There was a Radiolab episode[1] back in 2013. It's been a while since I listened to it, but I believe they used to sell it for manure, but some regulation bann

There was a Radiolab episode[1] back in 2013. It's been a while since I listened to it, but I believe they used to sell it for manure, but some regulation banned that. [1] http://www.radiolab.org/story/poop-train/ http://www.radiolab.org/story/poop-train/