Fertilizer percentages don't add up.

Just ordered some dry fertilizer to sprinkle on the seedings. Two tons of 19-19-19 at $983 a ton. Ouch.

I've never understood the percentages. Nitrogen - Phosphorous - Potassium, I get that.

The percentages never add up to 100%. 19 + 19 + 19 = 57%.

What's the rest? Inert rocks and dirt, I assume.

Why 19-19-19? Why not 33-33-33 and spread 2/3 as much? Why am I paying for inert rocks and dirt?

My guess is that the 19% represents a level that the processes to obtain those numbers is most efficient.
Maybe going from 19 to 33 is expotentially more expensive per ton.
Might could spread 2/3rds less but it would cost more per sq ft.

That is the max ACTUAL of the 3 elements that is possible in the mix. For example Muriate of potash is 0-0-60.
So to get 19 pounds of actual potash you need to spread 31.6 LB of Muriate of Potash. Similar for N and P each supplied by the sources like
Urea 46-0-0 about 46% N of the the total weight.

Have you completed a soil test? For example on my farm I have high levels of natural phosphorus. So putting more P on my ground is a waste of money. A soil test , free in many counties, can save you a lot of money.

Get a soil test first. I have had some corn ground that only required nitrogen, p and k were good . At the price of fertilizer the test will save you money.

The elements shown, N P and K, are combined with other molecules.


For example, potash, is 60 or 61 percent K20, the unit used for fertilizer purposes. However, the potash itself is KCl, part potassium, part
chloride.

You could likely buy pure straight K, but the refining process would cost more.

this is way oversimplefied, but hopefully helps a little bit.

Hay hay has it right just can not get pure so it takes some filler in there yes you are having to
spread more weight we ran a lot tripple 19 on corn ground for years. As others have noted in the
days of this high price stuff soil test makes sense . Your prices are pretty much in line with here
in Tennessee.

It would be extremely expensive to get pure of any of the 3 fertilizer products. Like, insanely expensive.

Most fertilizer is a blend of 4 major common products. these are cheap and easy to produce.

Urea
Map
Dap
Potash

Oh, also some ammonia combinations too, such as ammonia sulfate gives some sulfur which most areas need now that we dont have acid rain.

None of them is pure. Most are created with some sort of salt solution to extract the element we want. The final salt percent is low, but there is lots of other inert stuff left
in them.

This is very general and looking at granular fertilizer, whole lot of details to be more accurate I know.

It is very rare for a 19-19-19 to supply what exactly your crop needs. Its best to get a soil test, anyhow once every 4 years or so, and then feed the ground what is
lacking for the crop and yield you need. Some dirt is high in one thing, and to add more of it creates an imbalance that the plants dont take up the other products well
either. It has its place once you know where you are at, and if you are in lower yielding areas or crops. Usually tho you need a lot more of one product for a great crop,
and should do a custom blend to level your soil up into a good balance.

Its time for me to grind sample again, half the farm is due, and I think the other half is a couple years past due..... dang time passes......

Paul

Paul

You want a good understanding of soil,fertilizer,minerals,etc? Get a copy of Hands on Agronomy by Neal Kinsey,read it cover to cover.

Lets say for easy math all 3 fertilizers are 60 percent. 0 0 60.
60 0 0 and 0 60 0. When you mix and spread them together
you have 20 20 20.

Soil tests in our fields are a waste of time. Any given field can have up to seven different types of soil. Most have at least three, and they don't line up in nice rows so you'd really need GPS guided yield monitoring, along with GPS guided variable rate application. All that is cost-prohibitive on 80 acres.

The ground has not seen appreciable amounts of fertilizer in several years. I figure I can't go wrong 100lbs per acre of triple-19. It's probably not enough, in fact, but will be better than nothing. I expect the ground is lacking in everything.

By convention, the potassium is expressed as equivalent weight of K2O, and phosphorus as equivalent of p2o5. neither of these
substances is present in the fertilizer, because the potash is KCl and the phosphorus is some form of phosphate, either diammonium
phosphate or a phosphoric acid derivative.

Actually that is exactly the place variable rate pays off the best. I had the grid sample, and we spread with them gps grids for 4 years. For a time after that things were
leveled up good enough we went back to spreading more cheaply for another 4 years.

Really made a difference in the crops, even in the variable soils like you say the crop was much closer to even across the field. The sampling and the surcharge for the
gps spreading costs money; but actually saved on the fertilizer bill because they used what was needed on each 2.5 acres, not just put probably enough maybe too
much on each acre.

Anyhow, better crops and fertilizer bill stayed about the same even with the high tech, its not as bad as you think. When things are straightened out you can go back to
simple spreading for a time agsin.

Its nice to know what you have, where you are at.

Dont mean to preach, I know what you are saying, how you feel. I get it.

I typically put on 280 lbs an acre, should feed the corn and the following year bean crop. With the variable was from 140 to 320# I think an acre.......

Paul

(quoted from post at 22:29:47 07/27/22) Actually that is exactly the place variable rate pays off the best.

Click to expand...

No doubt, but the price of admission is too high for a small farmer. Sure you could hire it done but that eats up any "profit." May as well sell out to the BTO.