Nitrogen loss to air

[Maddog66]

I’m sure this has been discussed before but, because of my job, I keep coming back to it.

Assumption : That I start to lose nitrogen the moment I spread fertilizer and will continue to lose it to the atmosphere until water washes it into the soil. Nitrogen evaporates.

Since I happen to know more than a little about plastic packaging and materials / processes used to make it, we might have a problem

Fertilizer is packaged in a plastic bag comprised of blends of very tough types of polyethylene resins (Lldpe, Mdpe mostly) to provide a CHEAP, high puncture resistance package with strong seals that won’t fail when bags are handled. Each package is needle-perforated as a means of allowing air OUT for easier stacking on pallets when they are filled and sealed at high speed.

The OTR (oxygen transmission rate - cc/m*2/ 24 hours) of all Polyethylene materials is known in the industry as an oxygen sieve……which means very low barrier to most gasses.

So what we have in fertilizer bags is a packaging material with low barrier to gasses, that is punched full of holes……containing a material that evaporates into the atmosphere.

It seems to me that the older the fertilizer the lower the nitrogen content. Anybody know if this is true?

 

[Turkey Creek]

Above my pay grade, but ...... I have also wondered about an open bag of fertilizer that is stored. Is the Nitrogen level greatly reduced by the time you use it next year? Though I do know that some Nitrogen sources are more volatile than others.

 

[SD51555]

I haven’t used nitrogen on my place in five years. But if a person must, try to get ammonium sulfate. No atmospheric loss with AMS, and you get a nice shot of sulfate sulfur with it. Just be sure to add pound for pound lime with it to maintain pH.


Sent from my iPhone using Tapatalk

 

[FarmerDan]

Nitrogen fertilizers come in many chemical forms; urea, ammonium nitrate, ammonium sulfate, anhydrous ammonia, and several others. Anhydrous is a different animal existing only in a gaseous form. Multiple nutrient fertilizers are either blends of different sources or are what is know as ammoniated fertilizers. I would contented urea is the only N source of concern.

More years ago than I would care to consider I managed ag centers where we blended fertilizers, urea being one of the main components. Memory is a funny thing. As I remember it, we kept bins full of urea, maybe 250 - 500 tons total, all stored under roof in a closed sided building. We were told to tarp the top of the urea and we did not. Shrinkage comes in many ways, but I think urea shrinkage was no worse that the other fertilizers. In this case humidity would have been the precipitating factor. Research indicates it has to be 70% or greater for the transformation from solid to gas to occur. So, I guess loss could occur but it seems to not have been an economic issue.

Put the urea in a plastic bag and I would think the potential loss would be further reduced. Cool dry environments for storage would be best.

Good question, but uneventful in my opinion.

 

[Maddog66]

Uneventful for sure. I work in the meat packing side of plastics so I only know that, and the materials. Certainly not fertilizer packaging….unless it’s in the advanced form of chops, steaks, and burgers.

I didn’t know about the 70% humidity thing and I also incorrectly thought that ANY N-component in commercial granular fertilizers was subject to atmospheric loss. thx for that all.

Having so much to learn……this is truly part of the fun for me. Maybe the biggest part.

 

[Jerry-B-WI]

Nitrogen fertilizers come in many chemical forms; urea, ammonium nitrate, ammonium sulfate, anhydrous ammonia, and several others. Anhydrous is a different animal existing only in a gaseous form. Multiple nutrient fertilizers are either blends of different sources or are what is know as ammoniated fertilizers. I would contented urea is the only N source of concern.

More years ago than I would care to consider I managed ag centers where we blended fertilizers, urea being one of the main components. Memory is a funny thing. As I remember it, we kept bins full of urea, maybe 250 - 500 tons total, all stored under roof in a closed sided building. We were told to tarp the top of the urea and we did not. Shrinkage comes in many ways, but I think urea shrinkage was no worse that the other fertilizers. In this case humidity would have been the precipitating factor. Research indicates it has to be 70% or greater for the transformation from solid to gas to occur. So, I guess loss could occur but it seems to not have been an economic issue.

Put the urea in a plastic bag and I would think the potential loss would be further reduced. Cool dry environments for storage would be best.

Good question, but uneventful in my opinion.

I'm pretty sure anhydrous ammonia is in liquid form, and turns to a vapor after it's injected in the ground. The cloud you see while it's being injected is from the temperature and the fact that the ammonia is sucking any moisture out of the air. I used to work with anhydrous ammonia right out of the railroad tank car and mix with water to make aqueous ammonia. It's not the type of stuff you want to mess with. You can get burned three ways, chemical, thermal and it'll suck the moisture right out of your skin.

 

[FarmerDan]

I'm pretty sure anhydrous ammonia is in liquid form, and turns to a vapor after it's injected in the ground. The cloud you see while it's being injected is from the temperature and the fact that the ammonia is sucking any moisture out of the air. I used to work with anhydrous ammonia right out of the railroad tank car and mix with water to make aqueous ammonia. It's not the type of stuff you want to mess with. You can get burned three ways, chemical, thermal and it'll suck the moisture right out of your skin.

You’re right.

 

[Wild Thing]

This question does come up a lot and I know there is always concern when someone broadcasts Urea into their plot and then the forecasted rain fails to appear as forecasted. It has probably happened to all of us at one time or another. We all wonder how quickly the Urea will evaporate unless we get some rain soon. Nice to know that we really don't need to worry too much about it unless the humidity exceeds 70%. Thank you Farmer Dan for sharing that.

One other thing I have noted.... I always tried to wait until the forecast was for 1/2" of rain before top-dressing Urea. I was disappointed one year when we only got 1/4" of rain instead of the 1/2" which was forecasted. I went out and checked and found that the majority of the Urea had, in fact, dissolved with only 1/4" of rain, although I could still see some small crystals here and there.

 

[FarmerDan]

This question does come up a lot and I know there is always concern when someone broadcasts Urea into their plot and then the forecasted rain fails to appear as forecasted. It has probably happened to all of us at one time or another. We all wonder how quickly the Urea will evaporate unless we get some rain soon. Nice to know that we really don't need to worry too much about it unless the humidity exceeds 70%. Thank you Farmer Dan for sharing that.

One other thing I have noted.... I always tried to wait until the forecast was for 1/2" of rain before top-dressing Urea. I was disappointed one year when we only got 1/4" of rain instead of the 1/2" which was forecasted. I went out and checked and found that the majority of the Urea had, in fact, dissolved with only 1/4" of rain, although I could still see some small crystals here and there.

Let's revisit this subject. The original question, I think, was about N loss while it's in storage. The 70% humidity number is the one I remember about urea stored in bulk in a roofed and covered building. I suspect bagged urea stored in the same facility would suffer little loss at any humidity.

Urea, when broadcast to supply N to plants faces many more loss factors when left on the surface. Urea incorporated into the soil by tillage, irrigation, or rainfall assures the smallest possible loss. On the surface soil temperature, soil pH, surface organic residue, humidity, and air temperature combine to elevate urea volatilization to varying degrees. There's lots of research on the subject. Here's where straight line thinking about science fails in practical application. Your experience will probably be different because your circumstances will be different. Science guides us. Science over many experimental replications says the noted and discovered maximum loss might be 50% under the most tragic circumstances, Most of us stop there and assume the worst. I look for typical maximum losses and I see 20% - 25% under situations where such an application might be useful.

Will you? I doubt it. Yes it might be 10% - 15% or it might be zero.

Personally, at a practical level I think the discussion of urea N loss is way over thought. I'll leave you with this from the article linked below:

"Because of all the interacting factors, it's impossible to predict exactly how much nitrogen will be lost when urea is applied to the soil surface. Soil temperature, soil pH, soil texture, soil moisture, the amount of time between application and a significant rain and, of course, the amount of residue, all play a role.

https://www.agriculture.com/crops/fertilizers/how-to-handle-urea_174-ar2055

 

[Wild Thing]

Let's revisit this subject. The original question, I think, was about N loss while it's in storage. The 70% humidity number is the one I remember about urea stored in bulk in a roofed and covered building. I suspect bagged urea stored in the same facility would suffer little loss at any humidity.

Urea, when broadcast to supply N to plants faces many more loss factors when left on the surface. Urea incorporated into the soil by tillage, irrigation, or rainfall assures the smallest possible loss. On the surface soil temperature, soil pH, surface organic residue, humidity, and air temperature combine to elevate urea volatilization to varying degrees. There's lots of research on the subject. Here's where straight line thinking about science fails in practical application. Your experience will probably be different because your circumstances will be different. Science guides us. Science over many experimental replications says the noted and discovered maximum loss might be 50% under the most tragic circumstances, Most of us stop there and assume the worst. I look for typical maximum losses and I see 20% - 25% under situations where such an application might be useful.

Will you? I doubt it. Yes it might be 10% - 15% or it might be zero.

Personally, at a practical level I think the discussion of urea N loss is way over thought. I'll leave you with this from the article linked below:

"Because of all the interacting factors, it's impossible to predict exactly how much nitrogen will be lost when urea is applied to the soil surface. Soil temperature, soil pH, soil texture, soil moisture, the amount of time between application and a significant rain and, of course, the amount of residue, all play a role.

https://www.agriculture.com/crops/fertilizers/how-to-handle-urea_174-ar2055

All good to know. Thanks again.

 

[Catscratch]

I think it also requires a temp over 90 for the nitrogen to volatize.

So I'm thinking an experiment needs to be performed. It's easy enough to measure weight and mass. If we knew the percentage of nitrogen per unit of fert then we could simply do a daily measurement of some fert that's been stored a couple of different environments to see how much volatation was happening. Easy peasy!

 

[Wild Thing]

I think it also requires a temp over 90 for the nitrogen to volatize.

So I'm thinking an experiment needs to be performed. It's easy enough to measure weight and mass. If we knew the percentage of nitrogen per unit of fert then we could simply do a daily measurement of some fert that's been stored a couple of different environments to see how much volatation was happening. Easy peasy!

May not be as easy as you think Catscratch. No doubt, the fertilizer will absorb some moisture, essentially adding weight to its mass so your weight measurement would be influenced by that issue.

I think i will just try to fertilize prior to a rain event and then not lose too much sleep over it even if I don’t get the forecasted rain.

Actually, I have not used any synthetic fertilizer for the past 2 years anyway so I know I am not going to lose sleep over it

 

[Brian662]

There is a thread that @SD51555 started about soil health and one of the first videos was about nitrogen destruction of the soil. Early in that video, it is stated that 70-90% of nitrogen applied to soils is lost through different forms of runoff, volatization, and other methods. I'm not sure of the science that backs up this claim, but it was shocking to see those numbers.

 

[FarmerDan]

Probably true. Synthetic N doesn't sit in the soil waiting for you. It leaches, turns to gas or gets absorbed by plants. I would say 100% disappears quickly. The objective is to maximize plant use and minimize any form of other (loss) use.

 

[Wild Thing]

There is a thread that @SD51555 started about soil health and one of the first videos was about nitrogen destruction of the soil. Early in that video, it is stated that 70-90% of nitrogen applied to soils is lost through different forms of runoff, volatization, and other methods. I'm not sure of the science that backs up this claim, but it was shocking to see those numbers.

Link??

 

[BobinCt]

When I top dress nitrogen to my brassicas like I did the other day just before a rain, I see a big difference two days later after a rain. Maybe it’s just in my head. My head has never been normal.

 

[Brian662]

Link??

Soil fundamentals library

There seems to be enough interest here to warrant a digital library of sorts. This is not my own, so if you've got some great lessons you've found out there, either video or written, please post them up here. I suspect many of us have seen a good bunch of them, but if you don't see it here...

habitat-talk.com

Third video in the first post.

 

[FarmerDan]

There is a thread that @SD51555 started about soil health and one of the first videos was about nitrogen destruction of the soil. Early in that video, it is stated that 70-90% of nitrogen applied to soils is lost through different forms of runoff, volatization, and other methods. I'm not sure of the science that backs up this claim, but it was shocking to see those numbers.

Soil fundamentals library

There seems to be enough interest here to warrant a digital library of sorts. This is not my own, so if you've got some great lessons you've found out there, either video or written, please post them up here. I suspect many of us have seen a good bunch of them, but if you don't see it here...

habitat-talk.com

Third video in the first post.

Interesting perspective. To be honest I don't believe I have ever thought about quantifying soil N losses. Much of the focus here has been on urea and it's volatile nature. I have infrequently mentioned leaching losses. While the linked video is informative and presents numerous stories for consideration the focus is on a generalized macro view. I would caution against using the loss metrics in your micro situation. I firmly believe you do much better.

 

[Wild Thing]

Soil fundamentals library

There seems to be enough interest here to warrant a digital library of sorts. This is not my own, so if you've got some great lessons you've found out there, either video or written, please post them up here. I suspect many of us have seen a good bunch of them, but if you don't see it here...

habitat-talk.com

Third video in the first post.

Thanks Brian

 

[Brian662]

Interesting perspective. To be honest I don't believe I have ever thought about quantifying soil N losses. Much of the focus here has been on urea and it's volatile nature. I have infrequently mentioned leaching losses. While the linked video is informative and presents numerous stories for consideration the focus is on a generalized macro view. I would caution against using the loss metrics in your micro situation. I firmly believe you do much better.

I hope so, I definitely don't plan to increase inputs by a few hundred percent to overcome potential losses.