If you ever decide that you HAVE to get the post out...try using a Root Feeder device.

http://www.buyhardwaresupplies.com/?...emNumber=71686
Turn the hose on; insert the long tube into the ground all around your post...and pull the post out much more easily than doing it dry. We used two old fashioned car jacks, along with a single piece of SS pipe run through a hole in the posts to clear about ten posts from a friend's back yard. regards, Rich