Urea as fertiliser

[gonewild]

Lance, I do follow you in saying that somehow the plants were deficient in N if they green up by N addition. My point is how quick it is and the effect overwhelmed me. Even plants growing like weed changed significantly - over night- getting much greener and shinier.It seems to work a little like that stuff housewifes spray on plants to meke them shine "leaf-gloss" or whatever its called. Well it had that effect - and over night. And without any of the stuff getting into the soil. Truly amazing. Whether that is something to aim for is another thing, to me its a bit like putting the plants on steroids - but I like it:evil:.

:clap: If you like what you see then that is a win!

But I think it might be more like putting the plants a sugar diet rather than steroids. Excess Nitrogen makes leaves dark green, bigger and shinny. All that equals a more attractive plant, but long term effect is not good. That is unless you continue to like what you see! :evil:

About the missing ppm: Firstly a disclaimer: My numbers are approximate. Then the reason for the deviation: Over here(Norway, Europe), NPK is given as the elements Nitrogen-Phosphorous-K(potassium): in USA (could be all English-speaking countries for what I know?) and some other places its actually as the oxides: N-P2O5-K2O even if they write NPK.
So my 90-10-40 European NPK is 90-23-48 US NPK. Its confusing, right?

No not at all confusing. What were we talking about? oke:

Thanks for the explanation I did not know the ratios had different values with other languages. More important than the percentages or ratios is that the plants have the nutrients they need when they need them.

Regardless of the ratios It is still my opinion that the use of Urea on potted plants will likely lead to a sudden problem at some point. I'm not talking about when used in commercial mixes like Peters but rather Urea on it's own. If you want to see some beautiful foliage pile on some blood meal and see what happens. It contains the perfect balance to green up leaves but it does smell a lot on a hot day!

Keep us informed about how your plants are doing with continued Urea use, maybe I'll change my opinion if you have continued success.

 

[Rick]

please tell more about calcium nitrate reacting with fertilizer?

"reacting" may not be an accurate way to put it. Calcium nitrate is hygroscopic (it wants to absorb water) and will turn into a big gooey mess if you add a bunch of it to your fertilizer in a granular fashion.

So, like Bjorn indicated, I dissolve it separately in a cup of water and add it to the rest of the fertilizer mix. after it has been dissolved.

Actually I add in step to water:
1) the Mag sulfate (stir until dissolved). It tends to be slow but not as stupid slow as messing with calcium sulfate (gypsum).
2) the Calcium nitrate (in the same cup as the dissolved Mag sulfate), the calcium nitrate will dissolve in just seconds anyway.
3) add in the rest of whatever fertilizer in whatever form. I also add a kelp extract which acts like a chelator with the cations (keeping them soluble).

 

[Rick]

Can a paph (or any plant) absorb nutrients and make enough chlorophyll to noticeably 'green up' the leaves in 24hr?

Can't vouch for 24 - 48 hours, but I've seen fast improvement of less than a week with Epsom salt addition for "greening up".

Magnesium is very labile through plant tissue, and since it is the core atom in chlorophyl it is crucial for "greenness".

 

[cnycharles]

yes, plants can green up from applications of iron, fertilizers, other chemicals, rain... in a short period of time. plants can react to growth regulators by greening up, and b-9 applied to plants to make them stay more compact can also make them look greener and healthier

calcium nitrate does both soak up water like a huge vacuuming sponge, and if you mix it with the wrong fertilizer in high concentrations you will get an endothermic reaction (one in which energy is absorbed by the reacting chemicals so the stock tank will get cold and icy, and your calcium and a few other things will harden and precipitate to the bottom of the tank). so, feed with calcium at one time, then other things the next time, problem solved. or, mix your fertilizer to appropriate levels in your water so that you can water your plants with it, and then mix up your calcium to application levels, then mix the two together. it's only when you have high concentrations that you will have the most precipitation and ice floes in your fertilizer tank (the fog rolling off and the ice on the side of the stock tank are cool, though!

 

[Bjorn]

Lance,we are totally in line here, I would neither have used it alone or extendedly. More like a "tonic" for unhealthy looking plants. Thats why I wrote "on steroids".
About hygroscopy of calcium nitrate: yes it is but might be better if you use the hydrate instead of the waterfree? Ca(NO3)2x4H2O
I have never noticed that endothermic effect from dissolving calciumnitrate into water but have seen it with ammonium nitrate. Perhaps you get it using calcium nitrate without crystal water?

 

[Rick]

Lance,we are totally in line here, I would neither have used it alone or extendedly. More like a "tonic" for unhealthy looking plants. Thats why I wrote "on steroids".
About hygroscopy of calcium nitrate: yes it is but might be better if you use the hydrate instead of the waterfree? Ca(NO3)2x4H2O
I have never noticed that endothermic effect from dissolving calciumnitrate into water but have seen it with ammonium nitrate. Perhaps you get it using calcium nitrate without crystal water?

I've never had a noticeable endothermic reaction with the small amounts of calcium nitrate I use either. In order to keep plants (and potting mixes) from excess loading on K then Ca and Mg should be present at the same time as K.

 

[cnycharles]

if you are using a large stock tank and making a concentrated solution that would be drawn at 1:100 and you put calcium nitrate and certain other fertilizers together, then you can get this reaction. you would notice it after a period of time, not sure if it would happen on a tiny scale but if you were mixing everything at 'application rate' to put directly on plants, the concentrations are probably too diluted for this to happen.

 

[Ray]

Ray, I might misunderstand you, as you know, English is not my native language and this time I feel uncertain.
Sure, I was inprecise, but I think most got the point. Peters 20-20-20(US) would have been labelled 20- 8.6-16.6 over here. On the other hand; people should remember that 1 ppm is the same as 0.0001%. Just saw that the Wellensteins have treated this quite extensively so I stop here(http://www.ladyslipper.com/minnut.htm) There is a lot of good things written on their pages. The fertiliser issue is well described and I would suggest that anyone having questions lookup their pages.

Again, while your conversions to cations, rather than the oxides we see on the label is correct, the numbers in a fertilizer formula are expressed in weight percent, not ppm.

A 20-20-20 is - by weight - 20% N, 20% P2O5, 20% K2O, with the rest being other ingredients. Hence, the N, P, & K of your 90-10-40 would be 140% of the total - impossible.

 

[Rick]

if you are using a large stock tank and making a concentrated solution that would be drawn at 1:100 and you put calcium nitrate and certain other fertilizers together, then you can get this reaction. you would notice it after a period of time, not sure if it would happen on a tiny scale but if you were mixing everything at 'application rate' to put directly on plants, the concentrations are probably too diluted for this to happen.

Yes you wouldn't notice on a tiny scale like I do.

I'm just feeding a few hundred plants, so I dilute to final mix rates without making up a concentrated super stock for large scale application.

 

[Rick]

http://www.google.com/url?sa=t&sour...sg=AFQjCNHFsbLHugTaQySiEte75ENtL7QpQg&cad=rja

Here's another view on the application of Urea vs Nitrate based nitrogen sources with the emphasis based on pH/alkalinity

 

[gonewild]

Rick, That is a very good explanation article.
It defines why not to use Urea with low pH water.
What about effects of the use of Urea with high pH water?
And what about effects of use of Nitrate fertilizers with high pH water?

 

[Rick]

Rick, That is a very good explanation article.
It defines why not to use Urea with low pH water.
What about effects of the use of Urea with high pH water?
And what about effects of use of Nitrate fertilizers with high pH water?

Lance

Check out the University of Georgia extension article in the link I added to the nitrogen - pH thread. It essentially covers David Mellards article but covers your questions too. There is a chart that optimizes % nitrate against alkalinity.

 

[Bjorn]

Prepare for chemistry class

Please folks, do not mix up Ammonium with Urea. I hope that you follow me in this treatise, I might not be able to explain it properly but can at least try:
Please enjoy:
This has all to do with weak acids and salts of weak acids and as you might remember from chemistry class: Ammonium is a weak acid that may be involved in several reactions: A weak acid is an acid that does not dissociate fully and an aqueous solution of it contains significant amounts of unreacted substance. To describe this we commonly write equilibriums like i)
(for more details http://en.wikipedia.org/wiki/Weak_acid)
Ammonium , NH4+; has an acidifying effect in water due to the equillibrium with Ammonia, NH3,
i) NH4+ = NH3 + H+(acid).
(since NH4+ is a weak acid, significant amounts of NH4+ does not get transformed to NH3 and acid, This depends on pH though)
Although Urea can be assimilated through the leaf surface, normally when its used as fertiliser it gets into the soil. There, Urea decompose to ammonia, NH3, and carbon dioxide (CO2) under the action of the enzyme urease that is quite common in soil bacteria etc. The decomposition may be quite quick. The ammonia is poisonous and reacts in an alkaline manner with water:
ii)NH3 + H2O = NH4OH = NH4+ and OH-(base).
The two reactions i) and ii) are linked by the dissociation of water:
iii)H2O = H+ + OH-.
In pure water the concentration of OH- is equal to the concentration of H+ and is 1x10exp-7. As pH is defined as the negative logarithm of the H+ concentration, the pH is then 7 for pure water (this is a matter of definition, if you try to measure you will get acidity due to dissolved gases etc).
So Urea makes the soil increase in pH due to equilibrium ii). This equillibrium is also pH dependent, through reaction iii). But since our common substrates like bark and moss are generally pretty acid, the Ammonia gets converted almost quantitatively to ammonium. A part of this ammonium reacts acoording to eq i), but much less than what is produced. The net effect of urea then becomes an increase in the pH.
If the mix contain ammonium salts like ammonium-nitrate, then you get an acid reaction according to eq. i)
If pH of your substrate is really high, then ammonia becomes an issue, being poisonous (eq ii)) and in these cases urea becomes unsafe to use.:evil:

 

[Bjorn]

I have checked up, and endothermic solution enthalpies are quite common. Personally I saw it yesterday when I was preparing a 20% solution of Epsom-salt (Magnesiumsulphate heptahydrate).

 

[Bjorn]

Again, while your conversions to cations, rather than the oxides we see on the label is correct, the numbers in a fertilizer formula are expressed in weight percent, not ppm.

A 20-20-20 is - by weight - 20% N, 20% P2O5, 20% K2O, with the rest being other ingredients. Hence, the N, P, & K of your 90-10-40 would be 140% of the total - impossible.

Ray I do not really get to your point, what is so bad about calculating the ppm of nutrional elements in a fertiliser solution?oke:
If we are to be picky, then I could ask why you add K2O to your fertiliser mix. Its labelled like that just by convention, we both know that its not there. As with P2O5, or for that sake N. N and P and K are there in other compounds but neiter of the above oxides for sure!:rollhappy: Anyone that has been in contact with K2O and P2O5 knows why :clap:

 

[Ray]

Bjorn, I work with ppm all the time. My point is that when specifying a fertilizer formula on a commercial package, by law (in this country, at least) the ingredients are listed in weight percent, not ppm.

As to why the P & K are specified as oxides, it all dates back to old analytical methods that required that the compounds be "dead burned" to oxides for measurements, and is simply a holdover.

 

[cnycharles]

Anyone that has been in contact with K2O and P2O5 knows why :clap:

.. or had very strong h2o2 drop onto leather boots or gloves! (flames, I believe)

 

[Rick]

.. or had very strong h2o2 drop onto leather boots or gloves! (flames, I believe)

I was so bummed with H2O2. I wanted to test it as a hypergolic rocket fuel.

Really need to get something up >>75% maybe even 90+% to get a good reaction with simple organics as a starter slug.

I tried some 35% with oils and could barely get fizzing

So for the saftey issues with concentrated peroxide it ain't worth it as a decent rocket fuel. It will burn your hands off at concentrations long before getting some good flames going.

 

[Bjorn]

My MK is too vigorous!

Stupid me, I did not account for the nitrification of the Ammonia. According to some that makes soil acid when Urea is used. Others have different views.:sob: Difficult to understand these things - so many dependencies so complex relations. Still Urea as foliar feed seems to work. As a precaution, no need to mix it with the regular fertiliser. Enough of that.
Right now I got this other worry; My Michael Koopowitz has grown from seedling of approx 4" LS to 10" LS plus two new leads in one year. (NB without urea) The problem is that the plants lacks substance, should have had more "dry matter" it gets prone to rot ++ Can you visualise the problem?
What to do except stopping feeding? My Sandie and a Roth is also displaying similar traits though not as bad.

 

[cnycharles]

I was so bummed with H2O2. I wanted to test it as a hypergolic rocket fuel.

Really need to get something up >>75% maybe even 90+% to get a good reaction with simple organics as a starter slug.

I tried some 35% with oils and could barely get fizzing

So for the saftey issues with concentrated peroxide it ain't worth it as a decent rocket fuel. It will burn your hands off at concentrations long before getting some good flames going.

darn, I like my hands... our spray gloves also weren't high-test enough for it also, so I'm glad we no longer have any

bjorn, about your plant being insubstantial(?) and more prone to rot - maybe the light is a bit too low so it stretches. this could lead to thin cell walls. the word is that too much ammonium type fertilizer can make plants grow too lushly, which can lead to possible disease. also if a plant can normally grow too quickly, it can be deficient in both calcium and phosphorus. calcium moves at one speed and sometimes if it isn't available all the time in a small amount a fast-growing plant can outpace the movement from the roots to the rest of the plant. with things like mums that can grow very quickly, have large floral structures (lots of branching and flowers), a lack can cause brittleness, less branching and flowers. not exactly sure how this would translate to orchids though I noticed when I was trying a too-low phosphorus fertilizer things that grew quickly would have problems. actually also for larger plants a breeze can help toughen up plants. movement causes some plant cells to react and toughen cell walls and slow upwards growth. air jets over the top of easter lilies have been used in lieu of growth regulators to keep them shorter. I think that you can use too much nitrate fertilizer for orchids (my opinion based on work, reading and seeing discussions here, not experimental), but I believe a balance of different types could be the most benefitial, and from Rick's experiments, one with less potassium and more calcium.

it could be just that you are using an ammonium-high fertilizer and/or your light could be a little too low. also you might just be under-fertilizing and the plant can't get enough mass as it might normally. also a little more air movement might help