Milan Posted September 2, 2005 Report Share Posted September 2, 2005 (edited) I'm just curious what is the math behind N-P-K ratio calculations. Here is an example: There are three basic formulas: all are mixed in 500 ml bottlesratio is N03 to P04 to K at .75 to.25 to 1.00 Kno3 using 20.38 grams KH2Po4 @ 5.97 grams K2S04 @ 15.74 grams It probably has something to do with individual contents/ratios of NO3, PO4 and K in the mass of a particular chemical and the solution volume. Chemistry not being my world, I figured I better ask ... Edited September 2, 2005 by Milan Quote Link to comment Share on other sites More sharing options...
Garhan Posted September 3, 2005 Report Share Posted September 3, 2005 Density is the key to the measurements. But powder and granual forms vary. We also want to use a common factor in the dosing. Thats where the 50/10 comes to play. 50 gallon tank 10 ml of ferts. It is easier to scale accordingly to the different tank sizes a person/s may run. Garhan Quote Link to comment Share on other sites More sharing options...
Milan Posted September 3, 2005 Author Report Share Posted September 3, 2005 So, it's the density of a chemical IN THE TANK, not solution (500ml), ... if I get it right ... Still, ... how did you get the 0.75% if you mix 20.38 gr of KNO3 in 500 ml of water and administer 10 ml of such into 50 gal tank? Quote Link to comment Share on other sites More sharing options...
Garhan Posted September 4, 2005 Report Share Posted September 4, 2005 Dont forget the K value in the K2SO4. I assume you are talking about the Standard Stock Solution. Quote Link to comment Share on other sites More sharing options...
Milan Posted September 4, 2005 Author Report Share Posted September 4, 2005 Yes, standard solution, ... but I'm referring to 0.75% of NO3 in the fert, which is present only in KNO3. K2SO4 has nothing to do with it. So, ... how did you come up with # 0.75? Quote Link to comment Share on other sites More sharing options...
Garhan Posted September 7, 2005 Report Share Posted September 7, 2005 To my understanding the K in both or all 3 chemicals will play a role in a 500 ml solution. Correct me if I am mistaken. KN03 K2S04 KH2PO4 The S04 doesnt play a significant role. Quote Link to comment Share on other sites More sharing options...
andyg Posted September 8, 2005 Report Share Posted September 8, 2005 Milan, Garhan. I don't know if you guys have already seen this but it has some good info on the concentration of various chemicals in some of the ferts we use. http://www.thekrib.com/Plants/Fertilizer/dosing.html Quote Link to comment Share on other sites More sharing options...
Milan Posted September 8, 2005 Author Report Share Posted September 8, 2005 Thanks Andy. The article is really useful. I think this is where my confusion comes from, ... not knowing the percentage of individual ion/element in the compound. According to this, KNO3 is comprised of 39%K and 61% NO3. It would be helpful to find out the same analysis for K2SO4 and KH2PO4, but the article doesn't show it. As Garhan mentioned earlier, Chuck's fert calculator may reveal these ratios. All this came out of my pure curiosity, and I guess it is nothing critical to know. Who knows, some day I may learn chemistry ... <_< Quote Link to comment Share on other sites More sharing options...
andyg Posted September 9, 2005 Report Share Posted September 9, 2005 I saw a similar tread listing K2SO4, once I find it again I'll post it here. Andy Quote Link to comment Share on other sites More sharing options...
andyg Posted September 11, 2005 Report Share Posted September 11, 2005 Milan, here's the other info page I found. Hope it helps. Andy http://users.ev1.net/~spituch/Chemicals/ch...cular%20Weights Quote Link to comment Share on other sites More sharing options...
Milan Posted September 12, 2005 Author Report Share Posted September 12, 2005 Thanks Andy ... I'll read it with pleasure .. Quote Link to comment Share on other sites More sharing options...
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