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How did the Aztecs create floating gardens?
Like the Aztecs, they still send their sewage into the canals. Researchers have found a unique bacterium living in the sludge at the bottom of the canals which makes it an excellent composter, treating - and neutralising - the sewage organically (and speedily) as it converts it into nutrient-rich fertiliser. With its help, the Aztecs created ‘one of the most productive farming systems ever known’.