permaculture

[Toby Hemenway <toby@patternliteracy.com>]

On 3/12/05 5:03 AM, "Graham Burnett" <grahamburnett@blueyonder.co.uk> wrote:

> I'm sure that in one of Mollison's books he says you can use gypsum
> wallboard as sheet mulch.

--though I'd advise busting it up into chunks first; used as the "sheet" in
sheetmulch it will probably take longer than cardboard, or even wool carpet,
to break down enough for roots (and, initially, water) to get through it.
I've played around with it, and as a solid sheet under a layer of mulch it
stays impermeable for a year or more.

And as noted, it is mostly gypsum, which is good at lightening clay soil.
Gypsum (CaSo4) also releases dilute sulfuric acid when mixed with water, so
it will acidify soil considerably (and is used as such in ag--the opposite
of lime)

Toby
www.patternliteracy.com