Ammonium

[Stone]

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.

 

[Paul]

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.

 

[Rick]

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.

 

[Rick]

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.

 

[quietaustralian]

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

 

[Stone]

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.

Rick, I've been growing orchids for 28 years and IMHO fairly successfilly, Sometimes in order to do this we need to take a less ''clinical'' approach and use our innate sense of imagination to arrive at a desired outcome. Please forgive if my explanation seems a bit nebulous. The preference of Ammonium or Nitrate (and most plants definately have a preference and perform up to 50% better when provided with it.) appears to be a result of the particular habitat in which a species has evolved. So this is the way I'm looking at it at the moment. It is well known that high rainfall areas like the monsoonal tropics results in massive leaching of nutrients like Ca = more acid = less nirification = less avaiable nitrate N. So I'm talking about the evolutionary preferece in plants rather than what they are forced to consume in captivity with variable medium ph.
Taking paphs as an example it stands to reason ( to me ) that those like superbiens, callosum, veustum etc. which have evolved on acid substrates would possibly have more Ammonium N available to them than Nitrate N and therefore may be more adapted to Ammonium N and prefer it in cultivation.

Then there are those species which grow on limestone which would supposedly modify acidity somewhat ( apparently only to around neutral from what I've read so far ) so they possibly may resond better to incresed Nitrate or a combination. Of course I realize all this is only speculation based on shreads of information and observations but often the only way to go without getting bogged down with too much conflicting scientific data. It may all amount to very little just like your low K theory may end up ''a road to nowhere''.

There have been a number of examples in ST of people like Roth, Bjorn, Paul and others having positive growth responces using various combiations of different N forms and I think it is wrong to simply dismiss this with the medium ph factor alone.

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.

Mike

 

[Stone]

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?

 

[Stone]

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

Very true in all aspects of science Mick. The search continues:rollhappy:
By the way, I got my vitenamense from Ivans. Thanks for the tip.

Mike

 

[Ray]

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 NH4 either, and was wondering what point you were attempting to make.

 

[Stone]

I think you're being overly sensitive to Rick's response. Seeing that, I didn't automatically think of NH4 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

 

[Ray]

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!

 

[Stone]

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?

 

[Rick]

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.

Mike

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.

I grow about 80% of known paph species. The "acid lover's from the forrest duff and the species found on limestone cliffs. They all get the same primary nitrate based fert and have really inproved in the absence of a primarily ammonia or urea based fert.

But you are right that lots of people have looked at nitrogen issues at both the casual level and in depth. Some have seen lots of good results and some not so good. I think instead of criticising me for my "clinical" bent you give diservice to those who have spent considerable time and resources to the answering the question you are posing.

I'm satisfied with my present results to not have to reinvent the wheel for nitrogen fertilizer requirements.

 

[Stone]

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.

Thank's for your reply, It would be nice if we could get some other peoples experiences on this issue,( maybe they like to keep their secrets secret-- ssssshhhh ), but be that as it may, I'm glad to see that you have obtained good results with your program and I've been trying it myself and I think this sort of feedback from different growers is probably the most valuable kind on the forum. Unfortuantely due to limited availablity of fert. components, its rather complicated for me to feed low K without lots of juggling. I keep in mind though that many people are growing well with traditional fertilizers. Case in point-- the last society meeting someone brought in a magnificent kolopakigii with a dark green leaves spaning 30'' and a thick spike carrying 6 flowers.(first blooming) The first question from me was '' What are you feeding it?'' and he answered ''just your normal peters hi-K stuff''

I think instead of criticising me for my "clinical" bent you give diservice to those who have spent considerable time and resources to the answering the question you are posing.

That was not meant to be critical at all I've already said in another post that I respect your views and read your posts (and others) with interest. I was simply (or confusingly) trying to say that we should not rely on any given paper without reservations.

As far as doing a disservice to the researchers, on the contrary, my cupboard is full of horticultural publications going back years and I spend far too much time reading scholarly articles on the web but one thing I have learned is to be skeptical. Just look at the dissageement concerning globle warming, psychology, phyisics, medicine, even history!!! nobody agrees on anything!
From my own experiences with certain acquaintances, qualifications can mean ''Jack s**t.

I'm satisfied with my present results to not have to reinvent the wheel for nitrogen fertilizer requirements.

No one is asking you to do that.

Mike

 

[Rick]

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.

 

[Stone]

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?

 

[Rick]

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).

 

[Stone]

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.

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

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).

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. Knowing that the mosses and lichens in which many of these paphs grow generally cannot tolerate alkaline substrates , I wonder just how much of a part the limestone is contributing at the interface between root and rock?
The fact that many of these orchids have been found growing on trees as well as rock, and that this environment is most certainly quite acidic ( I would guess pH 5 or lower going by measurements made in Ecuador) I also have to wonder what kind of micro flora are prolifertating there.

Not that it might mean that much, but it would be interesting if you could measuer the pH of any humus or moss in direct contact with the limestone in your area and compare that with say moss scraped from a tree trunk.

Mike.

 

[Ray]

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-

 

[Rick]

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: