dennis@home wrote:


"Chris George" wrote in message
...
On 30 July, 02:42, The Natural Philosopher
wrote:
Dave Liquorice wrote:
On Wed, 29 Jul 2009 18:32:29 +0100, The Natural Philosopher wrote:

What kills wood in under a year if not treated is being pushed into
the
ground. Perfect breeding ground for fungi.

But the bit in the ground will be OK and the bit 6" or so above
ground level. It's the bit in air just above ground level that rots,
plenty of oxygen and just the right amount of damp by capillary
action up the timber.

I think not., if the mushrooms that spring up from bits of buried timber
in the garden are anything to go by..sure, the spores strike above
ground, but they rapidly expand below as mycelia. Fungi dont need light,
or air..

The other big rotter is the flat topped post where rainwater soaks
into
the end and most and algae accumulates.

Yeah, tends to rot the core out.

Yup.

The Natural Philosopher is right

Dr Ed Bains did the original work on this in the ICST lab back in the
early seventies when we were both students together doing our theses
It transpires (pun intended) that what happens when a stake is put in
the ground that there is some wicking of the salts in the ground
up the timber to the point at ground level where they can evaporate.
These salts bring nitrogen to the substrate (wood) and make it really
rather
tasty for the precursor (generally stainers) fungi only to be followed
by the rotting fungi
The wood immediately adjacent to the ground rots preferentially. The
wood above ground and the wood below ground at the point where it is
anaerobic
does not rot.
Most of us who have replaced old fence posts will confirm this on
looking at the posts on removal.
Generally at the top there is much less decay (albeit some) as it gets
to dry out and gets too hot in the sun

The tops are usually OK because you either fit post caps or saw them at an
angle to allow runoff.
That's why you use triangular rails on fencing too.

The worst thing you can do (as far as rot is concerned) is have flat
horizontal areas of timber to collect water like many decks are.

If you want rot free posts use concrete (even concrete rots, but not usually
in a lifetime).

Our 9 acres are fenced with flat topped posts in the main. They don't
generally fail anywhere above ground, as describe further up this
thread they rot just below the surface (of the ground).

--
Chris Green