Stpuid NPK question of the day.

[SensiBC]

After more than a few years of blindly following others recipe's I'm finally trying to crack the NPK nut and figure out how these nutrient profiles work. It's one of the few things that's eluded me; partly because it's never really been explained to me in a way I understood, and partly because I guess I never really took the time to look into it further and learn.

So let's start out really basic. You've got a fert labeled 20:20:20. If you feed at half strength would that make it 10:10:10?

 

[HydroJen]

Have you played with the angelfire nutrient calculator?
http://www.angelfire.com/cantina/fourtwenty/articles/profiles.htm

It changed how I feed, for sure

 

[BudToker]

You may have made a typo. (you wrote 20:20:20 instead of 20-20-20, I believe.)

If you meant 20-20-20 and feed at half strength then yes it is equal to 10-10-10.

Both mixtures will have the same "ratio" of 1:1:1.

-BT

 

[Carl Carlson]

How to Read a Fertilizer Guaranteed Analysis Label

The diagram below shows the guaranteed analysis label that appears on the Greenview Fairway Formula Spring Fertilizer (26-4-12) bag label, and is typical of the labels that you will find on fertilizer bags. The nitrogen (N), available phosphate (P), and soluble potash (K), are the primary nutitional components to look for, and these are typically listed first, in (N-P-K) order, (26-4-12) in this example. Other nutrients and information generally follows.

Home / Learning Center / Topics / Fertilization / Guaranteed Analysis Label
How to Read a Fertilizer Guaranteed Analysis Label

The diagram below shows the guaranteed analysis label that appears on the Greenview Fairway Formula Spring Fertilizer (26-4-12) bag label, and is typical of the labels that you will find on fertilizer bags. The nitrogen (N), available phosphate (P), and soluble potash (K), are the primary nutitional components to look for, and these are typically listed first, in (N-P-K) order, (26-4-12) in this example. Other nutrients and information generally follows.

The parts of the diagram that are annotated provide you with the following information:

1. Total percentage nitrogen (N) in the bag.
2. Total percentage available phosphate (P) in the bag.
3. Total percentage soluble potash (K) in the bag.
4. Other nutrients, if any, will follow the soluble potash.
5. The total percentage of the bag that is slow release nitrogen (water insoluble and other water soluble nitrogen sources combined). Note: Choose a fertilizer with a high percentage of slow release nitrogen (the higher the better), to provide a controlled release of nutrients which will be better for your lawn and the environment.
6. Total percentage of fast release nitrogen (ammoniacal nitrogen and urea nitrogen).
7. Ammonical nitrogen and sulfur nutrients provide fast early green up.

For further information about the ingredients indicated on a guaranteed analysis label read about understanding fertilizer ingredients1.

 

[SensiBC]

You may have made a typo. (you wrote 20:20:20 instead of 20-20-20, I believe.)

I sure did, thanks for clearing that up because it could have taken the topic in the totally wrong direction!

Thanks for all of the info folks! I'll start reading up and hopefully I can make sense out of it all.

 

[s00thsayer]

After more than a few years of blindly following others recipe's I'm finally trying to crack the NPK nut and figure out how these nutrient profiles work. It's one of the few things that's eluded me; partly because it's never really been explained to me in a way I understood, and partly because I guess I never really took the time to look into it further and learn.

So let's start out really basic. You've got a fert labeled 20:20:20. If you feed at half strength would that make it 10:10:10?

It can be confusing. From what I understand....

If you have a 20-20-20 fertilizer it has 20% N, 20% P, 20% K, then the remainder of the solution (40%) is water and some trace minerals listed on the label.

The NPK percentages refer to the bottled concentrated nutrients, not the mixed fertilizer made following the instructions but your logic works regardless.

The NPK percentages are extremely low when mixed. There are 768 teaspoons in a gallon....if 1 t of 20-20-20 fertilizer is used in a gallon of water it would yield a 1/5 t N, 1/5 t P, 1/5 t, 2/5 t water solution and minerals, and 767 t of water. The mixed NPK would be 0.00026042-0.00026042-0.00026042

But basically you are correct in that using a 20-20-20 fertilizer mixed at half strength (say 1/4 t per gallon) would make the NPK comparable to a mixed 10-10-10 fertilizer (at 1/2 t per gallon)...it just doesn't make it a 10-10-10 fertilizer.

A 20-20-20 fertilizer mixed with an equal part of water would literally yield a 10-10-10 solution that could then be mixed following a 10-10-10 feeding regimen but halving the doses of a 20-20-20 fertilizer accomplishes the same thing.

 

[poipu79]

hey sensibc...just to give ys some more basics heres some greenhouse math on your 20-20-20...if you dilute at 1g per litre you get 200 ppm N ...200 x.44= 88ppm P...200 x .83=166ppm K just divide by 3.78 for a per semi gal result or 4.55 if imperial

...poipu