16.5 Calculating Nutrients in Liquid Fertilizer (Bulk Density!)

We unpack why liquid fertilizer math trips people up and discuss how to figure out how to determine pounds of fertilizer in a liquid fertilizer. We talk real examples and show how small liquid fertilizer densities can drastically affect starter outcomes, especially in cold soils.

In this Tiny Bytes, we talk

• the dry vs liquid mindset shift 
• how density changes gallons into pounds 
• where to find pounds per gallon on fertilizer labels 
• comparing phosphorus from 10-34-0 and 6-24-6 
• implications for starter fertilizer in cold springs 
• simple rules to avoid under or over application

Tune in next time for a Tiny Byte of knowledge from GK Technology, where we have a map and an app for that

https://gktechinc.com/

Episode Transcript

Jodi and Sarah (00:00):
And now it's time for a tiny byte of
knowledge.
Hey Sarah.
Why is it so easy to figure outhow many pounds of nitrogen are
in a dry fertilizer like urea?

(00:21):
But it's really hard to figureout how many pounds of nitrogen
are in something like 28%.
Yeah, Jodi, that is a greatquestion.
And actually, I've spent a lotof time on a phone with crop
consultants, agronomists, andfarmers going through and

(00:42):
explaining how to figure out howmany pounds of nutrient is in a
gallon or a certain rate ofliquid fertilizer.
It always seems like the liquidfertilizer calculations kind of
trip us up a little bit.
And it's because differentliquid fertilizers have
different densities.
So let's back up.

(01:02):
Let's talk for a second aboutthat dry fertilizer concept that
you just put forward, right?
So a pound is a pound is apound.
We're not talking about volumein any way, shape, or form.
We're talking about so manypounds of, for example, urea.
Urea is only 46% nitrogen.
So in a hundred pounds of urea,you're only gonna get 46 pounds

(01:28):
of nitrogen.
And that's because the analysisfor urea is 4600.
It means that it's 46%nitrogen.
Okay, when you take a look at aliquid product, like 28%, it is
28% nitrogen, but you have tothink about how much that liquid

(01:50):
weighs.
And different liquid productshave different densities, they
weigh different amounts for thatone gallon volume.
So, for example, and just tohelp you understand the
magnitude of difference, 28%weighs 10.67 pounds per gallon,
10340, another very commonliquid fertilizer, weighs 11.67

(02:15):
pounds per gallon.
6246, another common liquidfertilizer, at least in our
area, 11.1 pounds per gallon.
And water?
Do you know what water weighs,Jodi?
Is it 8.34 pounds per gallon?
Oh, gall dang.
You just know everything.
How about Bush Light?

(02:36):
What does Bush Light weigh?
I'm afraid that if I say it, Iwill offend some people.
It's about 8.33 pounds pergallon.
So that's how that's how thatparticular product is weighing
up.
Anywho, here we are talkingabout different weights of
products.
So when you are talking aboutfiguring out how much nutrient

(02:59):
is in a certain amount of liquidfertilizer that you're putting
down, you always have to takeinto account that density of
that product, how much that thatliquid fertilizer weighs per
gallon.
You just told us some numbers.
Is there another place that wecan find this density
information about these liquidproducts that we're planning to
apply?
Absolutely.

(03:19):
The number one place, and thisis always the recommendation
that I give to farmers andagronomists, if you need to know
how much a product weighs pergallon, look on the label.
That's some of the informationthat's always contained in the
label.
If you're selling a fertilizerproduct, you have to display how
much the percent that nutrientis in there on the fertilizer

(03:42):
label.
And below that analysis, you'regoing to be able to find how
much that product weighs inpounds per gallon.
Beautiful.
That's helpful.
So if you want to figure out,for example, how many pounds of
nitrogen is in 10 gallons of28%.
28% weighs 10.67 pounds pergallon.

(04:08):
You multiply that by your rate,10 gallons.
And then you div you dividethat by 0.28 because it's 28%.
It's 30 pounds of nitrogen.
And this makes a bigdifference.
Up here in the great northernplains, we use a lot of starter
fertilizers on many of ourcrops, like sugar beets and

(04:31):
corn.
And it's a big deal.
And and we've got a lot ofdifferent liquid products out
there to accomplish that goal.
They have different analysesand they've got different
amounts of uh or they havedifferent densities.
And both the density and theanalysis affects how much, for
example, phosphorus you're goingto put down.
So 10340 weighs 11.67 poundsper gallon.

(04:57):
6246 weighs 11.1 pounds pergallon.
If you apply both of thoseproducts at five gallons to the
acre, you're going to get verydifferent amounts of phosphorus
going down.
10340 at five gallons is goingto give you 20 pounds of

(05:17):
phosphorus, and 624.6 is goingto give you 13.3 pounds of
phosphorus at five gallons.
So very different amounts ofnutrient getting applied with
those liquid fertilizers.
Ooh, that's such a greatexample, Sarah.
That's a big difference whenwe're thinking about starter
fertilizer and making sure we'vegot enough for our plants when

(05:41):
they're dealing with the coldsprings of the northern Great
Plains.
Absolutely.
So the take-home message, whileeverybody is probably getting
annoyed with listening to theamount of numbers that are
getting tossed around on thispodcast, and it might not make
for the most entertaininglistening entertainment ever.

(06:02):
Guess what?
You still get to listen to Jodyand I banter back and forth.
And are you going to sing onthis one, Zoro?
I don't even know how to makethose numbers sound fun and in
uh different different pitches.
If anybody has a density songthat they want to recommend to
us, our emails are open or thewebsite's open.

(06:24):
So, anyways, take home message.
The take-home message is whenyou are trying to figure out the
amount of nutrient that'sgetting applied with liquid
fertilizer, make sure you takeinto account the density of that
liquid product.
Tune in next time for a TinyByte of knowledge from GK

(06:47):
Technology, where we have a mapand an app for that.