphae exploring the cracks and crevices in a piece of biochar I had in my garden. I had broken a piece that was covered with fungi open to see what it looked like inside, and this is what I had found! Pretty cool!
This fungus will not break the biochar down as it would with wood, it will just live on it since the biochar will provide it with a moist, nutrient rich environment allowing it to thrive.
The fungus will also act as a transportation system for nutrients, transporting them from within the biochar to the surrounding plants and other fungi.
Carbon Capture
Stepping back and looking at the big picture, we see that biochar interrupts the carbon cycle and can sequester carbon in the soil so that it does not turn back into CO2 again when plant material decays. This method of carbon capture requires very little energy compared to other methods, and the energy it requires can be provided by the wood itself that is being pyrolyzed to create the biochar. At the simplest level, no fossil fuels are necessary to create biochar. The wood itself can come from local sources such as your yard, local arborist, or town lawn waste pickup. The methods to create biochar are low-tech, in fact, it’s been made since the first fires were started.
Because one molecule of CO2 weighs a little over 3 times the weight of one atom of carbon, putting 1 pound of biochar into your soil will prevent approximately 3.3 pounds of CO2 from entering the atmosphere. Put another way, 1 ton (2000 pounds) of CO2 can be prevented from entering the atmosphere by putting just 600 pounds of biochar in the soil!
