The Environmental Protection Agency confirmed that treated biosolids, or human waste materials, are safe to use as plant fertilizers and generally superior to chemical fertilizers, per Mental Floss. The nutrients in biosolids promote growth and help the soil retain water.

So, the City of New York decided to transmute its bountiful sewage into a bounty of crops. Of course, the would-be recipients of the waste were skeptical at first, and only a few farmers in Colorado agreed to take on the first load of cargo in 1992. The biosolids proved effective, increasing the crop yield and deterring pests. Before long, New Yorkers’ excrement was, quite literally, hot s***, and farmers across the United States were joining the waiting list.

The biosolids proved less desirable when a “poop train” traveled to Alabama and got stuck. The train, which was loaded with thousands of tons of human waste, was marooned in the 1,000-person town of Parrish, Alabama, for over two months, as reported by The New York Times. The result was a powerful and lingering stench that hung over the town. “It smells like rotting animals, or a dead carcass. It seems like there’s a dead animal nearby,” Heather Hall, the town’s mayor, said in 2018. “And it’s not like you just get a whiff of it where it’s just a subtle smell. It is so overpowering you cannot go outside.”