Ammonium

[gonewild]

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:

 

[Rick]

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.

 

[Rick]

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.

Mike.

0 alkalinity occurs at pH 4.5 and nitrifying bacteria only need 7X the amount of alkalinity (as CaCO3) to convert equivalent amounts of ammonia.

So 1ppm of ammonia only needs about 7-10 ppm of bicarbonate ion for nitrifying bacteria to convert it to nitrate. So you have to get to acid levels not frequently found in the orchid hobby to stop nitrification.

Seems like below pH 5.5 we are getting out of the "sweet spot" for ideal nutrient uptake for most plants (including orchids), so I don't know how relevant it is to consider ammonia vs nitrate uptake out of the typical ideal ranges for bacterial nitrification.

 

[Rick]

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


This one may be just the ticket.

 

[Stone]

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!!

 

[Stone]

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!!

 

[keithrs]

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

I battle that almost everyday!oke:

 

[Rick]

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

Yes that will get your attention!

 

[Stone]

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

 

[Stone]

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???

 

[Stone]

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

This a Dend. gracilicaule (many large weeds removed ) which has not received any feed for at least 24 months. No osmocote, no soluble, no blood/bone, just heavy winter/spring rain and hose. It's a bit yellow but has 9 new leads as big as last year's. Its growing in treefern/sphag. No obvious deficiecies except maybe a little N? and old yellow leaf tips could be showing low Mg? Maybe the weeds robbed a lot of nutrients but its hanging in there

Mike



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[Rick]

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:

 

[Brabantia]

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.

 

[Rick]

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.