# How much rain on urea



## rjmoses

So, for years, I've always tried to spread my urea for grass hay just before a rain because of volatility. Put mine out Thursday; got .2 inches yesterday.

This got me to thinking: Just how much rain is necessary to get the urea in the ground and what percentage will be lost to volatility at what rain levels? How much dispersion, penetration, depth for what rain?

Has anybody tripped across anything about urea and rainfall studies?

Ralph

One of these days, I'm going to quit thinking--but not today--and tomorrow doesn't look good either.


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## TJ Hendren

Take this for what it's worth Ralph, I've always heard a 1/4 inch of ran or you till it in you can loose up to 35% of it.


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## Vol

I remember reading that .25" was enough to get Urea to leach into the soil. I spread some fert yesterday too, but so far I have received only .04" .

Regards, Mike


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## endrow

We live 10 miles from several fertilizer blend plants . a Any urea we use gets Agritain sprayed on it that extends the window to 15 days before volatilization begins.


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## rjmoses

endrow said:


> We live 10 miles from several fertilizer blend plants . a Any urea we use gets Agritain sprayed on it that extends the window to 15 days before volatilization begins.


I always treat with Agrotain as well.

I was told that untreated urea evaporates about 20% per day; treated, about 10% per day.

I'm working pretty much off of hearsay, but this all has got me to wondering what the actual numbers are and if there have been any studies done on this issue.

The stuff I spread Thursday is no longer visible. Now I'm wondering where it went.

Ralph


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## mlappin

Always liked at least a quarter inch after spreading Urea. Even spread in the rain a few times.

When we still worked ground we wouldn't spread anymore than could be worked in a day.


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## vhaby

In my experience with hand-applied urea to small plots, 0.2" dissolves the prills and moves the urea into sandy soil. If it was less than 12 hours from the time of application until the rain came, you didn't lose much N as ammonia.

Keep on thinking...


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## IH 1586

Here is my response from Doug Beegle from last year.

I went to one of your soil classes this spring and with the information I received was going to order my urea with the treatment to protect it from volatilization. Due to time constraints I ordered on Mon. knowing there would be no chance of rain until Wed.. Growmark talked me out of spending the extra $85/tn to use the treated urea citing these reasons. Cooler temps and heavy dews. Weather was sunny and upper 60's for Mon. Tues. and getting a light rain now. Was I wrong to ignore your advise? Thank you for taking the time to read this.

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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## rjmoses

IH 1586 said:


> Here is my response from Doug Beegle from last year.
> 
> 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


That's the kind of info I was looking for.

Thanks

Ralph


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