Can someone refresh my mind on fertilizer calculations?

I If I recall correctly, in NPK terms, N is reported as N, P is P2O5, and K

as K20. So using the gravimetric factors for the P & K, a 10-10-10 fert

gives me 10% by weight N, 4.4% P, and 8.3% K. Am I OK so far?

If it's a liquid, and is dosed at 1 teaspoon per gallon, that's an addition

of approximately 5 ml into 3785 ml of water.

If I assume a sp. gr. of 1 for the liquid fertilizer solution (probably not

correct, but OK for the calculation verification), my 5 ml weighs 5 g, of

which 0.5g is N, 0.44g is P and 0.83g is K.

If I have 0.5g N in 3790g of total solution, my nitrogen concentration is

0.5/3790 or about 132 ppm, right? And my TDS (assuming pure water) would be

(0.5+0.44+0.83)/3790 = 467ppm?

--

Ray Barkalow <> First Rays orchids

http://www.firstrays.com

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