To avoid completely full, frozen water troughs and ensure that there is always access to open water (which is hugely important for horses any time of the year) simply fill a jug half full of salt water. It will always float and never freeze. Horses quickly catch on to pushing down this "bobber" to access open water. How simple is that?! We love it!
I want somebody to do this for me when I die. By doing this you will be contributing to the well-being of the earth, and instead of your loved one visiting your tombstone, they can visit your tree and sit under its branches and know a piece of you is still there with them. That's a much more pleasant thought than a gravesite in a cemetery.