Question
An oak tree in our backyard recently split (almost in half). It did not split all the way down the trunk, but almost (maybe a couple of feet before it reached the ground)  I believe the trees is about 35 years old.  Just split-have no idea why.  We had the part (the smaller part) that fell way from the trunk onto the ground  removed. Can this tree be saved?  We would like to save it.

Answer
Sounds like the tree with a forked tree (one having two main trunks) and one split off from the other. When it was very young the top broke off and two limbs grew and both became the new top of the tree. Where they are connected the wood is weaker than if it were one trunk. As the two grew the weight of the foliage caused one to break off causing the split.

The remaining fork can survive but it will take it many years to fill in and not look lop-sided. I would cut any loose bark or splintered wood off smooth and the wound will heal over. On most tree wounds I do not recommend wound dressing but for what sounds like a large wound I would paint the wound with a tree wound dressing (check with your local nursery for this). I would also watch the wound area for sawdust a sign that an insect has bored into the wound. If this is seen I would spray the wound with and insecticide called Onyx--this will kill ay insect attacking.

I would fertilize the tree with 10-10-10 fertilizer at the rate of 1 lb of fertilizer per inch of trunk diameter scattered around the tree and watered in good. This will promote faster growth.

A picture would have helped but if you are still concerned call the local office of the State Forestry Agency and ask one of their Foresters to come take a look at the tree.