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!
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.'"
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.
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........