Akerne rain mix + CaNO3 to get low K result?

[eds]

I'm getting back into slippers and orchids again and bought a load of rain mix thinking it would be a better fertiliser than the standard fare. After reading on here I can see the logic in the low K approach for these plants but obviously would rather not just chuck the kilo of ferts I've just bought.

Can I mix it 50:50 with Calcium Nitrate to give a similar result?

Should I also add some more micro fertilisers as well? (I have various ferts from my planted aquatics days.)

 

[Ray]

Rain Mix is a 11-2-13-8Ca-5Mg formula, if I recall correctly. CaNO3 is 15-0-0-19Ca

Mix them 50/50 and you get a 13-1-6-13Ca-2Mg, still high in K compared to K-Lite, but better.

 

[eds]

Rain Mix is a 11-2-13-8Ca-5Mg formula, if I recall correctly. CaNO3 is 15-0-0-19Ca

Mix them 50/50 and you get a 13-1-6-13Ca-2Mg, still high in K compared to K-Lite, but better.

Thanks Ray. Pretty near spot on! I should have put the quoted levels in my initial post sorry.

My tub says Akerne mix is:
11.7% N, 2.7% P2O5, 13.7% K2O, 11.8% CaO, 3.5% MgO and 4.8% SO3

The CaNO3 just says 15.5% N and 26.3% CaO (so 19% Ca would be about right).

So I reckon a 50/50 mix is 13.6%N, 1.35%P2O5, 6.85%K2O, 19.05%CaO, 1.75%MgO and 2.4%SO3.

Do you think there are any benefits to going more dilute with the rain mix? I reckon at 25/75 mix would be 14.55%N, 0.68%P2O5, 3.43%K2O, 22.68%CaO, 0.88%MgO and 1.2%SO3.

Or will it probably be just as good to feed the 50/50 mix at half strength?

 

[Ray]

I'd just use the 50/50 blend, but I don't know what you mean by using it at half strength.

I prefer to follow the lead of commercial growers and manage the fertilizer application by ppm N. How much you feed should be determined by how often you feed, and I have found that 50-75 ppm applied weekly is very good. I also prefer to feed at every watering, so this time of year, with one watering per week, I do 75 ppm N. In the summer, when the plants are outside on the deck and I water 2-3x a week, I use 25 ppm N each time.

Using the 25 ppm level, a reasonable estimate is to divide 2.3 by the %N of the fertilizer to get the ml to add to a liter for 25 ppm N for any formula fertilizer.

Rain Mix: 2.3/11.7=0.2 ml/L
CaNO3: 2.3/15.5=0.15 ml/L
Blend: 2.3/13.6=0.17 ml/L

Or if you want to be more precise and weigh the powder for mixing, just calculate it: if your blend is 13.6%N, and you want 25 ppm N (25mg/kg), then .025g/0.136=0.184g of powder per liter.

For we less-civilized folks who are stuck with teaspoons per gallon, the volume estimate is simply 2/%N for teaspoons/gal to yield 25 ppm N.

 

[troy]

I know there is optimum calcium absorption by plant roots at 70° f is there an optimum nitrogen absorption?

 

[Ray]

I know there is optimum calcium absorption by plant roots at 70° f is there an optimum nitrogen absorption?

Where did you learn that?

 

[eds]

That's an amazing reply, thanks Ray. Thank you so much for taking the time to work out and relay that information. When I use this up I will definitely be buying some K Life from yourself, assuming you'll ship to the UK.

 

[troy]

A biology major person told me that, is that info incorrect?

 

[Ray]

After I posted that, I dug out my copy of Marchner's book on mineral nutrition and learned the uptake dynamics is a whole lot more complex than just temperature, as well as the fact that it varies from plant to plant.

The most significant factor isn't temperature, but the rate at which compensating protons are exuded, and that is a day/night thing.

While I found nothing about calcium, there was a mention that nighttime nitrate uptake in soybeans was double that of daytime. Interestingly, when 3 hours of extra light was added, simulating long days, the nighttime uptake rate increase was prevented. That makes me wonder about what folks who grow under lights do when they extend the "on" time...

Generally speaking, a 10C increase in temp only increases the mineral uptake by 10-20%.

K seems to have a peak uptake rate in maize at 25C, while P maxes out around 40C. Interesting thing about the temp is that where the temperature is applied also has a significant impact:

Maize was tested with roots and shoots at (A) 12C/12C, another set (B) at 24/24, and a third (C) where the root were 12C and the shoots 24C.

The nitrate uptake of B was about 50% greater than A, but that of C was about 80% more than A. With potassium, the B plants took up about 110% more than the A plants, but the C plants took up almost 200% more.

 

[Stone]

I'm getting back into slippers and orchids again and bought a load of rain mix thinking it would be a better fertiliser than the standard fare. After reading on here I can see the logic in the low K approach for these plants but obviously would rather not just chuck the kilo of ferts I've just bought.

Can I mix it 50:50 with Calcium Nitrate to give a similar result?

Should I also add some more micro fertilisers as well? (I have various ferts from my planted aquatics days.)

A waste of time. Give normal K. As much as or a bit less than N. As the season ends, reduce N or give KSo4 a few times to help harden the plant. The whole low K thing should be seen for what it is. A failed hypothesis from the distant past. It's complete nonsense in every way. The most important thing is to water according to your mix. I like to use a quick drying mix and water a lot. With this, you also need to feed a lot but in low concentration. That is low NPK not low K. Paphs find this practice natural to them. Most of the K is absorbed during the rainy season and stored for later use. There is no logic in the ''low K approach''. None whatsoever. This has been proved through practice a million times. The fact that plants can get by on low K shows that they are very efficient at taking it up and storing it. It does not mean they should be treated that way.

 

[Ray]

"Welcome back", Stone.

You're certainly entitled to your opinion, but my plants - now in their 9th year of this "failed hypothesis" - seem to be loving it.

While there was a great deal of speculation in its conceptualization, there is actually a great deal of logic in the approach, which I am not going to rehash, but let me just say that if "they are very efficient at taking it up and storing it", why cannot that suggest that their demand does not required doses nearly as large as we have historically applied, and why should history dictate that "they should be treated that way" ? (Both rhetorical questions.)

 

[eds]

A waste of time. Give normal K. As much as or a bit less than N. As the season ends, reduce N or give KSo4 a few times to help harden the plant. The whole low K thing should be seen for what it is. A failed hypothesis from the distant past. It's complete nonsense in every way. The most important thing is to water according to your mix. I like to use a quick drying mix and water a lot. With this, you also need to feed a lot but in low concentration. That is low NPK not low K. Paphs find this practice natural to them. Most of the K is absorbed during the rainy season and stored for later use. There is no logic in the ''low K approach''. None whatsoever. This has been proved through practice a million times. The fact that plants can get by on low K shows that they are very efficient at taking it up and storing it. It does not mean they should be treated that way.

That's an awfully definitive response! I don't think anything in hobbyist-level horticulture can be that cut and dried. I've not read anyone saying other fert mixes don't work, just that this might be better in reducing the build up of salts, especially K, in the media orchids are grown in long term.

Personally I'm trying alternating different mixtures and I don't think the approach you outline above is really that different. In fact it seems to me that the biggest difference could be that 'Low K' is really more like high N when compared to your dosing rates.

 

[troy]

Plants need phospourus for root production and metabolizing other minerals and potassium for transpiration for absorption of co2, a well balanced fertilizer at 1/4 strength with ro water will have best results alternated with a cal mag

 

[troy]

Uh oh, now I'm going to get banned from this website for posting the statement above this one lol..

 

[Ray]

OK folks. Feel free to use the search function for old threads. They were extensive. No need to rehash this all over again.

 

[richgarrison]

I'll throw in a practice i made up on my own maybe someone will provide some valid criticism that will help me improve my practice

Since i have a reasonably large hobby collection (1200ish plants) and i water/feed daily with tank mixed RO/fert solution, i needed a cost effective way to accomplish what i wanted to do which was work in the direction of the k-lite formula.... yes i was sold on the counter productive effects of potassium blocking nitrogen uptake... (your mileage may vary but that's where i started)...

so turns out that peters makes 2 products that appeared foundational for the formula cal-trate, and mag-trate. both have micronutrients added in what appear to be good proportions but are x-0-0 + Mg or Ca + micros...

and the Cal trate really doesn't like being introduced to higher concentrations of the Mag trate or you get that nice gummy precipitate... so....

after some math, and discussion with Peters folks... i have a ratio of Magtrate : Caltrate : Peat lite where i use the Peat lite to give me phosphorus and potassium... cloudy days in the winter get about 130-150 microsiemens sunny days get more like 250 microsiemens... i mix up gallons of 'concentrate' that i tank mix into my 30 gal fert tank.. (gal of Mg sol first then a gal of Ca sol)...

Plants appear to love it... (after 6 months...) obviously more testing to come...

So let the entertaining criticism follow!

 

[Stone]

That's an awfully definitive response! I don't think anything in hobbyist-level horticulture can be that cut and dried. I've not read anyone saying other fert mixes don't work, just that this might be better in reducing the build up of salts, especially K, in the media orchids are grown in long term.

Personally I'm trying alternating different mixtures and I don't think the approach you outline above is really that different. In fact it seems to me that the biggest difference could be that 'Low K' is really more like high N when compared to your dosing rates.

I grow many many different species of orchids - not just Paphs, but I also grow cacti both terrestrial and epiphytic (some of which grow on pure limestone or pure gypsum and some of which grow in humus on trees. The recommendation by the experts for these BTW is high K fertilizer). I also grow 90 species of Tillandsia which rely on air borne and rain born nutrients (very low concentrations obviously. The recommendations by the bromeliad experts for these BTW is high K fertilizer) I also grow a large selection of trees and shrubs from extremely varied habitats. The Paphs come from both limestone and acidic habitats.
That's all I do all day, every day, It's my job as well as my hobby. Why do I mention it? Because all these plants receive a K to N ration of approximately 1. All do very well on this. If a plant does not exhibit it's full potential, It's always always because I have not been able to or to cared to supply it with the correct conditions. Not the make up of the fertilizer. (fertilizer will NOT make up for 5 degrees lower than is optimal) All the best growers in the various societies I belong to use a K to N ratio of about 1. Generally, I do not lose old leaves prematurely. If I get brown leaf tips it's because of too high a concentration of TOTAL dissolved (or undissolved) salts not too much K. I do not have deficiencies showing up on plants with good roots. Deficiencies only ever manifest on plants that have been mistreated. Either temperature, root loss or lack of fertilizer or lack of a specific nutrient. Never ever because of too much K. If it ever is too much K it is because it's too much NPK. In short, it is the correct ratio of essential nutrients and it's concentration which makes the difference. Time and time again, the correct ratio giving the best results for N to K is about 1. (1N to 1K) All you need to do when fertilizing plants well is to settle on a good fertilizer (I use 1/2 organic and half manufactured) and then add some form of calcium carbonate for limestone plants or omit it for non limestone plants. This addition or omission will allow for the correct chemical reactions to suit the particular plant. Also vitally important is to get a feel for what is going on in the pot. Nutrients usually build up over time regardless of how low the concentration but not just that, certain fungi build up as well if the pot is not full of roots, these fungi kill roots. Not directly but probably some exudation from them. It's what is normally referred to as stale mix. To prevent this you need to leach by flushing out with a strong and sustained stream of water 2 or 3 times in one day one hour apart. (if you're not sure that the pot has been flushed well it probably hasn't) This seems to wash out all the crap including salt build up which inhibits healthy roots. After that let the plant dry out and start again. This has been the most important point for me as far as good growth.

 

[Stone]

"Welcome back", Stone.

You're certainly entitled to your opinion, but my plants - now in their 9th year of this "failed hypothesis" - seem to be loving it.

While there was a great deal of speculation in its conceptualization, there is actually a great deal of logic in the approach, which I am not going to rehash, but let me just say that if "they are very efficient at taking it up and storing it", why cannot that suggest that their demand does not required doses nearly as large as we have historically applied, and why should history dictate that "they should be treated that way" ? (Both rhetorical questions.)

Hi Ray and thanks for the ''welcome''
There most certainly is NOT a great deal of logic in the approach for the very simple reason that the best growers with the best results and all the awards don't do it. Therefore, the only logic remains in the minds of those who do it and not in reality.

 

[Stone]

Plants need phospourus for root production and metabolizing other minerals and potassium for transpiration for absorption of co2, a well balanced fertilizer at 1/4 strength with ro water will have best results alternated with a cal mag

Yes plants need P for root production but they need it just as much for the whole plant. The old claims that P is for root growth is not true. In other words, giving more P than is necessary for the normal growth of a plant will NOT increase root growth. It has been tested in trials a number of times. But yes I agree that any standard fertilizer off the shelf of your favourite hardware store will give you the basic NPK that you need. 1-0.3-1 or 10-3-10 is about right..Yes plants need P for root production but they need it just as much for the whole plant. The old claims that P is for root growth is not true. In other words, giving more P than is necessary for the normal growth of a plant will NOT increase root growth. It has been tested in trials a number of times. But yes I agree that any standard fertilizer off the shelf of your favourite hardware store will give you the basic NPK that you need. 1-0.3-1 or 10-3-10 is about right. I use these types and add my own mix of trace elements which includes Ni which is vital if you use Urea.

 

[Stone]

repeated