Re: Phosphorus questions
iris@hort.net
  • Subject: Re: Phosphorus questions
  • From: &* S* <s*@molalla.net>
  • Date: Sat, 7 Apr 2012 16:39:23 -0800
Scarlett: The formula is 9-58-8 and the source of the potassium is <<Derived from Monoammonium Phosphate, Monopotassium Phosphate, Iron DPTA, Manganese EDTA, Zinc EDTA>>. Suggest you Google BR-61 formula. 

Dave Silverberg
----- Original Message ----- From: <SDAyres2@aol.com> 
To: <iris@hort.net>
Sent: Saturday, April 07, 2012 2:25 PM
Subject: [iris] Phosphorus questions



Hi All:

I am writing a newsletter for the  club.  I have been reading about
superphosphates on the web and am  confused.

1.  Is treble superphosphate  harmful to earthworms?

2.  Some websites suggest  that treble superphosphate has to be carefully
measured to avoid burning the  plants.   Though other websites  state that
salt index is the usual measure of a fertilizer's tendency to burn  roots.
According to these sources, triple superphosphate has an exceptionally low 
salt index and is very unlikely to harm roots.   Who do you believe?

3.  Rock phosphate is very insoluble.    It will stay where you put it
unless the soil washes away. However, Superphosphate is rock phosphate that 
has been treated with acid to make it soluble.  Does  that mean it can be
washed away from the point of application? How long before it gets converted 
to the regular rock phosphate?  Or does it too  combine quickly with just
about any available mineral in the soil (i.e. iron,  zinc, manganese)?

4.   Does anyone know what type of phosphate BR-61 contains?   It's  the
club's favorite and high in the middle number. We buy it in bulk and parse 
it out to members.  Instead of being $9 a lb it comes out to $3 a  lb.
However, I have no container to  read.

Thanks  a bunch

Scarlett

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