# Questioning Nitrogen Recommendations



## Grizzly Adam (May 5, 2017)

Does this recommendation chart make sense to anyone? If they are basing the rate off of a nitrogen test, why does it change according to the P (24-3-4 vs 24-4-4)? Nitrogen is still 24% of the mix... What am I missing here?


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## Mightyquinn (Jan 31, 2017)

Where and Who is recommending this?


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## Grizzly Adam (May 5, 2017)

It is from a soil testing kit.


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## Mightyquinn (Jan 31, 2017)

I'm not a huge fan of off the shelf soil testing kits as you are not 100% sure of what kind of lab they are getting their lab results from. You are better off going through your local state AG office or one of the more accredited private testing labs. As for the nitrogen, it's not something you should really be worrying about as it's one of the most consumable nutrients in the soil. The amount of Nitrogen you need to add to YOUR lawn will be different. Have you posted the whole soil test here for someone to interpret?


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## Grizzly Adam (May 5, 2017)

Quinn-- take a closer look at the original image. This is included in a DIY test kit, there are no lab results. It is telling you what fertilizers to use in what amount based on the nitrogen test you run yourself. Their math doesn't add up for me, and I am simply asking if the chart is screw or if I am missing something.


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## Lawn Whisperer (Feb 15, 2021)

They are just assuming the amount of P and K that the lawn will use. There is no way to tell the amount of P or K needed from a nitrogen test alone.

There is no math involved it just an assumption.

For every pound of nitrogen, ~1/4#P and 1/2#K will be used. If your mulching most of the P&K will go back into the soil.


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## Grizzly Adam (May 5, 2017)

Lawn Whisperer said:


> They are just assuming the amount of P and K that the lawn will use. There is no way to tell the amount of P or K needed from a nitrogen test alone.
> 
> There is no math involved it just an assumption.
> 
> For every pound of nitrogen, ~1/4#P and 1/2#K will be used. If your mulching most of the P&K will go back into the soil.


Yes, that much is obvious. Let me simplify this a little. My question is-- for the same nitrogen reading, why are they recommending 4lbs of one 24% nitrogen fertilizer, and 3.1 lbs of another 24% nitrogen fert?


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## bernstem (Jan 16, 2018)

Grizzly Adam said:


> Lawn Whisperer said:
> 
> 
> > They are just assuming the amount of P and K that the lawn will use. There is no way to tell the amount of P or K needed from a nitrogen test alone.
> ...


I can't really think of a reason other than carelessness - which should tell you something about the quality of the test itself.


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## Ridgerunner (May 16, 2017)

What you are missing is the time you lost trying to analyze an off the shelf gimmick.


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## Grizzly Adam (May 5, 2017)

Ridgerunner said:


> What you are missing is the time you lost trying to analyze an off the shelf gimmick.


No issue, this is how we have fun.


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## Ridgerunner (May 16, 2017)

:beer:


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