I went to Wikipedia to read up on Terra Cotta. When I finished digesting that information I looked up clay and found a note that seemed very interesting and followed that. There they were using iron rich clay minerals that had been used to treat Buruli ulcer patients to see if they had antibacterial properties. AsAgO2 did have pathogenic properties against bacteria and antibiotic resistant bacteria. I wonder if these properties would have worked in the soil and could be one of the reasons clay shards were incorporated in TP. I tend to think that TP was created with Humanure because of the lack of nutrients in the tropics. Perhaps the use of the clay shards helped to control soil pathogens from the human manure if it was not properly composted or poorly composted?
Broad-spectrum in vitro antibacterial activities of clay minerals against antibiotic-susceptible and antibiotic-resistant bacterial pathogens -- Haydel et al. 61 (2): 353 -- Journal of Antimicrobial Chemotherapy
