You describe a common misconception.Humans can't smell it? Clearly you have never visited the toilet at Solstice services KFC, or any lorry park between Calais & Antwerp!
The wee of a healthy human is just water with a few minerals in it. It is sterile and inert. If it smells a bit when it first comes out, the smell is very rapidly neutralised as it dissipates into the air. Natural soil microbes quickly utilise it so within a very short time in contact with soil it is not even wee any more.
What you describe is the smell that happens when anaerobic bacteria feed off wee, such as in the plastic containers of portaloos. Such anaerobic bacteria feed off and breed in the contained wee, and release a multitude of noxious gases. That doesn't happen when you wee on soil.