MSU fertilizer PPM scale
 

I was wondering what scale(500/700) MSU used to calculate 125 PPM?

I'm not sure what you mean exactly, but for ANY fertilizer, for 125 ppm N (not 125 ppm TDS):

10 / %N = teaspoons per gallon

13 / %N = ml/liter

So, Why do they calculate just PPM's of N? Every other fertilize company uses EC to calculate PPM.

It is common for professional nurserymen to manage their feeding regimen by controlling the nitrogen application, as that has the most impact on growth, while "tuning" the remaining nutrients via their selection of specific formulas.

The classic example is poinsettias - it is well established that it takes 1/2 g N to raise the rooted cuttings to maturation and blooming. If you are raising them in different substrates - soil, peat-based, coir-based, etc. - you still need the same amount of nitrogen, but will change the rest of the formula to accommodate the substrate. The EC of each will be different for the same nitrogen loading.

The Greencare folks provide EC as well, for a target nitrogen loading. I think that is how it is specified on most professional fertilizers, not EC for a total dissolved solids level.

MSU RO (ppm N-mS)
50-0.4, 100-0.8, 150-1.0, 200-1.6

MSU WW
50-0.34, 100-0.68, 150-1.02, 200-1.34

Thanks for the explanation!

To get 125 PPM N for MSU, your TDS is about 450-630.... depending on the scale?

So, Im guessing that the hydroponic world is alittle different than. Being that they can add up to 5 or more different products in the tank at one time.

So.... When your plants go into blooming cycle do you want to measure PPM's of P?

At a constant nitrogen concentration, the TDS will vary with each different formula, but will be constant, and I don't know the number.

Look at it this way: if you total up the cations in all of the minerals and chemical used to make up the Greencare MSU RO formula, the TDS would be 355. However, we know that the anions play some role in the dissolved solids, but how much?

If we take the total mass or powder added - again for 125 ppm N - that's 3.55g in a gallon, or 3550mg/3.785kg = 938 ppm, but depending upon how the particular species in solution dissociate, some of them are not part of the TDS either, so it's probably somewhere in between.

If we switch to the Well Water version, those numbers are 263 ppm and 661 ppm, respectively.

Why would you want to measure the phosphorus? A plant has little demand for it to start with, and that does not change in relation to blooming.

I not wanting to measure phosphorus...... I'm no chemist nor botanist, But it just make sense to me that if you measure N for the growth cycle since thats what's responsible for growth, you would want to measure P when your plant is about to go into bloom cycle and lowwer the PPM of N.... It's my understanding that P is a major player in bloom. Again, I'm probably all wrong about this but Im ok with that.... That how you learn.

How and by whom was the value of 125 ppm of nitrogen determined? Why not a value of 100 ppm or 150 ppm?

Edit:
This is intended as a rhetorical question because some people here seem to have become fixated on this value of 125 ppm nitrogen as some inflexible requirement instead of just a quick rule of thumb. And in fact you mention here ( TDS and EC ) that 125 ppm is just a value that you "typically shoot for".

If you dissolve 3.55 grams of material in a gallon of RO water then the TDS _is_ actually (by your calculation) 938 ppm. The only thing approximate (as you mention here: TDS and EC ) is what reading will be obtained from an EC meter that is being used to estimate the TDS.

If I dissolve 3.55 grams of sugar in a gallon of RO water then an EC meter will give a TDS reading of 0 even though the actual TDS is 938 ppm.

And, actually, what is really important is the osmolarity of the nutrient solution which is yet another topic.

There is absolutely nothing "magic" about 125 ppm N, at all.

The number is the one that the folks who developed the so-called "MSU Fertilizers" decided to use when evaluated their formulas, and found it worked well for their varied collection of orchid genera. (Coincidentally, I happened to have discussed that with Bill Argo, on of those developers, just last week.) One of them simply suggested it, and they went with it.

It seems to be a reasonable level to apply frequently without fear of "burning".

Ray,
Thanks for your explanation - but this guy seems to believe that Phosphorus has something to do with blooming. Not unusual but a chance to get on the soap box if you are anything but a fertilizer salesman.:)

My understanding - gleaned from discussions with folks who actually studied nutrition as part of their plant biology courses - is as follows:

Phosphorus may be a critical nutrient, but not in large quantities, and they have active "pumps" to draw it in (as opposed to equilibrating with the environment, as happens with many nutrients), storing the excess in vacuoles.

Phosphorus being a "Bloom Booster" is either marketing BS used to cover up a flaw in a product, or folks' poor and inaccurate interpretation of the facts:

Dr. O. Wesley Davidson of Rutgers University, understanding that orchids like a more acidic environment than many plants, devised the 30-10-10 formula sold as "Mir-Acid". His assessment was apparently correct, as the plants fed that high-nitrogen formula grew like weeds.

Then, with time, it was noted that those plants grew great, but bloomed reluctantly, if at all. Sooooo.... Inexpensive phosphorus compounds were added to the Mir-Acid formula to "dilute" the nitrogen, and Lo! and Behold!, the plants bloomed well again.

It was the removal of the nitrogen "restraint" that allowed the blooming, not any supposed "boost" by the phosphorus that caused it.

To reiterate: a plant in the peak of health will bloom to its genetic maximum capability. There is nothing you can add nutritionally that can push it beyond that.

Oh, and I do sell fertilizers. (and a bunch of other stuff, too)

Ray,
I know you do and I buy it. A lot of it is great stuff.
Too bad shipping has gotten so expensive.

Interesting.....

So, "bloom boosting" fertilizers will do nothing if your plant has all nutritional requirements meet?

I have another question for you Ray.....

Would you mix ever fertilizer to 125PPM N? Being that every fertilizer is make differently.

It seems to me, running that high of a overall TDS with every watering will burn your plants?

I did buy some stuff from you not to long ago......Great service!!!!!

Its also my understanding that high N fertilizer will make your plant grow fast but the cell structure will be weaker making your plants more prone to infections. Any truth behind this?

Feeding a lot of nitrogen has been shown to produce leggy, and "soft" growth. One grower likened it to feeding kids candy - gives them lost of energy, but has no nutrition to back it up.

FWIW, I have fed my plants at 125 ppm N at every single watering for the last 8 years (+/-), without flushing, and I have never experienced root burn.

Semi-hydro
 

Ray, I grow most of my orchids using the semi-hydro setup you describe so well. Using MSU for well water according to the directions (¾ tsp/gal), I will get 125 ppm nitrogen, but my total tds is around 800. (I start with 80 ppm in my well water). I’m concerned that this is high enough to cause problems, especially for paphs. Some of them and a couple of catts had leaf tip burn. I lowered the amount to ¼ tsp/gal, giving me about 300 ppm, and the new leaves were fine. But I’m concerned that they’re not getting enough nitrogen.

Tony, you jumped into an 8-year old thread here, and my recommendations have changed significantly since then!

After several years of frequent application of the MSU RO formula @ 125 ppm N, I noticed that while my plants grew very well, I just wasn't getting the blooming I should. In discussions with folks well-educated in the field, it was suggested I was overdoing the nitrogen. (In retrospect, if you look at what orchids see in nature, it's VERY frequent watering with very pure water containing almost nothing [analyses have demonstrated a max of 15-20 ppm TDS, almost all of it nitrogen], so it make a lot of sense).

After doing some more research on epiphytic plant biology (and plants in general), I decided to modify my feeding regimen, reducing the nitrogen loading to about 20% of the former, to 25 ppm N. I have been feeding at that concentration, using K-Lite (12-1-1-10Ca-3Mg) for 6 or 7 years now, and after about a year or so of that - watering 3-4 times a week in summer, maybe half that in winter in PA - I saw the blooming significantly improve.

Over the next couple of years, I incorporated monthly doses of KelpMax and Concentric Ag Garden Solution into that, and am constantly amazed how well my collection grows, blooms, and multiplies.

Thanks, Ray! This confirms my observations, so I’ll stop worrying about the N and keep my solution at a low tds. I’m getting good flowering, but may try the regimen you suggest on some of my collection and see what happens. Thanks!

Remember ambient conditions need to be ideal before fertilizer becomes a big factor in plant growth. Orchids in less than ideal circumstances - most of us - can't use as much fertilizer as can orchids in nice warm humid growing areas with plenty of light.

It's the same thing with food supplements for athletes. They can't help people who go to the gym to sit and talk.