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Subject: Compost Teas: 24 hour, EM, IM, BD & fermented plant extracts

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  • From: Graeme Gerrard <ggerrard AT resonant.com.au>
  • To: compostteas AT lists.ibiblio.org
  • Subject: [Compostteas] Chromas - clarification
  • Date: Mon, 15 Jul 2002 18:37:28 +1000

I just wanted to clarify a couple of things re doing chromas in general.

First you take a dilute solution of silver nitrate and saturate a circular filter paper. Takes about 10 minutes. Then you have to dry it - couple of hours maybe.
Meanwhile you let your substance sit in a dilute solution of sodium hydroxide
Liquids like juices or compost teas take an hour - solids like soils or composts take about 6 hours.
Then you let the solution spread over the paper - up to an hour but usually a lot less.
Then it has to dry and then develop. This takes a few hours to a day.

W hen you have done it a few times and you know what you are doing, it's simple pimple! (Isn't everything?)

Set up cost? You need a measuring cylinder, the chemicals, couple of petri dishes, the papers and maybe a couple of beakers. It could cost AUS$150. But that would set you up for 100 chromas. Much cheaper than assays. But if I was doing chromas for a living I'd have to be charging about the same per test to survive!

The question of interpretation is difficult - I am still learning, but it is a matter of sharpening your observation skills and just doing a lot of chromas. It is a combination of art and science really.
But I agree this is not something everyone could or would want to do.
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  • [Compostteas] Chromas - clarification, Graeme Gerrard, 07/15/2002

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