Re: understanding soil testing

From: Elaine Ingham (Soilfoodweb@AOL.COM)
Date: Sat Apr 12 2003 - 21:23:06 EDT


There needs to be some explanation of the difference in extraction methods
used by different labs. This has interested me a great deal in the last few
years.

Does the lab you use use an extraction method that extracts ALL the nutrient?
 Or some portion of that total? Or just the soluble nutrient? What is the
difference between extractable, versus available, versus soluble (ah,
soluble in what? is that water, or Universal buffer, or Morgan extract?),
versus what is actually in the plant. Huge differences here.

Just because something is extractable with a strong reagent does not have any
meaning with respect to whether the plant can access it.

I'm not an expert on these differences in methods, but different extraction
methods result in very different understanding of what is happening in your
soil. You need to understand if you are using a lab doing Reams testing,
LaMotte testing, Albrecht, versus standard conventional. Even standard
chemcial labs aren't all that standard. Each lab has their own way of doing
things.

We are working with the Environmental Analysis Lab here at the University,
and they compare standard chemcial analysis with Albrecht, Reams and plant
tissue. Really interesting the information you get comparing the different
methods!

But those of you interested, should talk to Arden Andrson, or Graham
Lancaster, or Dan Skow or Gary Zimmer about these differences. I understand
a great deal about how biology works. We have yet to integrate how the bio
logy changes the chemistry, and vice versa.

Elaine Ingham
President, Soil Foodweb Inc.
www.soilfoodweb.com
SFI Oregon, USA
SFI Australia
SFI New York
SFI Europe
SFI New Zealand

"Hope is not a feeling. It is not the belief that things will turn out well,
but the conviction that what we are doing makes sense, no matter how things
turn out." -- Vaclav Havel, former President of the Czech Republic






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