One of the things I have been making recently besides charcoal is biochar. So far I have cooked up kitchen waste, pine needles, and mule manure. All of which have interesting properties (and smells).
What I do is in my garbage can kiln get a good fire going, put in some more medium pieces of wood and then two large chunks of wood to seperate my biochar material from the heat source. Then let it cook. This always takes longer than just making charcoal as my biochar usually has more mosture.
One very interesting thing that has happened is that the smoke from the charring wood seems to collect on my biochar material making it almost gooey when I take it out. This was very evident in the pine needles. They came out mostly black and charred but still sticky. One article I read mentions condensed smoke as having the same effect on biochar (and its application to crops), as glucose so maybe I am getting some of that effect.
Another interesting effect is that smoldering manure seems to be able to provide some of its own oxygen as even if I totally close off all air sources it stills burns for up to 24 hours!
The reason I am making as much biochar as charcoal is that I believe that charred non-woody material may break down quicker in the soil than wood charcoal. The reason I want this is to make long lasting soil organic matter (humus, humin), by providing charcoal in a unstable form that microbes and fungi can break down into stable SOM.
In much of my scientific reading on Terra Preta it seems that charcoal is very recalciterent (not breaking down), but some seems to break down very quickly. I don't know if its true but maybe its the difference between wood charcoal and biochar from non-woody material. Of course charring temperature has something to do with it also. By seperating my heat source from the charring material I know I am making biochar at a low level because of the time it takes to char and the incompletness of some of my char.
What I have ended up with is several boxes of real good looking black biochar that I will mix with an equal part wood charcoal and add to some very poor soil for a garden this Spring. One of the problems with these experiments is it will take time for the results but I will let people know as I get there.
One very interesting thing that has happened is that the smoke from the charring wood seems to collect on my biochar material making it almost gooey when I take it out. This was very evident in the pine needles. They came out mostly black and charred but still sticky. One article I read mentions condensed smoke as having the same effect on biochar (and its application to crops), as glucose so maybe I am getting some of that effect.
Hey RB,
Awesome thread. I really don't have the knowledge to address your other points, but wanted to share my immediate thought on the quote above. It seems more likely that the "goo" is from the sap in the pine needles, and not a result of charring wood/condensed smoke. However, I could very well be wrong, and would like to see the article you mention.
The place I read the glucose fact was a Danny Day/Eprida power point presentation. He credits Steiner, Garcia, Forster, Zeck for that and I don't know the paper that is from.
He also has this quote:
Quote:
This is part of the secret of creating Terra Preta. Smoldering fires produce low temp char with Bio-Oil trapped inside. High Temperature fires drive off the oils as vapor and reduce charcoal to inert carbon with limited microbial effect.
Your idea about the pine sap may be partially correct for the uncharred or partially charred material but I know there is some bio-oil from the smoke because after each burn when I start the next I see the sides of my garbage can kiln "flash" as the volatile oil from the previous burns smoke combusts. I also get this sticky goo like effect when I char kitchen wastes also.
I don't know if that is really bio-oil that is on the sides of the can or on the charred material but it is some kind of volatile oil.
As I write this I wonder just what the bio-oil that is mentioned exactly is? Anybody have a definition?
Another idea that comes to mind in regards to how the Amazonian Indians made Terra Preta is that this "bio-oil" seems to evaporate/disappear within a short time after I take the material out of my kiln. Since I mix this material with charcoal maybe it is adsorbed into the mix. Since the Amazonians most likely did their burns in place and didn't immediately process what they did maybe this bio-oil being adsorbed into their soil/charcoal/wastes mix is part of what makes Terra Preta work. Just a thought.
Very interesting observations, RB. I think some of the charcoal will probably break down to a very limited extent, because I've also read that some of the carbon in the charcoal will oxidize or chemically react to form carboxylic acids, which help to increase the nutrient- and water-holding capacity of the terra preta. This happens over time.
I'll try to post a little more when I get over this nasty flu I'm battling. I've felt like a crisped bit of organic matter what with the fever the last week.
__________________ Logic
The art of thinking and reasoning in strict accordance with the limitations and incapacities of the human misunderstanding.
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On the original thread I discussed my numerous attempts at making charcoal and it turned out to be quite decent. What it taught me is that making your own gives you a real good sense of what kind of charcoal to buy when you actually find some to buy. I now buy mine at Lowe's -- a brand called Cowboy Charcoal.
But the problem has been how to pulverize it since this is lump charcoal and in good sized lumps, many being several inches in length by a half inch in depth and a couple inches in width.
Here is the aboriginal method I "discovered" to make small particles.
Quite simple. Take a flat rock. Take a rubber mallet. Put charcoal on rock and pound. Imagine an aboriginal with a wood mallet instead of a rubber one.
Would not recommend a metal hammer face at all because of the danger of a broken piece of rock flying.
Works very well for the small garden.
I also discovered that taking clods of dried clay and breaking them makes for a pretty good mix.
Perhaps this is a bit off topic, but if you are going to make biochar, you still are going to need some means to break it up.
What I have found that works best for pulverizing charcoal is 3 2x4's about 5 feet long nailed together and used in a pile driver motion on charcoal that is in a box on a flat surface. I actually have a smaller box with the charcoal in it inside a larger box that gives it more stability so when I hit a large piece of charcoal the whole thing doesn't tip over. This keeps me five feet from the action and soot and if t is slightly windy then the particles drift away. Also when I am done I just take the small box with the charcoal powder, take out any large pieces and pour or store it where I want. This avoids most direct handleing of the charcal. It works well as the larger pieces of charcoal work their way to the top during pulverization and I gets lots of powder and small pieces as the large pieces keep getting pounded down into the mix. This works well on biochar also but is rather hard on boxes (I use the old ones as starter material for my next batch).
I don't remember where I saw it but there was a picture of a blender full of charcoal. I am smart enough NOT to have done that with my wife's blender!
The work you all are doing is really fascinating to me. I do have a few questions if you would indulge me and my ignorance of the subject. Is there an optimal temperature at which the pyrolitic process occurs? What is the reason for the addition of regular lump charcoal to the biochar? What is the optimal ratio of lump charcol to biochar? Would a regular wood chipper work for beaking up the lump charcoal and the biochar to a size that would be optimal for use? I'm looking forward to trying to make my own soon. I need to give the neighbors something new to talk about. Thanks for your help.
All of the people who regularly post and reply on this site are great sources of information and have helped me tremendously. So ask away on any of your questions and post anything you feel is important.
To answer your above question on optimal temperature. The higher the charring temperature that less impurities are in the charcoal and the greater cation exchange capacity (CEC) because there are more "open" sites for ions (nutrients) to bind to. However there are many of us the think that the impurities in the charcoal help make Terra Preta work. Also it seems that the higher the temperature the more the charcoal is recalcitrant (harder to break down).
In answer to your other questions on charcoal vs. biochar and the optimal ratio there are no set answers. There are three main factors in making charcoal, parent material, degree of charring, and charring temperature.
In short your parent material can be wood (traditional definition of charcoal), non-woody material such as leaves, stalks, and grass clippings, organic matter such as kitchen wastes and other top end organic matter, and manure. I base my thinking on the anthropological studies of how the Amazonian Indians may have made their charcoal and bio-char (Steiner Chapter 23 Amazonian Dark Earths and Lisa German's research both available on-line). Also Susan Hecht and others have information on practices that current tribes in the Amazon use.
The degree of char can be across what is called the "combustion continuum" the starts with partial char, char, charcoal, soot, and graphite. Partial char and char are most likely easier to break down and start the soil organic matter (SOM), cycle that seems to be vital to Terra Preta. Charcoal seems to adsorb nutrients and act as a storage site for other soil processes like microbial agents to get source materials. Charcoal also breaks down by oxidation but this is not well investigated and seems to be a slow process.
The charring temperature I mentioned above but again; lower temperature material seems to be easier to break down to SOM and high temp lends itself to more adsorption of ions and storage of nutrients.
The optimal ratio is harder to answer because that would depend on your soil and what you are trying to accomplish. The soil I am working on is clay with no SOM so I am currently making both charcoal and biochar and composting it with regular compost material because I am after about a 10% level of SOM to start with this spring and hope that this fall there will be a 5% level after it degrades.
Personally I feel (and again I get this idea from the Amazonian practices), that charcoal and biochar should be composted with organic matter for four reasons; first to avoid nitrogen "shock" where to much charcoal can tie up nutrients for your first year, second to buffer the ph levels to a neutral level, third to let the carbon-nitrogen ratio balance out, and fourth to start the microbial process going before you put your mix into the soil. I call this "Carbonposting" and am currently researching (not much information), and writing up this idea.
Nathan I encourage you to research as much as you can on Terra Preta because there is a tremendous amount of information available of the web and you are the only one who knows how it applies to your situation. Terra Preta and its application for temperate crops and climates is in its infancy and all of us have our own ideas based on what we have read.
I have thought about the wood chipper idea and if you can find a way to keep the charcoal powder from drifting away it should work although the whatever color wood chipper will become black!
As far as neighbors my whole town thinks I am crazy because last Friday evening I was charring up some biochar (mule manure), and the wind was blowing the "wrong" way. I got feedback from the Library Board meeting and the High School dance committee. Don't they know we are trying to save the world!!
There is no reason why those of use investigating Terra Preta can't research parts of its applications and properties. After all we are the ones getting our hands black, tilling carbon into our gardens, and trying different things to see what happens.
Many of us have science backgrounds/work experience that makes our ideas valid and resonable (until shot down by others), and we should share them with each other.
This ph investigation of pine needle biochar was something I have been interested in since a Colorado State Universtiy professor mentioned that most Colorado soils are akaline and that Terra Preta may not be a good idea. I took the idea that pine needle mulch can lower soil ph because of its acidic qualities and wondered if pine needle biochar could do the same. And it does. What was real interesting was the "bio-oil" from the condensed pine needle smoke that was collecting on the top of my garbage can kiln. I collected it as an after thought when it spilled onto my gloves as I was "kickin the can" to settle the wood/pine needles. Turns out this was concentrating the volitile oils/acids from the pine needles and its ph lowering qualities are huge. Got me to thinking about adding this back to pine needle char to stablize it and use the large surface area and adsorption properties of char to create a long term soil amendment. I don't know if this would work in soil until I try it but thought I would share it with all. If you find holes in the science let me know perferrably by private mail so my "on-line" reputation dosn't get too trashed. I do have a few qualifications to do this, BS in Physics, 5 years of soils enginerring, had my MS in Eduction work published, but more importantly have made 20 plus different loads of charcoal/biochar.
The ph of Pine Needle Biochar by Randy Black
Note: This experiment was done in my kitchen using a blender, small measuring cup, and litmus paper. Do not confuse this with a real laboratory science experiment or a real science journal article. I tried to be as exact as I could but the variability of the pine needle biochar, the charring process, and my measuring and material processing make the results a measure of generalized trends not specific facts. I encourage others to try this or other Terra Preta science experiments and report the results as there are huge areas of Terra Preta applied technology that we are only now experimenting with and understanding.
Introduction and Experimental Procedures
Pine needles are an acidic material and pine needle mulch has been used to lower the ph in soil. This investigation looks at the ph effects of pine needle biochar on water with ph levels of 7, 8, and 9. It also looks at pine needle char from across the combustion continuum of partial char to char and compares them with uncharred pine needles and an oil/water material collected from condensed pine needle smoke. Charcoal has the affect of increasing the ph in soil and this experiment investigates the ability of pine needle biochar to decrease the ph in soil.
The pine needles were charred in a small metal kiln at a low temperature for 6 hours. There was a high variability in the temperature as the heat source from burning wood in the bottom of the kiln was closer to the some of the pine needle material than other parts of the sample. The pine needles were separated by larger wood pieces from the burning pine wood (heat source), but were exposed to smoke from this source. It has been noted in previous burnings that this smoke leaves a thin coat of volatile oil on the sides of the kiln and material at the top of the kiln so it is presumed that the partial char pine needles also were coated with this oil and a small part of the ph results may be due to this oil.
The pine needles were collected from the forest floor and were a combination of last years needles which were tan (70%), and previous year’s needles which were tan to grey (30%). The needles maintained their structural integrity and were dry to the touch. One thing noted in this and in previous experiments with charring pine needles is that the smoke given off is much thicker than regular pine wood being charred and there is noticeably higher moisture content. This was evident by the condensation on the top of the kiln lid which was collected and is the “bio-oil” in this investigation. One interesting fact when charring pine needles is that when the oxygen is restricted to stop the burn unlike regular charcoal loads the mix continues to smolder at a low level until put out by water. This implies that the gases from the heated pine needles provide enough oxygen to continue the charring process. The pine needles in this study continued to smolder in these conditions for an additional 9 hours.
When the mass of needles was removed from the kiln it was layered with partial char on top to charred pine needles on the bottom. The samples in these ph experiments are from these two layers and have the following characteristics. The partial char is a golden brown color, maintains the original pine needle structure, and is sticky wet to the touch due to the condensate from the pine needle pitch and burning wood. The pine needle char still looks like pine needles but is dry and can be easily crumbled into small pieces and powder. The variability of the pine needles across the combustion continuum and variability of the charring process temperatures and conditions makes the data of this study highly subjective and the results should be looked at as generalized trends not specific data points.
All of the ratios in the following results are by volume not weight and further studies using weight ratios will need to be done to calibrate the ph reduction capacity of pine needle biochar. The processing of the material (dry unburnt pine needles, partial char, char, and bio-oil), and its effective surface area lends further uncertainty to these results and again these results are generalized trends not specific facts.
The pine needle material was tested with distilled water (ph 7), tap water (ph 8), and water that had been soaking in pine charcoal (ph 9). The testing was done with litmus paper and read visually so the data is not exact figures but approximations of the ph affects of pine needle biochar.
Results Experiment 1
The four types of pine needle material are dry unburnt needles, partial pine needle biochar, charred pine needles, and bio-oil made from condensed pine needle smoke. In the first set of experiments each material was mixed with an equal volume of water stirred for 30 seconds and measured in the next 30 seconds. Data is given in ph of water followed by ph of the change.
1. Dry unburnt pine needles with ph 7 water – 6.9 to 7 ph; ph 8 water – 7 ph; ph 9 water – 8 ph.
2. Partial pine needle char with ph 7 water – 6.4 ph; ph 8 water – 6.5 ph; ph 9 water – 6.5 ph.
3. Charred pine needles with ph 7 water – 7 ph; ph 8 water – 7.5 ph; ph 9 water – 8.1 ph.
4. Pine needle bio-oil with ph 7 water – 6 ph; ph 8 water – 6 ph; ph 9 water 6 ph.
Experiment 2
The following results are from charred pine needles in both ph 8 and ph 9 water with readings taken at 1, 5, 10, and 20 minutes.
1. In ph 8 water – 7.5 ph at 1 minute; 7.1 ph at 5, 10, and 15 minutes.
2. In ph 9 water – 8.1 ph at 1 minute; 7.8 ph at 5 minutes, 7.5 ph at both 10 and 20 minutes.
Experiment 3
The following experiment uses ph 8 water and charred pine needles in increasing ratios of water to charred pine needles with readings taken at 1, 2, 5, and 10 minutes.
1. Ratio 4 to 1; ph 7.4 at 1 minute; ph 7.1 at 2 minutes; ph 7 at both 5 and 10 minutes.
2. Ratio 8 to 1; ph 7.6 at 1 minute; ph 7.3 at 2 minutes; ph 7.2 at both 5 and 10 minutes.
3. Ratio 16 to 1; ph 7.9 at 1 and 2 minutes; ph 7.8 at both 5 and 10 minutes.
Experiment 4
The following experiment used ph 9 water and bio-oil in increasing ratios of water to bio-oil. Measurements were taken at 1 minute.
1. Ratio 4 to 1 ph 6
2. Ratio 8 to 1 ph 6
3. Ratio 16 to 1 ph 6
4. Ratio 32 to1 ph 6.5
5. Ratio 64 to 1 ph 7.1
Discussion
The results in Experiment 1 show that the acidic effects of pine needles rest mainly in the volatile oil/acids contained in pine needles as seen in the partial char and bio-oil results bringing the ph levels down to below 7. However pine needle char will bring the ph level of water down to towards the neutral level of ph 7 as seen in Experiments 2 and 3 with longer exposure. The difference between the ph affects of bio-oil and charred pine needle may be due to a chemical process versus and physical-chemical process as low temperature biochar does contain some of the parent materials properties as impurities with the char. More investigations are needed to identify what affects the high surface area, adsorption properties, and impurities in low temperature pine needle biochar have on modifying ph. Dry ground uncharred pine needles also lower the ph of water but take much more processing time and energy and do not have the adsorption properties or increased cation exchange capacity of char.
The results of Experiment 4 show that a small amount of pine needle bio-oil can significantly reduce the ph of large amounts of water. At a ratio of 16 parts ph 9 water to 1 part bio-oil the ph was still reduced to 6 within one minute. At a large ratio of 64 to 1 the bio-oil still reduced the ph to 7.1. It is clear that the condensed pine needle smoke concentrated the acids in pine needles. Field investigations should also look into this bio-oil being applied back to pine char before use and if the adsorption properties and recalcitrance of char might make this a long term ph modifying soil amendment.
What affects partial char, char, and bio-oil would have on high ph soils would need to be field tested with a variety of soil under various condition and with differing percentages of pine needle biochar/bio-oil. Reducing the ph of water and reducing the ph of soils are two different processes and long term field testing is needed. Most likely the acidifying affects of the bio-oil and partial pine needle biochar would be temporary but due to the recalcitrance of charcoal, its high surface area, and adsorption properties, charred pine needles may be able to maintain soil at a ph level of 7 for much longer.
Summary
The implications of pine needle biochar for Terra Preta research and charcoal enhanced soils are tremendous. First, we now have the ability to add char to soil that will reduce the ph level instead of increase it but still contribute the benefits of charcoal in soil using a common readily available material. This has implications for alkaline soils and to create soils for crops that need acidic conditions. Second, this demonstrates that we can tailor one of the chemical properties of biochar to match soil conditions based on the chemistry of the parent material. This means that Terra Preta science can be applied to a wide variety of soils and has the potential to be individualized to match soil ph conditions and crop ph ranges. Third, if we can do this with ph levels can Terra Preta science be applied to doing this with trace minerals for crop nutrients or for a chemical/mineral balance that may be selective in establishing a desirable specific microbial community. The physics and chemistry of pine needle biochar’s ph affects are entirely different from what would be needed to add specific minerals/chemicals to soil but demonstrates that Terra Preta technology is much more than just adding charcoal to the soil and could revolutionize our ideas on soil and crop management.
Nice write-up Randy!
It got me thinking about using native materials to char and help stabilize the pH of native soils (ie TP). The implications are huge!
The soils in my yard are slightly acidic (mainly Cartecay Soils; slightly acidic, alluvial). There are several pines that grown in the yard...Bingo, a control! As another control in the meantime, you should try some un-charred pine oil. You can obtain it by boiling pine needles (tons of them, about 1lb. for a thimbleful) and scooping up the oil that accumulates on the top. (As a side bonus, this oil is a natural substitute for Pinesol floor cleaner)
I might try this pine needle idea to see what the effects are on my soils. Heck, I might as well, I already have the methodology laid out before me.
I still have MUCH reading to do before I start though...
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