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Fertilizer Math
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lawfarms
Posted 4/6/2012 00:48 (#2323315)
Subject: Fertilizer Math



King City, Mo
I pickuped up a load of mixed fertilizer today. I was looking at the ticket and trying to reverse engineer the info they gave me because I have always wondered how they came up with the spread 229lb to the acre when 10.6+50+80 = 140.6


The info I have

actual 10.6-50-80
analysis 4.61-21.78-34.87

Map 11-52-0

Potash 0-0-62

Cost per ton $548.70

$63.03/acre

Weight/Acre 229.4869

53000lbs

This isn't something that i must know, but i'd like to learn how mix fertilizer is figured.







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grgsrvc
Posted 4/6/2012 01:27 (#2323350 - in reply to #2323315)
Subject: Re: Fertilizer Math


Barley Belt west of the fifth Meridian
your 10.6-50-80 is what you told your dealer you wanted to apply per acre. the 10.6 is the actual pound of nitrogen the 50 is the potash and 80 is the K. now when they blend up the fertilizer if you took exactly 100 pounds of the mixed blend the percent of that 100 pounds is what the analysis means. in your blend example here that means you have 4.61 lbs of N, 21.78 lbs of Map and 34.87 lbs of Potash. however you want to apply a rate of 10.6-50-80 so you have to apply 229.4869 lbs to get your desired amount.

I wish sometimes the computer would break that spits out these blend batch sheets and the dealer would have to figure out on paper how to calculate a blend. it is really easy once you get the hang of whats going on. but at first glance it is quite confusing.
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rank
Posted 4/6/2012 06:22 (#2323398 - in reply to #2323350)
Subject: Re: Fertilizer Math


SEON
Has anyone ever had the fertilizer analyzed?
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Don Smith
Posted 4/6/2012 06:57 (#2323416 - in reply to #2323398)
Subject: Re: Fertilizer Math



Centre county Pennsylvania, USA
We've never had our dry blended fertilizer analyzed but we compute our own and order it by pounds of dry Urea, MAP, and Potash in the blend and ask for those pounds to be included on the dry blend invoice. By law, supplier must also include N-P-K of delivered dry blend on invoice so we can check that out against our own computed analysis for that blend. We 'trust' supplier's quoted analysis of dry Urea,MAP, and Potash. Supplier quotes prices on dry Urea,MAP,and Potash so we can compute cost of that dry blend before we order.
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dawdge
Posted 4/6/2012 07:39 (#2323461 - in reply to #2323315)
Subject: Re: Fertilizer Math


NE colorado. & south central SD
96LB MAP + 129LB POTASH/PER ACRE

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lawfarms
Posted 4/6/2012 08:07 (#2323489 - in reply to #2323350)
Subject: Re: Fertilizer Math



King City, Mo
I would like to learn the math.

So in my load of 53000lbs how many weigh-able lbs of MAP and Potash are there in the mix?

N

53000*4.6%=2438 /230 acres = 10.6lbs actual per acre

P

53000*21.78%=11543.4 / 230 = 50lbs actual per acre

K

53000*34.87%=18481.1/ 80lbs actual per acre

Ok, so that matches and comes out good....

but......If you add up 4.6%+21.78%+34.87% = 61.25%......so where is the other 39%??? It is just inert ingredients?

How many lbs or ton of MAP was mixed and lbs or ton of P was mixed to get my mix?

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Don Smith
Posted 4/6/2012 08:38 (#2323545 - in reply to #2323489)
Subject: Re: Fertilizer Math



Centre county Pennsylvania, USA
Yes, that extra 39% is "inert material".... that you will have to carry with your planter. It's like the water "inert material" that you carry with your planter when you use liquid fertilizer. In both cases is extra weight with no extra fertilizer value.

When you order dry blend as tons of Urea, MAP, and Potash there will be no "inert material" for your planter to carry.

To do the math for ordering mix as tons of Urea, MAP, and Potash start with the Potash. compute pounds of Potash required to provide all of the K (or K2O) in your mix. Next, compute pounds of MAP required to provide all of the P (or P2O5) required in your mix. Then compute pounds of N that is in that MAP. Finally, compute pounds of Urea to provide the remaining pounds of N required in your mix.
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redwngr
Posted 4/6/2012 09:27 (#2323611 - in reply to #2323489)
Subject: Re: Fertilizer Math


SW Ont
Simplify your question by considering only one of the products. The potash is 0-0-60. (60% K or 60 lbs k per 100 lbs product). You must apply 100 lbs of 'weigh-able' product to get 60 pounds of K and the balance is inert. In your blend, you want 80 lbs/acre actual so you need to apply 133 lbs of product. (80/.6 = 133 or 133total product x .60 product per unit = 80lb actual). The same logic applies to the other products. Then add up the total anount of each product (133 potash + xxMap +... = 239total to be applied)
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musicman44
Posted 4/6/2012 09:32 (#2323618 - in reply to #2323489)
Subject: Re: Fertilizer Math


You bring up an important point- "inert materials". The potash at 62% is mostly potassium, but brings along with it a whole bunch of chloride as part of the other 38%.
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mennoboy
Posted 4/6/2012 10:06 (#2323678 - in reply to #2323315)
Subject: RE: Fertilizer Math


Rivers, MB

Don Smith has it right. Lots of inert material.

You probably asked for a blend that had 50 lbs of actual P and 80 lbs of actual K. The 10.6 lb comes as a bonus because phosphate has some N in it.

To calculate the blend, you need to remember that 11-52-0 means that 11% of phosphate is N, 52% is phosphorus and that 0-0-60-0 is 60% K.

So to get 50lbs of actual P, you need 50 / 0.52 = 96 lb/ac of 11-52-0 which also gives you 10.6 lb of N (96 lb/ac x 11%)

To get 80 lbs of actual K, you need 80 / 0.60 = 133 lb/ac of 0-0-60.

Therefore your blend has 96 lb/ac of 11-52-0 plus 133 lb/ac of 0-0-60 which totals 229 lb/ac.


To calculate the % analysis the way the retailer showed it as 4.6-21.8-34.9 :


N - 10.6/229 = 4.6% of the total blend weight is Nitrogen

P - 50/229 = 21.8% of the total blend weight is Phosphorus

K - 80/229 = 34.9% of the total blend weight is Potassium   



As a general rule of thumb, you calculate the phosphate, potash, and sulfur needs first and do the N last because both phosphate and sulfur both have Nitrogen components in them that contribute to the N requirements.


Hope that simplifies the fertilizer mystery.               

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paul the original
Posted 4/6/2012 10:41 (#2323718 - in reply to #2323350)
Subject: Re: Fertilizer Math


southern MN
I wish sometimes the computer would break that spits out these blend batch sheets and the dealer would have to figure out on paper how to calculate a blend. it is really easy once you get the hang of whats going on. but at first glance it is quite confusing.


Was sitting in the dealer's office last December 29th or so, and they had switched from map to dap, or the other way around, I forget - and the software wasn't switched to handle that. So yes, he was sitting there for an hour figuring out each field converting by hand.

Wasn't as much fun as you'd think. ;) Felt like buying him a beer after that....

--->Paul
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paul the original
Posted 4/6/2012 10:47 (#2323724 - in reply to #2323398)
Subject: Re: Fertilizer Math


southern MN
Years ago I was having the truck loaded, a car drove up with a State of MN sticker on the door, hopped out with a can on a long stick, took a sample of what was falling out the leg onto the truck (was a low open-back grain truck, he liked sampling from the ground!) and said he was the state inspector, did I want a copy of the results as well? I said sure. He got the paperwork from the fertilizer office as to what was being sold, and a couple weeks later I got a letter from them, the blend was within a few 100th's of what it was called. I was actually impressed it would get that close.

--->Paul
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novaman
Posted 4/6/2012 11:25 (#2323765 - in reply to #2323489)
Subject: Re: Fertilizer Math


ND
Keep in mind that phosphorus is expressed as P2O5 on the analysis and potassium as K2O. So you actually have about 55% of the 50 pounds of phosphate as actual P and about 82% of the 80 pounds of potash as actual K.
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twraska
Posted 4/6/2012 21:44 (#2324384 - in reply to #2323718)
Subject: Re: Fertilizer Math


Wallis, TX
paul the original - 4/6/2012 10:41

I wish sometimes the computer would break that spits out these blend batch sheets and the dealer would have to figure out on paper how to calculate a blend. it is really easy once you get the hang of whats going on. but at first glance it is quite confusing.


Was sitting in the dealer's office last December 29th or so, and they had switched from map to dap, or the other way around, I forget - and the software wasn't switched to handle that. So yes, he was sitting there for an hour figuring out each field converting by hand.

Wasn't as much fun as you'd think. ;) Felt like buying him a beer after that....

--->Paul


An hour per field???????? He should have been in the fertilizer business back before computers, I can do one in less than 5 minutes, even quicker if you let me use a calculator.
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JK SCLA
Posted 4/6/2012 21:58 (#2324425 - in reply to #2323315)
Subject: Re: Fertilizer Math


I am amazed at the people selling fert that DO NOT have a clue how to manually figure fertilizer for blending and analysis, or it takes them more than 5 min to work out a mulitple input blend.
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grgsrvc
Posted 4/6/2012 23:07 (#2324589 - in reply to #2324425)
Subject: Re: Fertilizer Math


Barley Belt west of the fifth Meridian
JK SCLA - 4/6/2012 19:58

I am amazed at the people selling fert that DO NOT have a clue how to manually figure fertilizer for blending and analysis, or it takes them more than 5 min to work out a mulitple input blend.


amen to that...

As to the guy trying to work with map and changing to dap whats the analysis of the two phosphates? Up here in Alberta I have only ever dealt with 11-52-0
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Brandon SWIA
Posted 4/7/2012 08:42 (#2324912 - in reply to #2324589)
Subject: Re: Fertilizer Math


DAP is 18-46-0
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trapperjon
Posted 4/7/2012 09:07 (#2324948 - in reply to #2323315)
Subject: Re: Fertilizer Math


east central iowa
I have had my fertilizer analyzed I and I would STRONGLY recommend sending in a sample to be analyzed. That's all I'm going to say.
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School Of Hard Knock
Posted 4/7/2012 09:21 (#2324967 - in reply to #2323724)
Subject: Re: Fertilizer Math


just a tish NE of central ND
paul the original - 4/6/2012 09:47

Years ago I was having the truck loaded, a car drove up with a State of MN sticker on the door, hopped out with a can on a long stick, took a sample of what was falling out the leg onto the truck (was a low open-back grain truck, he liked sampling from the ground!) and said he was the state inspector, did I want a copy of the results as well? I said sure. He got the paperwork from the fertilizer office as to what was being sold, and a couple weeks later I got a letter from them, the blend was within a few 100th's of what it was called. I was actually impressed it would get that close.

--->Paul

I don't know if they are still doing it in our state, but due to the loss of so many dairy producers (no dairy's left for them to inspect)they gave the fertilizer inspection responsibilities to some of the state employed milk inspectors that didn't have enough to do.Surprisingly, the blends come out pretty close from the one I saw.
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lawfarms
Posted 4/7/2012 21:58 (#2325825 - in reply to #2323678)
Subject: RE: Fertilizer Math



King City, Mo
Thank you, i'm going to print this off and work out my blend by hand (w/ help of calculator) and see if i come up with the right answer.

It just makes me feel better knowing more about something that i spend so much money on each year. Last year was my first year buying mixed fertilizer wholesale and hauling it home in my semi. It may be me micro managing it but i fell better learning more about it.
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benerdman
Posted 4/8/2012 19:36 (#2327068 - in reply to #2323315)
Subject: Re: Fertilizer Math


Marcus, Iowa
want got need rule of thumb....
What you want/what u got=What u need
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