This is a fairly new topic to me. I assume the same is true for many people. I am only scratching the surface in my endeavor to learn more about this stuff. I wonder if anyone else is using or looking into this. I would love to hear other people's knowledge and/or experience.
Here is an article from Mother Earth News. I copy and pasted it as links seem to break down over time, and this way it will be on the forum forever.
Make Biochar — This Ancient Technique Will Improve Your Soil Charcoal made from brush can increase your soil’s fertility and help slow climate change. By Barbara Pleasant February/March 2009
Last year, I committed one of the great sins of gardening: I let weeds go to seed. Cleaning up in fall, I faced down a ton of seed-bearing foxtail, burdock and crabgrass. Sure, I could compost it hot to steam the weed seeds to death, but instead I decided to try something different. I dug a ditch, added the weeds and lots of woody prunings, and burned it into biochar, thus practicing a “new” soil-building technique that’s at least 3,000 years old.
What’s biochar? Basically, it’s organic matter that is burned slowly, with a restricted flow of oxygen, and then the fire is stopped when the material reaches the charcoal stage. Unlike tiny tidbits of ash, coarse lumps of charcoal are full of crevices and holes, which help them serve as life rafts to soil microorganisms. The carbon compounds in charcoal form loose chemical bonds with soluble plant nutrients so they are not as readily washed away by rain and irrigation. Biochar alone added to poor soil has little benefit to plants, but when used in combination with compost and organic fertilizers, it can dramatically improve plant growth while helping retain nutrients in the soil.
Amazonian Dark Earths
The idea of biochar comes from the Amazonian rain forests of Brazil, where a civilization thrived for 2,000 years, from about 500 B.C. until Spanish and Portuguese explorers introduced devastating European diseases in the mid-1500s. Using only their hands, sticks and stone axes, Amazonian tribes grew cassava, corn and numerous tree fruits in soil made rich with compost, mulch and smoldered plant matter.
Amazingly, these “dark earths” persist today as a testament to an ancient soil-building method you can use in your garden. Scientists disagree on whether the soils were created on purpose, in order to grow more food, or if they were an accidental byproduct of the biochar and compost generated in day-to-day village life along the banks of the Earth’s biggest river. However they came to be, there is no doubt that Amazonian dark earths (often called terra preta) hold plant nutrients, including nitrogen, phosphorous, calcium and magnesium, much more efficiently than unimproved soil. Even after 500 years of tropical temperatures and rainfall that averages 80 inches a year, the dark earths remain remarkably fertile.
Scientists around the world are working in labs and field trial plots to better understand how biochar works, and to unravel the many mysteries of terra preta. At Cornell University in Ithaca, N.Y., microbiologists have discovered bacteria in terra preta soils that are similar to strains that are active in hot compost piles. Overall populations of fungi and bacteria are high in terra preta soils, too, but the presence of abundant carbon makes the microorganisms live and reproduce at a slowed pace. The result is a reduction in the turnover rate of organic matter in the soil, so composts and other soil-enriching forms of organic matter last longer.
In field trials with corn, rice and many other crops, biochar has increased productivity by making nutrients already present in the soil better available to plants. Results are especially dramatic when biochar is added to good soil that contains ample minerals and plant nutrients. Research continues (track it at The International Biochar Initiative ), but at this point it appears that biochar gives both organic matter and microorganisms in organically enriched soil enhanced staying power. Digging in nuggets of biochar — or adding them to compost as it is set aside to cure — can slow the leaching away of nutrients and help organically enriched soil retain nutrients for decades rather than for a couple of seasons.
Finding Free Biochar
Biochar’s soil building talents may change the way you clean your woodstove. In addition to gathering ashes (and keeping them in a dry metal can until you’re ready to use them as a phosphorus-rich soil amendment, applied in light dustings), make a habit of gathering the charred remains of logs. Take them to your garden, give them a good smack with the back of a shovel and you have biochar.
If you live close to a campground, you may have access to an unlimited supply of garden-worthy biochar from the remains of partially burned campfires. The small fires burned in chimineas often produce biochar, too, so you may need to look no further than your neighbor’s deck for a steady supply.
Charcoal briquettes used in grilling are probably not a good choice. Those designed to light fast often include paraffin or other hydrocarbon solvents that have no place in an organic garden. Plain charred weeds, wood or cow pies are better materials for using this promising soil-building technique based on ancient gardening wisdom.
How to Make Biochar
To make biochar right in your gardens, start by digging a trench in a bed. (Use a fork to loosen the soil in the bottom of the trench and you’ll get the added benefits of this “double-digging” technique.) Then pile brush into the trench and light it. You want to have a fire that starts out hot, but is quickly slowed down by reducing the oxygen supply. The best way to tell what’s going on in a biochar fire is to watch the smoke. The white smoke, produced early on, is mostly water vapor. As the smoke turns yellow, resins and sugars in the material are being burned. When the smoke thins and turns grayish blue, dampen down the fire by covering it with about an inch of soil to reduce the air supply, and leave it to smolder. Then, after the organic matter has smoldered into charcoal chunks, use water to put out the fire. Another option would be to make charcoal from wood scraps in metal barrels. (For details, go to Twin Oaks Forge. )
I’m part of the Smokey-the-Bear generation, raised on phrases like “learn not to burn,” so it took me a while to warm up to the idea of using semi-open burning as a soil-building technique. Unrestrained open burning releases 95 percent or more of the carbon in the wood, weeds or whatever else that goes up in smoke. However, low-temperature controlled burning to create biochar, called pyrolysis, retains much more carbon (about 50 percent) in the initial burning phase. Carbon release is cut even more when the biochar becomes part of the soil, where it may reduce the production of greenhouse gases including methane and nitrous oxide. This charcoal releases its carbon 10 to 100 times slower than rotting organic matter. As long as it is done correctly, controlled charring of weeds, pruned limbs and other hard-to-compost forms of organic matter, and then using the biochar as a soil or compost amendment, can result in a zero emission carbon cycling system.
Burning responsibly requires simple common sense. Check with your local fire department to make sure you have any necessary permits, wait as long as you must to get damp, windless weather, and monitor the fire until it’s dead.
The Bigger Picture
If global warming is to be slowed, we must find ways to reduce the loss of carbon into the atmosphere. In the dark earths of the Amazon, and in million-year-old charcoal deposits beneath the Pacific Ocean, charcoal has proven its ability to bring carbon release almost to a standstill. If each of one million farmers around the globe incorporated biochar into 160 acres of land, the amount of carbon locked away in the Earth’s soil would increase five-fold.
But there’s more. What if you generate energy by burning a renewable biomass crop (like wood, corn, peanut hulls, bamboo, willow or whatever), while also producing biochar that is then stashed away by using it as a soil amendment? (For an example, see the Archive article, Mother's Woodburning Truck , about wood-gas generators.) The carbon recovery numbers in such a system make it the only biomass model found thus far that can produce energy without a net release of carbon. Research teams around the world are scrambling to work out the details of these elegantly Earth-based systems.
Much remains to be known about how biochar systems should tick, but some may be as simple as on-farm set ups that transform manure and other wastes into nuggets of black carbon that help fertilizer go farther while holding carbon in the soil.
As gardeners, it is up to us to find ways to adapt this new knowledge to the needs of our land. To make the most of my bonfire of weeds, I staged the burn in a trench dug in my garden, and then used the excavated soil to smother the fire. A layer of biochar now rests buried in the soil. Hundreds of years from now, it will still be holding carbon while energizing the soil food web. This simple melding of soil and fire, first discovered by ancient people in the Amazon, may be a “new” key to feeding ourselves while restoring the health of our planet.
(To learn more about this fascinating topic, read Amazonian Dark Earths by Johannes Lehmann.)
To make biochar, pile up woody debris in a shallow pit in a garden bed. Burn the brush until the smoke tins and then damp-down the fire by covering it with about an inch of soil. Let it smolder until the brush is charred, then put the fire out.
Using biochar is a great way to give carbon back to the earth, increase water retention, drainage air permeability and cation exchange capacity. Since I started using biochar in the grow room, my EC drops slower and my plants burn easier. I've seen best results when I use biochar in larger volume containers with lava rock cinders.
I use 25% vermicompost, 25% biochar and 50% coco coir for vegetative growth, and 10% vermicompost, 20% biochar, 30% lava cinders and 40% coco coir in flower. I regularly send my mixes and teas into Soil Foodweb Oregon for testing and analysis. After adding biochar and lava rock cinders, my results came back with a increase in total active biomass by over 15% my veg mix and nearly 30% in my flower mix.
When it comes to microbial activity, biochar acts like a coral reef for soil microbiology. Because of it's complex carbon structure and chemical stability, it is indigestible to microbiology and just like perlite it won't breakdown over time, so it's great for balancing water to air ratios. I haven't even touched perlite since I first switched to coco.
In 1542, the Spanish explorer, Francisco de Orellana ventured along the Rio Negro, one of the Amazon Basin's great rivers. Hunting a hidden city of gold, his expedition found a network of farms, villages and even huge walled cities. At least that is what he told an eager audience on his return to Spain.
The prospect of gold drew others to explore the region, but none could find the people of whom Orellana had spoken. The missionaries who followed a century later reported finding just isolated tribes of hunter-gatherers. Orellana's story seemed to be no more than a fanciful myth.
With no trace of such a vast civilization in an area so inhospitable to agriculture, who would conclude differently? Without extensive agriculture major population centers could not have existed, but in the Amazon all attempts at intensive agriculture have led to disaster. That is until researchers began to question the mysterious presence of terra preta.
A proven liar?
When scientists came to weigh up the credibility of Orellana's words, they reached the same conclusion. As productive as the rainforest may appear, the soil it stands in is unsuited to farming. It is established belief that all early civilisations have agriculture at their hearts. Any major population centre will have connections with a system of intensive agriculture. If a soil cannot support crops sufficient to feed a large number of people, then that serves as an effective cap on the population in that area. Even modern chemicals and techniques have failed to generate significant food from Amazonian soil in a sustainable way . The thought that indigenous people could have survived in any number - let alone prospered - was dismissed by most scientists. Scientific consensus was sure that the original Amazonians lived in small semi-nomadic bands and that Orellana must have lied.
Clues from the Bolivian savannah
Bolivia's Llanos de Mojos (Mojos Plains) are 2,000km from Orellana's route down the main channel of the Amazon. The terrain is savannah grassland with extreme seasons - floods in the wet; fires in the dry. Crops are hard to grow and few people live there. But back in the 1960s archaeologist Bill Denevan noted that the landscape was crossed with unnaturally straight lines. Large areas were also covered with striped patterns.
Recently, Denevan's work has been followed up by Clark Erickson, a landscape archaeologist. His attention was drawn to the numerous forest islands dotted across the savannah like oases. Down on the ground he found them littered with prehistoric pot sherds, a clear sign of early human habitation. Some mounds were as much as 18m high and much of the pottery was on a grand scale as well. Such huge vessels were too big for wandering nomads. Here were permanent settlements, where hundreds or even thousands of people had once gathered for huge ceremonies. To Erickson, these were signs of an advanced society - a civilisation.
Erickson and a colleague, William Balée, needed evidence for organised farming and found help working with the region's Amerindians. Some of the mounds are still inhabited by indigenous people. The language of the Sirionó offers clues to their past. Words for staple crops like maize, as well as cotton and dye plants, hint at what may have been farmed hundreds, even thousands, of years ago.
Erickson's interpretation of the lie of the land is that the mounds were built to offer protection from floodwaters, with the most sacred buildings always at the centre of the mound on the highest level. There is historical evidence for this - a Spanish expedition of 1617 remarked on the extent and high quality of a network of raised causeways connecting villages together. Those causeways can still be seen as straight lines cutting across the savannah. Alongside them run canals, a result of their construction.
Denevan and Erickson have shown that the striped patterns are relics of a system of raised fields. From the air, the area which appears to have been turned over to such agriculture is clear. It covers thousands of square kilometres. In conjunction with the controlled irrigation a canal network might offer, it could have sustained hundreds of thousands of people. Erickson believes the Mojos Plains were home to a society which had totally mastered its environment.
If land now little suited to agriculture could once have supported hordes of people, is there a chance Orellana's mythical El Dorado has some basis in fact?
When anthropologist Michael Heckenberger met the Kuikuru tribe in the central Amazon he was impressed by the complexity of their social structure. Why, he wondered, would a tribe of just 300 people adopt such a hierarchical way of life? (Received opinion held that Amazonian tribes were small, egalitarian societies.) He found evidence that the Kuikuru had once lived in an integrated network of villages, each one many times the size of their modern-day settlements. Heckenberger believes the prehistoric Kuikuru were not the semi-nomadic wanderers of anthropological theory. Instead, they lived in large chiefdoms - the advanced society described by Orellana.
The Secret of the Soil
The search for clues in the Amazon takes place right at the grass roots level - in the soil itself. Along Brazil's Tapajos River, archaeologist Bill Woods has mapped numerous prehistoric sites, some with exquisite, 2,000 year old pottery. There is a common thread: the earth where people have lived is much darker than the surrounding yellow soil of the rainforest. Closer investigation showed that the two soils are the same, but the dark loam is enriched with biological matter. The Brazilians call this fertile ground terra preta. It is renowned for its productivity and even sold by local people.
Archaeologists have surveyed the distribution of terra preta and found it correlates favorably with the places Orellana reported back in the 16th century. The land area is immense – the size of California (or twice the size of the Britain). It seems the long ago Amazonian peoples transformed the earth beneath their feet. The terra preta could have sustained permanent intensive agriculture, which in turn would have fostered the development of advanced societies. Archaeologists like Bill Petersen, from the University of Vermont, now regard Orellana's account as highly plausible. But if the first Conquistadors told the truth, what became of the people they described?
Tragically, the visitors brought diseases to which the Amerindians had little resistance: smallpox, influenza, measles. Orellana and his men were the first and last Europeans to set eyes on an Amazonian civilization. They themselves may have been the ones to trigger its rapid decline.
Yet the Amazonians' greatest achievement lives on. Soil scientists analyzing the terra preta have found its characteristics astonishing, especially its ability to maintain nutrient levels over hundreds of years. By comparison, traditional slash and burn practices yield a type of nomadic farming that can sustain only a few. Even modern techniques have simply led to ecological catastrophe with vast swathes of forest being cleared, only for the land to be abandoned. With the vegetation burned off, the high rainfall soon leaches all the nutrients out of the soil. Research has shown that even chemical fertilizers cannot maintain crop yields into a third consecutive growing season, yet terra preta remains fertile year after year.
Local farmers testify, “The soil is easy to work and very fertile. We plant papaya, we plant banana, corn, beans and manioc in terra preta. Whatever you plant in terra preta does exceptionally well.” Terra preta is so fertile that Brazilian farmers have prized it for centuries. Somehow the prehistoric Amazonians transformed the world's worst soil into some of the best.
Nature and Nurture
Again, Orellana's accounts offer potential insight. He reported that the indigenous people used fire to clear their fields. Bruno Glaser, from the University of Bayreuth, has found that terra preta is rich in charcoal. He believes it acts to hold the nutrients in the soil and sustain its fertility from year to year. This is the great secret of the early Amazonians: how to nurture the soil towards lasting productivity. In experimental plots, adding a combination of charcoal and fertilizer into the rainforest soil, Glaser recorded an 880% increase in yields compared with fertilizer alone.
Yet terra preta may have a still more remarkable ability. Almost as if alive, it appears to reproduce. Bill Woods has met local farmers who mine the soil commercially. Farmer, “After digging the soil,what is left will grow deeper. It's because it's being fed by the leaves that fall on it.” Like the lump of dough once saved from a batch of bread making to leaven the next batch, these farmers find that, as long as they leave 20cm of terra preta undisturbed, the bed will regenerate over a period of about 20 years. He suspects that a combination of bacteria and fungi is causing this effect.
Today the Amazon rainforest is under threat as never before. Millions of acres have been wiped out and every year farmers continue to slash and burn their way across the jungle in a largely futile attempt to turn it into farmland. Meanwhile, scientists are busy searching for the biological cocktail that makes barren earth productive. Scientists are now working to find out how terra preta does it. There are literally tens of thousands of species of bacteria and fungi in the soil and they suspect that somewhere among them must be unique microorganisms that allow the terra preta to grow. If they can succeed in recreating the Amerindians' terra preta, then a legacy more precious than the legendary golden city of El Dorado could spare the rainforest from destruction and help feed people across the developing world.
I see two ironies in the story of the hunt for El Dorado. There was once a great civilization in the Amazon, one the Europeans destroyed even as they discovered it. And, one has to wonder if that ancient civilization had understood the healing virtues of charcoal for sick bodies as they evidently did for sick soils, they may have survived their European guests. Today, that black earth, the terra preta, and its supernatural ingredient charcoal may offer the solution to more than just our small vegetable gardens.
Who will benefit most if the bio/chemical secret of terra preta is ultimately unlocked? It could have profound effects on tropical agriculture, especially in light of a worldwide crisis in soil fertility. Terra preta seems especially suitable for the cultivation of fruit and vegetables, what we would call market gardening. These crops have high economic and nutritional value for poor farmers in the developing world, and they would be the main beneficiaries if it could be recreated on a wide scale in local communities.
In order to get a charcoal production method that avoids emissions of methane during pyrolysis, is simple to build even with small means, produces charcoal from the garden waste that is not easily added to the soil, makes a bit of atmospheric carbon reduction and supports the local ecosystem -- this simple backyard/allotment/home garden sized system can be used.
The unit consists of two steel barrels. Only. The smaller with no alterations a all. It is filled with dry biomass and put upside down in the larger one.
In the larger one, holes are cut on the side, some centimetres (an inch) above the bottom, large enough to let in an ample amount of air.
The larger barrel shold reach at least ten centimeters (4 inch) above the smaller vessel, to get a good "chimney"-effect, i.e. a strong draught from the air inlets, and a hot fire throughout the process.
Fill the smaller vessel with biomass, preferrably dry to make the charring procedure more efficient. Use chips, dry grass, bamboo or Miscanthus stalks, twigs, sawdust or what you have. Even some hard bones are good to put in. Put the material in as tight as possible.
Fill the vessel level with the top, it will be placed upside down. Put the larger drum upside down on top of the smaller vessel, so the bottom of the drum fits close to the top of the biomass filled vessel.
When you have done that, the smaller vessel stands upside down in the larger. No lids, no fastening (although it could be fine with some cover, just to keep the material inside the vessel when turning).
Put dry firewood in the space between the two vessels (and some on top). Light it.
Replenish the firewood, so it burns at least 30 - 40 minutes.
After 30-40 minutes, the pyrolysis of the biomass starts. The gases will emerge from the vessel through the chink between the vessel and the barrel and immediately take fire and heat the vessel more, so more gases emerge, and so on. It is easy to see when this happens.
To be sure that all the pyrolysis gases take fire, be sure that the air inlets really gives an excess of air, and the passage between the vessel and the jar is long enough (if it takes 1 second, you are on the safe side). Otherwise, the fire will smoke and powerful greenhouse gases will emerge into the atmosphere.
After about half an hour, the fire will stop burning rather abruptly. At that time, there is (hopefully) only charcoal left in the vessel. Let it cool at least an hour. If you take hot charcoal into the air, it may catch fire.
When the vessel has cooled down, turn everything back again (preferrrably over the soil in a garden plot, to take care of the ashes). The char is ready to dig down in the soil, to put into the compost or let it absorb urine for increased soil fertility. Also, put on the soil, it will deter snails.
*This system is aimed to be a 'backyard charring method'. It is cheap and easy to construct and handle, and meant to replace the backyard burning of twigs, taking place everywhere, with a method of increasing soil fertility at the same time as reducing CO2 in the air.
It is not meant as a large scale method, since the surplus gases, that could be of industrial use, are burnt and the useful heat is dissipated (although you could easily cook food on the fire if you put a grid on the top). But it should be seen as an introduction to charring, and as an eye-opener for the usefulness of charcoal in the soil. That the threat of climate change, in an infinitesimal way, simultaneously is reduced should be seen as a bonus.
I have been using charcoal and ashes in my garden here for 20 yrs now. I garden in jackpine sand and all the organic matter you can add the better. I have a wood boiler and add all the left over ashes and charcoal to my garden I also use green manure crops and cover crops to increase soil fertillity. I am the only person with a garden where i live because the soil is so poor and most people try for a few years then quit. I grow bumper crops on that sand with out any chem fertilizers its all organic. I found out all by simple observations on our family farm.
Great Post GB and Fulvic! The downside is now I have yet more stuff to add to my 'look up this stuff' list
Biochar has been used probably since the Neolithic as early farmers learned to burn off their fields, both to keep them free of other plants and to increase the soil's harvest potential. Makes sense this would help in our gardens as well.
It's a jeep. If I'd wanted a hummer, I would have called your sister.