brainagro
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Math question about Formula for Nutrient Solutions using Liquid fertilizers

Hello

I'm learning about hydroponics and I was reading an excellent article about Nutrient Solutions Formulas but there is something that doesn't make sense to me.
Let's me explain:

I want to use a Liquid Fertilizer "X" to supply a required target of 40 ppm of Mg

The fertilizer "X" contains the following nutrient percentages (w/w):

1.70 % Mg
3.50 % Fe
0.75 % Mn
0.75 % Zn
0.20 % B
Density: 1.30 Kg/L

Following the formula FR = NA / (%N x D x 10)

Where:

FR= fertilizer rate to apply in ppm (or mL/L).
NA = required nutrient concentration to be added by this fertilizer in ppm (1 ppm = mg/l = 1 g/m3).
N = concentration of the nutrient in the fertilizer.
D = density of the fertilizer in kg/L

Then I have:

FR= 40 / (1.7 x 1.3 x 10)
FR= 1.81 mL/L of product "X"

Using the same formula to calculate the rate of the others elements added by this fertilizer we obtain the following numbers:

Ej:

For Fe:
1.81 = X / (3.5 x 1.3 x 10)
X = 0.04 ppm Fe

0.04 ppm Fe
0.18 ppm Mn
0.18 ppm Zn
0.69 ppm B

Looking at this final numbers....the Iron is the element in mayor proportion in the fertilizer "X". Why the formula shows me the Iron in the smallest quantity? (same thing with the other elements).

Thank you

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