Thoughts on sulphur?

[Stone]

Given that the loss of Sulphate-S from containers is in direct proportion to the amount of water leaving the pot (sulphate being an anion), I think it is safe to assume that in some cases the leaching of S from pots may be too much unless there is a continuous supply.

Also, considering that many plants use as much S as they do Phosphorus I believe that some ferts are not providing enough.
I wonder if the greening of plants sprayed with Mg sulphate are showing a response to the S as much as the Mg in many cases. Remembering that the Mg is held much more in the media than the S.

If we are using very pure water and water a lot, perhaps we need to consider supplementing S in some way.
I have gone back to adding a sprinkling of crushed rock gypsum to the top of pots as well as a little (as fine powder) to the irrigation water.
I am pretty sure I have observed some greening.

It is suggested that S should be around 1/8 of the N. 95% of the SO4 in the soil comes from decomposed organic material (the kind of stuff Paph roots grow in)

Has anyone else considered this?

 

[naoki]

Tim (myxodex) made a very interesting point about the similar topic last year:

http://www.slippertalk.com/forum/showthread.php?t=35172

It appears that atomospheric SO2 can contribute somewhat. But precipitation of Ca SO4 could be an additional cause of S deficiency.

 

[Stone]

Thanks naoki. I should have searched
However the point remains relevent! It seems S is often easily forgotten. There is very little S in the water or the air down here. (at least insufficient)

 

[naoki]

After Tim's point, I read a bit about S deficiency. "Generally" S deficiency should show up in the relatively new tissues since the phloem mobility of S is intermediate.

http://www.ces.ncsu.edu/plymouth/cropsci/docs/sulfur.html
http://plantscience.psu.edu/researc...itional-disorders-displayed/sulfur-deficiency

After I saw the results of a nutrient deficiency experiment of my students (with sunflowers), I re-confirmed that those "typical" deficiency symptoms quoted to some crop plants are not general to all species. So we shouldn't be stuck with what people say about corns or tomatoes. I wish we could do the same kind of deficiency experiments with Paphs!

There were several opinions about the chlorosis I observed in this thread:
http://www.slippertalk.com/forum/showthread.php?t=36454
But I still think that S deficiency (via Ca So4 precipitation in the stock solution) is the most likely cause in this case. The plant is completely recovered now. I'm (stupidly) still using the heavily precipitated MSU with MgSO4 addition (for some plants), and I haven't seen another victim yet....

If I'm right about this (i.e., S is relatively immobile in orchids), then greening up of the whole-plant chlorosis by epsom might not be due to S deficiency. But this is a pure speculation, and good to hear what others think about it!

I might be wrong, but didn't Rick say that he is supplementing K-lite with MgSO4 recently?

So is there advantage to use not-so-soluble Gypsum over Epsom, Mike? Is it like a slow-release fertilizer?

 

[Bjorn]

I am currently feeding With my home-made mix at approx 60ppm TDS. Below, the composition is given in ppm

ppm
N total 10,136
NH4 6,399
NO3 3,737
P 0,948
K 1,580

Ca 3,442
Mg 1,157

Fe 0,057
Mn 0,343
Zn 0,192
Cu 0,161
B 0,111
Mo 0,056
Co 0,007
Ni 0,009
Na 0,027
Cl 0,011
S 7,897
You might notice that there is only 10ppm N, no urea but 2/3rds of it as ammonium, and an almost equal amount of sulphur (as sulphate). Additional is citric acid to regulate pH and to complex.
Occasionally (once a month) I also add kelp and recently started an addition of 50ppm fulvic acid with the fertiliser.
Although the addition is tiny, so far I have not seen any signs of deficiency, actually a few of my plants have shown quite an improvement after turning into this feeding regime. The leaf-colors are nice grass-green, not very dark and not yellow, just green. I pay a particular attention to the leaf-sizes, the last leaf should never get smaller. Seems to work out fine so far, most new leaves are significantly bigger than the previous.
What is obscuring the total picture somewhat and potentially be the reason for the good growth, is tha water I use. Its coming from a bog and has a conductivity of some 150 microsiemens, which should transform to some 100ppmTDS if I remember rightly. Some of it is probably humic substances, there is no alkalinity nor Ca or Mg or nitrate. I simply do not know whats in it. Guess its low in nutrients though.
I firmly believe that the slippers do not need more nutrients than I give them and that my proportions in the micro-range is closer to their needs than what is commonly offered. If you look at the proportions in the micros, (below) my Fe:Mn:Zn is 1:6:3, more common is 3:2:2 (K-Lite)
Fe/X
Fe 1,00
Mn 6,07
Zn 3,39
Cu 2,85
B 1,96
Mo 0,99
Co 0,13
Ni 0,15
Na 0,47
Cl 0,19
There is much more of the micros as well, in my mix there is e.g. 0.57% Mn, below 0.1% is common in other fertilisers (K-Lite has 0,08%Mn) All micros are twice to four times higher than common. The reason is of course to have them available at the very low fertiliser levels I am using.
Results? so far so good, after three months of application, and before that three months of no fertiliser, I have not seen any new symproms of deficiency. Some of the plants have shown , I would phrase it shockingly, good growth, a few leaves being not bigger than their predecessors, but that is it. My canhiis are prospering, my kovachiis seem to thrive, marginal decease incidents only etc.
Is it due to the feeding regime? I do not know, still too early to judge long term effects but so far its good.

 

[Stone]

So is there advantage to use not-so-soluble Gypsum over Epsom, Mike? Is it like a slow-release fertilizer?

Yes it is.
I don't think there is a specific advantage. If you feed at every watering and your feed has good SO4 levels you won't need to do it. However I water very heavily (with rainwater mainly) when I do and I suppose one ''advatage'' is that with the use of solid CaSO4 there is always a certain imput of Ca and S. Gypsum is some 10 times more soluble than limestone so you can use quite large particle sizes (up to 3mm). All of the gypsum samples I have tried have a small percenatge of Carbonate in them as well (going by pH)
I also use my organic fertilizer as my main source of nutrients and there is good S levels in that as well.

 

[Stone]

I am currently feeding With my home-made mix at approx 60ppm TDS. Below, the composition is given in ppm

ppm
N total 10,136
NH4 6,399
NO3 3,737
P 0,948
K 1,580

Ca 3,442
Mg 1,157

Fe 0,057
Mn 0,343
Zn 0,192
Cu 0,161
B 0,111
Mo 0,056
Co 0,007
Ni 0,009
Na 0,027
Cl 0,011
S 7,897
You might notice that there is only 10ppm N, no urea but 2/3rds of it as ammonium, and an almost equal amount of sulphur (as sulphate). Additional is citric acid to regulate pH and to complex.
Occasionally (once a month) I also add kelp and recently started an addition of 25ppm fulvic acid with the fertiliser.
Although the addition is tiny, so far I have not seen any signs of deficiency, actually a few of my plants have shown quite an improvement after turning into this feeding regime. The leaf-colors are nice grass-green, not very dark and not yellow, just green. I pay a particular attention to the leaf-sizes, the last leaf should never get smaller. Seems to work out fine so far, most new leaves are significantly bigger than the previous.
What is obscuring the total picture somewhat and potentially be the reason for the good growth, is tha water I use. Its coming from a bog and has a conductivity of some 150 microsiemens, which should transform to some 100ppmTDS if I remember rightly. Some of it is probably humic substances, there is no alkalinity nor Ca or Mg or nitrate. I simply do not know whats in it. Guess its low in nutrients though.
I firmly believe that the slippers do not need more nutrients than I give them and that my proportions in the micro-range is closer to their needs than what is commonly offered. If you look at the proportions in the micros, (below) my Fe:Mn:Zn is 1:6:3, more common is 3:2:2 (K-Lite)
Fe/X
Fe 1,00
Mn 6,07
Zn 3,39
Cu 2,85
B 1,96
Mo 0,99
Co 0,13
Ni 0,15
Na 0,47
Cl 0,19
There is much more of the micros as well, in my mix there is e.g. 0.57% Mn, below 0.1% is common in other fertilisers (K-Lite has 0,08%Mn) All micros are twice to four times higher than common. The reason is of course to have them available at the very low fertiliser levels I am using.
Results? so far so good, after three months of application, and before that three months of no fertiliser, I have not seen any new symproms of deficiency. Some of the plants have shown , I would phrase it shockingly, good growth, a few leaves being not bigger than their predecessors, but that is it. My canhiis are prospering, my kovachiis seem to thrive, marginal decease incidents only etc.
Is it due to the feeding regime? I do not know, still too early to judge long term effects but so far its good.

Not a bad mix Bjorn (your K is too WAY too low for my liking though)
So what is the EC of your final watering mix?

 

[Bjorn]

Not a bad mix Bjorn (your K is too WAY too low for my liking though)
So what is the EC of your final watering mix?

Varying a bit but approximately 250µS as far as I remember. The addition is 1:160 using 0,5% solution twice (one stock without Mg and Ca and one with) using two proportioners. Should give approximately 60ppm into the water. The K is kind of compromise

 

[Ray]

Also, considering that many plants use as much S as they do Phosphorus I believe that some ferts are not providing enough.
I wonder if the greening of plants sprayed with Mg sulphate are showing a response to the S as much as the Mg in many cases. Remembering that the Mg is held much more in the media than the S.

If we are using very pure water and water a lot, perhaps we need to consider supplementing S in some way.

I agree with Naoki's assessment that we can't read too much into studies done with other plants, so we really don't know if that first statement quoted is even pertinent.

Also, S demand varies all over the map, and as it plays a key role in protein synthesis in plants, it makes sense that slow-growing plants, like orchids, probably don't need as much as fast-growing plants.

I use pure water (RO @ <10 ppm TDS), flood the plants at least 3x/week, but have 25 ppm N K-Lite in it at every watering. K-Lite is 0.1% S or roughly 10% of the level of P, and at 3.5 years into that feeding regimen, I see no indications of any deficiencies. They're not getting a lot of anything, but they get a little, and get it often.

 

[gonewild]

However I water very heavily (with rainwater mainly) when I do and I suppose one ''advatage'' is that with the use of solid CaSO4 there is always a certain imput of Ca and S. Gypsum is some 10 times more soluble than limestone so you can use quite large particle sizes (up to 3mm). All of the gypsum samples I have tried have a small percenatge of Carbonate in them as well (going by pH)
I also use my organic fertilizer as my main source of nutrients and there is good S levels in that as well.

Adding gypsum to the media supply S seems like it kind of defeats the value of pure water. The advantage of having pure water (rainwater or RO) is that it has no nutrients in it. This gives you the opportunity to add to the water exact amounts of any nutrient you want o supply and you know what the amount is. When you add solid materials that slow release nutrients to the substrate you have no idea how much will dissolve with each watering so you have no idea what nutrients are actually available to the plant.

Sulfur should always be available for the plants so it should be included in the nutrient list of the fertilizer being used. There does not seem to be a problem with over supplying S so I always use MgSO4 and it seems to provide enough so that I've never had an S deficiency.

In reality there probably is enough S leaching from the bark and organic matter in the media or coming from the atmosphere that keeps the plant supplied without adding S to the water.

 

[Stone]

Also, S demand varies all over the map, and as it plays a key role in protein synthesis in plants, it makes sense that slow-growing plants, like orchids, probably don't need as much as fast-growing plants.

Obviously slow growers will need less of everything. But lets not get caught up in arguments about concentrations again. It's really the ratios that are important. So if we accept that all plants require between 1/8 and 1/10 S of their N, a feed should also contain these types of ratios.

I use pure water (RO @ <10 ppm TDS), flood the plants at least 3x/week, but have 25 ppm N K-Lite in it at every watering. K-Lite is 0.1% S or roughly 10% of the level of P, and at 3.5 years into that feeding regimen, I see no indications of any deficiencies. They're not getting a lot of anything, but they get a little, and get it often.

Therefore I would suggest that the S in k-lite is nowhere near enough and your plants are either getting enough from the kelp you use or are deficient in S whether it is visually obvious or not. Symptoms may not be apparent unless there is a severe deficiency.

 

[Stone]

Adding gypsum to the media supply S seems like it kind of defeats the value of pure water. The advantage of having pure water (rainwater or RO) is that it has no nutrients in it.

Well not really. The value of pure water is having no unwanted elements in it.

This gives you the opportunity to add to the water exact amounts of any nutrient you want o supply and you know what the amount is.

Yep. As long as you add the correct ratios of nutrients

When you add solid materials that slow release nutrients to the substrate you have no idea how much will dissolve with each watering so you have no idea what nutrients are actually available to the plant.

When it comes to gypsum I know exactly how much is dissolving with each watering.
When added at 0.75gm/L of media there is about 40mg/L in the drainage water after 20 days and about 20mg/L after 60 days when used at 2 to 4 mm particle sizes. (I use less than these amounts) But I know there will be aprox 10mg/L or 10ppm S (at least) in the media water at all times.

Sulfur should always be available for the plants so it should be included in the nutrient list of the fertilizer being used. There does not seem to be a problem with over supplying S so I always use MgSO4 and it seems to provide enough so that I've never had an S deficiency.

No doubt. However I'm not crazy about supplying S with only MgSO4.

In reality there probably is enough S leaching from the bark and organic matter in the media or coming from the atmosphere that keeps the plant supplied without adding S to the water.

That's where you're wrong. S is depleted within weeks from a bark medium without more constantly coming in.

 

[gonewild]

So if we accept that all plants require between 1/8 and 1/10 S of their N, a feed should also contain these types of ratios.

Therefore I would suggest that the S in k-lite is nowhere near enough and your plants are either getting enough from the kelp you use or are deficient in S whether it is visually obvious or not. Symptoms may not be apparent unless there is a severe deficiency.

Or you were wrong in assuming all plants require 1/8 - 1/10 S of their N.
Or orchids extract S from the media. Pine bark has about 2ppm S content that would add to the S supplied in the fertilizer solution.

 

[gonewild]

That's where you're wrong. S is depleted within weeks from a bark medium without more constantly coming in.

Within weeks is pretty fast. Is that fact or assumption?

 

[gonewild]

I was incorrect pine bark has a higher sulphur content than I wrote above.

Pine bark composition ppm:

NO3-N (ppm) 0.1
NH4-N (ppm) 0.1
P (ppm) 4.0
K (ppm) 52.5
Ca (ppm) 16.2
Mg (ppm) 11.5
SO4 (ppm)50.9

 

[Stone]

Within weeks is pretty fast. Is that fact or assumption?

Fact

 

[Stone]

I was incorrect pine bark has a higher sulphur content than I wrote above.

Pine bark composition ppm:

NO3-N (ppm) 0.1
NH4-N (ppm) 0.1
P (ppm) 4.0
K (ppm) 52.5
Ca (ppm) 16.2
Mg (ppm) 11.5
SO4 (ppm)50.9

You are only going to see a tiny fraction of that from the SURFACE of the bark as it breaks down over time. Not nearly enough for any plant Lance.

 

[gonewild]

Fact

Can you please share the documentation for the fact.

 

[Stone]

Can you please share the documentation for the fact.

Man why can't you just take my word for it for once!oke:

 

[gonewild]

You are only going to see a tiny fraction of that from the SURFACE of the bark as it breaks down over time. Not nearly enough for any plant Lance.

Mike in your previous arguments about sources for plant nutrients you insisted that most nutrients come from decaying plant matter. Now you have reversed your thinking?