Wednesday, December 3, 2008

Alan Balliett terra preta Q&A

I pulled this Q&A on Terra Preta out of a good article by Alan Balliett from last year. It can be located at:

It is a good article for those unfamiliar with Terra Preta.

This gives us a better sense of the why the knowledge was lost on contact so easily. Of course, population loss and endemic warfare would have sped it on its way.

What is not alluded to is the truly massive extent of the culture throughout the Amazon. There is reason to believe that millions were thus supported.

That slash and burn is a child of the steel axe was not so obvious and explains why the collapse was so total.
Once good crop land was abandoned for a fresh field that gave several years of crops because of the ash, it was hard to return to the likely back breaking work of the old ways. You went from a hectare to a ten hectare field and good crops for a few years. Then you went on to the next ten hectare field forgetting the one hectare ancestral plot.

It is going to take modern equipment to generally implement Terra Preta.

Why did production of terra preta stop after European contact?

Although the decimation of the Amazonian population and the collapse of the elaborate social systems that supported terra preta creation (to make all that pottery and to make all that charcoal and incorporate it up to 2 feet in the ground really does take a village) was a contributing factor, it was undoubtedly the introduction of the steel axe by the Spanish that, in combination with the impact of contact, led to slash-and-burn by small bands replacing slash-and-char by large groups. When clearing land with a stone axe, a conservation of all biomas and an intensification of soil production becomes a necessity. Steel axes — and, later, chainsaws — contributed to exploiting the very short-term benefits of ash. It must be remembered that traditional methods can die out in a single generation, and that in Amazonian social structure, the elders were responsible for all technical knowledge. It makes sense that the elders were the hardest hit by epidemics, and the loss of their cultural knowledge combined with social disruption would lead to the replacement of a deeply effective technology with an less-effective mimicry.

Did natives use special microbial brews to innoculate the soil to create terra preta?

There is no proof that a “mother” culture was used for starting terra preta. Current research indicates that the incorporation of charcoal of certain qualities (created in relatively low heat, for example) in combination with appropriate initial fertilization (often, in university tests, with conventional fertilizers that are damaging to soil life) will produce a substantial increase in yields. It is assumed that the char provides such an effective habitat for microbes that effective communities will rapidly develop within most soils. What we don’t know yet is whether the simulated terra preta will have the ability to maintain its fertility for as long as the ancient form.

Has terra preta been discovered outside of the Amazon?

Yes, high-carbon terra preta-like dark soils have been discovered in Holland, Japan, South Africa and Indonesia and are currently being studied.

Can carbon inputs other than charcoal be used?

The Japanese are extensively investigating the use of coal dust for promoting field fertility. Coal dust does seem to reproduce many of the positive effects of wood charcoal.

The research of Siegfried Marian on the benefits of carbon incorporation, as reported in Leonard Ridzon and Charles Walters’ The Carbon Connection and The Carbon Cycle, led to the development of Ridzon’s NutriCarb product (no longer being produced), which claimed agricultural benefits very similar to those claimed for terra preta . Those who want to use coal dust for soil fertility need to make certain that the dust is from brown coal, which is more humic, and that the coal does not contain toxins.

Why is terra preta often linked to alternative energy and climate change?

Terra preta is a carbon sink, as is most carbon in the soil. Slash-and-burn agriculture contributes greatly to global warming. If terra preta technologies were applied to tropical farming, less land would have to be cleared for farming, and if farmers in temperate zones such as the Midwest incorporated charcoal or other chars into their soil, more carbon could be sequestered. If this char is produced by appropriate technology, such as pyrolysis, both fuel and a “restorative, high-carbon fertilizer” can be produced. This process does not require wood — it is just as effective when agricultural wastes, such as peanut shells, are used as input. A good place to learn about this technology is at

How much charcoal needs to be incorporated?

In published reports on pot tests of the effect of charcoal on plant growth, incorporation at 20-30 percent by weight tended to consistently produce the most benefit. In row crops, this would translate to 30 percent by weight of the top 6 inches.

Are there benefits for plant health from terra preta ?

Better plant growth and health is evident with the use of native terra preta. Current investigations are primarily being conducted by archaeologists, geologists and soil scientists. There is no evidence of terra preta studies by an agriculturist, but positive reports from growers suggest that eco-farmers would be well advised to investigate terra preta technology.


Unknown said...

Biochars do indeed seem to have a magnificent potential.

There is one facet of biochar production that concerns me, which is the production of polycyclical aromatic hydrocarbons (PAHs) that occurs during pyrolysis of the carbonaceous waste materials. While other problematic hydrocarbons are also created, the PAHs seem particularly worrisome as they tend to be persistant as well as potential health hazards. PAHs are mutagens, carcinogens, and teratogens.

I'm wondering if are any there studies of PAHs remaining in the biochars as a result of the pyrolysis?

arclein said...

My sense on most biochar manufacture like that of charcoal itself was that tight control was impossible.

however, a burn chimney was usually created that caught and consumed most of the volatiles, likely limiting the problem.

Best practice was in fact likely to mitigate the problems nicely.

then we look at current practice in Brazil and choke.

I have not tried to isolate biochar papers and PAH measurement and they may simply not exist yet although that will now change.