Re: [compost_tea] Inclusion of clay in compost

From: Stephen Steyn <ssteyn_at_wcaccess.co.za>
Date: Fri, 4 Feb 2005 17:15:36 +0200

A question for someone in the group;
I intend using a compost for extraction which has about 10% clay. The rati=
onale of the composters for including the clay is that they believe the cla=
y serves firstly to adsorb the cations and secondly to moderate the tempera=
ture in the compost pile so that it doesn't build up excessively. Both thes=
e arguments appear plausible. This composter has done the CNC composting co=
urse in Holland where it would seem the inclusion of clay is recommended. C=
NC are a company involved in the mushroom business and it would appear they=
 specialise in preparing the feedstock for the mushroom farms namely a mix =
of lime, horse manure and straw. You can check their web site if you like, =
Google CNC.

The problem is that the extraction process commonly used here consists of a=
n airpump (I think its specs are 2500lt per minute at 2bar) with a membrane=
 bubbler in the bottom of the 1500lt tank. Extraction times are about 20 ho=
urs. No mechanical agitation is used - again it's a system adopted from the=
 Dutch. I have noticed though that there is a build-up of clay in the botto=
m of the tank leading me to suppose that the system is not stripping the c=
ations and biota from the clay and that the clay is simply settling below a=
nd between the bubblers without being agitated.

I am having a sample of the compost tested through the kind offices of SFI.=
 I'm sure some knowledgeable person amongst you would like to comment on th=
e inclusion of the clay. I guess I should have a sample of the tea tested a=
nd maybe test the clay from the bottom of the tank.

Your comments/suggestions would be much appreciated.

Steve Steyn ssteyn_at_wcaccess.co.za








Received on Fri Feb 04 2005 - 12:31:27 EST

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