Can someone please explain nutrient calculations to me?

[TwoBirdStoned]

I've seen calculations for NPK done a few different ways and want to get the facts straight.

Nutrients:

Veg Nutrient: 9-3-6

Bloom Nutrients 3-12-6

Mag Pro - 2-15-4

Protekt 0-0-3

Where N = NH₄ and NO₃ , P = P₂0₅ , and K = K₂O

Is it as simple as averaging the numbers off the bottle? Example:

10ml Bloom (5 parts) , 2ml Mag-Pro (1 part) , 4ml Protekt (2part) = 8 parts total

N = (3x5)+(2x1)+(0x2) /8 = 2.13

P = (12x5)+(15x1)+(0x2) /8 = 9.38

K = (6x5)+(6x1)+(3x2) /8 = 4.5

N-P-K ratio of 1 - 4.4 - 2.11

Or do I need to find the real concentration by dividing the molecules?

Example: 12% P₂o₅ is found by multiplying 12 by 0.436 to get 5.23.

For K they say to multiple the percentage by 0.83 to get the real concentration of K.

For some reason I only see people doing this with the P (P₂O₅) and K (K₂O) values and not Nitrogen, why is that?

Carrying out this method I get the following result for real concentration values for each nutrient:

Veg Nutrients: 9 - 1.31 - 4.98
Bloom Nutrient: 3 - 5.23 - 4.98
Mag Pro actual: 2 - 6.54 - 3.32
Protekt actual: 0-0-2.49

Then I use the same method as above to average the mixture:

10ml Bloom (5 parts), 2ml Mag Pro (1 part), 4ml Protekt (2 parts) = 8 parts total

N = (3x5)+(2x1)+(0x2) /8 = 2.13

P = (5.23x5)+(6.54x1)+(0x2) /8 = 4.09

K = (4.98x5)+(3.32x1)+(2.49x2) /8 = 4.15

NPK ratio of 1 - 1.92 - 1.95

As you can see, I get two very different N-P-K ratios from each method. Are either of these correct?

 

[AKgramma]

i doubt that the average grower can understand, much less explain, all those numbers. Plants are not that complicated. Feed em, water em, keep em warm, give em light.

Use a liquid fertilizer that has trace elements and is designed for edibles (vegetables). Dilute 1/4 to 1/2 the recommended strength listed on the bottle. Feed about once a week. Water well when plants just begin to droop.

It really is that simple. MJ is a weed. Treat it like one.