Water retained by various soil ingredients

David Pilling pbs@pilling.demon.co.uk
Wed, 24 Oct 2012 06:43:23 PDT
In message <fc9884635e19f6f68f3145bbc358c825.squirrel@http://www.possi.org/>,
Leo A. Martin <leo@possi.org> writes
>It is possible to buy large horticultural perlite. Particles are about the
>size of dry beans. This retains much less water than the fine stuff. Used
>by itself it is not good for anchoring roots so it needs something else
>for more stabilization.

One might distinguish between the water retained inside the medium and
that held between the particles of it. Smaller particles can retain more
water between themselves. The bigger gaps between bigger particles hold
more air than water.

A medium that took no water in at all would show only this effect, Hmm.
cavity wall insulation consists of 2mm polystyrene balls...

There are pictures of various mediums like pumice, usually with a size
scale here:


David Pilling
email: david@pilling.demon.co.uk
  web: http://www.davidpilling.net/

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