I think people would be even more surprised to learn how common it is to use processed sewage for fertilizer. Human waste.

In California, 76% of processed sewage goes to farming. 86% in Colorado.

https://investigatemidwest.org/2024/08/07/fertilizer-from-hu...

And its not just the US https://www.theguardian.com/environment/2020/sep/02/sewage-s...

>Spreading the sludge on farmland is banned in the Netherlands, where incineration is preferred, but allowed in the UK. Dutch water authorities are eyeing the UK as a possible destination for their sewage