From: "Lawrence F. London, Jr." <venaurafarm@bellsouth.net>
To: permaculture <permaculture@lists.ibiblio.org>
Subject: [permaculture] Fwd: Re: [SANET-MG] Soil solution concentrations of phosphorus
Date: Wed, 29 Dec 2010 11:45:01 -0500
-------- Original Message --------
Subject: Re: [SANET-MG] Soil solution concentrations of phosphorus
Date: Wed, 29 Dec 2010 10:47:39 -0500
From: James Kotcon <jkotcon@WVU.EDU>
To: SANET-MG@LISTS.IFAS.UFL.EDU
Perhaps this discussion illustrates the problems that growers have in
understanding soil test reports. While the soil solution concentration
of phosphate may be 1 ppm, the "available" (extractable) phosphate
levels are much higher, and soil test recommendations often aim for the
450 ppm "available" phosphate as a basis for fertilizer recommendations.
The complexity is hard enough for experts to grasp, and a clearer
description in soil test reports would help many of our growers. It is
surprising how many growers attend our workshops on "How To read Your
Soil Test Report" each year.
In our soils, we often run into problems with phosphate fixation
(precipitation as insoluble iron or aluminum phosphates) especially at
acid pH levels. Adding lime increased the "available" phosphate in our
soil even without adding compost or other amendments. It is not
necessarily a microbial function, just "simple" solution chemistry.
Jim Kotcon
[permaculture] Fwd: Re: [SANET-MG] Soil solution concentrations of phosphorus,
Lawrence F. London, Jr., 12/29/2010