Urine is also a source of phosphate. I do believe phosphate recovery form sewage is commonplace in Germany and not unheard-of elsewhere. Plus, phosphorus was originally isolated from urine by the German alchemist/proto-chemist, Hennig Brand of Hamburg in 1669. He boiled down hundreds of gallons of urine and then roasted the remaining solids, eventually to produce a white, waxy substance which glows in the dark and catches fire when left exposed to the air. From this property Brand gave phosphorus its name.

I find this to be curious:

*phosphorus (as phosphate/ATP) is key to energy transfer processes in living organisms, thus being a real 'bearer of light' inside all of us;

*'Brand' also means 'fire';

So, back to the environment theme of the OP - we really ought to be taking care of what we do with our urine because of Peak phosphorus. This is because most phophates used for agriculture come from phosphate minerals; phosphate minerals are a finite resource.