The internet will say “apply lime”:
Lime for dog spots is unfortunately a bit of an old-wives-tale. Lime can help balance the pH of acidic soil but dog urine is not acidic. It is very salty and high in nitrogen – so much so that it over-fertilizes and burns the grass. You can often see a dark green ring around the outside of the dog spot where the nitrogen content dissipated, wasn’t enough to burn, but was enough to green up the grass on that ring.
The soil has been heavily salted and sterilized. Water and time is about the only solution short of spreading some black dirt on top and seeding. Read more on seeding here
We’ve had clients give us great testimonials for “Dog Rocks” that reduce or eliminate dog spots: https://www.amazon.com/Dog-Rocks-Natural-Prevention-Prevents/dp/B000NE2UH4