What are some good treatments to stop horses hoofs from cracking?

Daily soaking in water. Products that you brush on your horse's hooves are often oil based, and repel water, and water is what your horse really needs. If there is a natural water sourse, great! walk your horse in that and let him sit there for 20-30 minutes. You could give him some hay or just let him sleep-whatever makes him happy.

If you do not have a natural water sourse, in the related links are links that will show you how to make a little "foot pond".