Market Farming

["Bill Shoemaker" <wshoemak AT inil.com>]

    Sorry about not snipping more but I think the context is very important
here.

    Rock phosphate is NOT 46% phosphate. According to Tisdale & Nelson in
Soil Fertility and Fertilizers, rock phosphate is a mined product that is
ground up and is then from 11.5 to 17.5% phosphorus. To get a higher
concentration can only be done by acidifying it. If it's black, granular and
46% phosphorus, it is triple-super phosphate no matter what anyone tell's
you.

    The US has about 40% of the world's supply of  mineral phosphorus and
most of it is in Florida. So that is where rock phosphate comes from but it
is where rock phosphate is converted to other phosphorus fertilizers as
well.

    I have a small supply of rock phosphate at home and it is a very fine
powder, creamy colored. Using it as a fertilizer is a long-term proposal. It
breaks down rather slowly. But that has it's benefits as over time your
supply in the soil remains adequate. To ensure that your organic soil mix
has available phosphorus, don't use rock phosphate. Just sterilize a batch
of garden soil and add that to your mix. If your garden soil has adequate P,
your mix will too.

Bill Shoemaker
Sr Research Specialist, Food Crops
Univ of Illinois - St Charles Hort Research Center



>I'm away from my reference materials, can't find clear info on the web
>(limited time to search), & really need some expert answers.
>Is rock phosphate also called triple phosphate??
>Does the color vary from mine to mine?
>
>Liz
>
>PS  I went to purchase more rock phosphate at the same location where I got
>my stuff last year.  A new guy was available to help (They said the owner
>was still on vacation, but I think he was hiding in the back!).  I very
>slowly, very plainly explained what I wanted-black rock phosphate from our
>local state mine.  They proceeded to load 14-50# bags.  The clerk began
>filling out the receipt & I looked over her shoulder.  The loaded bags were
>not what I ordered!! It was something else entirely.  I asked if this was
>rock phosphate, & they told me I could call it what ever I wanted.  By this
>time every worker on the dock was watching!  (How embarrassing-this is a
>very redneck area!)  I repeated that this stuff must come from our local
>state mine.  I was again assured that it did.  So I asked to see their
>records of delivery.  Guess what?  Came from Florida, nothing wrong with
>that, but NOT what I ordered.  Why, I asked, when we can get our own,
>BETTER, stuff just 50 miles away,like I did last spring.  Cooporate
>consolidation was the answer.  They were flabbergasted when I kindly (with
>gritted teeth!) requested those bags to be off loaded pronto.  And then, as
>I was leaving, the head guy had the gaul to ask, just what is organic
>farming.  I've got a long row to hoe!!
>
>
>
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