[Terrapreta] Re-mineralization and Ceramics

[teelws at jmu.edu]

Lou,

My soil science is incomplete, but I do know a few things.  Most ceramics are made from Kaolinite type clays.  These are highly weathered, 1:1 layered clays that have little to no shrink-swell action in the presence of water.  They also have very low cation exchange capacity in relation to the 2:1 clays like montmorillanite, illite and smectite clays.  In this regard most pottery clays in the Amazon were probably made from iron oxide rich kaolinite type clays and not really suitable for remineralization.

The good remineralization rocks would probably be sedimentary rock with high amounts of calcium, magnesium and phosphorus, or volcanic rock like basalt, or pyroclastic materials that give rise to eutric andesites, fertile, young volcanic soils.  These rock powders are loaded with micronutrients that plants needs in tiny amounts to enhance growth rate and overall vigor.  You would not get that from the clay pots.

However, and here I will speculate, clay pots were the primary cooking utensils of native peoples around the world for millenia.  They are porous to a degree.  After being used over fires cooking nutrient rich foods for weeks, months or years before breaking, they are likely to have embedded nutrients in their pores.  This would attract soil organisms of all types to the slowly leaking nutrient supply, and as they are in the soil for a long time, become a kind of soil nutrient bank.  I don't think this benefit would last long without the more important component of the terra preta, the char, which appears to have both physical and chemical attributes that improve productivity on nutrient poor sites.

Wayne

---- Original message ----
>Date: Thu, 30 Aug 2007 01:47:32 -0500
>From: "lou gold" <lou.gold at gmail.com>  
>Subject: [Terrapreta] Re-mineralization and Ceramics  
>To: Terrapreta at bioenergylists.org
>
>   I know so little about soil chemistry, etc that this
>   maybe be an odd question.
>
>   Can the need for soil re-mineralization offer
>   another possible explanation
>   for the function of the pottery found in the TP
>   sites of the Amazon?
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Wayne S. Teel
MSC 4102 ISAT
James Madison University
Harrisonburg, VA 22807
Tel: 540-568-2798
Fax: 540-568-2761