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/

Chapters

• 0:00 Opening And Big Question
• 0:30 Dry Fertilizer Basics And Analysis
• 1:38 Why Liquids Are Tricky: Density
• 2:53 Where To Find Pounds Per Gallon
• 3:52 Step‑By‑Step Nitrogen Calculation
• 4:24 Starter Fertilizer Impacts In Cold Springs
• 5:04 Phosphorus Example: 10‑34‑0 Vs 6‑24‑6
• 6:08 Humor, Recap, And Key Takeaway

Transcript

Jodi and Sarah: 0:00

And now it's time for a tiny byte of knowledge. Hey Sarah. Why is it so easy to figure out how many pounds of nitrogen are in a dry fertilizer like urea? But it's really hard to figure out how many pounds of nitrogen are in something like 28%. Yeah, Jodi, that is a great question. And actually, I've spent a lot of time on a phone with crop consultants, agronomists, and farmers going through and explaining how to figure out how many pounds of nutrient is in a gallon or a certain rate of liquid fertilizer. It always seems like the liquid fertilizer calculations kind of trip us up a little bit. And it's because different liquid fertilizers have different densities. So let's back up. Let's talk for a second about that dry fertilizer concept that you just put forward, right? So a pound is a pound is a pound. We're not talking about volume in any way, shape, or form. We're talking about so many pounds of, for example, urea. Urea is only 46% nitrogen. So in a hundred pounds of urea, you're only gonna get 46 pounds of nitrogen. And that's because the analysis for urea is 4600. It means that it's 46% nitrogen. Okay, when you take a look at a liquid product, like 28%, it is 28% nitrogen, but you have to think about how much that liquid weighs. And different liquid products have different densities, they weigh different amounts for that one gallon volume. So, for example, and just to help you understand the magnitude of difference, 28% weighs 10.67 pounds per gallon, 10340, another very common liquid fertilizer, weighs 11.67 pounds per gallon. 6246, another common liquid fertilizer, 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? What does Bush Light weigh? I'm afraid that if I say it, I will offend some people. It's about 8.33 pounds per gallon. So that's how that's how that particular product is weighing up. Anywho, here we are talking about different weights of products. So when you are talking about figuring out how much nutrient is in a certain amount of liquid fertilizer that you're putting down, you always have to take into account that density of that product, how much that that liquid fertilizer weighs per gallon. You just told us some numbers. Is there another place that we can find this density information about these liquid products that we're planning to apply? Absolutely. The number one place, and this is always the recommendation that I give to farmers and agronomists, if you need to know how much a product weighs per gallon, look on the label. That's some of the information that's always contained in the label. If you're selling a fertilizer product, you have to display how much the percent that nutrient is in there on the fertilizer label. And below that analysis, you're going to be able to find how much that product weighs in pounds per gallon. Beautiful. That's helpful. So if you want to figure out, for example, how many pounds of nitrogen is in 10 gallons of 28%. 28% weighs 10.67 pounds per gallon. You multiply that by your rate, 10 gallons. And then you div you divide that by 0.28 because it's 28%. It's 30 pounds of nitrogen. And this makes a big difference. Up here in the great northern plains, we use a lot of starter fertilizers on many of our crops, like sugar beets and corn. And it's a big deal. And and we've got a lot of different liquid products out there to accomplish that goal. They have different analyses and they've got different amounts of uh or they have different densities. And both the density and the analysis affects how much, for example, phosphorus you're going to put down. So 10340 weighs 11.67 pounds per gallon. 6246 weighs 11.1 pounds per gallon. If you apply both of those products at five gallons to the acre, you're going to get very different amounts of phosphorus going down. 10340 at five gallons is going to give you 20 pounds of phosphorus, and 624.6 is going to give you 13.3 pounds of phosphorus at five gallons. So very different amounts of nutrient getting applied with those liquid fertilizers. Ooh, that's such a great example, Sarah. That's a big difference when we're thinking about starter fertilizer and making sure we've got enough for our plants when they're dealing with the cold springs of the northern Great Plains. Absolutely. So the take-home message, while everybody is probably getting annoyed with listening to the amount of numbers that are getting tossed around on this podcast, and it might not make for the most entertaining listening entertainment ever. Guess what? You still get to listen to Jody and I banter back and forth. And are you going to sing on this one, Zoro? I don't even know how to make those numbers sound fun and in uh different different pitches. If anybody has a density song that they want to recommend to us, our emails are open or the website's open. So, anyways, take home message. The take-home message is when you are trying to figure out the amount of nutrient that's getting applied with liquid fertilizer, make sure you take into account the density of that liquid product. Tune in next time for a Tiny Byte of knowledge from GK Technology, where we have a map and an app for that.