Fertilizer ppm N from Any Fertilizer Formula

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Ray

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Folks that have been around for a while know of my long "campaign" to get folks to manage their fertilizing regimens through the use of parts-per-million nitrogen (ppm N), and my disdain for meaningless recommendations like "1/4- to 1/2 the recommended amount on the label". The former, when coupled with the frequency of application, allows you to know what you're doing and truly control it. The latter is an undefined shot in the dark, and really offers no control, while pretty much helping the fertilizer manufacturers (who don't know diddley about orchids) to sell more fertilizer!

Manufacturers that cater to professionals routinely publish charts that give the mass of that formula needed for specified ppm N levels. When I sold fertilizers, I had those charts available with the specific product listings, but most producers and vendors of consumer brands either don't do that, or publish misleading info on their labels.

It's actually a pretty simple calculation, but... I just built a Fertilizer Mixing Calculator Using Nitrogen Concentration that will do it for you, no matter what the formula, whether you're mixing it up gallon-by-gallon (or liter-by-liter), or will be making concentrates.
 

Stone

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Thanks Ray

I find this even easier...

Multiply the % of the nutrient element in the powder x 10 x the number of gms to be used per litre of solution. There's your ppm.

Example:

A fert contains 15% N. The instruction is to dissolve 5gms in 10 litres of water. So the addition rate is 0.5 grms per litre.
So...15 x 10 x 0.5 = 75ppm N
 

Secundino

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Thank you!

Ray, I follow every post you share about fertilizing and I wonder if you have some in spanish? If not, would it be OK for you if I - when I've got a bit more of time than right now - to traduce some to share it in 'infojardin/orquídeas' and eventually in my blog? Credits and all, of course.

Though I sometimes think it is a lost battle, for most people believe fertilizers are 'nutrients' and nutrients are good, especially if you get a lot of them when you are weak ... :rollhappy:
 

Brabantia

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Ray you are preaching to a converted since many many years. The distribution frequency is equally important as the concentration in ppm.

Envoyé de mon Nexus 9 en utilisant Tapatalk
 

Ray

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Stone: yes, metrics makes it MUCH easier.

Ozpaph: that can be a can of worms.... I found that 25 ppm N, used at every watering, which was 3-4 times a week in summer, once or twice in winter up north, was a great level.

Secundino: Feel free to translate. I would like credit in the txt, but that's all I ask.

Brabantia: You're right. I wish I had discovered that combo decades ago.
 

Ray

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Angela, 1/4 tsp is hard to measure accurately and repeatedly, courtesy of the heterogeneity of the blend. And then you have to know the bulk density to be able to assess just how much mass that is, but if you assume 5g/tsp, then you're looking at 40-45 ppm N. I think that's probably sufficient for twice a week, although I'm beginning to think, based upon my own experience since moving (during which time I've probably fed my plants and average of every 6-8 weeks) that even that may be too much.
 
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