- apple cider vinegar in the water (1 tbsp/gallon) helps to reduce the smell of the urine
- peat moss
- baking soda
- horse stall bedding - which is compressed sawdust. works really well.
- products such as abate xp : these words from a user of it
There's a product called ABATE XP which is really outstanding at all odor control/neutralization. Worst case, when I had to scrape the entire rabbit area down to black STINKY gunk, a pound of this stuff, sprinkled dry, then lightly watered, on a 40x40 foot area....totally eliminated ALL odor within 2 hours. That's pretty darn impressive!
More detailed info:
Home use: http://agritectx.com/abatehom.html
Farm use: http://agritectx.com/abatefrm.html