Urea fertilizer - outstanding results

[Bjorn]

Exactly Paul, so why are they making the fertilizers with almost reverse proportions Fe:Zn:Mn?
I have been using Kelp rather extensively but the effect came with the mancozeb. One disclaimer though, it may also come from copper, I add some copper-oxychloride to the mix. I do spray on dendrobiums as well, have not seen any negative effects on them but I use hard water for mixing the spray. For reference; Xaviers anecdotes particularly abour Vacherot et Lecoufle.

 

[Brabantia]

Some reflections about this subject:
A plant with green leaves absorbs it more light than a plant having yellow leaves?
If a plant absorbs more light make it more sugars?
If yes it should make more dry material and have an accelerated growth versus a plant with yellow leaves.
If you can say yes at these questions and affirmations here are the reasons why one wants green leaves.
PS: Members of my club and myself have also observed that all nitrate fertilysers make plants with yellow leaves.

 

[gonewild]

Obviously if a plant such as the roth there is growing in full sunlight, its leaves can never be dark green no matter how much N it is getting. I have seen other pics of roth growing in shaded spots which were much darker.
However, the plant will grow wherever the seed lands. If in full sun, it will be destined to be yellow and more stunted than its counterparts. So there is an optimum position for all plants.
For the urbanianums?? above I would say that they are in the optimum situation. No doubt there are others nearby in a much sunnier place which don't look as good or as lush. BUT! have a look at how much light they are recieving! Still very bright. Easily as bright as my G/house yet they are what I would call the ''perfect'' colour for this type of Paph. Obviously exremely healthy and prolific. So you CAN have dark green leaves in very good (relatively) bright light and this points more to the nutrition they are getting.

It was a yes or no question! You wrote more than 150 words and still did not answer the question.

 

[Ray]

To Bjorn's earlier comment: It's a matter of degree, but the foliar uptake of urea is far greater than that of ionic species, while just the opposite is true of the roots, where ionic species bond instantaneously with the roots so that they cannot be extracted by rain, while nonionic stuff like urea is easily extracted.

I also have to think that there was "something else" contributing to the yellowing of your plants with K-Lite, as that is the only fertilizer I have given my plants since November of 2011, and I'm seeing nothing of the sort.

 

[gonewild]

Some reflections about this subject:
A plant with green leaves absorbs it more light than a plant having yellow leaves?

It probably absorbs less light since it is reflecting more of the green light. The dark leaves absorb more heat energy which may be a good or bad thing depending on the environment.

If a plant absorbs more light make it more sugars?

Yes in theory. It can only process as much light as hits the chlorplasts.

If yes it should make more dry material and have an accelerated growth versus a plant with yellow leaves.

Yes...But in reality the dark leaves may not be receiving all the light the chloroplasts are capable of processing and the plant may not have the additional nutrients needed for growth. "DARK" green can also be a sign of a bottleneck in the plants growth resources.

If you can say yes at these questions and affirmations here are the reasons why one wants green leaves.

Yes you want green leaves on a plant that is supposed to have green leaves. The point is not about green or yellow leaves. Forget yellow and think medium green or dark green. Dark green leaves may not be growing as fast as medium green simply because they are not using the light efficiently. When you have a pleasant medium color you know the plants are growing at maximum best rate. When you see DARK green you must consider if there is too little light or to much nitrogen. In order to make the growth evaluation you need an understanding on what should the normal shade of green be for the plant type.

PS: Members of my club and myself have also observed that all nitrate fertilysers make plants with yellow leaves.

Then the nitrate fertilizers are not being used correctly.

 

[Brabantia]

Then the nitrate fertilizers are not being used correctly.

Do you think on a too high pH? 5.6 would be better that 6 when we use a fertilizer having the total of its nitrogen under nitrate form?
Thank you for your comments.

 

[TyroneGenade]

Plants can up- or down-regulate chlorophyll levels in response to light. In dim light they will increase chlorophyll so they can harvest more light. In bright light they may decrease it or simply not make as much. There is only so much photosynthesis that can occur. This is limited by the amount of water, nitrogen, CO2 etc... Simply increasing chlorophyll does not directly translate into more photosynthesis and more growth. For instance, the yellowness of leaves of plants grown in strong light is because of an increase in carotenoids. These carotenoid molecules will absorb blue and green light and emit yellow light. They play another import role and that is as free radical scavenger. Blue light photons tend to damage chlorophyll and produce more free radicals so the plant has to adapt to this by becoming more yellow (if this doesn't happen fast enough then the leaves burn). The carotenoids can transfer some of the light energy to the photosystems that do the energy capturing steps of photosynthesis but this is small (estimates range between 4 and 40% with the better studies favoring the lower values). So, no, dark green leaves do not necessarily mean more photosynthesis and nor do light green leaves mean less photosynthesis. Leaf color is only evidence of leaf color.

Light green or yellow leaves have multiple sources. It can be due to a failure to produce chlorophyll as caused by a lack of Fe, Mg, B, Mo etc... AND nitrogen. The urea could, since it is absorbed via the leaves (thanks Lance, I never knew that) make up for a nitrogen deficiency caused by problems with the roots or medium.

There is lots of evidence in this thread that the urea made up for some deficiency in culture but no hard evidence that it is better than alternative fertilizers that are used under proper conditions. Perhaps, if you have a plant struggling and it hasn't got a good root system then maybe the urea fertilizer is the way to go? (At least, this the idea this thread gives me.)

It may be worthwhile noting that K-lite is a 12:1:1 (NPK) fertilizer and the urea based one discussed here is 14:1:1. MSU is 13:3:15. The urea fertilizer is much closer to being a version of K-lite than a "normal" fertilizer. If anything, it has less K than K-lite.

 

[polyantha]

It was a yes or no question! You wrote more than 150 words and still did not answer the question.

"Are these leaves dark?" and posting some of the lightest green paph leaves on the net is not a yes-or-no question, it is a rehtorical question oke: That's why Stone didn't give you an answer I guess

 

[gonewild]

"Are these leaves dark?" and posting some of the lightest green paph leaves on the net is not a yes-or-no question, it is a rehtorical question oke: That's why Stone didn't give you an answer I guess

I did not choose the lightest green paph leaves on the net. Because the discussion had focused on multifloral type paphs and the declaration was made that in nature they have dark green leaves I searched for pictures of them growing in situ. These are what came up, not many to many choose from. I have seen many pictures of them over the years and they are always medium green and not what I would call dark green. Stone says he has seen pictures but does not share them as examples.

SO I asked an honest question that relates to the paph species discussed. Based on that maybe we can understand what people perceive to be dark green.

 

[gonewild]

Plants can up- or down-regulate chlorophyll levels in response to light. In dim light they will increase chlorophyll so they can harvest more light. In bright light they may decrease it or simply not make as much. There is only so much photosynthesis that can occur. This is limited by the amount of water, nitrogen, CO2 etc... Simply increasing chlorophyll does not directly translate into more photosynthesis and more growth. For instance, the yellowness of leaves of plants grown in strong light is because of an increase in carotenoids. These carotenoid molecules will absorb blue and green light and emit yellow light. They play another import role and that is as free radical scavenger. Blue light photons tend to damage chlorophyll and produce more free radicals so the plant has to adapt to this by becoming more yellow (if this doesn't happen fast enough then the leaves burn). The carotenoids can transfer some of the light energy to the photosystems that do the energy capturing steps of photosynthesis but this is small (estimates range between 4 and 40% with the better studies favoring the lower values). So, no, dark green leaves do not necessarily mean more photosynthesis and nor do light green leaves mean less photosynthesis. Leaf color is only evidence of leaf color.

Light green or yellow leaves have multiple sources. It can be due to a failure to produce chlorophyll as caused by a lack of Fe, Mg, B, Mo etc... AND nitrogen. The urea could, since it is absorbed via the leaves (thanks Lance, I never knew that) make up for a nitrogen deficiency caused by problems with the roots or medium.

There is lots of evidence in this thread that the urea made up for some deficiency in culture but no hard evidence that it is better than alternative fertilizers that are used under proper conditions. Perhaps, if you have a plant struggling and it hasn't got a good root system then maybe the urea fertilizer is the way to go? (At least, this the idea this thread gives me.)

It may be worthwhile noting that K-lite is a 12:1:1 (NPK) fertilizer and the urea based one discussed here is 14:1:1. MSU is 13:3:15. The urea fertilizer is much closer to being a version of K-lite than a "normal" fertilizer. If anything, it has less K than K-lite.

Well said, thank you.

 

[tomkalina]

Some great information here. I never realized urea based fertilizers were primarily useful as a folliar feed.

 

[gonewild]

Do you think on a too high pH? 5.6 would be better that 6 when we use a fertilizer having the total of its nitrogen under nitrate form?
Thank you for your comments.

There really should not be much difference seen between pH 5.6 and pH6.

If you are using nitrate fertilizers at recommended doses and leaves are yellow and not green then something is far out of balance. pH is important but pH5.6 or 6 is good. So must be something else.

If the members of your club all have the same problem with nitrate fertilizer having only yellow leaves then look at what you all have in common. What forms of nitrate are you using? Are you sure you are using fertilizer with a high ratio of nitrate compared to ammonia? Are you all using the same nitrate source?

Before UREA is used by plant roots it is changed into nitrate in the soil so even when you apply UREA the plants are eating nitrate.

 

[gonewild]

Concerning the comparison between nitrate and UREA...
I have been researching information on ammonia toxicity dealing with some fertilizer issues and came across this UREA use info. Since it relates directly to the point of this thread I'll share the link.

http://scienceinhydroponics.com/2010/05/urea-in-hydroponics-positive-or-negative.html

The info is about hydroponic use but in reality since most orchids are grown in soil less media hydroponics apply very closely.

 

[Stone]

.

I never realized urea based fertilizers were primarily useful as a folliar feed.[/

QUOTE]

They aren't

 

[Stone]

Paphs (especially multifloral) are known to need high Zn, Mn and Cu (search for Xavier works in the forum)[/

QUOTE]
I have looked into this as much as I could find.
There is no proof that they need more of these elements. Xavier's analysis showed higher concentrations of these but from a Phalaenopsis trial they found higher Mn and Zn in the leaves when fed with ''normal'' fertilizer therfore is seems they just take up more of these?
But I have no proof of that either.

 

[Stone]

It was a yes or no question! You wrote more than 150 words and still did not answer the question.

If the question was ''are these yellow leaves'' then the simple answer (if you need one) is yes to the roth and no quite to the other one

 

[Stone]

Before UREA is used by plant roots it is changed into nitrate in the soil so even when you apply UREA the plants are eating nitrate.

Its first changed to ammonium (which is held on colloids) in a couple of days and SOME is changed to nitrate (which is easily leached) after that.

 

[Stone]

]

The info is about hydroponic use but in reality since most orchids are grown in soil less media hydroponics apply very closely

.

If orchids are grown in organic media, not very close at all. Most Hydro media have no CEC so cannot hold ammonium and that is why ammonium toxicity is feared in hydro systems and used very sparingly if at all.

 

[gonewild]

If the question was ''are these yellow leaves'' then the simple answer (if you need one) is yes to the roth and no quite to the other one

You fail. The question has nothing to do with "yellow".
The question was "Are these leaves dark green?"

Now I have to ask how you can say the roth leaves are yellow?

At least you are demonstrating my point (bet that hurts)
You look at the roth and see yellow leaves and I see medium green.
I consider both plants to have medium green foliage.
Both plants have leaf color that is natural for the plant growing in a balanced environment.

 

[gonewild]

Its first changed to ammonium (which is held on colloids) in a couple of days and SOME is changed to nitrate (which is easily leached) after that.

And during the ammonium phase ammonia toxicity can occur if the environmental conditions are not correct for UREA use.....pH, soil type, temperature and balanced with nitrates.

In most orchid media all nutrients are easily leached.