Pot shards

In the earlier documents about terra preta, they mentioned small clay pot shards being consistently found in the material, but the more recent works don't mention them.

Do you think that the shards provide anything of value, or were they just part of the garbage cycle?

Just a passing thought...

I suspect that it was normal wear and tear on household crockery. Judging from the number of plates, bowls and glasses that we go through, anyway.

I translate a decent amount of archaeological research articles and soil studies out of Amazonia, they are still finding plenty of potsherds. There are still plenty of ideas about what/why/how, some more whackadoodle than others, but the most reasonable seems to be that there is always breakage from pottery firing and that people probably noticed that in the areas where char and pottery shards were, the plants grew better.
There are also suggestions that the shards (and bones) acted as mulch to halt erosion during heavy rains, they stopped the soils from baking totally solid when the rains stopped, I've seen some weird theories claiming that clay is antibacterial (?), the clay vessels were actually primitive charcoal kilns because their shapes were so odd (?), and that the clay vessels were actually used to store urine in a one-stop-shopping kind of solution for soil remediation (?).
Probably the most likely story is that there were a LOT of people living in these places (Colombian exchange and other events led to population reduction of 90%): these folks used a lot of breakable pottery and created a lot of waste, and it has to go somewhere. Recent LIDAR studies in the jungle show there is a lot to still be dug up and studied.  

Awesome reply Tereza! I'm currently working on a blog post about this very subject. I'm now deep in the writings on Amazonia of Juliana S. Machado, Betty Jane Meggers, Alceu Ranzi, Michael Heckenberger, William Balée, William I. Woods, Clark L. Erickson, Maria Luísa Mendonça... and I think I'm now most excited about the works of Carolina Levis & colleagues. Have you perhaps done any translations of any of works of the aforementioned authors?
An interesting fact I happened upon a few days ago is that -according to Clark L. Erickson- some of these pots were in fact way too large to be carried around by wandering, nomadic hunter-gatherers. That there were in fact large sedentary populations in the Amazon, as Gaspar de Carvajal duly noted in 1541-1542, before the 90% population reduction. It appears that James C. Scott may be right once again!

Glad you found it helpful!! The names don't ring bells, but I translate a LOT of articles. Honestly most are on soil science for reforestation applications-- for industry the terra preta is more of a curiosity.
You may find these links interesting- this is an article done in association with an institution I often work with (the Emilio Goeldi Museum) that tends to publish a decent amount on terra preta https://www.academia.edu/15228024/Dark_earths_and_the_human_builtlandscape_in_Amazonia_a_widespread_pattern_of_anthrosol_formation
this is a clearinghouse on terra preta info that I have used in research on the subject. The info in some places is quite old but there are resources, links to ongoing research, etc.
http://www.css.cornell.edu/faculty/lehmann/research/terra%20preta/terrapretanet.html

Thanks for the links Tereza, I will certainly check them out.

Here's a passage I happened upon recently too:
"'Landscape' in this case is meant exactly—Amazonian Indians literally created the ground beneath their feet. According to William I. Woods, a soil geographer at Southern Illinois University, ecologists' claims about terrible Amazonian land were based on very little data. In the late 1990s Woods and others began careful measurements in the lower Amazon. They indeed found lots of inhospitable terrain. But they also discovered swaths of terra preta—rich, fertile 'black earth' that anthropologists increasingly believe was created by human beings.
Terra preta, Woods guesses, covers at least 10 percent of Amazonia, an area the size of France. It has amazing properties, he says. Tropical rain doesn't leach nutrients from terra preta fields; instead the soil, so to speak, fights back. Not far from Painted Rock Cave is a 300-acre area with a two-foot layer of terra preta quarried by locals for potting soil. The bottom third of the layer is never removed, workers there explain, because over time it will re-create the original soil layer in its initial thickness. The reason, scientists suspect, is that terra preta is generated by a special suite of microorganisms that resists depletion. 'Apparently,' Woods and the Wisconsin geographer Joseph M. McCann argued in a presentation last summer, 'at some threshold level ... dark earth attains the capacity to perpetuate—even regenerate itself—thus behaving more like a living 'super'-organism than an inert material.'"
https://www.skennedyushistory.com/before-1492

I found my first reference to the claim in David Tyndall's book sacred soil that the ceramic vessels were for fermented humanure.  

"In literature on Terra Preta, the prevailing view is that the ceramic shards come from middens, household waste, also from some burials, and, most importantly, also from clay vessels for fermenting human excrement into humanure (also see terra preta: how the worlds most fertile soil can help reverse climate change an reduce worl hungar by david suzuki pg 42 and chapter 6) Clay vessels of 20-60 liter capacity with lids were found lined up in terra pretta soils.  They contained fermented human excrement, a potent source of fertility." (pg 83)

This is so fascinating to me...  As someone who is deep into my soul searching about aerobic and anaerobic microbes this adds fuel to the fire.  The possibility that they made the vessels to be disposable with terra preta in mind adds new layers the the "cradle to cradle" materials philosophy.  Also more cases about how advanced indigenous cultures were about understanding nutrient cycles and fertility.  

Perhaps we should switch from bucket loos to flower pot potties?

William Bronson wrote: Perhaps we should switch from bucket loos to flower pot potties?

I think that was intended as humor, which it was, but...... It is said that urine and solid waste shouldn't be mixed due to odor issues, but if you used a flower pot, the urine could drain through the hole in the flower pot, into another container.  Hmmmmmm........

a poo-kashi bucket, as it were.....

I suspect that the clay in the pot shards might contain useful metal oxides or aluminum/metallic salts, which could be playing some sort of catalytic role. Aluminum is present in all clays, and aluminum compounds are uses in some other chemical reactions as a catalyst.

Michael Weatherl wrote:I suspect that the clay in the pot shards might contain useful metal oxides or aluminum/metallic salts, which could be playing some sort of catalytic role. Aluminum is present in all clays, and aluminum compounds are uses in some other chemical reactions as a catalyst.

Thank you for this addition Michael. At least one source I have come upon in this research suggested that the clay might be aiding in cation-exchange capacity in the soil. Might the "useful metal oxides or aluminum/metallic salts" present in the clay be in some way involved in catalyzing cation-exchange?
Thanks.

We have heavy clay soil here and lots of rain in the winterish months. Baked clay shards break up the clay, so that it drains better, but it also retains a bit of moisture in it, so it is useful in wet climates with clay soil.
John S
PDX OR

Very good to know John. It appears that clay shards may be playing multiple important roles in these soils.

Here is an update on our research on terra preta referred to in our earlier posts on this thread: "Forests or Deserts: a Choice".

Warning...pure speculation from the meandering mind of Greg Martin....ok, disclaimer disclaimed!
From what I've read about the "pottery shards" they are described as primitive....unglazed, low temperature fired, and containing a decent amount of plant fibers.  This, along with the biochar and fish bones makes me feel pretty confident that they are not pottery shards, but that they are actually clay mixed with grass that was packed around food for cooking in a pit oven.  A classic way of cooking was to dig a pit, line it with rocks, burn wood in the pit to charcoal, then drop what you want to roast in there and bury it.  Come back many hours later and dig out a great meal.  But you don't want the outside burnt and you want even cooking and moist food.  What to do?  First you wrap the food (say that big fish you pulled out of the Amazon) in large leaves.  That keeps it clean, but they will burn up.  So next you pack a clay coating over the leaves.  That will hold in the moisture and help eliminate hot spots from burning the meat.  Problem, the clay will crack.  Solution, you mix in fibrous material like grass.  That keeps it from cracking.  When you're done you break it open to get your delicious meal....making "primitive fired pottery shards" exactly like those described.  These shards will have high CEC (much higher than that of the biochar) like clay, but will drain like gravel.  The plant fibers will make it even better because it creates channels to create more water holding and exchange surfaces.  These partially fired shards along with the biochar and any left over bones would be dug out and moved to the tera preta beds as it's easier to dig out the charcoal then to dig a new pit.  That the area you dump this stuff into grows plants amazingly would become very obvious and then it becomes intentional and is repeated.

Wikipedia Earth Oven article

Here in New England the native traditions of baking beans and clam bakes are still practiced a bit.

Great posts Mike and Greg,
There is nothing wrong with speculation that is transparent. The problem is today, it goes as an accusation and a conspiracy. "Those guys are evil!"  

There is a legitimate place for imagination and speculation in science in order to conceive of what is possible. We need to look at different possible models of what could be happening.  We look at the data.   Then we can connect the dots.  

There might be a double blind, placebo controlled lab experiment in there somewhere, but it is not necessary at every level. Insisting on it at every level can be used to stop the imagination so we can't see what's really happening.

John S
PDX OR

Greg,
Those are great points! I was once told by a Hawaiian farmer that "back in the day they used to move their imu (Hawaiian earth ovens) around to different locations & plant into where the earth ovens had been to take advantage of the charcoal."
It's really important for the microbes, especially in the tropics.

Mike,
it seems that you believe that biochar works well in the tropics  but not as well as hugulkultur in the temperate areas.  I don't know if you've seen my thread about the improved productivity and flavor in my fruit trees since I started using biochar, but it is amazing.  I live near Portland Oregon. Certainly not tropical.  Temperate general area.  Quite rainy.

I seem to notice that biochar seems to help more in rainy areas than in dry ones.  I don't think that the big difference is temperature. Rain washes out nutrients no matter the temperature.  Sure, it's easier to maintain a depth of soil, percent of organic matter, or whatever your measure in the temperate areas.  Also rainy areas tend to be acidic, while drier areas tend toward alkalinity. The ash is generally quite alkaline, which can set things toward neutral or 6.5 if more acidic.  If an area is already alkaline, adding biochar will help less.  That's why I think the key difference is that biochar helps more in rainy areas.  
John S
PDX OR

John, I totally agree. Some friends & I did a biochar v. non-biochar trail in side-by-side beds of corn, beans, & squash in the temperate Plant Hardiness Zone 8a. The results were stark: biochar corn was literally 5 feet taller and more luscious than non biochar corn and were more productive. I am also a firm believer in biochar inside and outside the wet tropics. :-)