Setting Fence Posts, Concrete or Not?

This topic has been debated on this forum for at least three years. Some, like OhMike, take the position that concrete attracts or traps moisture, and shortens the life of the post. Others have said that there is absolutely no evidence for this belief.

I have put in posts using three different methods, for what it is worth here is how the techniques performed.

I put in six 4x4 cedar posts in concrete 20 years ago for a fence. To date, the posts seem to be in perfect condition. I put in a 4x4 pressure treated mailbox post in gravel/soil mix 20 years ago, to date no issues.

The previous owner of my house installed two long cedar post fences in 1959 using direct burial in soil. After 50 years, all of the posts are rotten.

I built a deck using 6x6 PT posts installed on concrete sonotubes using Simpson standoff brackets. Only been two years, but so far no damage. I have seen similar deck designs where the posts have lasted at least 20 years.

I like the idea of using dry concrete mix, let the moisture in the soil wet the concrete. It might take a year to fully cure, but so what, you don't really need any strength. From my perspective, it seems that the concrete would harden right up against the post, leaving little or no room for moisture to penetrate against the wood. Even if a little moisture wicks through, I don't really see this as much of an issue. I would like to see a definitive study on whether embedding posts in concrete is really a problem, I have not found one yet.

If I were going to put in fence posts, I would set them in concrete. BUT, in order to have them last more than 10 years or so, I would first attach a metal post support rail and then set them both in concrete as one unit. If the wood rots after a few years, the fence posts will still be supported by the metal rail. I had a 6' cedar fence installed in the early 80's and after a few years a few sections blew down due to high winds causing the posts to snap at the ground. Turned out they were partially rotted already. The fence contractor came out and redid the posts but I wanted something that would last longer and they supplied metal supports. (pic attached) To this day, about 25 years later, those posts are still standing. Unfortunately, the fence contractor no longer has those support rails and when I called a few years ago they didn't know where to get them. Here's a link to another company that has a different version of support rails. By the way, the support rail in the attached pic is on the neighbors side of the fence so I don't even see it.

http://contractors.masterhalco.com/Contract.nsf/woodpostmaster?OpenForm