Fertilizer

General discussion about Lithops & stuff that doesn't fit anywhere else.
Allan1
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Re: Fertilizer

Postby Allan1 » Thu Jul 28, 2016 1:18 am

If you keep feeding high N. Marc, you will get boated plants and some will regenerate at the wrong time and some will die. Most tomato foods should be OK.
As you have no organic matter in your potting mix I would suggest that you apply a dilute fertiliser each time you water.
Allan
Orkney
Lithops,Cacti,Conophytums,Tylecodons,Sempervivums and Sedums

mary44
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Re: Fertilizer

Postby mary44 » Thu Jul 28, 2016 3:07 am

The tomato fertiliser I have here is levington's tomorite. N4 P 4.5 and K 8.0. I haven't used any yet but it sounds like it could be used if diluted a lot.

Regulus
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Location: Belgium

Re: Fertilizer

Postby Regulus » Sun Jul 31, 2016 6:01 am

There is a lot of confusion about fertilizers !

Those NPK figures (maybe topped up with Mg) are just the % concentration of the fertilizer. So actually 10-10-10 or 20-20-20 or 30-30-30 are "the same" fertilizer only their concentration is different.
This results in the fact that only the ratio of the elements between them is important because concentration can be adjusted as needed. For instance a 30-30-30 NPK can easily be used as 10-10-10.

But the real general reference is NOT to stick to those % NPK values but calculate everything as ppm based on Nitrogen. With such calculation every fertilizer can be reduced to a basic type of concentration irrespective of its commercial composition. OK, the ratios stay the same !

Simple reference calculation ? take a 10-52-10 fertilizer (like Scotts). used at 1 gram (or 1 milliliter) per liter water will yield a 100 ppm N solution. Same simple rule for, say, a 4-5-6 NPK ... one gram(or one milliliter) in one liter of water will yield a 40 ppm N solution.

How much to use ? I was suggested by "one of the best" that, for cacti, 100 ppm is a good concentration for regular fertilizing, 150 to maybe up to 200 a season's boost in Spring. .. but everything can be easily adjusted with this calculation trick ...
For Lithops I tried 50 ppm but that is far too much, even 25 seems plenty ! It may be clear that with a fertilizer, high in N, one cannot make a 25 ppm dilution even in a 10 liter bucket it is kind of tricky ...
BTW The according P and K concentrations cannot be directly calculated in this way because their analytical concentration is given as P2O5 and K2O ...
I made an excell speadsheet for this but the only important parameter is Nitrogen anyway ...

An important side factor to consider however, is salt build up especially for P and K as N is washed away ... also keep an eye on the Ca/Mg content as those tend to be converted into their corresponding carbonates ... ;)

.. and of course one can just go on with the regular "splash" of fertiliser if calculating is a pain ... :lol:

Australian
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Location: Australia

Re: Fertilizer

Postby Australian » Sun Jul 31, 2016 12:19 pm

Well written, Regulus!

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David1971
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Re: Fertilizer

Postby David1971 » Mon Aug 01, 2016 6:20 pm

Very interesting thread. I only feed very occasionally adult plants, and only if they haven't been repotted in the last two years. The reason is that I always include a touch of organic stuff in my potting mix. I use a 5-5-7 cactus fertilizer diluted 25% which yields 47 ppm N solution.
The issue I would like to put is that of water alkalinity and the form in which N is present in fertilizers. As probably you know, many cactus growers use acids (mostly vinegar and citric acid) to low water pH to 5-6 values. Many also add sulphate of amonnia to generic fertilizers because it has been said that N in most of them is in the non-assimilable Urea form. I adjust water pH because my water is basic, and I am thinking in moving from my cactus-specific fertilizer (very expensive) to a more generic one adding the corresponding ammount of sulphate of ammonia. What do you think? Any advice or experience?

Regulus
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Location: Belgium

Re: Fertilizer

Postby Regulus » Mon Aug 01, 2016 9:36 pm

If you use 5-5-7 fertilizer at 25% then your final concentration in N is not 47 ppm but 50/4 = 12.5 ppm. As I wrote on another forum, that may be barely stronger than "holy water". I mean, standard rain water may have an higher N content just by "falling" through the atmosphere and down the rain pipes 8-)

I use vinegar or phosphoric acid once in a while for mild acidification. Using a strong acid, like phosphoric or "similar", is a PITA because the pH can hardly be adjusted (overshoot). Vinegar is much easier to use as our standard commercial vinegar is 6% which is roughly 0.1 molar solution ... and acetic_acid/acetate is a buffer combination.
But standard I may also use an additional very low concentration of ammonium sulphate because, indeed, it has quick assimilation Nitrogen AND it can lower the pH to about 5.5. The big caveat is its content in Nitrogen which in NPK terms is 21-0-0. But it is dirt cheap as it is an N fertilizer in agriculture.
A long time ago I was using KH2PO4 for good buffering and lowering the pH as it has no N but only P & K but it is cost prohibitive.

EDit: PS .. The use of vinegar in watering techniques for cacti was documented in extenso in the CSSA by Elton Roberts and Malcolm Burleigh many years ago and there are a couple of addenda. For the use on Mesembs I found a very short mention in the MSG bulletin not very long ago (by S Hammer) .. as if they just came to discover it !

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David1971
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Re: Fertilizer

Postby David1971 » Mon Aug 01, 2016 10:46 pm

Regulus wrote:If you use 5-5-7 fertilizer at 25% then your final concentration in N is not 47 ppm but 50/4 = 12.5 ppm. As I wrote on another forum, that may be barely stronger than "holy water". I mean, standard rain water may have an higher N content just by "falling" through the atmosphere and down the rain pipes 8-)

I use vinegar or phosphoric acid once in a while for mild acidification. Using a strong acid, like phosphoric or "similar", is a PITA because the pH can hardly be adjusted (overshoot). Vinegar is much easier to use as our standard commercial vinegar is 6% which is roughly 0.1 molar solution ... and acetic_acid/acetate is a buffer combination.
But standard I may also use an additional very low concentration of ammonium sulphate because, indeed, it has quick assimilation Nitrogen AND it can lower the pH to about 5.5. The big caveat is its content in Nitrogen which in NPK terms is 21-0-0. But it is dirt cheap as it is an N fertilizer in agriculture.
A long time ago I was using KH2PO4 for good buffering and lowering the pH as it has no N but only P & K but it is cost prohibitive.

EDit: PS .. The use of vinegar in watering techniques for cacti was documented in extenso in the CSSA by Elton Roberts and Malcolm Burleigh many years ago and there are a couple of addenda. For the use on Mesembs I found a very short mention in the MSG bulletin not very long ago (by S Hammer) .. as if they just came to discover it !


Thank you very much Regulus. I dilute my 5-5-7 fertilizer at 25% of manufacturer recommendation (which is 3.8 ml per liter of water, I know this number sounds rather strange, but dosification was calculated from instructions "add one stopper to 6 liters of water"). So I am actually adding almost 1 ml of fertilizer per liter.

Regulus
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Location: Belgium

Re: Fertilizer

Postby Regulus » Tue Aug 02, 2016 12:24 am

Sorry, my stupid mistake ! :shock: I went with the silly idea of 1 ml/Liter and 25% thereof ... not with the possible "recommended concentration" as given by the manufacturer, my bad! ... As you may have noticed, that recommended concentration brings you at 190 ppm N which I think is about the rule of thumb for house plants ... at least, most of what I see as "recommended" end up with around 200 ppm N ... :)

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David1971
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Re: Fertilizer

Postby David1971 » Tue Aug 02, 2016 1:50 am

Don't worry :) , my English is a bit rudimentary and probably I have not made it sufficciently clear. I have sometimes used another specific fertilizer (a Spanish one, Massó) and the recommended N dose is 270 ppm!!! :shock: This morning I have found a generic fertilizer at an affordable price particularly recommended for fruit production (NPK: 5-15-30). The good point is that it is designed for foliar application, so all N is in its ammoniacal (2%) and nitric (3%) forms.

I came to the use of vinegar and sulphate of amonnia from the Roberts and Burleigh articles in the Cactus and Succulent Journal, and from them I began to investigate in the forums. Most online information in this regard is for cacti and it is rare to find references from mesembs growers. Did Hammer say something new or interesting?

Regulus
Posts: 69
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Location: Belgium

Re: Fertilizer

Postby Regulus » Tue Aug 02, 2016 2:13 am

ah I see .. you followed the same road as I did ;)

No Hammer didn't say anything at all, it sounded as if he had struck gold in using vinegar for acidifying ! I mentioned the Roberts & Burleigh articles to the editorial board of the MSG by email but they did not even answer me. :x

BTW I use 10-52-10 Scotts and 6-12-36-3 from Krystalon ..


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