I did not find any information on the web about this.
I am currently thinking about protecting the soil of several pots on my west Germany southside balcony before the sun and any kind of stranger plant or vermins with a layer of low-nutrient soil, and topping it with a layer of Stone or Granite.
The idea roots back to an earlier idea in spring, when I used this technique to maximize solar radiation on my Tomato and Chili freshmen (this idea itself is based on my Computer Graphics / Illumination interest).
I am just beginning with my adventures in gardening, so experience with this experimentation is pretty low, and I wonder if anyone has tried this out, too.
What I've found out is that you can pour faster, as the mass of the stones will decelerate and spread the falling water enough, such that it does not nuzzle up the soil so much anymore. But this question is more about the protection part of it.