You mean, it could help to just pee on the crack?
It seems that some people do that (peeing on their feet) to get rid of athletes' foot - if urea is the magic ingredient, that would explain why it works...
Well, urea is magic when it comes to cracks. I don't know if it is also magic when it comes to athlete's foot (but I have also heard the anecdotes, though it might be a different component in urine).
I had a friend with awful cracks on his fingers (from his job, if I remember correctly). He'd tried everything (except urea). Within 2 weeks he got it all healed up. I wrote it up in http://ahcuah.wordpress.com/2012/01/09/dipping-a-toe-in-your-ria/