permaculture

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

On 12/28/2010 1:54 PM, David Muhl wrote:
> Excellent info...thank you.

I learned a lot, cleared up a lot of mystery and the thread is still 
going though I haven't gotten a reply to this yet:

-------- Original Message --------
Subject: Re: [SANET-MG] Question for Elaine: Fwd: Re: [permaculture] 
Fwd: Re: [SANET-MG] Soil minerals and nutrition
Date: Tue, 28 Dec 2010 08:31:58 -0500
From: Lawrence F. London, Jr. <venaurafarm@BELLSOUTH.NET>
To: SANET-MG@LISTS.IFAS.UFL.EDU

On 12/28/2010 6:50 AM, James Sprunt wrote:
> A common test for soluble nutrients is a Reams type test using Morgan
> extracts. These use a relatively weak extractant and Reams wanted 
farmers to
> be able to conduct this test on a very regular basis.
>
> Then there are tests for exchangeable cations(Ca, Mg, K, Na, H, 
NH4+,Al) i.e
> those adsorbed to colloids.
>
> There are also a number of tests for the anions: P, S, N which some
> stronger, some weaker (some less available, some more available) 
again based
> on the ability of the extractant to extract.
>
> There are tests for trace elements, some of which are cations, some 
anions.
>
> Then there are the totals (largest pool), strongest extractant.
>
> Note that very few labs do the exactly the same test and will thus have
> different results.

Maybe it would be expensive but for any and/or all nutrients selected
for testing in soil samples and with factors of nutrient interactions
limiting availability and site specific factors (if any) accounted for
somehow, is it feasable to do a range of extractions using weak to
strong extractants for each nutrient providing a clearer image of what
exists or doesn't exist and to what degree in multiple samples taken on
a farm. This would tell a farmer what nutrients are immediately
available for use at planting time and what could become available over
time. Maybe the test data could be plugged into a database or
spreadsheet and correlated with pH, soil moisture, SOM, humus (humate?)
levels, soil microbiology  and nutrient interactions. Something like
this, though imprecise, might still provide a clearer and long term
picture of field conditions and realistic expectations for crop
production than other types of testing procedures. Other information
that should be added to the db dataset through the use of a linked GIS
system would be a history of crops planted and harvested for each
defined site and the condition of each of those crops. This would also
be useful in planning succession schemes.