Fertilizer Formula Question?

[gertman]

Does anyone know the formula for figuring out your fertilizer mixture for example one of my soil tests for fescue came back as 100N-80 Phos.-40 Potash so the recommended mix was 300lbs. per acre of 19-26-13 which gives me 57lbs. N, 78lbs.Phos, and 39lbs. of potash, the fertilizer dealer said putting more than 60lbs. of Nitrogen at once on fescue grazing pastures isn't cost effective, so what I want to know is how do you figure out the 19-26-13 formula.

 

[llcupit]

Sorry don't understand your question. 19-26-13 is what it is 19 lbs of N per 100 lbs, 26 lbs of Phos per 100 lbs and 13 lbs of Potash per 100 lbs.

 

[Angus Guy]

From what your soil test shows I would say that the 19-26-13 is a good way to go. I would normally reccomend 50-60# of N for pastures. On my own I will usually spread a 36-92-120 because my tests tend to be low on K.

The 19-26-13 is # per 100# of actual NPK. The K is pretty simple because you are only dealling with one product. Divide 13 by .60 = will be the amount of potash that you would need to apply. In your case 65#/a of potash to get 40# actual. I am assuming that your dealer is using DAP so the same formula does the P. 26 divided by .46 = 56.5# of DAP plus 10# of N. So to get the 80# of P you will need 174# of DAP. This will also give you 31# of N. To finish off the N you will urea or one of the products.

This coming out about as clear as mud but hope it helps.

 

[gertman]

Sorry don't understand your question. 19-26-13 is what it is 19 lbs of N per 100 lbs, 26 lbs of Phos per 100 lbs and 13 lbs of Potash per 100 lbs.

I guess I didn't phrase the question correctly I want to know what method the fertilizer dealer uses to figure out the combination of (19-26-13) from a soil test that reads (60N-80Phos.-80Potash)

 

[bigbull338]

Sorry don't understand your question. 19-26-13 is what it is 19 lbs of N per 100 lbs, 26 lbs of Phos per 100 lbs and 13 lbs of Potash per 100 lbs.

I guess I didn't phrase the question correctly I want to know what method the fertilizer dealer uses to figure out the combination of (19-26-13) from a soil test that reads (60N-80Phos.-80Potash)

thats easy he looks at your soil test results.then he looks at the blends of fertalizer that he has.an tells you wich blend an how meny pouds pre ac you need.example 300lbs of triple 17 would be 54lbs ea of npk in 1 app.so he looked a matched your needs in 1 fertalizing insted of 2 with triple 17.

 

[john250]

Does anyone know the formula for figuring out your fertilizer mixture for example one of my soil tests for fescue came back as 100N-80 Phos.-40 Potash so the recommended mix was 300lbs. per acre of 19-26-13 which gives me 57lbs. N, 78lbs.Phos, and 39lbs. of potash, the fertilizer dealer said putting more than 60lbs. of Nitrogen at once on fescue grazing pastures isn't cost effective, so what I want to know is how do you figure out the 19-26-13 formula.

Start with the per acre P requirement.
80 lb actual =173 lb 18-46-0
You get that by multiplying 80 by the inverse of 46 or 2.17

Now the N. In one application you only want 50 lb.
You have 31 lb of actual N in your 18-46-0.
Multiply 18*173 lb of 18-46-0.

To get to 50 you want to add urea. (46-0-0).

You need 19 lb N. Add in 41 lb of urea. 19*2.17=41.23 lb of urea.

To get 40 lb of potash, add 67 lb of 0-0-60.
40*1.67=66.67.

Now you have per acre amounts for product.
173 lb of 18-46-0
41 lb urea
67 lb 0-0-60
281 lb. is where you set the spreader gate.

Throw all that in a blender and apply 281 lb/acre.

 

[novaman]

To be honest I have no idea how he came up with that blend. I'm guessing he started with nitrogen. If you were shooting for 60 pounds you would need 300 lbs/acre of this blend. From there he has me lost. 300 pounds at 26% for P gives you 35 lbs/acre. In case you are wondering how i arrived at that you take 26% of 300 which is 78 pounds. But then you must remember that the phosphorus used in most fertilizers in is the form P2O5. So only about 45% of the "phosphorus" applied is actual phosphorus, giving you 35 pounds. The potash would be about 32 lbs/acre because potash is about 81% actual potassium since it is in the form K2O. I am using 300 lbs/acre only because I wanted to get my N and find the values of the other two. So we get 57 pounds of N, 35 pounds of P, and 32 pounds of K. That doesn't come close to meeting your requirements for P or K. I would have to question how he figures this will work for you.

 

[gertman]

Does anyone know the formula for figuring out your fertilizer mixture for example one of my soil tests for fescue came back as 100N-80 Phos.-40 Potash so the recommended mix was 300lbs. per acre of 19-26-13 which gives me 57lbs. N, 78lbs.Phos, and 39lbs. of potash, the fertilizer dealer said putting more than 60lbs. of Nitrogen at once on fescue grazing pastures isn't cost effective, so what I want to know is how do you figure out the 19-26-13 formula.

Start with the per acre P requirement.
80 lb actual =173 lb 18-46-0
You get that by multiplying 80 by the inverse of 46 or 2.17

Now the N. In one application you only want 50 lb.
You have 31 lb of actual N in your 18-46-0.
Multiply 18*173 lb of 18-46-0.

To get to 50 you want to add urea. (46-0-0).

You need 19 lb N. Add in 41 lb of urea. 19*2.17=41.23 lb of urea.

To get 40 lb of potash, add 67 lb of 0-0-60.
40*1.67=66.67.

Now you have per acre amounts for product.
173 lb of 18-46-0
41 lb urea
67 lb 0-0-60
281 lb. is where you set the spreader gate.

Throw all that in a blender and apply 281 lb/acre.

Thanks I now understand since the fertilizer dealer only has a few products to blend in the first place.

 

[donnaIL]

John you have a "smart way" of explaining it...like our fertilizer dealers...course they all want to sell fertilizer according to the folks here.

I have no complaints with them and truth be known most of fertilizer people i have talked will under sell you than over sell you, expecially with a soil test.. other wise they give you 100+ ... they have a reputation too...

i dont know about fescuse...but personally i think we will really kick in some *N* this year and hope for a good one..

Good Luck!

 

[sros990]

Here are a couple of useful links:

http://anlab.umesci.maine.edu/handbk/fertil.HTM[/url]

http://www.tulsamastergardeners.org/bla ... alc.htmurl]

Hope it helps,
Steve