Re: Potasium phosphate
- To: woodyplants@mallorn.com
- Subject: Re: Potasium phosphate
- From: D* M*
- Date: Sun, 4 Apr 1999 16:41:43 -0600
>Is there a difference in plant utilization OR material handling
>between
>
>POTASSIUM PHOSPHATE (monobasic)- monopotassium phosphate; KH2 PO4
>and
>POTASSIUM PHOSPHATE (dibasic)-dipotassium phosahate; K2 HPO4-3 H2O
>
>Are they similarly soluble in water therefore likely to be induced into the
>plant system equally.
>
>Regards
>Joel Kroin
>jkroin@hortus.com
>
Well, I can provide a bit of the chemical data, but for plant utilization,
you'll have to ask the physiologists.
The dibasic, K2HPO4 (anhydrous) is more soluble in "cold" water - 167g/100
ml (20 deg C), while the monobasic KH2PO4 is soluble at only 33g/100 ml at
(25 deg C) (Don't know why they measured the solubility at different temps).
Also, the monobasic, will be more acid in solution, since it will ionize to
release 2 hydrogen ions (per molecule) instead of only one for the dibasic.
I'm out of the lab, so I don't have access to the actual values, tho I
don't think you need those. In my usage of these chemicals, they are
prepared as aqueous mixtures of the two to achieve a particular pH value
and the resulting solution will be buffered against rapid changes in either
direction, either towards acidic or alkaline.
Perhaps this was more than you wanted to know.
Don Martinson
Wauwatosa, Wisconsin (Milwaukee suburb)
USDA Zone 5 (-10 to -20F)
AHS Heat Zone #4
d*@post.its.mcw.edu
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