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Lake Stevens, WA, USA

I bought a bag of ammonium sulfate (21-0-0) and a bag of triple superphosphate (0-45-0) and a bag of muriate of potash (0-0-60). If I were to mix a cup of each of these together, would I end up with 3 cups of 21-45-60, or would it be something different.

Somebody posted a message about this (mixing fertilizers) awhile back, but I can't seem to find it or remember where it was posted.

Thanks,
David

4/9/2002 2:30:38 AM

Garden State Pumpkins

as an educated guess...you now have 15 lbs of material and as a percentage they would be a third of the percentage or 7-15-20...just a guess chuck

4/9/2002 8:22:09 AM

Cologne / Germany

David, I know a german website where the problem is discussed. I´ve translated it with an internet speech engine, so it may sound a bit funny...
"Important is the selection of the raw materials in such a manner that the desired final result can be achieved at all by mixture. From two fertilizers with NPK = 6-4-6 and NPK = 8-5-9 will be able to never and mix you never a fertilizer also in the comparison to the nitrogen higher phosphorus portion, since both possess a decreased phosphorus portion. With the release of the equation it becomes apparent by the fact that negative values arise. The minus sign is going by to be interpreted that one would have to extract a certain quantity of fertilizers B from fertilizer A or in reverse. That cannot be done naturally."
Will post an example for this afterwards. Hope this helps a bit, it`s a lot of calculation before the fertilizer is done.
Ingo

4/10/2002 3:21:04 AM

Cologne / Germany

Here´s the example:

"Assumed, you possess a fertilizer 1 with 15-5-20 (blue grain) and a fertilizer 2 with 10-11-8. A goal should be of concentrating in the mixture nitrogen and potassium (i.e. first and the last value) directly. If x represents the quantity of fertilizers 1 and y the quantity of fertilizer 2, the following equation applies (on the basis the selected numbers you can see easily, from where you originate from the NPK indication of the fertilizers):

15 x + 10 y = 20 x + 8 y | from both sides 15 x subtract
10 y = 5 x + 8 y | from both sides 8 y subtract
2 y = 5 x


If one divides now x/y = 2/5, the looked for result by y and receives then by 5, one. This means that you must mix 2 parts of x (= fertilizer 1) and 5 parts of y (= fertilizer 2) and so that 2 + 5 = 7 parts receive fertilizers. Or you take 2/7 parts of fertilizers 1 and 5/7 parts of fertilizer 2 and receive 1 part of fertilizers.
Thus you receive a fertilizer with a nitrogen portion of (2/7 * 15) + (5/7 * 10) = 11.4 , a phosphorus portion of (2/7 * 5) + (5/7 * 11) = 9.3 and a potassium portion of (2/7 * 20) + (5/7 * 8) = 11.4 , i.e.. NPK = 11,4-9,3-11,4 . "

4/10/2002 3:21:33 AM

Cologne / Germany

Addition: This was only an approach to show how you can mix fertilizers to stress or decrease a certain portion. If you have "pure" N, P or K portions, one cup of each means exactly the percentage of these portions in your final fertilizer.

4/10/2002 3:46:51 AM

Cologne / Germany

Sorry, that one was misunderstable, I meant in the way Chuck said, 1*N + 1*P + 1*K = 1/3-1/3-1/3.

4/10/2002 5:21:48 AM

Paradise Mountain, New York

the fertilizer would come out to be 7 - 15 - 20

4/13/2002 1:57:03 AM

Lake Stevens, WA, USA

Flohberger, you said that if I have "pure" n, p, k, fertilizers, then mixing a cup of each would give that value in the final formula............. That's what my question really deals with.

The 21-0-0 I have contains only ammonium sulfate, does that make it pure? Same Question for the triple superphosphate 0-45-0 and the muriate of potash 0-60-0.


David

4/13/2002 1:44:47 PM

Lake Stevens, WA, USA

Ooops! I meant muriat of potash 0-0-60, but you probably already figured that out.

David

4/13/2002 2:36:39 PM

Western Pa.

David,

Your 21-0-0 is 21% ammonium sufate, the rest is "filler". If you have 10# each of (21-0-0), (0-45-0), and (0-0-60), and mix them together, you will have 30# of 21-45-60.
kilr

4/13/2002 3:15:57 PM

Ann Arbor, Mi

Kilr,
The total of the 3 numbers can not add up to be more than 100...you would have 30# of 7-15-20...Bob W

4/13/2002 4:37:14 PM

Western Pa.

Ooops!

4/14/2002 11:10:55 AM

Paradise Mountain, New York

Kilrpumpkins, your answer is wrong. it doesn't matter if it's ammonium sufate or filler. you add them all up and divide by three and get 7-15-20. After all, i once worked in a fertilizer place that made fertilizer

4/17/2002 12:02:58 AM

Lake Stevens, WA, USA

Hey PumpkinBrat, So if you worked there, what do you really know.................Can you explain the whole mixing thing to me a little better.

Specifically, I don't quite get the point in "pure" fertilizers. Why should I go to the trouble of hunting down 21-0-0, 0-45-0, and 0-0-60 in the first place if what I am ending up with is 7-15-20. Wouldn't I get the same results if I just used 7-15-20 or what ever blend I could find that would be close.

For that matter, can anyone explain..........whats the difference between applying 21-0-0, 0-45-0, and 0-0-60 instead of 7-15-20. Does it all just come down to applying the "correct" fertilizer at the "correct" time? Stressing phosphate for root growth first, then nitrogen for foliage growth, then potash for fruit growth? But again I ask, wouldn't a "blended" fertilizer do this for me, afterall, doesn't the plant only use what it needs?

If I had perfectly fertilized soil (I can dream)and a soil test told me that I didn't need to add anything (still dreaming) then wouldn't all of the required nutrients be utilized when the plant needed them, but otherwise just remain in the soil until the plant needed them.......with the possible exception of nitrogen as it leaches from the soil so quickly.

Anybody want to take a stab at this?
David

4/17/2002 1:54:53 AM

Western Pa.

Brat,

If you will look at the posting above yours, I knew my answer was wrong. Sometimes daily stress, too much on the mind, a few beers, etc., can cause "brain farts"! I'm really sorry, but we ALL make mistakes, and once that post reply button is pushed, you can't take it back.(By the way, what is ammonium SUFATE?) David, An AG plant should have roughly 3# of nitrogen per year. It is best accomplished by adding a little at a time more frequently, than a whole lot at once. I figure the total % N in my fertilizers to arrive at how much (weight) in N to add every 7-10 days. I add more potassium in mid-August, but I'm not so concerned about % of phosphate and potash on the fert bags, as much as the nitrogen. In growing these pumpkins, we are basically dealing with optimum nutrients. Just because the nutrients are in your soil, doesn't mean that they are readily taken up and "available" to the plant. This is why growers are taking tissue tests to see what the plant is "using". E-mail me if you need any more details on how I figure my ferts.
kilr

4/17/2002 9:16:46 AM