Van Gogh, Potato Eaters 1885

Ever since I first learned about it, I’ve been fascinated and horrified by the Irish Potato Famine, also known as the Great Hunger. But it wasn’t until recently that I learned the probable source of the blight: bird poop.

The blight first appeared in Ireland in 1845. It had spread to many other European countries as well, but the Irish were especially hard-hit because 4 out of 10 people in that country subsisted exclusively on potatoes, and a big percentage of the rest of them ate mostly potatoes. As many as a million people died of starvation, and two million more fled the country.

The potato plants were attacked by a kind of mold that acts as a fungus. Phytophthora infestans means “vexing plant destroyer.” The spores get blown on the wind, land on plants, germinate, and kill it quickly. The spores love wet weather (such as can be found in Ireland). Rain washes them into the soil, where they attack potatoes six or more inches below the surface. In that first awful year, 1845, the mold could turn a field of healthy potato plants into black, stinking mush in just a few days.

For centuries, farmers have used poop as fertilizer; plants need nitrogen, and poop contains nitrogen. In my POOP book, I wrote about how most major urban centers carted their human and horse poop outside the city and sold it to nearby farmers. But as cities grew larger and larger, farms became father and farther away, and rather suddenly, it was no longer cost effective to cart poop to the farms. As a result, cities became much smellier, and waterways more and more polluted, as there was nowhere to put the poop except to dump it into the nearest river. (See my Poop book for the disastrous consequences to cities.) So what did farmers use to fertilize their fields instead? Guano–bird poop–from Peru.

All this I knew, but it wasn’t until I recently read Charles C. Mann’s new book 1493: Uncovering the New World Columbus Created, that I learned much more about the mining of guano. It’s a grim tale.

Fertilizer ships from Europe sailed to the Chincha islands, thirteen miles off the coast of Peru, where  huge piles of sea bird poop were stacked as high as a twelve-story building. According to Mann, the islands gave off a stench that could be smelled long before a ship reached them.  And nothing grew on the islands; the only living things were “bats, scorpions, spiders, ticks, and biting flies.” There was no drinkable water, and not a single plant on the barren, smelly, dry landscape. Mining the guano was wretched work. Miners had to hack away at the guano, enveloping themselves in corrosive dust clouds. The poop was dumped through a long tube, where it dropped directly into the ships’ holds below, exploding into toxic dust that enveloped the ship. No one wanted to work in those miserable conditions. They tried convicts and African slaves, but the convicts killed themselves (and one another) and the slaves were too valuable to “waste” in the mines, as life tended to be brutish and short for those forced to perform this wretched work. The solution? Enslaved Chinese workers. As many as a quarter million Chinese indentured workers were shipped there, to live in virtual slavery, in a horrific alternate Middle passage you don’t hear much about.

Van Gogh, Woman lifting potatoes, 1885

Although we may never know for certain, many scientists believe that it was the guano ships that carried P. infestans over to Europe. The plant disease that emerged from the guano fertilizer then decimated Europe’s potato fields in the 1840s.