Many urban households kept a cow or two for milk; others were grouped in urban dairies. Antebellum cities had existed within a closed ecological loop, one Chadwick had hoped to retain by turning human and animal excrement into fertilizer. In antebellum New York City manure, as well as human excrement—night soil—had found a ready market on Long Island, where farmers used it to fertilize the hay and oats that they resold to urban buyers to feed their horses and other animals. Waste as fertilizer flowed out, and food flowed in.
