# Urea Degradation and Heat



## Hayman1 (Jul 6, 2013)

Does anyone on HT know how many hours it takes in the 90s to lose 150# of urea? Put on 65# N worth late yesterday with a for sure storm headed our way except it got lost and vaporized (the storm). It is noon now and about 90 with remnants of Barry due tonight from 7pm on. We had a heavy dew this morning-all the house screens were soaked. Just took a drive around and there is not a prill to be found in what I spread yesterday. Going to wait until 6 tonight to do the rest of the field. So, did the dew dissolve it or did it just volatilize away for full loss?


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## PaulN (Mar 4, 2014)

When I worked at a co-op back in the 1980's, we always told customers to have it worked in within 24 hours for minimal loss. It was implied that after 24 hours is when loss becomes significant. In your case, I'm almost certain it was the dew that dissolved the urea.

In recent years, I've been using Super Urea. It's treated with 2 different stabilizers, it's blue in color. Supposedly there is less evaporation and leeching. The bad news is that it costs $100/ton more.


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## Vol (Jul 5, 2009)

Ric, I read somewhere that the major volatilization begins to occur after 48 hours. Not sure where I read it, but remember it distinctly as I have been in your same situation. But, I also read that the loss of Urea is not as grand as some have made it out to be.....that it takes several days to suffer major losses. If you get rain this evening, I think that your volatilization will be very minimal.

Regards, Mike


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## rjmoses (Apr 4, 2010)

My understanding is, that without treatment of Agrotain or equivalent, you lose about 20% per day.

You said you had a heavy dew this AM. You might have gotten lucky to get much of the N in the ground. I'd look harder to see if the there was any solids left anyplace.

Ralph


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## IH 1586 (Oct 16, 2014)

Email when I asked a similar question couple years ago:

I don't know if you were right or wrong, but probably the most important factor determining whether it was right or wrong is how much rain you get and how soon after application. To minimize the N loss it would be best to get ½ in rain within 24 hours. Any significant rain ( >0.1in) within the first few days will help, but just a sprinkle enough to settle the dust or a heavy dew is actually worse, because that is enough moisture to dissolve the urea and start the reactions that lead to volatilization, but not enough to soak it in. Cooler weather also helps but that effect is greater below 50°. Windy weather like we had here this morning will usually increase the losses. Other factors that can influence the loss are surface soil moisture, there will be less loss on a very dry soil surface. Generally, heavier texture soils will have less loss. Finally, if the urea get down below the residue, that can reduce losses a little.

I hope this helps,

Doug

Douglas B. Beegle, Ph.D.

Distinguished Professor of Agronomy

Department of Plant Science

116 ASI Building

Penn State University

University Park, PA 16802


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## Hayman1 (Jul 6, 2013)

IH 1586 said:


> Email when I asked a similar question couple years ago:
> 
> I don't know if you were right or wrong, but probably the most important factor determining whether it was right or wrong is how much rain you get and how soon after application. To minimize the N loss it would be best to get ½ in rain within 24 hours. Any significant rain ( >0.1in) within the first few days will help, but just a sprinkle enough to settle the dust or a heavy dew is actually worse, because that is enough moisture to dissolve the urea and start the reactions that lead to volatilization, but not enough to soak it in. Cooler weather also helps but that effect is greater below 50°. Windy weather like we had here this morning will usually increase the losses. Other factors that can influence the loss are surface soil moisture, there will be less loss on a very dry soil surface. Generally, heavier texture soils will have less loss. Finally, if the urea get down below the residue, that can reduce losses a little.
> 
> ...


IH- that was my thinking exactly on the heavy dew. Just started getting front band of what is left of Barry. So we will know next week when I get back from the beach. Will get the rest on this evening in breaks in the rain.


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## rjmoses (Apr 4, 2010)

Fertilizing grass hay is a challenge!

I like urea because I can get a better, more evenly distributed, spread. I don't like it because of the volatility. And I ALWAYS treat with Agrotain, even when there's rain clouds on the horizon. Beside, I can't get it after June 1st.

I like knifing in 28% because it is in the soil. But, on 30" centers, I have to make two passes which increases crown damage, takes more time and is still too far apart.

I like ammonium sulfate because I can get my sulfur on at the same time. But, it's only available early on. And I don't need that much sulfur.

I like anhydrous ammonia because it goes deep in the ground and is relatively cheap. But those big knives leave ridges throughout the field and it takes time for the root system to reach it.

I like ammonium nitrate, but it isn't even stocked hereabouts any more.

But my preferred nitrogen source is snow. Doesn't cost anything, no work, goes directly in the ground, immediately available to the root system, adds moisture to soil--it's a winner. Now if I can just figure how to get it in July.

My next trial will be dribbling 28% from my sprayer. We'll see....

Ralph


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## IH 1586 (Oct 16, 2014)

I passed on treated urea last week with 80% chance of rain and luck was not with me. It finally got rained in yesterday. 6 days on the ground. Roll the dice


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## Hayjosh (Mar 24, 2016)

Similar to what's been mentioned, what my dad had told me was you need at least a quarter inch rain to really send the nitrogen into the ground, and dew is bad. I just fertilized earlier this week and opted for the treat urea. The cost increase was not significant but they said it gave you a window of protection from volatility for about 2 weeks. I'm glad I did because we didn't get the amount of rain the following day I was hoping we would, but look to be getting a nice shower today.


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## Hayman1 (Jul 6, 2013)

Well shucks, I didn’t need that 400$ anyway


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## stack em up (Mar 7, 2013)

Urea treated with Agrotain will not begin to volatize for 21 days I believe.


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## Hayman1 (Jul 6, 2013)

It also makes it slow release. I have witnessed that several times with my use of it if there isn't plenty of rain. It may just make it slow release regardless. Top dressed aug 1 several years ago. no rain in aug or sept to speak of. Then about oct 10, it started. Had the darnedest nitrogen bloom you ever saw late oct. Of course, you can't make dry hay here then.


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## hog987 (Apr 5, 2011)

I have experimented with melted urea this year as well as broadcasting test strips. Lets just say the broadcasting happened when hot and dry and cant see anything different. The melted urea that i sprayed on i can see great results. Every check strip left unsprayed i can see at a distance except one strip. But that one strip at a distance is just as tall as every thing else but when i get close and walk through it the check strip is a lot thinner.


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## Hayman1 (Jul 6, 2013)

Hog, is melted dissolved in water and sprayed on?


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## PaulN (Mar 4, 2014)

The first time I used super urea on corn was in 2014. That was a wet year with late plantings just like this year. My corn had a nice dark green color all season, when all the other corn fields in the neighborhood were turning yellow. I attribute that to the slow release of the treated urea.


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## hog987 (Apr 5, 2011)

Hayman1 said:


> Hog, is melted dissolved in water and sprayed on?


Yes
I put the urea in a tank, filled with water and put a sump pump in tank to stir things up for a few hours, fill sprayer and go.


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## Tim/South (Dec 12, 2011)

hog987 said:


> Yes
> I put the urea in a tank, filled with water and put a sump pump in tank to stir things up for a few hours, fill sprayer and go.


How many gallons per acre do you spray?


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## notmydaytoday (Sep 16, 2016)

hog987 said:


> Yes
> I put the urea in a tank, filled with water and put a sump pump in tank to stir things up for a few hours, fill sprayer and go.


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## notmydaytoday (Sep 16, 2016)

How much urea to how much water?


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## hog987 (Apr 5, 2011)

I was spraying 10 pounds actually N per acre at 10 gallons per acre. So mixing about 21-22 pounds product in 10 gallons water. When making the mixture the water gets ice cold. Spray it directly on, it doesn't burn, unless you stop the tractor while sprayer is still running.

Its actually a common practice is other parts of the world.


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## r82230 (Mar 1, 2016)

This is from Progressive forage. Mentions up to 40% loss, but more like 20%.

https://www.progressiveforage.com/forage-production/fertilizing/managing-urea-fertilizer-to-reduce-vaporization-losses

Larry


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