I sort of do this with wild birds.  I throw black oil sunflower seed under my fruit trees in the winter, so they will come there, eat a few seeds, scratch around for hours, maybe find a tasty codling moth larva, and leave their droppings.  The permaculture books tell you to get chickens for this but 1) I don't want to have to take care of chickens; 2) we eat very few eggs; 3) our dog would lose her mind if we got chickens, and we probably would not have chickens for long (she was a stray for at least a couple of months).

Regarding the article I was expecting it to say that the plants used the urine directly.  But I guess that would be asking a lot from a small planter.  Maybe hardy kiwi would be a better choice?  That is the only plant in my yard that I fertilize.

Urine might be OK, or not.  The system would surely need occasion "Rinsing".  Too much salt in human urine.  We love the stuff, and consume too much.  Then, we pee it out.  At least, it seems that way to me.  

NaCl would accumulate in the lower levels of soil over time, killing deep rooted plants.  Large volumes of water would need to flush salt out of the system during seasonal rains.