permaculture

["Lawrence F. London, Jr." <venaurafarm@bellsouth.net>]

Useful information.

-------- Original Message --------
Subject: [SANET-MG] phosphorus
Date: Fri, 1 Apr 2011 08:30:30 -0400
From: Joel Gruver <jgruv@HOTMAIL.COM>
To: SANET-MG@LISTS.IFAS.UFL.EDU

just noticed the following typo in my early morning message:

Regarding 2 parts phosphate to 2 parts potash, a lab like Logan labs 
that uses an ICP spectrophotometer...

this should read "2 parts phosphate to 1 part potash"...
It is certainly possible to load soils with P to the point that 
extractable P levels are twice as high as extractable K levels but I am 
not aware of any reason why one would want to do this and can think of 
many ecological reasons why this would be undesirable.

In terms of food quality, crops that store P in phytate aka phytic acid 
(e.g., grains) tend to have very elevated levels of phytate when soil P 
levels are extremely high. My understanding is that high levels of 
phytate interfere with the availability of a number of metals in human 
and animal diets.

Joel

BTW here is a link to a presentation on soil phosphorus (developed for 
my soil fertility class last fall) that may be of interest.
I think I posted a link to this presentation last fall during an earlier 
discussion of phosphorus.
https://www.yousendit.com/download/UFh0OGNTOC9uSlJFQlE9PQ (presentation 
is a powerpoint file ~ 7 Mb)
link will only remain active for 1 week or 100 downloads

Joel Gruver
School of Agriculture
Western Illinois University
jgruv@hotmail.com