Funnily enough, leather tanners and pee is where the terms "piss poor" (being so poor that you need to sell your pee to tanners for cash) and "doesn't have a pot to piss in" (can't even afford a thing to hold your pee to bring to tanners) came from.

The nitrogen cycle can be short-circuited really easily at scale.

No need to wait for algal blooms to turn into oil.

Its usage in tanning is pretty wasteful in comparison as it was just used for its high pH and presumably thrown away afterwards.

Getting only the urea-rich golden liquid might require some coöperation like back in the day, but it is idiotic to synthesize ammonia from oil without recycling the vast amounts we have in our bladders; a mistake we have been committing for the past 100 years.