The exist in Brazil red earths produced by laterization having 5 meq.(100g) −1 Fe 3+ . These minerals are such strong oxidants that workers digging trenches in Amazonia were suffocated by the carbon dioxide produced as soon (5–10 mn) as the organic matter of the humus came into contact with air in the presence of the underlying clay : Persio de Souza Santos. Ciência e Tecnologia de Argilas, 2 nd ed., Edgard Blücher, Sao Paulo, SP, Brazil 1989 ; and ...
