Thoughts on sulphur?

[gonewild]

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

If I believed it was true I would take your word for it. :evil:
I'd like to know how all the sulfur leaches out of bark in a few weeks time and also when does the time start....when the tree is cut or when it gets put into a pot? Come on show the proof!

Personally I know that a good supply of S is a benefit to the plant but since you started the thread and have said Rays plants are deficient of S even though they show no symptoms then you need to support that with proof of some sort.
We can't just leave this for people to think they need to add more S if in fact they don't.

 

[Stone]

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?

Actually no I don't think I said that in relation to orchids in the habitat. Most nutrients for epiphytes (apart from N) comes from rain and canopy leaching.
Most soil S does come from organic matter but it would be from decomosed leaves, moss, lichen, fungi, humus etc. All of which have an enormous surface area. But not big chunks of pine bark.

 

[gonewild]

Actually no I don't think I said that in relation to orchids in the habitat. Most nutrients for epiphytes (apart from N) comes from rain and canopy leaching.
Most soil S does come from organic matter but it would be from decomosed leaves, moss, lichen, fungi, humus etc. All of which have an enormous surface area. But not big chunks of pine bark.

I assume we are not talking about soil. Chunks of pine bark leaching would be somewhat similar to canopy leaching from rainfall.
Pine bark is only an example of many organic components of orchid growing media and it is not just big chunks in a pot.

I think you think I'm arguing against your idea that plants need more S than normally supplied in fertilizer? I'm not.
What I am suggesting is that they get a certain amount from the substrate media and what is normally in fertilizer is enough to make up the difference.

 

[gonewild]

Here...
http://www.isaet.org/images/extraimages/B114003.pdf

Indicates N/S ratio is optimum at 15:1 for invitro seedlings.
That is much higher than K-lite has that Ray mentioned he is using.
But it also does not take into account the long term growth effect of elevated S. Rays observation does take into account long term growth.

 

[Stone]

.

Chunks of pine bark leaching would be somewhat similar to canopy leaching from rainfall.

Nowhere near it

Pine bark is only an example of many organic components of orchid growing media and it is not just big chunks in a pot.

yes. I was refering to pine bark and other chunky material that is used in orchid mixes. However my statement about the lack of N in pine bark was actually taken from my Growing media book which was refering to potting mix with much finer particles (.5 to 4mm) so you would run out of S even more quickly with orchid bark.
If you add moss, leafmould etc, that would be a different story.

I think you think I'm arguing against your idea that plants need more S than normally supplied in fertilizer? I'm not.
What I am suggesting is that they get a certain amount from the substrate media and what is normally in fertilizer is enough to make up the difference.

Which is what I initially said. I just like the idea of having soluble S (and Ca) available to the plant when I am using plain water.

 

[Ray]

I'll drop in a couple of points here.

1) None of us actually knows what a plant requires. It's all conjecture based upon incomplete data, and that data is particularly sparse when it comes to orchids.

2) I don't think we should underestimate the array of chemicals exuded by the forest canopy-producing vegetation. Most minerals are, indeed, in the soil. Their roots draw them in and spread them around the terrestrial plants, and I have no doubt that they ultimately get exuded and end up in the solutions the epiphytes see. (For example, Alan Koch mentioned that rupicolous laelias are common to areas where the soils are particularly high in iron, so it should be enhanced in their feeding regimen.)

3) "Concentrations mattering less than ratios" is crap. (Forgive me, Mike. I'm trying to make a point.) An insufficient supply of the "ideal dietetic ratios" will still result in starvation. Considering the extremely dilute nature of those solutions the epiphytes see, I suppose one might conclude that in the case of orchids, ratios might be of more import, but I think the general statement is too broad to be valid.

 

[Stone]

3) "Concentrations mattering less than ratios" is crap.

I can give same plant a concentratrion of solution varying from an EC of 0.1 to 1.0. and it would still grow perhaps much more slowly with the first or more quickly with the second. However, because the ratios are in correct balance it would not suffer any particular deficiency as the growth is mainly coverned by the amount of N.

Remember that a orchid can survive for years without ANY fertilizer applied. I have a few in my shadehouse. You could say they are staving maybe but they do not show signs of a particular deficiency, just generally stunted.

Now if I varied the ratios by the same factor of 10, for example 10 times less S or 10 times more Mg, I would kill the plant.
That is hardly ''crap''

I'm not proposing to know what the best ratios are, but going by has been shown so far we have a ''rough'' idea what they should be in some cases.

 

[naoki]

Now if I varied the ratios by the same factor of 10, for example 10 times less S or 10 times more Mg, I would kill the plant.
That is hardly ''crap''

I think this part is the key; if the orchids can have a wide sufficiency range, then it becomes what Ray is saying. From the perspective of deficiency, it is the system where one limiting factor determines the growth rate (within the limitation of the plant physiology). I know that you all know this, but here is the quote from the growing media book (p. 147):

"... As far as nutrients are concerned, each nutrient is a separate necessity. One cannot substitute for another. Plant growth is limited by that nutrient in lowest supply... Increasing the supply of that nutrient will increase growth, as in Fig 14.3, until it is again limited by the nutrient in second lowest supply, ...."

So as long as there are sufficient elements, then photosynthesis (C supply) becomes the limitation. So the actual ratio doesn't matter as long as there is enough of each (Ray's view). But too much of some elements can cause the toxicity (via direct physiological problem or indirect effect of interference among minerals). If the sufficiency range is relatively narrow as Mike thinks, then the ratio starts to become more important.

I've been thinking more closer to Ray's perspective; epiphytes (slow growers) are quite flexible in sufficiency range, so as long as there is enough of each, they should be ok (but we all know that high EC can cause the problems with water uptake and root dehydration). But it's just my gut feeling.

Anyway, thanks for the gypsum topic, Mike. I started to read the chapter of the grow media book, and I agree with Mike that it is something interesting to experiment with. I'll wait to see what you will find out!

Also Mike's recommendation of the grow media book was great! Here is the link to the book. The amazon price in the US has come down recently (but it is starting to go up again), and it covers a wide range of topics. It is quite a bit easier to read, and more practical than Marrchner's Mineral Nutrition of Higher Plants (which goes into scientific literature at a deeper level).

Lance's link to N/S ratio of Phal bellina is pretty interesting. Thanks for finding this, Lance! The abstract seems to be an overstatement (1:15 is the best). Statistically, it seems that they should have said that as long as S is lower than 1:15, the plants grew well. The grow media book mentions that S requirement vary widely among among taxonomic groups (p.197), so it is a good info!

 

[Happypaphy7]

Mike's original question has still not been answered.

"Ratio among different elements available to plants mattering less as long as there is enough of all required elements" is rather different than saying ratio matters less than concentration.

As much as I hate to stray away from the original topic, is there any good study done regarding how different orchids show deficiency symptoms of different elements? I don't think I've come across with good examples and many people tend to go by examples taken from very well studied food crops, which can be highly misleading as different plant groups show deficiency symptoms quite differently.

Also, does that book mention N/S ratio ideal for paphiopedilums? Then again, even among paphs, there are subgroups that might or most likely have different requirements.

By the way, Mike said orchids can survive years without any fertilizing, I'm not sure about years, but in the past I got lazy and never fertilized for at least full year. This is when I had just phals (straight sphag or straight bark), yellow dancing lady oncidiums (promix) and paph maudiae type hybrids (straight bark or promix). I watered them all with tap water. never fertilized for one full year or more.
Phals all grew well and flowered in time. Oncidiums grew well and flowered twice a year with many flowers. Paphs grew and flowered up to three times a year. I wonder if they can store nutrients in their leaves for very long time or maybe the potting mix maintain some fertilizers from earlier fertilizing? This I would say no because with all the watering, I would think almost all might have been washed away. hmmm no idea. or breaking down of mix that helped a little?

 

[Stone]

So as long as there are sufficient elements, then photosynthesis (C supply) becomes the limitation. So the actual ratio doesn't matter as long as there is enough of each (Ray's view).

Some nutrients are taken up at the expense of or more easily than others. This is the reason why ratios are so vital.
BTW, I'm also talking about the FORM of the nutrient as well as how much of it.

You cannot disolve 10 or 50mg of every nutrient in water and expect the plants to sort it out.
Another example, Some hydroponic people discovered that they could reduce their concentration by 50% without affecting the yield at all! That is reducing the concentrations of ALL nutrients by 50%! The ratios do not change.
It is vital that the correct ratios are determined (as near as possible) for a species. Eg, I think I have the ratios of elements pretty good for my Phaleanopsis. (I went roughly by this:

http://www.researchgate.net/profile...omposition/links/53e9bba10cf28f342f413ba4.pdf

(you may have trouble with this link but if you type it into google scholar you will find the full text)

I got massive growth so ratios are good so far. The concentration varies between 0.5 and 1.0 dS/m. I'm sure I could feed the kind of concentrations seen in the habitat (almost nothing) and still get healthy growth. (but much reduced)

If I used the Peters or Ross formulas rather than Ichihashi in this paper growth would reduced. However, all formulas give more than enough concentration of each nutrient. (remember the habitat concentrations)
It's the ratios (or composition) which makes all the difference.

 

[Stone]

Personally I know that a good supply of S is a benefit to the plant but since you started the thread and have said Rays plants are deficient of S even though they show no symptoms then you need to support that with proof of some sort.

No, I said that either they are deficient OR they are getting it from some other source. (probably the kelp)
When researching sulphur I read that plants can be deficient in S long before they show symptoms and maybe then just a general paleness. Seems the slower the growth the more vague visual deficiency symptoms are. (that's just my theory though)
Personally, I don't think there is enough S in K-lite alone. I remember reading quite a few people having problems with leaf colour with k-lite. S could be one of the factors affecting that.
As there is good K and S in kelp, it may be the perfect addition to balance K-lite?
Actually, I found K-lite worked really well if I mixed it a little with a bloom booster which raised the P, K, NH4 and S concentrations.

 

[gonewild]

Actually, I found K-lite worked really well if I mixed it a little with a bloom booster which raised the P, K, NH4 and S concentrations.

The logical experiment for you is to try using k-lite and add only additional S. Then you will have the answer whether it is the S that made a difference or if it was the addition of one or all of the other nutrients.

Then you need to define what you mean by "worked really well". What improved by the addition of bloom booster and what was the problem before you added it.

 

[myxodex]

One point I initially found confusing in the sulphur literature was the use of the terms S-limited and S-deficient.
S-limited means that there is insuffient S for the assimilation of available N. Most of the single component fertilisers are providing S at a limiting ratio simply because of the practical problem of CaSO4 precipitation. It is very easy to fix this situation, simply by adding a bit of tap/well water to your mix. Even rain water typically has a few ppm S courtesy of volcanoes and fossil fuel burning, so it is only in the exclusive use of RO water that S limitation is likely. In the wild, my guess is that orchids are far more likely to be N limited than S limited because of the S in rainfall and the fact that they need only 1/15 of the S as N.

One issue with S limitation that I think just might be worth consideration is oxidative stress. High light levels, toxic metals and pathogen infection are all situations in which plants are exposed to above background levels of reactive oxygen species (ROS). ROS cause damage, including mutation, and are neutralised by antioxidant systems, the most important of which are glutathione and vitamin C. In fact ROS are generated all the time during photosynthesis and the need for an efficient antioxidant system is continuous in all aerobic organisms, not only plants. The glutathione system is sulphur based and competes with protein synthesis for the supply of cysteine. In addition to the glutathione antioxidant system, there are other S compounds such as phytochelatins which bind toxic metals, phytoalexins (some of which are S containing) which are involved in pathogen defenses. These S compounds are all induced, i.e. rapidly synthesized on demand, so under S limitation this protective response to any additional oxidative stress is compromised. My guess is that chronic S limitation may be asymptomatic for the most part, but may result in plants that are less robust and more prone to accumulative genetic damage (senescence ?) than those that have adequate S. Also there are numerous papers out there about S and pathogen resistance in plants, just google it, and you will come across a whole field of research about SIR, "Sulphur Induced Resistance".

 

[Stone]

The logical experiment for you is to try using k-lite and add only additional S. Then you will have the answer whether it is the S that made a difference or if it was the addition of one or all of the other nutrients.

Then you need to define what you mean by "worked really well". What improved by the addition of bloom booster and what was the problem before you added it.

I have completely abandoned the idea of low K being particularly beneficial in itself so I won't bother to experiment further with it. However I do believe that high N, P, or K concentrations are not needed and may be counter-productive with many orchids. So I reduce all three not just the K. (and P)