I agree- What I've done is hauled in some bentonite and put around my water tanks (out about 8 feet)- then I just run the tanks over every once in a while- cleans out the tanks and the bentonite holds the moisture- Every time the horses go to get a drink they have to walk thru this wet area- seems to keep them a lot softer and prevents cracking.
Well this solution may be a test of how broke your horses are. but I have seen it done many times by an old horse shoer, scorch the sole with a prppane torch till you smell it alittle WARNING! JUST SCORCH TO MUCH HEAT WILL LAME THEM! but its common in theses parts to do it in the winter and on very hard hooves just go slow and dont get your head kicked off lighting the torch