carmenkid
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Ammonium Nitrate for fertilizer
I'm new here so if this is the incorrect forum please excuse me and let me know where I should post. I'm a neophyte when it comes to chemistry.
I'm attempting to build a custom liquid fertilizer. I'm copying the formula for a commercial product that I derived using some software called
HydroBuddy.
Sadly one of the components is ammonium nitrate which appears to be essentially unavailable to me. I have read this thread: http://www.sciencemadness.org/talk/viewthread.php?tid=3129 concerning how to derive ammonium nitrate from calcium nirtate and ammonium sulfate
both of which are available to me.
My reagent-related question is this: I am not using the AN in any kind of combustible - just as a component for N in a liquid fertilizer. My
understanding is that Calcium Sulfate should precipitate out and then I should be left with Ammonium Nitrate in solution. This is perfect for me as I
need it in solution in the end anyway - but how impure will it be without recrystalization? Or is there any way to know in advance?
I'm not intrinsically bothered by the presence of the calcium sulfate so long as the particles will not clog a drip system (which I read they might).
I have also calculated the Ca that I want in the liquid fertilizer (in the form of actually added Calcium Nitrate) and would like to keep the Ca to
the correct proportion.
And while I'm asking questions of people who know something of chemistry I might as well ask for your opinion on the safety of combining these
ingredients into 1 gallon of distilled water:
Magnesium Nitrate (Hexahydrate) Mg(NO3)2.6H2O 282.266g
Potassium Nitrate KNO3 705.985g
Calcium Nitrate (Tetrahydrate) Ca(NO3)2.4H2O 637.833g
Magnesium Sulfate (Heptahydrate) MgSO4.7H2O 1.913g
Mono Ammonium Phosphate NH4H2PO4 253.083g
Ammonium Nitrate NH4NO3 723.394g
Phosphoric Acid (52%) H3PO4 17.445 mL
Supposedly this should give me a 9-3-6 ratio fertilizer with Ca and Mg that stay in solution (I've been told the Phosphoric Acid will keep the pH low
enough for things to get along).
I've also been told that I should maybe expect a serious exothermic reaction when I combine these things. Does that sound right?
I'm not married to the idea of using ammonium nitrate either - I can use any pure N source (urea, for instance) but I was told that urea+phosphorus =
too much heat for me to handle safely.
Any help/advice/warnings would be appreciated. Thanks!
ps: for anyone who cares here are links to the MSDS and the Datasheet of what I am trying to replicate. I am leaving out the micronutrients because I
can buy a commercial formula for that. They want 60$ a gallon for this locally. I can buy the ingredients and make it for 6$ a gallon according to
HydroBuddy - that's buying the ingredients retail.
http://www.dyna-gro.com/Website%20pdf%20Files/MSDS%20Grow-Bl...
http://www.dyna-gro.com/936.htm
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kryss
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Off hand I don't think there should be much heat generated, I would think your biggest problem would be stopping the Magnesium/Calcium from
precipitating out. You probably want to dissolve everything apart from the Magnesium Sulphate first, in a reasonable quantity of water. Dissolve the
Magnesium separately, then add to the much diluted mixture Nitrates - this will hopefully stop CaSO4 precipitating. Finally add the Phosphoric Acid.
Phosphoric Acid doesnt generate anything near the same amount of heat as Sulphuric Acid does when you dilute it, though bear in mind it is a strong
acid!
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carmenkid
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Thanks for the tips. I might just leave out the magnesium sulfate and use another source of S in the soil.
Is there any particular reason you suggest adding the acid at the end? I only ask because I understood that to keep everything in solution the pH had
to be low and I had planned on diluting the phosphoric acid first in an attempt to avoid any precipitation.
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