On Thu, 30 Jul 2009 01:03:17 -0700 (PDT), Chris George wrote:

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 Natural Philosopher is right

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.

Which isn't what TNP said but is what I said. Though perhaps not
being clear enough about the anerobic nature of the below ground
timber. Things do not rot in anerobic conditions, think the Bog
People...

There is a "comfort zone" for the fungi/bacteria that rot the timeber
that is above ground level and doesn't extend that far below it. A
lot does depend on ground conditions but for yer average bit of
garden soil the bit of a stake/pole more than a couple of inches
below ground will take a lot longer to rot than the section at/just
above ground level.

--
Cheers
Dave.