# Why don't most soil tests have a number for Nitrogen?



## Jacobpaschall (Nov 1, 2020)

I had some soil tests done by Clemson University last year. They did not provide a value for (N) nitrogen. I looked at many soil tests on the forum and noticed the same thing. Why don't they give a value for nitrogen?


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## SCGrassMan (Dec 17, 2017)

S3M from Waypoint Analytical. They'll even tell you what variety to put out and how much of it.


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## Ridgerunner (May 16, 2017)

Because values for N (especially nitrate as well as values for other soluble nutrients-e.g. Boron and Sulfur) can change quite rapidly due to plant use, leaching, etc. By the time you sample, mail and receive the results, the levels could change significantly making the reported results rather useless for purposes of calculating amendment adjustments.


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## lawnphix (Apr 13, 2019)

For cool season lawns, most all of the nitrogen gets used up by the end of the growing season. When spring rolls around, the soil is generally deficient and an application of N is required regardless. The exception to this is when organic matter levels are very high, and in cases of over-fertilization.


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## corneliani (Apr 2, 2019)

Ridgerunner said:


> Because values for N (especially nitrate as well as values for other soluble nutrients-e.g. Boron and Sulfur) can change quite rapidly due to plant use, leaching, etc. By the time you sample, mail and receive the results, the levels could change significantly making the reported results rather useless for purposes of calculating amendment adjustments.


Begs the question... why do labs even bother extracting & reporting the nitrogen values? Would it ever be so abundant in the soil that it would affect our nitrogen apps? I can't imagine it ever affecting me, at least not for my lawn. Maybe on the gardening side (?)


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## Ridgerunner (May 16, 2017)

corneliani said:


> Ridgerunner said:
> 
> 
> > Because values for N (especially nitrate as well as values for other soluble nutrients-e.g. Boron and Sulfur) can change quite rapidly due to plant use, leaching, etc. By the time you sample, mail and receive the results, the levels could change significantly making the reported results rather useless for purposes of calculating amendment adjustments.
> ...


Yes, there is a condition known as nitrogen toxicity. The science surrounding N levels is still developing. Studies have found a number of of N conditions can result in poor turf performance. N levels that exceed 40 ppm, when NO3:NH4 levels fall below 3:1 or when ammonium levels exceed 7ppm have been found to be related to poor turf performance. As with all things soil/turf related, these aren't bright red lines as a number of factors can be involved (OM levels, Microbial activity, Soil Oxygen levels, etc., etc.) and the impact of adverse outcomes are more of a continuum than a hard line.


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## Jacobpaschall (Nov 1, 2020)

I just submitted another soil test to Clemson University today. I noticed that you can select a nitrogen test for an additional $5 so I checked the box. That brings each sample to $11. It's the cheapest I've seen so far. I'm mainly concerned about having too much nitrogen. I applied UN32 multiple times while my prg was growing over the fall and winter. I killed the prg and scalped a couple weeks ago and the bermuda isn't coming back yet. I want to make sure there's not already too much N before I apply more to give the bermuda a boost.


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## RichS (Jan 28, 2019)

SCGrassMan said:


> S3M from Waypoint Analytical. They'll even tell you what variety to put out and how much of it.


Waypoint gives a N recommendation, but I believe it's based on the standard N needs for the type of grass (always 4lbs/k on my reports), not any N analysis. The specific type is based on other needs. I'm low on S, so they recommend Ammonium Sulfate, for example. Ammonium Nitrate, Urea, and other N sources would probably be recommended based on other finding of other elements, but I suspect the N recommendation would always be 4lbs/K.


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