The Eighteenth Amendment to the Constitution prohibited the manufacture, sale, or transport of alcoholic beverages. It was the product of a temperance movement that began in the 1830s. The movement grew in the Progressive Era, when social problems such as poverty and drunkenness gained public attention.
My conclusion, given the paragraph given, is that the Belgians likely made the choice given rubbers value to plant rubber trees instead of food wherever practicable.
