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Biochar? What is it, and what is it good for? Biochar is basically charcoal, the natural kind made from charring wood or other biomass by driving off the moisture and volatile gases, leaving mostly carbon. This carbon does 2 main things: it greatly aids soils for plant nutrition, and it holds (sequesters) carbon, creating a negative carbon footprint.
Biochar has been around for over 2500 years and only now have our soil scientists begun looking into it. The Terra Preta de Indio (or Indian Black Earth) is a Pre-Columbian dark earth mass re-discovered in the Brazilian Amazon region and several other countries in South America.[1] Soil scientists noticed the dark soil was fertile where identical soil adjacent to it was poor at best. Analysis showed the only difference was the dark soil contained charcoal. Yet these dark soils have remained fertile without additional amendments for hundreds of years. (Some other Terra Preta-like soils are currently being studied in Holland, Japan, South Africa and Indonesia, according to Allan Balliett in the Acres U.S.A. article Terra Preta, Magic Soil of the Lost Amazon.) What biochar does in the soil is several things that increase soil health. Initial testing supports increased water retention, plant growth, soil stability and reductions of organic fertilizers. The porous texture of the biochar provides an environment for microbes to flourish. “Biomass from woody charcoal has an interior layer of bio-oil condensates that microbes consume, and is equal to glucose in its effect on microbial growth.” ~ Christoph Steiner, EACU 2004. Biochar also absorbs nutrients in the soil. What is special about biochar is its effectiveness at retaining most nutrients and making them available to plants much better than other organic materials such as compost or manures. This is also true for phosphorus (P) which is not at all retained by ‘normal’ soil organic matter.[2]"Soils with biochar additions are typically more fertile, produce more and better crops for a longer period of time." ~ Johannes Lehmann[2] Making charcoal has been around for hundreds, maybe thousands of years, and the process has changed very little. Traditionally, wood was piled in a round stack having a central ‘flue’ and covered with a wet clay mud. The wood was set to a slow burn (Pyrolysis) in the absence of almost all oxygen other than small holes around the perimeter to control the burn. It could take up to 3 weeks and constant attention for a complete burn. Once cooled, the charcoal was bundled and sold by the colliers (charcoal makers) as a heating and cooking fuel.
Wood Mound to make charcoal, circa 1900
Modern wood mounds in Crete
Biochar is made active by thoroughly wetting the “char” in a liquid fertilizer like fish emulsion, soluble mineral fertilizer, compost tea, etc. and then drying before crushing. Leaving a small moisture content keeps the dust down when crushing (which can be done with a 2x4 in a heavy metal bucket, or a concave rock). It is suggested NOT to use manufactured charcoal briquettes (used for your barbeque grill) as they contain char plus other ingredients like starch, borax, paraffin and a hydrocarbon solvent in the ‘instant light’ briquettes . A quick biochar can be made from a commercially available hardwood lump charcoal by the name “Cowboy Charcoal” and available at places like Ace Hardware and Lowe’s. You can also easily and cheaply make your own charcoal.
Cowboy Hardwood Lump Charcoal
Charcoal Close-up
After crushing, screen the biochar with ¼” hardware cloth. Gravel sized pieces of biochar will work fine in the soil. Retain any larger chunks for further crushing. Biochar dust is better for the plants and soil but is also a concern for air quality. The finished biochar may then be broadcast and tilled in, or applied as a side dressing. The amount to use varies with your total soil condition: tilth, fertility, pH, etc. A rough estimate I saw mentioned was 1 pound per square foot although significantly less also produced substantial results. Biochar produces faster and more noticeable results on poor soils. Biochar is also very effective added to your compost pile. Add up 15-25% by volume and mix it in. Add it to your bokashi. The microbes will love it! After you add your biochar to the garden, it is important to test the pH. Biochar is slightly alkaline, and soil scientists don’t yet know how it affects pH in the soil when added with organic fertilizers and minerals. Some think biochar plus an organic fertilizer may produce a neutral pH. More research is needed.
The very significant other advantage of biochar is its ability to sequester carbon. We know oil and coal deposits long ago sequestered carbon in the earth… until we dug them up. Plant matter absorbs CO2 from the atmosphere while growing. The process of making biochar does release some of the plant’s CO2, using about +/- 30% of the biomass to carbonize the other +/- 60%. We can sequester that larger amount in our soils. If plant material is fully burned to ash or left alone to rot, that same biomass would all become carbon dioxide in the atmosphere, contributing to the greenhouse effect, or global warming. Think of all the scrap around of used pallets, lumber removed from houses due to termite infestation, corn cobs and stalks, peanut shells… even straw, dead leaves and dried weeds. They all can be used to make biochar, and sequester the carbon that otherwise would go into our atmosphere.
Biochar research is still in its infancy and Cornell University faculty member Johannes Lehmann is one of the foremost biochar researchers. Soil scientists around the world are actively researching biochar to combat global warming and to enrich soils to feed the world.
I have a 'growing my own food' obsession that comes from my overlapping interests in cooking, nutrition and gardening. I am also a "teacher", a writer, a builder… and a craftsperson and... and… and many other things, LOL. In fact, I guess I am a generalist, and a Seeker.
I live in the southern Appalachian Mountains on a hillside with a creek in front, and drive a 15 year old truck I lovingly call “My Farmer’s Ferrari.”
Posted by dave (from Jacksonville, TX) on January 24, 2009 at 08:20 PM:
Since reading this article, I've spent many hours in research concerning biochar and am convinced that it's an excellent addition to my soil building efforts. I'm making biochar now and will be adding it to my garden in large quantities during the coming months.
I have two 55 gallon drums. They have clamp-on lids that are air tight, and the lids have three holes with screw in caps to cover the holes.
Around the bottom of the barrels I punched 10 holes in a circle. These then are flaired outward and downward, to draw up air into the barrel.
So, after loading the barrel with wood, I light the fire and once it gets going (maybe 5 minutes) I clamp on the lid and open all three holes on the top. Then once the smoke is really pouring out, I close up 2 of the holes on top, leaving only the one hole in the middle open.
At that point, thick white smoke billows out of the top hole and continues like that for several hours. If it seems to be going "too fast", I will cover up (with dirt) half of the holes on the bottom of the barrel.
Eventually, the smoke turns blue and I know it's nearly done. Once the smoke is so light that you can hardly see it, I cover the remaining holes on the bottom, and place a thin sheet of metal across the top hole. I don't screw in the top hole because it's just too hot. :)
The following day the barrel is ready to be opened, and I find all the wood has turned into charcoal, ready to be crushed and primed with compost.
This picture is two batches we did today. The one in the foreground is just about finished, and I covered the holes right after the shot was taken. You can see half the holes are covered. The one in the background has just been started and covered.
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Posted by dave (from Jacksonville, TX) on January 24, 2009 at 08:20 PM:
Here is a macro shot of one of the flaired out holes in the bottom.
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Posted by dave (from Jacksonville, TX) on January 24, 2009 at 08:21 PM:
Here's the top. The bricks are there because it started raining a little this morning, so I surrounded the opening with bricks and laid the sheet of metal on the bricks. This kept the sprinkling rain from entering the barrel while it was cooking.
You can see the three openings, and you'll see only the middle one is open.
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Posted by dave (from Jacksonville, TX) on January 24, 2009 at 08:23 PM:
The barrels were $5 each from the local scrap yard. The wood was scrap wood and branches that I had lying around.
At some point, I want to try extending this to return the volatile gasses to the fire in order to improve the process.
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Posted by darius (from So.Appalachian Mtns, VA) on January 24, 2009 at 09:51 PM:
Thanks for posting the photos AND your process, Dave. Lots of folks are interested, and will benefit.
I doubt I will get a burner made before early summer.
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Posted by angele (from Elephant Butte, NM) on February 01, 2009 at 10:22 PM:
I've singed my eyebrows (charbrows) burning branches in an open barrel. I was doing it to get rid of brush & pruning left-overs. Would throw shovel fulls of the ash around plants. Same idea but not so efficient. Now I am more likely to make brush piles out in the desert for the birds. My mom used to make charcoal to heat her family home with when she was a little girl. I wondered when I saw your twitter post if that is what you were doing. I wonder what process she used. I'll have to ask ☺
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Posted by darius (from So.Appalachian Mtns, VA) on February 02, 2009 at 12:20 AM:
angele, I don't know if you saw it, but I started a new thread on the sustainability forum so I could post a link to the current Mother Earth News article about making biochar in a garden trench.
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Posted by angele (from Elephant Butte, NM) on February 02, 2009 at 12:23 AM:
Thanks darius! i'll head over there right now.
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Posted by Horseshoe (from Efland, NC) on February 02, 2009 at 12:42 AM:
I just saw the mention of Dave makes charcoal on the twitter thread and went looking for it earlier today. Thanks, Dave, for posting the link to this one. Great idea and pics, too!
Will also check out the link you mentioned, darius. On my way over there now. Thanks!
Shoe
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Subject: Look foward to more info
Posted by allwild818 (from East, TX) on October 14, 2008 at 10:30 AM:
I had read about adding burnt wood to your compost and now I have a better understanding of what it does. This is so interesting I want to know more, specifically how to make your own charcoal (easily and cheaply of course). Look forward to more readings. Thank you for sharing.
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Posted by darius (from So.Appalachian Mtns, VA) on October 14, 2008 at 02:49 PM:
Thanks. I hope to get all my materials and write about making 2 different burners before Christmas. I can build a cheap burner now from 2 steel drums of different sizes. However, I also want to make a better burner to capture the gasses and use them as the primary fuel to burn/char... and that takes more dollars for materials. That will probably be my Christmas present to myself!
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Subject: The Rest of the Biochar Story:
Posted by erichj (from McGaheysville, VA) on October 08, 2008 at 06:16 PM:
The Rest of the Biochar Story:
Charles Mann ("1491")in the Sept. National Geographic has a wonderful soils article which places Terra Preta / Biochar soils center stage.
I think Biochar has climbed the pinnacle, the Combined English and other language circulation of NGM is nearly nine million monthly with more than fifty million readers monthly!
We need to encourage more coverage now, to ride Mann's coattails to public critical mass.
I love the "MEGO" factor theme Mann built the story around. Lord... how I KNOW that reaction.
I like his characterization concerning the pot shards found in Terra Preta soils;
so filled with pottery - "It was as if the river's first inhabitants had
thrown a huge, rowdy frat party, smashing every plate in sight, then
buried the evidence."
Given the current "Crisis" atmosphere concerning energy, soil sustainability, food vs. Biofuels, and Climate Change what other subject addresses them all?
Biochar, the modern version of an ancient Amazonian agricultural practice called Terra Preta (black earth), is gaining widespread credibility as a way to address world hunger, climate change, rural poverty, deforestation, and energy shortages… SIMULTANEOUSLY!
This technology represents the most comprehensive, low cost, and productive approach to long term stewardship and sustainability.
Terra Preta Soils a process for Carbon Negative Bio fuels, massive Carbon sequestration,10X Lower Methane & N2O soil emissions, and 3X Fertility Too. Every 1 ton of Biomass yields 1/3 ton Charcoal for soil Sequestration.
Carbon to the Soil, the only ubiquitous and economic place to put it.
Erich
540 289 9750
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Posted by darius (from So.Appalachian Mtns, VA) on October 08, 2008 at 10:05 PM:
Thanks, great additional information! I'll take a good look at all the links you posted over the upcoming weekend, as I am very excited about all the possibilities for this lovely blue planet we inhabit!
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Posted by Sundownr (from (Bev) Wytheville, VA) on October 09, 2008 at 04:24 PM:
erichj, Whoa, what great info links! See what you started with this article Darius, LOL. I hope to see many more follow up articles on biochar down the road!! Could you start a thread, possibly in the Sustainable Alternatives forum, to house all the potential info for future reference, please?
Bev
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Posted by Horseshoe (from Efland, NC) on October 09, 2008 at 09:08 PM:
Yes, great links, Erich. I really liked the National Geo one and how it was put together, great info!
Darius, thanks for a great intro to Biochar. I bet that'll get lots more people interested in it. And when you stumble on a great home-made system to char some wood please post a follow-up article.
Lastly, in addition to the store-bought "real charcoal" you mentioned (Cowboy?) our local Wally World sells another clean brand, pure wood/no additives called "Royal Oak". (Ten pound bags were recently on sale for about $7.00. I suppose 'end of season'?)
Best!
Shoe
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Posted by GardenSox (from Sacramento, CA) on October 14, 2008 at 04:27 PM:
This has been really eye-opening for me and not at all eye-glazing. I do hope that this practice comes into play more often when we look at ways to preserve our world. The NG story mentioned that we could offset humankind's use of fossil fuels by storing more carbon in terra preta nova! This is amazing and at the very least deserves to be something that is wholeheartedly pursued.
I love the last quote of the story too: "With eight billion people, we're going to have to start getting interested in soil. We're simply not going to be able to keep treating it like dirt."
Thanks to Darius for writing the article and thanks to erichj for the additional resources. This is a topic I look forward to learning more about.
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Posted by darius (from So.Appalachian Mtns, VA) on October 14, 2008 at 05:35 PM:
GardenSox... think what a HUGE impact this could have, globally! If we all do our part, the word will spread... Thanks.
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Posted by paleorthid (from Spokane, WA) on October 23, 2008 at 09:49 PM:
Posted by Jayryunen (from Sapello, NM) on December 08, 2008 at 05:42 PM:
Wouldn't there be a difference between CO2 released gradually into the atmosphere, say over 10-20 years and the impact of releasing the same amount in a few weeks?
I don't have the computer capability to access all those wonderful sites, so I don't know if this question has been addressed in the research. (Old software, slow dial-up)
I thought it isn't so much the decay of the rain forest that contributes dangerously but the burning of such a large biomass all at once. Although bio-char seems to be a wonderful soil amendment, I'm not sure converting mega-quantities of biomass to char on an industrial level would appropriately address decreasing green house gases.
Has this been studied? =o)
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Posted by bokashicycle (from Lakewood, WA) on January 04, 2009 at 12:35 AM:
There is a great misunderstanding about how we are polluting the planet even by relatively experienced individuals and scientists who still seem to think composting and in some cases conversion of solid waste to methane to recapture energy are sustainable and useful approaches to handling biomass waste.
Part of the problem has to do with the well known problem of letting the organic mass remain in the landfill. That is certainly going to change as it is easy to prove it is toxic. If we want to adopt a sustainable practice of returning high quality nutrients (including carbon) in a manner that reduces greenhouse gas emissions, we will need to adopt a fermentation process. This fermentation must be done at low pH where none of the noxious gases are produced (e.g. nitrous oxide, methane, ammonia, carbon dioxide). Generally speaking, aerobic processes contribute to much pollution and anaerobic processes at or near neutral pH release gases that do ultimately damage the planet.
Biochar which involves minimizing oxygen (burning organic matter with much reduced oxygen...pyrrolysis) produces a very basic end product that has its own inherent problems in soil management. Municipalities that will ask you to separate solid waste so they can then either compost or use it to produce methane are compounding the problem and we hope to convince them they are headed in the wrong direction.
Fermentation sustains the soil microbes and produces a much richer nutrient end product for plants when done at low pH as occurs using bokashi culture mixes.
We do live in interesting times..........but there are also wonderful solutions.
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Posted by darius (from So.Appalachian Mtns, VA) on January 04, 2009 at 07:53 AM:
Thanks... another opportunity to learn more, esp. since I have been considering the aerobic/anaerobic factors lately.
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Posted by Jayryunen (from Sapello, NM) on January 04, 2009 at 04:40 PM:
Thanks, that's sort of what I've been thinking...
So what would biomass fermentation at the home level look like? Is is reasonably possible? Are we just talking a cold compost, maybe with some elemental sulfur, pine needles or ?
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Subject: Great
Posted by phicks (from Lakeland, FL) on October 08, 2008 at 05:29 PM:
Good Article And Pictures Paul
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Posted by darius (from So.Appalachian Mtns, VA) on October 08, 2008 at 05:32 PM:
Thanks, Paul. :)
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Posted by patriciahunt (from Marysville, CA) on October 13, 2008 at 05:01 PM:
Nice, succinct!
The only problem I have is with crushing. I tried rolling over the charcoal on my driveway with auto; this reduces the chunks somewhat, but the last resourse is still my hammer.
Cordially,
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Posted by darius (from So.Appalachian Mtns, VA) on October 13, 2008 at 07:41 PM:
Sorry to say the hammer is my method too...
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Subject: You're on to something...
Posted by Sundownr (from (Bev) Wytheville, VA) on October 08, 2008 at 11:49 AM:
darius, Fascinating article! I checked out the video links and found myself still watching videos an hour later, haha. I believe biochar is a great soil amendment, and a potential DIY backyard project.
I'm looking forward to your next installment of biochar... so hurry up!
Bev
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Posted by darius (from So.Appalachian Mtns, VA) on October 08, 2008 at 11:52 AM:
Thanks. Next I need to find drums to cook up some char...
I'm adding biochar to my veggie garden this week, and added it to shrubs planted yesterday.
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Posted by Sundownr (from (Bev) Wytheville, VA) on October 08, 2008 at 12:11 PM:
The only drums we ever find have once stored chemicals, so we only use them for burn barrels. We assume a thorough washing and burning removes any residual chemicals. Could they be safely used for the biochar making process?
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Posted by darius (from So.Appalachian Mtns, VA) on October 08, 2008 at 12:46 PM:
Actually, I think I have drum(s) promised. I wouldn't use anything that once held chemicals without researching the chemical first. Probably a drum that held oil products would be okay... just consider that any previous traces could eventually get to foods grown in the garden. (I know I am more overly cautious than most.)
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Posted by Sundownr (from (Bev) Wytheville, VA) on October 08, 2008 at 01:20 PM:
I agree caution is best. I won't use the ashes until I'm sure what was burned in the barrel either. Our big burner sometimes becomes the community refuse barrel when I'm not looking!
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Posted by paulineristeau (from Warren, MI) on October 13, 2008 at 01:27 PM:
Wouldn't I be able to use the charred logs left over from the campfires for this? Seems like it would be easy to break them apart and just till them into the soil.
Would be a great use for them and there are always some in the fire pit.
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Posted by darius (from So.Appalachian Mtns, VA) on October 13, 2008 at 01:33 PM:
Yes, I should think charred campfire remains would work as well as buying charcoal. I often have lumps in the ashes from my woodstove, and I just pick (or sift) them out to use.
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Posted by Sundownr (from (Bev) Wytheville, VA) on April 17, 2009 at 10:28 PM:
My oldest son and I spent a few hours today trying various methods of pounding down 3 bags of Cowboy Charcoal into pea gravel size pieces. We looked liked two coal miners by the time we called it quits. There's got to be a better way... something with a push-button would be a big help, lol. We got the majority of it ready to spread on the garden tomorrow.
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Subject: Interesting
Posted by sallyg (from Anne Arundel Co., MD) on October 08, 2008 at 08:43 AM:
How interesting. I hadn't heard of this. But again, seems like we find so many natural processes are the way to go. Think of the 'biochar' that used to be created by small wildfires in N America.
About how much did you pay for your cowboy charcoal?
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Posted by darius (from So.Appalachian Mtns, VA) on October 08, 2008 at 08:58 AM:
I paid something under $5 at least 3 years ago... but I saw it in Lowe's just 2 days ago for around $6-$7.
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Posted by Pamgarden (from Central, VA) on October 08, 2008 at 10:01 AM:
Darius, Thank you for all the reading and investingating you do for us. I always enjoy your articles and intend to consider this as an amendment to my garden beds.
Pam
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Posted by darius (from So.Appalachian Mtns, VA) on October 08, 2008 at 10:29 AM:
Thanks, Pam. I hope to see a big improvement in the growth of the fruit bushes I transplanted yesterday with some biochar. Also, I'm tilling in a bunch before putting my veggie bed to rest for the winter.
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Posted by dahlianut (from Calgary, AB) on October 08, 2008 at 11:32 AM:
Very interesting. I've never heard of using this before now but my soil is on the alkaline side so I'm not sure that it would be good for me. I'll wait for more research. Thanks Darius.
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Posted by carrielamont (from Milton, MA) on October 08, 2008 at 11:36 AM:
I appreciate your research into things I never would have thought of! Thank you, Darius. I have quite a store of ideas to try!
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Posted by pajaritomt (from Los Alamos, NM) on October 08, 2008 at 12:42 PM:
This is a very interesting article. Gardenmermaid had sent me an article on this right after Hurricane Katrina because I had so much down timber. But it sounded difficult and expensive to buy the necessary equipment.
Anything you can find that will show me how to make biochar more easily would be very helpful. The farm is covered with timber and there are always down trees and limbs. It would be wonderful if I could use them in such an environmentally friendly way. The only way we can dispose of them now is by burning which I really hate to do, but it is important to clean up down wood for several reasons.
Alkalinity would be a plus on my farm -- the soil is very acid.
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Posted by garden_mermaid (from San Francisco Bay Ar, CA) on October 09, 2008 at 02:05 AM:
darius, thank you for keeping the biochar topic on the radar!
I'm trying to find the link.....there was a website with a photo series of someone making biochar in the backyard. They had inserted the perforated basket from a washing machine into a hole in the ground, then lit the fire, then used the lid from a weber grill over that hole to make the charcoal. The weber grill lid had a vent to control air flow. If I ever find that site again, I'll post it here for you.
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Posted by darius (from So.Appalachian Mtns, VA) on October 09, 2008 at 08:45 AM:
Thanks.... I have that link, and several others including some videos, for making biochar. What I want to make is a retort burner that burns the off-gases as fuel rather than becoming atmospheric waste.
I also want to enlist someone who does bokashi to do some experiments...
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Posted by garden_mermaid (from San Francisco Bay Ar, CA) on October 09, 2008 at 01:18 PM:
Ooooh! Do keep us posted on this experiment. Sounds wonderful.
Hopefully I can manifest a home with an attached yard soon so I can help you with the experiments.
