# Ammonium



## Stone (Jan 8, 2012)

Happy new fertilizer year to all!



There is a lot of information out there regarding prefereces for Ammonium or Nitrate in plants and although I've just begun to scratch the surface, it seems a great many plants have performed better with a combination of Ammonium and Nirate forms of Nitrogen in various trials rather than one or the other alone.

I have yet to find a trial specifically relating to paphs apart from two that both gave optimum NPK %s as 1.0 0.8 1.0 (any takers?) but there are some thought provoking bits of information.

It seems that (generally) preferece for Ammonium is given by plants evolved in wet habitats and the reverse for plants coming from dry habitats. And possibly an intemediate preference from intermediate habitat plants.

One study showed Dendrobium tissue in culture medium would only begin Nitrate uptake after all of the Ammonium supplied was exhausted.

Cymbidium sinense roots and leaves grew fastest with Ammonium Nitrate compared to No3 or No4 alone.

Nitrate conversion to usable Ammonium wthin plant tissues takes much energy compared with Ammonium which is immediately utilized.

If we consider that most if not all orchids come from the wetter type habitats, can we assume that they may show a preference for Ammonium or at least a combination of No3 and No4? rather than the 100% Nitrate which many of us are using?

Mike.


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## Paul (Jan 8, 2012)

Hi,
I have tried (for my own experience) to use nitrate as an only source of nitrogen for a year (some kind of MSU fertilizer).
It has resulted in growth = almost 0 for a few species, but not for all a of them. micranthum and armeniacum are the most spectacular: they die slowly if they have only nitrate provided.
However, most Paphs have seemed to grow quite well

No, I use both this fertilizer with nitrate, and a 28-14-14 with urea as main nitrogen source. 
The growth is by far superior in all species, and the micranthum / armeniacum have completly recovered in a month.

I have read a few papers on orchids, showing that urea was very important to get the best growths possible (+50% when fertilizer contains some, compared with only nitrate as nitrogen source). papers on either flasks, seedlings or mature plants.


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## Rick (Jan 8, 2012)

We covered this in a couple of other threads. I particular one started by Bjorn not too long ago.

The use of ammonia vs nitrate in plants has been extensively studied.

The preferential use of either depends on the availability of bicarbonate ion (expressed as alkalinity). Within one of those threads I added a link to a diagram of cellular use and uptake of N that included the use of bicarbonate ion.

In those previous threads I added links to Bill Argo's work that demonstrated that under low alkalinity systems nitrate was the preferred ( but not necessarily solely) form of nitrogen for use. As alkalinity goes up, the preference shifts towards use of ammonia.

MSU "pure water" is based on use of RO water which has alkalinity of 0. Hence primary N form is nitrate. Once you clear alkalinity concentrations of ~ 50 ppm (as CaCO3) then the % preference for ammonia starts shifting up.

Use of pH buffering materials in the potting mix essentially supply a source of alkalinity/bicarbonate ion. So even if you use a low alkalinity source of water for your fert addition, the potting mix can also effect the alkalinity levels at the roots, and subsequently the preferred form of N.

That goes back to analyzing drain water from your pots (pH is a very rough surrogate for alkalinity determination), and lower pH levels correlate loosely to low alkalinity levels and the preference for a nitrate based N source.


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## Rick (Jan 8, 2012)

Stone said:


> Happy new fertilizer year to all!
> If we consider that most if not all orchids come from the wetter type habitats, can we assume that they may show a preference for Ammonium or at least a combination of No3 and No4? rather than the 100% Nitrate which many of us are using?
> 
> Mike.



Nitrite is NO2 and nitrate is NO3 so what is NO4?

The amount of N in any normal aquatic environment is virtually 0 at any given time. Ammonia and nitrate are extremely toxic to freshwater organisms and in the old days before waste water treatment, discharge of ammonia laden waste waters caused massive fish/mussel kills.

Generally N supplied to plants is generated on the spot by bacterial degradation of proteinaceous materials (ie rotting dead things) or by nitrogen fixing bacteria taking N2 gas from the air and converting it into usable nitrate or protein.

The degree of wetness has nothing to do with the preferred use of ammonia vs nitrate, except for the type of geology it flows over to incur bicarbonate ion. Subsequently, water flowing over limestone will have greater alkalinity than water flowing over sandstone or through leaf litter.


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## quietaustralian (Jan 9, 2012)

There is so much conflicting information about this issue. Xavier has written extensively on this but some of those posts are quite old, I wonder if he has reached different conclusions more recently.
During a conversation last year, Xavier mentioned what I thought was a novel fertilizing regime for his Paph sanderianums ( I'll leave it to Xavier to explain if he wishes). It has been mentioned that slippers or some slippers may be saprophytes or partial myco-heterotrophs.

When asked about the nutrient requirements of slipper orchids, a young botanist said:
"There are known knowns. These are things we know that we know. There are known unknowns. That is to say, there are things that we know we don't know. But there are also unknown unknowns. There are things we don't know we don't know."

Mick


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## Stone (Jan 9, 2012)

Rick said:


> > The preferential use of either depends on the availability of bicarbonate ion (expressed as alkalinity). Within one of those threads I added a link to a diagram of cellular use and uptake of N that included the use of bicarbonate ion.
> 
> 
> 
> ...


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## Stone (Jan 9, 2012)

Rick said:


> Nitrite is NO2 and nitrate is NO3 so what is NO4?
> 
> Ok NH4, I find it curious why you feel the need to point out such an obvious and simple typing mistake?


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## Stone (Jan 9, 2012)

quietaustralian said:


> > There are things we don't know we don't know."
> 
> 
> 
> ...


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## Ray (Jan 10, 2012)

Stone said:


> Ok NH4, I find it curious why you feel the need to point out such an obvious and simple typing mistake?



I think you're being overly sensitive to Rick's response. Seeing that, I didn't automatically think of N*H*4 either, and was wondering what point you were attempting to make.


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## Stone (Jan 10, 2012)

Ray said:


> I think you're being overly sensitive to Rick's response.  Seeing that, I didn't automatically think of N*H*4 either, and was wondering what point you were attempting to make.



Sorry Ray I'll have to be much more careful in the future, I thought it was obvious I was on about Nitrate v Ammonia


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## Ray (Jan 10, 2012)

Stone said:


> Sorry Ray I'll have to be much more careful in the future, I thought it was obvious I was on about Nitrate v Ammonia



Hah! Maybe it was, and that glass of wine didn't allow me to see it. Rick's nitrite and nitrate comments caught me!


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## Stone (Jan 10, 2012)

Ray said:


> Hah! Maybe it was, and that glass of wine didn't allow me to see it. Rick's nitrite and nitrate comments caught me!



Pinot or shiraz?


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## Rick (Jan 11, 2012)

Stone said:


> Rick said:
> 
> 
> > In my own case I've been using a high nitrate formulation for about three years with rainwater of about ph6 and a mean medium ph of around 7. But lately I've begun to notice a general yellowing of foliage together with some nasty chlorosis in older leaves, and after reducing the calnitrate by 50% and including a small amount of Ammonium sulphate, I have noticed an almost overnight improvement throughout the entire collection which makes me wonder if these plants have preference for some Ammonium N in there diet ( possibly 50% ? ) Of course there is no way of knowing what each individual orchid prefers without doing trials every species we grow. Impossible, so all I can do is try different things and head in the direction of the favorable results and try to understand why it's happening.
> ...


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## Stone (Jan 12, 2012)

Rick said:


> > Now my experience (concerning yellowing, and chlorisis) is very similar to yours except that instead of altering the ratio of ammonia and nitrate, I lowered K and boosted Ca/Mg to see similar big improvements in my collection.
> 
> 
> 
> ...


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## Rick (Jan 13, 2012)

Ran a short experiment that may be of interest, although may be a limited applicability.

I took 1 tablespoon of shredded (by food processor) leaf litter and soaked it in 100 ml of RO water (for about 6 hours). Filtered out the solids and then ran ammonia and nitrate analysis.

ammonia = 2.8 mg/L-N 
nitrate = 17.2 mg/L-N

For more detail my leaf litter was collected after fall leaf fall, shredded and left to air dry/degrade for about 3 weeks. I live relatively far from urban settlement and the local forest is over karst limestone.

The RO is lab grade and probably more pure than rain water.

I have been using this leaf mulch for some sukhakulii and callosum seedlings for a "no fertilizing" trial, and so far after a few weeks they are growing.


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## Stone (Jan 15, 2012)

Do you have a ph for that leaf litter? Also Nitrate NO-3 is readily leached where as Ammonium NH+4 is held on negetively charged colloid surface so this may affect outcome of your test?


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## Rick (Jan 15, 2012)

Stone said:


> Do you have a ph for that leaf litter? Also Nitrate NO-3 is readily leached where as Ammonium NH+4 is held on negetively charged colloid surface so this may affect outcome of your test?



Filtration was conducted at 1.5um, which would allow the passage of colloid size particles (0.2-0.45um). The Nesslers reagent (for ammonia testing) is highly corrosive and would be able to take ammonia off of micro particles.
pH of the resulting solution was 6.3 s.u.
TDS jumped to ~40 mg/L

Whether charge bound or physically incorporated into solid materials I would suspect that a nutrient must be in solution for root uptake. So measuring the soluble fraction is a gross simulation of bio-available nitrogen species of rain water leachate samples.

I'm actually surprised to see this much soluble nitrogen at all. Once in a plant (especially by the time we are talking dessicated dead leaves) nitrogen gets incorporated into protein and other organic molecules as nitriles, amines, cyanides. Bacterial/fungal decomposition is required to release the nitrogen from the solid material. And under aerobic conditions nitrifying bacteria are gobbling up the ammonia and converting it to nitrate (although the reverse happens under anaerobic conditions).


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## Stone (Jan 16, 2012)

Rick said:


> Filtration was conducted at 1.5um, which would allow the passage of colloid size particles (0.2-0.45um). The Nesslers reagent (for ammonia testing) is highly corrosive and would be able to take ammonia off of micro particles.
> pH of the resulting solution was 6.3 s.u.
> TDS jumped to ~40 mg/L
> 
> ...


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## Ray (Jan 16, 2012)

Stone said:


> The roots of some plants-- and I suspect most comming from nutrient poor environments-- actually give off H+ ions which change places with other cations on colloid surfaces to make them available for uptake but whether that is relevant I don't know



Any time a plant takes up an ammonium ion, it emits a compensatory H+, but I thought that still applied only in solution, as H+ does not occur by itself, but actually as H3O+

If a nitrate ion is taken up, the compensatory emission is OH- or HCO3-


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## Rick (Jan 16, 2012)

I think its funny that every time we start speculating on the wild condition we find that the total amount of nutrients available is a tiny fraction of what we pour on our plants with fertilizer, but then we keep trying to justify our unnatural use of fertilizer by developing theorys on the natural condition:sob:


We also keep trying to define a narrow universal culture method to apply to 30,000 species and then continuously blame our poor culture results on the inability to come up with 30,000 different culture requirements tailor made to each species.:sob:


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## gonewild (Jan 16, 2012)

Rick said:


> We also keep trying to define a narrow universal culture method to apply to 30,000 species and then continuously blame our poor culture results on the inability to come up with 30,000 different culture requirements tailor made to each species.:sob:



You mean all 30,000 orchid species don't all have the same dietary requirements? What the Hell, who is in charge of this situation?
:rollhappy:


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## Rick (Jan 16, 2012)

http://books.google.com/books?id=0G...s in forest leaf litter decomposition&f=false


looks like an important first read if we are going to reinvent the wheel.


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## Rick (Jan 16, 2012)

Stone said:


> Rick said:
> 
> 
> > I have read that nitrifing bacteria can be completly absent from certain eco systems due to acidity. Plant sap is acidic, so generally leaf litter starts off being acidic (around 6). After the various break-down proceses have been completed, pH usually settles at about 7 depending on the amout of lime present.
> ...


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## Rick (Jan 16, 2012)

http://www.thaiscience.info/Article... on a tropical dry evergreen forest slope.pdf


This one may be just the ticket.


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## Stone (Jan 16, 2012)

Rick said:


> I think its funny that every time we start speculating on the wild condition we find that the total amount of nutrients available is a tiny fraction of what we pour on our plants with fertilizer, but then we keep trying to justify our unnatural use of fertilizer by developing theorys on the natural condition:sob:
> 
> 
> We also keep trying to define a narrow universal culture method to apply to 30,000 species and then continuously blame our poor culture results on the inability to come up with 30,000 different culture requirements tailor made to each species.:sob:



Hey, when it's all said and done, you want to grow a plant and you want to see a flower so you give it what you assume it wants. If it looks happy, you do it again. If it looks sad you don't.
One of the main attractions in growing orchids is trying to figure out just what the hell they need.
Forget fertilizer! I'm battling 95F and 20% humidity today!!


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## Stone (Jan 16, 2012)

Rick said:


> http://www.thaiscience.info/Article... on a tropical dry evergreen forest slope.pdf
> 
> 
> This one may be just the ticket.



This is interesting. Lots of data and maybe lots more questions. Yay!!


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## keithrs (Jan 17, 2012)

Stone said:


> Forget fertilizer! I'm battling 95F and 20% humidity today!!



I battle that almost everyday!oke:


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## Rick (Jan 17, 2012)

Stone said:


> Forget fertilizer! I'm battling 95F and 20% humidity today!!



Yes that will get your attention!


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## Stone (Jan 17, 2012)

Some more N speak. Particularly interesting is that combined NH4 and NO3 may actually cancell out some of the negetive features of each.

http://books.google.com.au/books?id...ferences of plants different habitats&f=false


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## Stone (Jan 17, 2012)

Just realized this is the same link you posted above but it wouldn't open so it did not dawn on me
Or maybe it's not the same???


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## Stone (Jan 17, 2012)

Rick said:


> > I have been using this leaf mulch for some sukhakulii and callosum seedlings for a "no fertilizing" trial, and so far after a few weeks they are growing
> 
> 
> 
> ...


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## Rick (Jan 18, 2012)

And it looks like a big plant too.

So why do we need 100ppm of N and 100ppm of K tossed on our plants on a weekly basis?oke:oke:


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## Brabantia (Jan 18, 2012)

Rick said:


> And it looks like a big plant too.
> 
> So why do we need 100ppm of N and 100ppm of K tossed on our plants on a weekly basis?oke:oke:


I agree with you Rick, I am always surprised when I read the quantities of nitrogen that some peoples recommend for Paphs culture. My regim is between 45 ppm N and 65 ppm N max. Next year I tried lower concentrations (30 ppm N) but it was to low, plants growth stagnated. Probably nitrogen was consumed faster by the substrate (bark, CHC, perlite) than by plants. After August I fed at 65 ppm N and after a few weeks growth started. My Paphs hirsitussimum, hirsutissimum var esqurolei, Paph. wilhelminae and my paph. lowi are in bud! A couple of years ago I fed at 80 - 125 ppm N and I lost several Paphios due to roots burn the survivors are recovering very slowly.


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## Rick (Jan 18, 2012)

Brabantia said:


> I agree with you Rick, I am always surprised when I read the quantities of nitrogen that some peoples recommend for Paphs culture. My regim is between 45 ppm N and 65 ppm N max. Next year I tried lower concentrations (30 ppm N) but it was to low, plants growth stagnated. Probably nitrogen was consumed faster by the substrate (bark, CHC, perlite) than by plants. After August I fed at 65 ppm N and after a few weeks growth started. My Paphs hirsitussimum, hirsutissimum var esqurolei, Paph. wilhelminae and my paph. lowi are in bud! A couple of years ago I fed at 80 - 125 ppm N and I lost several Paphios due to roots burn the survivors are recovering very slowly.



Presently I'm at ~ 40ppm, and growth for just about anything still seems real good (in Winter too!)

If you go to the article on the Thai rainforest leaf litter, and covert their values from gram-N/squareM/year to something like a daily dose for a 2inch pot, then N daily dose would be way below 1ppm per 2 inch pot per day. So boosting up things as high as we do for slow growing/long lived plants like orchids makes me think that most of what we see as "deficiencies" are more frequently antagonistic interactions of imbalanced and excess nutrients.


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