Bird droppings were a foundation of modern agriculture and American empire

An advertisement for guano to be used as fertilizer depicts not only seabirds but also a guano island. Bradley Fertilizer Company via Garden History The closure of the Strait of Hormuz, through which roughly one-third of the world’s fertilizer normally passes, has made clear that access to nutrients for crops remains as strategically important in the 21st century as access to oil. As an environmental historian, I study how fertilizer transformed the modern world. That history is about more…