We do see people dropping by here on this forum (and other GW forums) and making their first post on the same day they register. Which is fine, but... whenever said first post immediately promotes the wonders of some organic product for sale, it makes some of us kinda cynical about the motives of the new poster. Hence, my replies above.

As well, intelligent discussions do take place here. There are a number of them on this forum (and on Soil, Compost & Mulch, and other forums here) about the use of charcoal in soil. I'll try a search and demonstrate the results at the link, below.

Welcome to the GardenWeb forums, Pagardner. :)

All the best,
-Patrick

Black Is The New Green

As they note, soil scientists at Cornell University in the USA and at the University of Bayreuth in Germany have been studying Terra Preta for some time. Among other researchers on other continents.

Cornell website on Terra Preta

Terra Preta Web Site at the University of Bayreuth

Another article published in May 2007 in Scientific American, specific to biochar but also discussing Terra Preta:

Special Report: Inspired by Ancient Amazonians, a Plan to Convert Trash into Environmental Treasure

All the best,
-Patrick

What's missing are the hard facts. What are the various percentages of course sand, medium sand, find sand, course silt, fine silt, and clay? What are the minerals that make up the factions? PH? CEC, and is it high due to hydrocarbons or clay or both? How do the above compare to non- Preta soils nearby or with other Terra Preta soils at a distant location?

What I find on the net are commercial sites that know all the secrets of Terra Preta and have just the product to re-create the effect in your soil. Right.

Then there are those sites like the University of Bayreuth linked above. Go there and on the front page you will find a couple of photos distinguishing Terra Preta soils from Oxisol (a nearby soil type?). The soil profiles have been "Photoshoped". Makes me wonder if the rest of their facts have also been tinkered with.

Kimmsr, stating you have correspondants who have told you they could not replicate the experiments of others who have investigated Terra Preta -- proves nothing, scientifically.

Where are their studies? Where are the links to their published experiments? In short: where's their science?

I have correspondants and friends who think and believe all kinds of things. (A guy I know firmly believes he's the living reincarnation of Elvis Presley, for one example.) Yet it proves nothing -- scientifically -- to state "my friends think or believe X, Y, or Z."

Pls8xx, I've read hard science about Terra Preta on the net. Published scientific experiments done by scientists. They're out there. I'd suggest you start by following the links I've posted, you'll likely soon find them.

Whether they answer your questions or not, is entirely another issue. However, it's inherent in the nature of science that it raises more questions than it answers -- a well-known problem with the scientific method itself, when examined from a philosophical point of view.

This problem is especially obvious in relatively new areas of investigation in science. From my reading, serious scientific investigations into Terra Preta aren't even two decades old. Also from my reading, Terra Preta appears to be a complex and multifactorial process -- like soil itself -- which has not easily yielded up a clear and simple understanding, so far.

Finally, whether an individual photograph posted on a scientific website is (or is not) altered -- proves nothing scientifically. And while you may wonder all you please about whether this may mean the scientific results also posted on that website are altered -- your wondering also proves nothing. Scientifically.

Most of the time I enjoy most of the posts both of you write. And I welcome your sceptic inquiries.

But my welcome does not extend to giving more credit to your sceptical attitudes, than I do to published articles in Scientific American and Nature -- two of the oldest and best-known journals in science. If they take Terra Preta seriously enough to publish articles about it, I think it's worth my serious and thoughtful consideration.

Neither does my welcome of sceptical attitudes extend to dismissing what's posted on the Bayreuth or Cornell websites because somebody may have messed around with a photo, or because my online friends have told me those results can't be repeated.

Please don't misunderstand me: I don't believe or disbelieve in Terra Preta. There is some compelling evidence it works, in situ, where it was discovered. I've read some hard science which has indicated those positive results have been replicated in laboratory studies. And, there are also serious questions.

But I don't have a dog in this fight. I'm not using charcoal or biochar of any kind in my garden. I'm not advocating for the use of it. Neither am I saying it totally sucks dude, and no real gardener with half a brain in their head should like ever take it seriously, really.

I am advocating for thoughtful and serious consideration of Terra Preta -- until it's been thoroughly investigated. Whether it will be 100% proven a miraculous wundersoil, or debunked as a total fraud still remains (in my opinion) an open question at this point.

And until someone provides solid scientific advice to convince me -- one way or the other -- my mind will continue to remain open on this subject.

I posted the links above so others on this forum could learn about Terra Preta. I invite people to do so, and to make up their own minds. And if there is more recent science anyone can provide -- either for, or against Terra Preta -- please do provide it. We're all of us here to learn, I hope.

All the best,
-Patrick

One could argue the point that charcoal is totally inert, totally sterile, and of no use in a living soil, such as organic gardeners have.
At least one doesn't have compost it. It has all ready been done, overly.
Bryan

Marcia

I am a soil scientist (and no I don't sell products or services related to biochar) but this FAQ is in no way meant to plumb the depths of pedological and edaphological knowledge on the subject. It is meant to give folks the basic reference points to get folks oriented and started down the path to figuring out if there is anything of practical value as it applies to their personal garden space.

We know that some effects from adding charcoal are nearly instantaneous, like the increase in potassium and the liming effect related to the ash component of the biochar. That's the boring stuff.

It is the informed suspicion of soil scientists working on terra preta that it really isn't the charcoal, its the biology, that produces the most intriguing effects, the ones that haven't been figured out yet. For instance, we deduce that it is the biology that provides a patina of organic constituents that serve to increase soil CEC.

We know simple facts, such as that the bio-oil condensate component, when present, can stimulate microbial respiration and cause a a marked increase in biomass. Biomass stimulation occurs with compost also, but it is erroneous to conclude that charcoal can somehow replace compost as a soil additive. If anything charcoal use encourages the use of compost, in that the mineral and biological decomposition products from compost appear to marry well with charcoal.

In many parts of the world, thanks to the indigenous use of fire to manage the land, our native soils have 10-30% of their organic carbon as black carbon. So in many ways soil biology has already been primed to adapt to increased charcoal in the soil environment. What will happen when I add charcoal to my garden soil? Something good I feel certain, and I hope you all will join me in finding out. For me, biochar is already a vehicle of substantial personal change in my gardening habits, one that has me bringing ever increasing volumes of waste materials (and my neighbors waste materials) into the compost pile. If our experience with reduced tillage agriculture is any indication, it can take many years for soil biology to come into its own when we shift to promoting more soil biology. It could take decades in the case of charcoal. My grandchildren may see the real treasure I am cultivating in my soil, but I may be long gone by then. For me, being encouraged to transform my personal habits in utilizing the waste that would normally get away, this is more than enough encouragement for me.

What is the point? Are we talking about a different charcoal?

Soil scientist Christof Steiner measured an 880% increase in yield for fertilizer+charcoal in comparison with fertilizer alone on lateritic soils in the Amazon. In the video (see link) it looks like quinoa, but being European, CS refers to it with the term "corn", meaning grain.

More exciting than CS' yield response is that, although his charcoal+fertilizer plots had higher yield and more mineral nutrients were removed from the soil during the 4 year study, soil levels of these nutrients were depressed less in the char+fert amended plots than in the fertilizer only plots. The combination of decreased leaching and increased mineralization that would account for this points to a unlocked biological potential that transcends the simple physical and chemical effects one would expect from adding simple elemental, inert black carbon.

Very exciting that. However, used thoughtlessly, charcoal can impair crop yield.

As Steiner and many others have demonstrated, using fresh charcoal alone will reduce yield/biomass production for the first season or two unless soil is pretty healthy to start with. Steiner was aware of this when he designed his study. This effect implies that charcoal, although inert, stimulates microbial activity, and they out-compete the plants for the limited nutrient resource. We don't have the long term studies to demonstrate that yield then recover and trend to levels of productivity that exceed pre-amendment levels, but we suspect improved productivity will likely be the longer term norm.

Long before Steiner, the Japanese established that nodulation in legumes is stimulated in the presence of charcoal. As such, combining charcoal amendments with leguminous green manure rotation could prove to be an important tool for gardeners the world over.

The ash component of charcoal has an effective pH of 12-13. Certainly this accounts for the effect you have seen in your soil. I anticipate that the black carbon portion of charcoal itself, in isolation from the ash, has no liming effect.

The porous structure of charcoal is observed to utilized by plant roots, fungal hyphae, and colonized by archaea and bacteria. Theoretically quite inert, the structure of charcoal seems to stimulate soil life in a way reminiscent of marine reef structures.

Hey Pagardener, do you believe that charcoal is stable and absorbent enough to replace such sterile soil amendments like perlite or vermiculite?

By the way, ash is different from charcoal. The remains of a wood fire provide a mixture of the two.

I make my own charcoal (for grilling) from oak and have plenty of particles too small to use in the grill. I've been sprinkling some in beds and around fruit trees. I expect that the amounts are insignificant.

Charcoal _ash_ is a different matter. Very high pH (basically--no pun intended--it is Na2O and K2O, which become KOH and NaOH--lye--when they meet water). It is best put in the compost bin for a year, where the bases (anything with OH-) can react with acids (forming salts) or lipid acids (forming soaps), or generally get attached to the large indeterminate organic molecules of humic acid.

'Activated' charcoal has been heated to drive out all the things that like to stick to it. (WW I gas masks had charcoal filters, because the poison gasses of the day stuck to it well.) _Any_ charcoal in soil will gradually equilibrate and store nutrients; the activated variety just does it faster. Roots are chemical specialists at taking nutrients away from other things. (But they can't take phosphate from iron phosphate, for instance--which leads citrus growers with iron-rich soils to use foliar phosphate fertilizer sprayed from airplanes.) Charcoal doesn't hang on to things the way iron can.

Mind you, the above is just high-school chemistry. I am on my way to buy a bag of supermarket briquettes, batter them into BB-sized bits, and see if they improve my 30%-clay soil.

Using it in ground can make great places to live for microorganisms and store nutrients, air, filter, ect.. As far as "slash and burn", that is a common practice.

A funny story- Farmers where using ash on fields and some manure. Scientists came and tested the soil to find a 8+ ph with crops growing perfect. The natural buffering of nature at it's best. :)

Yes, we are on the same page. This is a point I try to make very much. This is why a rich potting mix will have a better ph buffer than a light soilless mix.