Biochar: how to build soil, lock up carbon & build fertility on the farm

Michael Low
Wednesday, 7th May 2014

Michael Low shares how he makes his own biochar and gains huge benefits by spreading it on his garden, hay fields and pasture on his 67 acre hill farm.

After reading about tipping points, my wife and I are even more convinced biochar is the best investment we've made to support the systems on our Vermont farm. A tipping point in nature is an unstoppable slide to a different set of circumstances. Temperature, rainfall, hydrological patterns, even prevailing winds can change1. We have a restorative vision of the future for our 67 acre hill farmstead, but realistically, that future includes uncertain weather patterns. In the past few years, we've seen one inch hail in April, snow in May, deluges in June and July, and a hurricane in August. The most effective way to adapt has been to focus on adding biochar carbon to our soils to create a resilient foundation for the diverse permaculture systems on our farm. 

We were inspired by reading about biochar used in the South American soils, the so-called black gold of the Amazon. So four years ago we built a brick Adam retort to begin making our own. In the Amazon rainforest, the carbon from photosynthesis is sequestered in the lush plant growth, and stored in the woody biomass, not the thin acid soils. Unless stored in biochar, the energy of the rainforest was 'lost' to the people after clear-cutting. Yet biochar enriched soils have remained fertile for thousands of years2. That ancient charcoal enriched soil can be dug up and used today as a fertilizer.  How could we resist that kind of fertility and longevity! We chose biochar not only for what it does but also because it has integrity.  It is not a mined resource like humates and minerals. When made in conjunction with restorative forestry, the entire production process and end product equal a positive impact with no hidden costs.

What is biochar

The way biochar works is this: plants store sunlight as woody carbon (stalks, trunks), then we use that plant biomass (trees in our case) to make charcoal, a long term stable carbon that we then add to the soil in all of our farm systems. This charcoal is a condensed form of solar energy, a long burning fuel for life.  

We've observed countless positive impacts on our farming systems with biochar.

Here are its four major functions:  

1. Biochar restores and maintains our soil health. By using inoculated biochar we re-introduce soil life, restoring dead or worn out soils. Biochar becomes a living reef holding beneficial microbes, mycorrhizae and nutrients near the plants roots as illustrated by improved flavor, increased vitality in root balls and vegetative growth. Biochar is carbon which is also one of the main components of a healthy soil.

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Spreading the biochar / compost mix

2. Biochar improves tilth, acting as a structural agent (glue for our sandy soils, loosening our clay soils by introducing water and oxygen flow). Biochar is a living sponge, retaining water in droughts and absorbing deluges. It promotes air circulation where we had compacting. Our soils are now easier to work. We see biochar as a permanent landscape feature.

3. Biochar allows for traction in our fertility building. We have seen exponential growth to new plateaus of fertility with no backsliding. Each year we have been able to graze more animals, harvest more hay and fodder even in overly dry and wet years. Biochar holds nutrients through heavy rains meaning our inputs last longer and we need fewer. 

4. Finally, biochar sequesters carbon into the soil to balance the increased atmospheric carbon and even turn back the clock of climate change3. We might be a small farm, but we are trying to do our part for the future. Biochar has been a great linking tool on our farm, tying our stacked systems together and positively benefiting each part or function of the whole.

Stacking with Biochar

Stacking is a design principle where each piece in the landscape is seen in terms of its relationship to the other pieces, as well as to the soil, the sun and the water. Our stone retaining wall becomes a solar sink, releasing early season warmth to the raised beds at its base. Diverse plantings, like the cover crop cocktail, pull minerals up from different root zones and makes these minerals available for the benefit of the coming fruit tree growing. The fruit tree mulches the soil in the fall with its leaves closing the cycle for one year. In stacking functions we are designing living, adapting systems that make the best use of time, space and available resources. But the real timeless factor and defining quality of our system's health is the soils they are built on. The true resiliency is in the soils and not in the systems growing on the soils. 

Biochar boosts any permaculture installation at the soil level. We've added biochar to swales, berms, irrigation systems, terraces, and raised beds: Biochar builds directly on what any of these landscape features are trying to do, making them many times more effective at holding and distributing water evenly through the year. Then biochar restores and maintains our soils fertility and health. The systems we plant on this base are more resilient, easier to maintain and more fruitful. Three basic factors lay the foundation for soil integrity: microbes, carbon and water. High quality foods are grown in soil with

1. High levels of microbial diversity,

2. High soil carbon content and

3. Soil with high water holding capacity

4. Biochar addresses all three of these criteria for healthy soils and nutrient dense growth. We put biochar under every growing thing here: seeds, seedlings transplants, veggies, fruit and nut trees, berries, pastures, compost piles, and bedding packs. It provides a boost to our different fertility needs: pasture, gardens, perennials, and hay fields.

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Lush pasture from using biochar

Our draft animal power is stacked onto biochar because the added carbon upholds the fertility of our pastures and hay fields.

Our logging is stacked on biochar: Biochar is at the base of the food (fuel) for our draft animals and in a tight circle the draft animals harvest the wood (fuel) for the biochar.  Stored sunlight in our waste wood trees can be converted to biochar with our “Worst First Logging”.  Harvesting the cull trees for biochar frees up the healthy trees and restores the forest ecosystem.  What is worthless for me to sell to the log yard, the acres of dead and dying softwood pulp on our land, is the perfect biochar feedstock and thereby gains more value to us than even healthy saw logs.

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Unloading the kiln

Our farming systems have real traction now with biochar; we don't just stay in a repeating loop of inputs and outputs year to year. We gain carrying capacity every year, just one measure of our land's ability to support more life. Our carrying capacity has grown 450% in four years. In the past we gained little momentum in our fertility building efforts by adding only minerals and compost. With biochar, now we can fix our ropes, holding our progress up the mountain of restoring our land's health, and arresting any chance of serious decline along the way. This long burning fuel source is restorative in it's use and production. It can provide a stable base for any permaculture system. We are banking that biochar, in combination with permaculture principles, will be our buffer against extremes, or even a tipping point.

Michael Low and his wife live in Northeast Vermont, in the United Sates. He farms and makes biochar with the help of draft animals on their small hill farm. To contact him at Green Fire Farm call 802-274-7826 or email michael[at]vermontbiochar.com. For more information about biochar and its role in restorative farming visit, www.vermontbiochar.com. To learn more about worst first logging visit,  www.healingharvestforestfoundation.org. Read more about the importance of carbon in soils at, www.soilcarboncoalition.org. 

1. Nordhaus, William  The Climate Casino: Risk, Uncertainty, and Economics for a Warming World. (Yale university Press 2013).
2. Ed. Lehmann, Johannes & Joseph, Stephen  Biochar for Environmental Management: Science and Technology. (Earthscan 2009).
3. Bill Mckibben founder 350.org
4. www.permaculturenews.org/2010/07/22/soil-carbon-can-it-save-agricultures-bacon

Further resources

For more information, check out the latest issue of Permaculture magazine issue 80, where Ed Revill looks at growing in biochar soils.

Ed has also explored:

Building soil with biochar PM79

Biochar stoves PM78

Plus read: What is charcoal and how can biochar help mitigate climate change?

Permaculture - practical solutions for self-reliance, a magazine filled with useful and inspiring features, stories and ideas about all aspects of sustainable living from gardening and farming to green building and renewable technology. Check out a free digital copy HERE. You can subscribe to the print edition HERE.

Nosaj Srebmahc |
May 8, 2014 - 4:20am
The first paragraph says" Michael Low shares how he makes his own biochar" I was excited to read about his technique, which wasn't discussed.
Maddy Harland |
May 8, 2014 - 10:37am
We will ask him to write another article about how we makes biochar in detail. Meanwhile have you read the Biochar Stove article in our Winter 2013 issue? You can find it online here - http://www.exacteditions.com/read/permaculture?sid=356

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