# Slow-release versus Stabilized Nitrogen?



## Green (Dec 24, 2017)

How does urea Nitrogen stabilized with N-(n-butyl) thiophosphoric triamide compare to coated urea in terms of performance?

Also, when you use polymer coated urea, what happens to the capsules after the N comes out? Do they stay on top of the soil forever, or break down?


----------



## Mightyquinn (Jan 31, 2017)

From my research I have done so far, you should be able to get similar results from stabilized nitrogen that you would get from coated urea. If you have ever heard of UMAXX or UFLEXX, they both utilize a nitrogen stabilizer which basically keeps it in the soil longer than just straight Urea all by itself. Stabilized nitrogen is NOT the same as slow release even though it's very similar as it uses a different mode of action.

I believe that the polymer coating just breaks down over time and dissolves into the soil which is how it releases the nitrogen.


----------



## Green (Dec 24, 2017)

Mightyquinn said:


> From my research I have done so far, you should be able to get similar results from stabilized nitrogen that you would get from coated urea.


Are there certain soil or weather conditions that cause the stabilized N to last longer like slow release N, versus getting used all at once like fast-release N?


----------



## Mightyquinn (Jan 31, 2017)

Green said:


> Mightyquinn said:
> 
> 
> > From my research I have done so far, you should be able to get similar results from stabilized nitrogen that you would get from coated urea.
> ...


Yes there is. Here is the label from the one I'm going to be using this year.


----------



## Green (Dec 24, 2017)

I've read as much as I can. It's still not clear to me if something like UMAXX can truly be used in place of coated urea to get the same extended feeding.


----------



## Mightyquinn (Jan 31, 2017)

Green said:


> I've read as much as I can. It's still not clear to me if something like UMAXX can truly be used in place of coated urea to get the same extended feeding.


I think it may depend on your soil make up and growing conditions but I'll try this weekend to see what I can find on what I found. Just like everything else when it comes to lawns, what works well for one person may not work as well for you.


----------



## Powhatan (Dec 15, 2017)

Mightyquinn said:


>


I normally let rainfall do my irrigation duties, so I'm curious about this water amount that's in the instructions.

Is the *".8 inches of rain or irrigation are required to move urea into the soil"* for this stabilizer product, is that considered an above average water application amount than if fertilizer product instructions just say to "water in"?


----------



## Mightyquinn (Jan 31, 2017)

Powhatan said:


> Mightyquinn said:
> 
> 
> >
> ...


I saw that too but I'm not too concerned about it as I think that is a general recommendation and all my other reading on the subject never mentioned it.


----------



## Mightyquinn (Jan 31, 2017)

Here are a few links to read. Let me know if you have read them already.

UFLEXX

Penn State

Grounds Maintenance


----------



## Mightyquinn (Jan 31, 2017)

The GrassFactor summed it up pretty good here. :thumbup:

[media]https://www.youtube.com/watch?v=J-M4Zeyl0gs[/media]


----------



## Jconnelly6b (Mar 4, 2018)

GrassFactor nailed it


----------



## Green (Dec 24, 2017)

@thegrassfactor, thank you for making this video and including the comparison between the main subgroups of slow release Nitrogen fertilizer types, and comparing them to the Urease inhibition types. I definitely have a better understanding now.

For my use this Spring on grass planted last Fall, PCSCU is probably a better idea than UMAXX, and definitely better than PCU, because I want a stretched out response over time, instead of the fast dump from temp-sensitive PCU, or in-between/variable behavior using the inhibitor.

I also didn't realize that some of the urea-form types were the best for stable release over longer time, versus coated urea, but have been using them when I spoon-fed Scotts Turfbuilder last Fall, with excellent results.

I think I'll stay away from plain PCU because I don't like the idea of dumping out N all at once when a certain temp threshold is reached. I'm sure it's probably not truly that simple, but still doesn't sounds like the best method for cool-season grass.

Now to check out the links from @Mightyquinn .


----------



## Green (Dec 24, 2017)

Quick question...

Does anyone know whether temp-dependent PCU or (PCSCU) can last through the Winter if the ground is frozen, and release in the Spring?


----------



## thegrassfactor (Apr 12, 2017)

Green said:


> Quick question...
> 
> Does anyone know whether temp-dependent PCU or (PCSCU) can last through the Winter if the ground is frozen, and release in the Spring?


Yes it can, but so can quick release. I prefer quick release for this effect. The cold temps stabilize the nitrorogen. Also, in cold weather ammoniacal N sources are less soluble so they tend to hang around longer. I've spent a fortune with the whole PCU, PCSCU release in the spring idea, And nothing works as well as straight AMS.


----------



## Green (Dec 24, 2017)

thegrassfactor said:


> Yes it can, but so can quick release. I prefer quick release for this effect. The cold temps stabilize the nitrorogen. Also, in cold weather ammoniacal N sources are less soluble so they tend to hang around longer.


That's really interesting. I've suspected this might be the case, because it seems that Scotts Turfbuilder (which as you know, has both urea-form molecules and Ammonium Sulfate in addition to regular urea) seemed to produce a slightly more sustained early Spring greening effect when it was used as final winterizer around time of topgrowth cessation....versus regular 100% generic 46-0-0 urea used on a different part of the lawn at the same time in December. And these effects are noticeable with as little as 0.5 lb N/M application rates.

This past year, I used Scotts Greenmax (with even higher AS percentage) as my final app. It's really greening now...without much if any topgrowth just yet, as it's too cold still.

Conventional wisdom from studies said it was just the late Fall carbohydtrate storage producing this effect, but now I'm thinking there's more to it. Soil temps are around 40F currently.


----------



## Green (Dec 24, 2017)

So, while I was taking my soil samples today, I saw a few tiny white objects in the thatch layer that might or might not be the remnants of some of the methylene urea from my final fertilizer app last year in early December.


----------

