A fun thought experiment.

[Rick]

http://ican.csme.utah.edu/wp-content/uploads/2012/02/Jordan-1980.pdf

Ok check out figures on pg 62. Throughfall (the appropriate term for the "washdown" water) generally runs less than a ppm (mg/L) for several of our favorite nutrients.

 

[Ray]

http://ican.csme.utah.edu/wp-content/uploads/2012/02/Jordan-1980.pdf

Ok check out figures on pg 62. Throughfall (the appropriate term for the "washdown" water) generally runs less than a ppm (mg/L) for several of our favorite nutrients.

I can only see a preview of page 1. Can you share it?

 

[Rick]

I can only see a preview of page 1. Can you share it?

That's odd, when I click on the link from my computor it loads the whole pdf.

Maybe if you cut and paste the link directly into your browser.

 

[gonewild]

The pdf loads for me OK by clicking the link.

 

[Rick]

Correct but as the water containing the washed out poop runs down the tree it is washing nutrients over the roots of all plants below and also dissolving more poop on the way to the ground.
Consider that the rainforest canopy may be several hundred feet tall, that is a lot of collective surface area to accumulate poop between rainfalls. The runoff water becomes a nutrient "enriched" irrigation. Note that I said "enriched" and not "rich".

The other thing to think of concerning poop from animals is that it originally comes from the plants they eat (directly or food chained). So you can't make more than you eat (unless you are a plant). So with minor exceptions of extreme traveling animals (like monkeys and birds). The delivered poop is a volume concentration of what was already present in the edible plant material on hand. Even in the case of traveling monkeys or birds they shouldnt be eating entire forests and then flying to the next adjacent forest and dumping on a single tree (that happens to have the only orchids in the forest).

When you look at this from a mass/balance standpoint poop just doesn't cut it.

 

[gonewild]

The other thing to think of concerning poop from animals is that it originally comes from the plants they eat (directly or food chained). So you can't make more than you eat (unless you are a plant). So with minor exceptions of extreme traveling animals (like monkeys and birds). The delivered poop is a volume concentration of what was already present in the edible plant material on hand. Even in the case of traveling monkeys or birds they shouldnt be eating entire forests and then flying to the next adjacent forest and dumping on a single tree (that happens to have the only orchids in the forest).

When you look at this from a mass/balance standpoint poop just doesn't cut it.

True, larger organisms like birds and monkeys don't poop enough but....
Insects poop too!
Insects also die and dissolve in the water and this provides additional nutrients in the "throughfall" water.

 

[Rick]

True, larger organisms like birds and monkeys don't poop enough but....
Insects poop too!
Insects also die and dissolve in the water and this provides additional nutrients in the "throughfall" water.

But insects also do not eat more than they poop, and the mass of insects in a rain forest cannot exceed the amount of vegetation that they eat. So you can never (by pooping) make more than you eat.

Now the ant thing is a different matter altogether since an ant nest will bring plant material back up from the forest floor (in addition to fungus and various other things growing in the nest). Its still basically recycling the original plant material, but its also a canopy input separate from straight washdown.

The leaf tissue concentration paper that Mike supplied seemed to support the idea that nutrient availability of plants with ant nests seemed to be much higher than for the plants not associating with ants. But that appears to be a very local phenomenon within the canopy.

 

[gonewild]

But insects also do not eat more than they poop, and the mass of insects in a rain forest cannot exceed the amount of vegetation that they eat. So you can never (by pooping) make more than you eat.

So what are we talking about, feeding orchids or feeding the entire forest?
The mass of insects in a tropical forest is huge and may compare to the mass of epithetic plants. In addition insects feed on more than plant material so their poop and dead mass would add to the through fall.

You have been writing that orchids may not need anywhere near the amount of nutrients that was previously thought yet now you seem to be implying that they need more than small amounts of nutrients.

Maybe I am not understanding what you are saying, but I don't see how you can dismiss any source of nutrient as too little?

 

[Rick]

You have been writing that orchids may not need anywhere near the amount of nutrients that was previously thought yet now you seem to be implying that they need more than small amounts of nutrients.

Maybe I am not understanding what you are saying, but I don't see how you can dismiss any source of nutrient as too little?

I don't know if you recall any of the food energy pyramids, but the biomass of primary producers is orders of magnitude more than the biomass of various consumers as you move up from the base. Plus nothing in the successeve layers is not derived from the base of the pyramid in the first place.

From looking at the flux data, probably 90% of the total nutrient base is tied up in the leaf litter and living plant material at any given time, and tiny quanity shuffles around (recycled) as things (mostly plants) die, poop, barf.... and even a tinier amount comes in from outside the system (noting the rainfall data supplied in that one study).

I'm still saying the amount of nutrients that epiphytic plants get is very low compared to what we feed domestic crops. The supplied paper (granted a single specific study I took 5 minutes to Google search), indicates the same very low availability of mobile nutrients in rainforests.

I'm not sure what you mean by dismissing small amounts as too little? Obviously small amounts are critical, but what I've been saying (primarily concerning K) is that the ginormous amounts we typically feed compared to the real world is toxic, or at least a massive waste.

 

[Rick]

Looking at the figures on page 62, the potassium concentration in the rain water and the throughput water ranges from 0.2 to 1.2 ppm (and this is for any given rain event).

If you where feeding MSU fert at 100 ppm you would also be feeding K at a bit over 100ppm.

That is 100X the concentration rained onto that particular forest at any given time.

Ocean water generally contains about 400ppm K.

So MSU fert fed at 100ppm N is 1/4 seawater with regards to K and 100X the normal input rate of K from rain in a normal rain forest.

So what do orchids need? It looks to me to be a tiny fraction of the normal application of MSU

 

[Stone]

I have a bunch of mature paphs (mostly old hybrids and insignes) which have not been fed anything since last May, but surprisingly they are continuing to grow well, have good colour and making new shoots. Proof to me that the amount of nutrient they require is indeed extremely low. I will start feeding a little now that its warming up, but it seems feeding is more to make me feel like I'm doing something rather than for the plants benefit. Certainly I think its totally unecessary during winter or low light. Probably needed under lights.
I remember reading an article by a commercial odontoglossum grower who fed his plants at quite low levels but he said that whenever he had growth problems he stopped feeding and the troubles almost always disappeared.
However although the plants experience low nutrients in the habitat, some at least seem to tolerate or even benefit from higher levels in captivity. You just need to keep a close eye on them and treat them individually.

 

[Rick]

However although the plants experience low nutrients in the habitat, some at least seem to tolerate or even benefit from higher levels in captivity. You just need to keep a close eye on them and treat them individually.

Yes with 30,000 species and 10X that in hybrids/cultivars it's not possible to come up with a single equation for the whole mess. Or to cover all the variability of artificial culture too.

But I think we have overused the expression "killing with kindness" in the orchid hobby for quite some time.

 

[Rick]

I was just wondering if it is really the differences in the plants/situations we argue about or the difference in expectations around the concept of "thriving".

Looking back on my hotrod years. The closer my car was to a Top Fuel Dragster the better. Even if that meant replacing the engine every couple hundred miles. Nowadays the notion of a thriving car for me is one that gets me from point a-b in the most economical, least problematic, lowest maintenance way. Both cars are internal combustion engines, seats, brakes, frames,......but the purpose is totally different.

I know from my hot rod days, I can take the family wagon and add nitrous, turbocharge or supercharge it and compete on the 1/4 mile circuit, but the cost to the life of that car (the other notion of thriving) will definitely suffer for it.

We recently commented on the growing practices for hybrid phals.

Seedling to blooming to trashcan in 2 years? Or monster specimen plant after 10 years?

I think there are a lot of parallels in this analogy.

 

[Rick]

http://www.zoo.cam.ac.uk/zoostaff/foster/PDFs/Ellwood_&_Foster_2004_Nature.pdf

Here's a cool paper relating the biomass of insects to the biomass of canopy vegetation.

I didn't go through all the numbers, but in one example a 200 kg fern contained 150 g of insects. So based on the biomass pyramid example it takes about 1000 X the amount of plants to support a 1g insect.

Or going back to nutrient transfer, the max nutrient transfer to insects is at best (assuming 100% efficiency) about 1/1000 the amount of nutrients in the plant biomass.

 

[bullsie]

I think we grow orchids like we farm. In truth, they obtain fertilization in quite a variety of quantities from never to bountiful. It comes in a variety of ways from living and dead to just plain rain. Surely they are opportunists much as anything alive in the wilds (or like the watermelon plants that come up in the compost pile). And I think we get regular results from growing them like we grow wheat and corn. Do I think there is a 'perfect' way to grow orchids. No, but I think we all search for that stage of growing!

 

[ChrisFL]

Or this thread?

 

[Happypaphy7]

As Stone said, I have in the past, went for nearly one year without any fertilizing at all and everything I had grew and bloomed beautifully.
Back then, I didn't have any seedlings, but all mature plants, so they might have had enough reserve in them plus potting mix breaking down?? I don't know.
Plants I had were mostly Phalaenopsis, Paphiopedilum (bulldog and maudiae types), lots of Oncidiums and some Dendrobiums.

Now I fertilize now, but not much.

 

[StreetVariety]

Have anyone tried growing orchids with leaf litter?