Pee as fertilizer ingredient

From the "Who knew?" Department:

New research suggests that a slurry of wood ash and piss makes a good fertilizer for tomatoes. It's the nitrogen in urine and the calcium and magnesium in the ash that does the trick.
After promising results in a greenhouse, University of Kuopio environmental scientist Surendra Pradhan and his colleagues plan a real world test in Nepal.

From National Geographic:

Human urine and wood ash have each separately been used as fertilizer for centuries. But until now, no one had explored applying them together...

Urine can be collected from eco-friendly, urine-diverting toilets. Or farmers could just collect their pee in cans.

The researchers estimate a single person could supply enough urine to fertilize roughly 6,300 tomato plants a year—yielding some 2.4 tons of tomatoes.

The farmer would just need to give plants ash three days or more after applying urine...

One potential setback may be that pharmaceuticals and hormones excreted in human urine—such as remnants of birth control pills—could negatively impact crops, Pradhan said. For instance, such byproducts could promote antibiotic resistance in local bacteria or get absorbed by the plants.

"Human Pee With Ash Is a Natural Fertilizer, Study Says"

Actually, you could probably find some old farmers almost anywhere on the planet who could have told you that pee on plants is good.
I mean humans have been farming for over 10,000 years so the subject has come up ... and 'tested' on more than one occasion to be sure.
Also, pee combined with ash is hardly a ground breaking concept - we humans have had the use of fire for well onto 1,000,000 years and more than a few fires have been dampened with pee over that time.