It's spring and during my yard clean up I noticed the bark of my tree is split open from just above the dirt to about a foot into the branches. It's a wide split. What is happening?
I am going to refer you to a very excellent article on bark splitting from Cornell University which discusses the possible reasons this occurred (various environmental factors). This split in your tree is not likely to be fatal but the article will outline things you can do to encourage the natural callusing process that the tree will undergo to close that split.
(Cornell University PDF – bark splitting on trees): https://bit.ly/1KEmrRn