An interesting bit of information comes out of the above article.
The "cauixi" mentioned is a freshwater sponge. Sponges have 'skeletons'
consisting of tiny needles (spicules) of SiO2----- glass to you. The
photomicrographs quite clearly show these little needle like structures
in the pottery made with cauixi. Embedded in a matrix of clay, these
quite simply operated as glassfiber reinforcement, not unlike the glass
fiber reinforced plastics we often see in things like automotive rear
vision mirrors and other, often injection moulded, plastic parts.
As well, it appears that the clay was not fired to very high
temperatures and therefore not fully vitrified, but the cauixi spicules
would have done a lot to strengthen the resulting pottery quite
substantially. The spicules apparently are also hollow, which would have
added to the porosity of the resultant pottery material, further
enhancing it's ability to soak up nutrients from the foods that were
cooked or stored in the containers made from it. Additionally, silicon
would have been available as a nutrient for plants from them, once the
wee beasties had quarried it out of the pottery.
The cariape was a siliceous ash that was also added to pottery, thereby
increasing the store of silicate in the TP soils, making it available to
plants, via the wee beasties efforts.
Silicone is a micro nutrient of some importance to plants, but really
only recently recognised as such. It increases plant stiffness and also
gives increased disease resistance.
Untempered clay shrinks and distorts considerably in drying and firing
and consequently potters add other materials, such as sand, and in the
case of the relevant amazon area, crushed rock, cauixi and cariape, thus
producing a usable pottery clay that could be effectively made into
vessels. I suppose, eventually someone noticed that garden plots which
contained cast off pottery sherds produced greater yields and as, with
the charcoal, people began adding the sherds on purpose.
If we want to emulate them, we might have to make and burn their
equivalents from clay, tempered with the rock dust that organic growers
use to re-mineralise their soils and perhaps the siliceous ash from
burned grass or bamboo. Perhaps even incorporate ground bones in the
clay. If using a TLUD type charcoal burner the clay blanks could perhaps
be mixed in with the biomass that is to be pyrolised
There is obviously something to this. The porous fired clay will act as a refuge for beneficial critters, potentially a significant effect with charcoal. This seems more significant than the silica nutrient effect.
Quote:
Originally Posted by Michaelangelica
Quote:
If using a TLUD type charcoal burner the clay blanks could perhaps be mixed in with the biomass that is to be pyrolised
I really like TLUD pyrolysis, but adding clay with the fuel seems like a stretch - it would have to have quite an effect on soil to warrant the effort.
A TLUD is a top-lit-up-draft configuration. It can be adapted to other biomass fuels besides charcoal, wood being a more common TLUD fuel than charcoal. It is capable of high fuel use efficiency and low CO and particulate emissions. It is scalable to individual or family meal cooking.
It is adaptable to batch charcoal production.
In regions that rely on wood for fuel, TLUD-based stove use could help make agrichar's benefits available for a vast population dependent on family plots for subsistence.
Here pottery shards litter the ground. At one of the site’s two excavations, the broken bits stick out from the earthen walls of a large square pit. The layers of protruding pottery are so tight and thick they look almost like wall coverings.
Climbing to the top of Ibibaté, a forested loma (mound) 18 meters higher than the surrounding savanna, Erickson comes to a bare patch of earth created by a fallen tree. Bending over the uncovered ground, he points out the dark, almost black soil, which is filled with fragments of pottery.
Several pieces of pot rim are visible, along with the leg of a vessel shaped like a human foot. Both the richness of the soil and the abundance of the potsherds are typical, in Erickson's view. "Many of the lomas are almost nothing but enormous heaps of sherds," he says. "I've never seen anything like it—10, 20, 30 feet of sherds"
The firing of the potteries occur in open atmosphere (Fig. 6), possibly in the same primitive way as the actual Indians and caboclos still do. The firing temperature didn't exceed 600 ºC, as demonstrated by partial dehydroxylation of clay material and the formation of maghemite. This phase formed the ceramic minerals: dehydroxylation of clay giving rise to burned clay, maghemite and recrystallization of anatase. Maghemite promotes the slightly brown to red color of the potteries.
. . .
Chemical elements such P, Mg, Ca, Mn, Ba, Zn, Pb, etc. are fixed partly and concentrated in the organic humus of ABE soils and possibly is partly absorved in the ceramic fragments, contributing to formation of phosphates and Mn oxyhydroxides in less extension.
Rich in humus, pieces of pre-Columbian unfired clay pottery, and black carbon, it's like a "microbial reef" that promotes and sustains mycorrhizae growth and other beneficial microbes, and it has been shown to retain its fertility for thousands of years.
. . .
South American terra preta soils are also full of pieces (sherds) of unfired pottery. It is generally believed that the pottery was introduced into the soil much as modern growers add perlite or sand to potting mix, as a way of keeping the soil from baking completely tight under the tropical sun before a cover of vegetation could grow over it. Much is made of these sherds as "proof" that terra preta deposits are really prehistoric trash piles, but Charles C. Mann asserts there are indications that much of this pottery was actually made specifically for incorporation into the soil.
he above described minerals and organic substances led to identify the following materials as raw materials for the ceramics:
1) clay material derived from weathering (saprolite/mottling zone) of fine crystalline and less frequent sedimentary rocks (indicated by clay-derived minerals and iron oxy-hydroxides, anatase and quartz );
2) fresh crystalline rocks crushed (feldspars, quartz and rock fragments);
“Unusual Tullawohara Indian vertical double pot with rawhide strip reinforcing. The Tullawohara are located in the Amazon drainage of Brazil.” - [8fli-105] - Floyd Lyerla collection. -
A pot from the pre-Columbian Guarita culture.In the afternoon, Neves takes me to the Hatahara site, about eight miles from Donna Stella, which contains traces of a more sedentary way of life. Here pottery shards litter the ground. At one of the site’s two excavations, the broken bits stick out from the earthen walls of a large square pit. The layers of protruding pottery are so tight and thick they look almost like wall coverings.
The Hatahara site contains traces of four separate occupations by farmers.
The people of the Açutuba phase, who are thought to have come from the Caribbean coast, may have been the first to settle the area, living in villages up to five acres in size, each supporting 100 to 200 people.
Neves believes that they lived on fish, wild meats, palms, fruits, and manioc, a root that can grow in poorer soils year-round.
Although this early culture had only rudimentary agricultural practices, Neves says, the plant and animal refuse they were leaving provided the substrate for future terra preta soils.
Helena Lima, a Ph.D. student at the University of São Paulo, is trying to pinpoint when and how this soil was used to support greater populations in the Amazon Basin.
She sees a stark difference between the Açutuba phase, from 300 B.C. to A.D. 400, and the later Manacapuru phase, from A.D. 400 to 900. “The Manacapuru were the first people who really changed the soil,” she says.
The terra preta soils at Hatahara and the other sites are made from a mixture of plant refuse and animal and fish bones, along with large quantities of charcoal that were deposited after settlers used stone axes and slow-burning fires to clear forest.
Such smouldering fires produced more charcoal than ash.
The charcoal, soot, and other carbon remains (collectively called biochar) retained nutrients, particularly potassium and phosphorus, that are limited in tropical soils.
The resulting improvement in soil fertility may have allowed the land to support a larger, more stable crop-based population, although studies of fossilised pollen have not yet revealed the specific plants they cultivated.
The next phase of settlement, the Paredão, occurred from about A.D. 700 to 1200.
Neves suspects that the Paredão were outsiders from the south. The occupation is peaceful, though, and the Paredão and the Manacapuru lived and traded with each other.
The Paredão exploited terra preta soils even more than their predecessors. While the initial settlers in this area may have created the dark soils by accident, William Woods, director of environmental studies at the University of Kansas, says that “at some point they recognize their importance and start to promote them.”
Over time, the villages of the Paredão become larger, denser, and surrounded by agricultural fields.
Populations grow into the thousands at sites ranging from 5 to 40 acres. The lack of fortification strongly suggests that the groups lived in peace.
But around 1200, the Guarita people from the east threatened to attack, and the Paredão built defensive structures. This phase lasted into the time of European occupation. Over the same period, the Paredão vanished. The Guarita apparently moved in from areas near the mouth of the lower Amazon, which have even more terra preta soils than the Paredão, and brought with them wilder, multicolored styles of pottery.
“They are like the barbarians attacking the Romans,” Neves speculates.
He suspects that the newcomers may also have had a valuable possession—corn. This new, more nutritious staple requires better soils, and it is not unreasonable to suspect that the Guarita drove the Paredão out to take over their valuable cropland, built on terra preta.
Analysis of buried human remains suggests that the inhabitants of all four occupations were robust—a well-being that extended even after death.
In the site’s remains, Anne Rapp and her husband, Claide Moraes, both students at the University of São Paulo, find evidence that hints at ceremonial procedures, priests, and perhaps a cottage industry of funerary artisans as well.
Last edited by Michaelangelica; 04-06-2008 at 04:32 AM.
Hmm... maybe the clay pots were low-tech retorts for making charcoal with less waste.
Put a bundle of twigs/branches/manures/etc... tight together, slather it with clay (except for a small opening), when it dries, build a fire on/around it. Then shatter the pots that should have charcoal in them.
My first post here! I would imagine that large amounts of clay pots were fired all at once in large pits or in piles. Lots of charcoal would likely remain in and around the pottery after the firing process. Any potter will tell you that some peices will allways crack and break during the firing process. Several hundred bowls, plates, pots and pans, toys and other trinkets might be fired in a single large burn pile. All of the dried clay peices would be filled with dried grass or small pieces of wood, carefully stacked in a pit, surrounded with larger pieces of wood, covered(wet branches and soil?) to prevent overfiring, and lit on fire. Some of the peices would break and be left where the were. The first terra preta was probably a by-product of pottery making. I would suggest that the eariest areas of black earth either exist where there were clay deposits that could be mined or where there were forests that lent themselves to the firing of clay to the extent that inhabitants transported clay there to be fired. After some time it was probably noted that plants grew better where the potters fired their clay. Only after the discovery that plants grew better in these areas is it likely that people started using charcoal and pottery peices to deliberately improve the soil fertility.
My first post here! I would imagine that large amounts of clay pots were fired all at once in large pits or in piles. Lots of charcoal would likely remain in and around the pottery after the firing process. Any potter will tell you that some peices will allways crack and break during the firing process. Several hundred bowls, plates, pots and pans, toys and other trinkets might be fired in a single large burn pile. All of the dried clay peices would be filled with dried grass or small pieces of wood, carefully stacked in a pit, surrounded with larger pieces of wood, covered(wet branches and soil?) to prevent overfiring, and lit on fire. Some of the peices would break and be left where the were. The first terra preta was probably a by-product of pottery making. I would suggest that the eariest areas of black earth either exist where there were clay deposits that could be mined or where there were forests that lent themselves to the firing of clay to the extent that inhabitants transported clay there to be fired. After some time it was probably noted that plants grew better where the potters fired their clay. Only after the discovery that plants grew better in these areas is it likely that people started using charcoal and pottery peices to deliberately improve the soil fertility.
Welcome aboard. I think you make some reasonable assertions.
Quote:
Originally Posted by Fukudairafarm
Hmm... maybe the clay pots were low-tech retorts for making charcoal with less waste.
Put a bundle of twigs/branches/manures/etc... tight together, slather it with clay (except for a small opening), when it dries, build a fire on/around it. Then shatter the pots that should have charcoal in them.
This sounds reasonable in general, however looking at the specific pots Mick posted with their decoration, it doesn't make much sense to me for them to have their use as retorts. Practically, decorating a pot you mean to break & bury is a waste of resources, in spite of the potential argument it served a ritual purpose. Follow the money.........
__________________ Brevity. ~Roger Thelonious George
Love the retort idea... many possibilities there.
....
Anyway, I've been reading 1491 (on my Kindle) ...and I'll have to get the quote, but....
Mulch!
That's the effect of the pottery!
Rain is what decimates the soils down there, leaching out the minerals as it drill through un-canopied soil.
Pottery shards protect the soil from the relentless rain of ruin.
...as well as being a bit sponge-like & hosting beasties & providing buffering surfaces.
How about adding soil mineralisation and homes for "wee beasties"?
I stopped half way though 1492.
The biggest human kill-off in history. The plague, at best, did 30% of the population. But 90%! No wonder. Cortez et., al., had it easy.
I am glad NASA takes such care with off-planet bugs.
The clay shards and pottery in TP What & Why? 
Re: The clay shards and pottery in TP What & Why? 
I think you make some reasonable assertions. 
Brevity. ~Roger Thelonious George 
