For these kinds of ideas, you best think of it with the notion if your body, or your family member's body will become compost or used for science after they die. Honestly, it makes me uncomfortable. Though logically, when you die, it shouldn't really matter what happened to you, or your family member's body. It's sentimental reason.
Nope, animal pee areas like stables or cattle pens were used to collect nitrates, used to make potassium nitrate.
Actually you can use your own pee to make potassium nitrate. In Middle Age Europe, they used human pee to soak straw in a barrel for nitrate production. Of course, the cattle soil was also used, but that method requires cattle soil in the first place. The straw and barrel method doesn't need cattle soil.
I like reading morbid stuff, but I want to make things easy as possible. So if my family doesn't want to eco-bury me with some local plants, I'll take a cremation and a gig as a poop shaped ghost. My oldest cat passed on. And even though my mom paid for her cremation, I haven't tried to use the remains for compost. I can't bring myself to do so.