# A fun thought experiment.



## ChrisFL (Oct 18, 2012)

I'm a climate guy, so it's fun to think of orchids with respect to climate. 

So, in regions of Papua New Guinea, Borneo, etc., it's not uncommon for a total of 3 meters (9.84252 ft) of rainfall to occur in a single year. 

Let that sink in. 

Now, lets take a sample, a hobby greenhouse. 8' x 12'

Let's do a simple calculation to see how much average daily "precipitation" it would require to give you a similar annual total. 

8' x 12' x 9.84252' = 944.88192 cubic feet of water, or 7068.21 gallons. Divide that by 365.25, that comes out to 19.35 gallons of water being dumped into this hobby greenhouse daily, on average. 

Let that sink in. 

Now with all that dilution and washover, how much "fertilizer" are these orchids, assuming epiphytes like Bulbos, REALLY getting?

You could also easily model a seasonal cycle in rainfall as well, but the places mentioned above rarely have one of any significance.


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## gonewild (Oct 18, 2012)

Look at how many cu' of water you actually used in the greenhouse in one year and see how many inches of rainfall that compares to.


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## mormodes (Oct 18, 2012)

Yikes, I really need to water more


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## Rick (Oct 18, 2012)

ChrisFL said:


> that comes out to 19.35 gallons of water being dumped into this hobby greenhouse daily, on average.
> 
> Let that sink in.
> 
> ...



I came up with similar conclusions looking at the papers on nutrient flux in rain forests, and then my epiphany of tracking pot EC to watering frequency (and water quality).

I was moving about 1-2 gallons a day in my 12X12 gh and attributed (by convention) root rot to overwatering. But then when measuring EC found that I was concentrating salts by underwatering/evaporation cycles. 

So now I'm watering at 2 x what I used to, fertilizing even less, and getting roots like crazy. I don't think I can afford to go to 20 gallons a day, but I'm completely in aggreement with your point.


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## keithrs (Oct 18, 2012)

I can't agree more with mimicking nature... After all, it is the best teacher!

I'm a firm believer in misting(heavy) orchids for longer periods, possibly several times each watering.... Rather than watering by hand with a heavy dump of water.

On the idea of how much diluted fertilizer do epiphytes really get is the reason way I cut my fertilizer from 125 PPM N down to 30 PPM N and I'm going to cut it even more starting next spring down to 10 PPM N.


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## keithrs (Oct 18, 2012)

Rick said:


> I came up with similar conclusions looking at the papers on nutrient flux in rain forests, and then my epiphany of tracking pot EC to watering frequency (and water quality).
> 
> I was moving about 1-2 gallons a day in my 12X12 gh and attributed (by convention) root rot to overwatering. But then when measuring EC found that I was concentrating salts by underwatering/evaporation cycles.
> 
> So now I'm watering at 2 x what I used to, fertilizing even less, and getting roots like crazy. I don't think I can afford to go to 20 gallons a day, but I'm completely in aggreement with your point.



4 GPD for the amount of plants you have..... Are you crazyoke: 

I would of thought you would be in the 10-15 range for sure!!!

I waste 15 GPD, some times more watering the small amount of plants I have and they could use more.:evil:

I guess a greenhouse makes all the difference!!!


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## Rick (Oct 18, 2012)

keithrs said:


> 4 GPD for the amount of plants you have..... Are you crazyoke:
> 
> I would of thought you would be in the 10-15 range for sure!!!



Part of it is based on the nature of the collection. Probably ~1/3 - 1/2 is mounted or in baskets with very little substrate. So it doesn't take much water to spray them off and end up with most of it hitting the floor.

And then with all the potted stuff we all are cautioned for years that "overwatering causes root rot", and just water to keep things moist (not dripping wet) between waterings. So with 70%+ humidity it doesn't take a lot of water to keep pots damp.

Before I put an auto fill valve on the sump to the wet pad/humidifier, I used to add about 5 gallons a day to keep up with humidification.

So my total water budget could actually be rated at 5 or so gpd more than what I actually squirt on the plants on a daily basis.


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## Rick (Oct 18, 2012)

In one of my earlier cooling/humidifcation itterations using simple misting I did go through at least 20 gal/day, and ended up having water seep under the foundation of my house, (and pooling up under the laundry room).

Anyway when I spray much more than a few gallons at a time, most just ends up on the ground and has no impact on the orchids whatsoever.


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## Stone (Oct 18, 2012)

If we assume that many paphs recieve 100 inches of rain over the growing period (in round figures) over say 6 months, thats 1/2 inch of water per day but obviously not every day. Sometimes they may get nothing and other times 4 inches. When I water my seedlings (especially) I dunk them 3-4 times. When I use the hose, I give the same amount. So for a tube 3 inches deep, thats around 10 inches of water each time.....(about every 3 days) so in fact they are getting lots more water than habitat. BUT with all that leaching its desirable to have a very low but constant supply of nutrients. Thats why comming up with a system of low-level slow release nutrient supply always seems to give me the best results.
Unfortuately no one has come up with a good controlled release fertilizer for paphs. Although Osmocote is working exeedingly well with all my epiphytes along with the roths, phillpis and lowiis etc. Maybe when my seedings are mature it might work well for all. I only worry about the left-overs when dormancy comes around.


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## NYEric (Oct 18, 2012)

Yay watering!!!


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## Ray (Oct 19, 2012)

So let's consider the impact this heavy water supply has on nutrient availability.

Chris mentions "dilution and washover", which certainly are factors, but there are other things to consider.

Plants exude all sorts of nutrients through their leaves, and a heavy rainfall may actually leach more, even thought the plants have mechanisms that try to slow that. There have been lots of studies that have shown the large nitrogen flux associated with drippage from the canopy. I suppose it's possible that the total mass of nutrition might be greater in a "high water volume x more dilute" scenario than one in which the rainfall is lower, even if the nutrient concentration per rainfall is higher.

For plants that live in humus and leaf litter on the forest floor, a lot of rain keeps it moist, freeing ions and making them more available - dry media = no absorption. Again, likely more dilute, but possibly still available in greater total mass.

And....I suppose we can add the elimination of conflicting solubilities. A drier substrate means less solvent. Try mixing calcium nitrate and Epsom salts as a concentrate - or Pro-Tekt and a fertilizer, for that matter. No go. Mix them in a dilute fashion and "no go" becomes "no problem", avoiding precipitation, hence making the minerals available to the plant.

Speculation.... (sigh).

Data, please.


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## Rick (Oct 19, 2012)

Ray said:


> Plants exude all sorts of nutrients through their leaves, and a heavy rainfall may actually leach more, even thought the plants have mechanisms that try to slow that. There have been lots of studies that have shown the large nitrogen flux associated with drippage from the canopy. I suppose it's possible that the total mass of nutrition might be greater in a "high water volume x more dilute" scenario than one in which the rainfall is lower, even if the nutrient concentration per rainfall is higher.



This thread is somewhat resurrecting the old K lite ideas from last year. I have some papers on nutrient flux in rainforests from that work and a couple more abstracts have trickled in since. Bottom line is that the total amount of nutrients cycled through a rainforest system is very low compared to an agricultural setting (with applied fertilizer). And given the rainfall amounts and the fact that water flows downhill, the creeks, rivers, and streams, are the final recipients of all this wash down. The amounts of nitrogen phosphorus and potassium at "the bottom of the hill" are negligible (by are heavy feeding agricultural standards), but easily able to support plant growth. When I get a break I'll dig out one of those papers to provide a number, but the wash down water collected as it came down off of the leaves and tree trunks was pretty dilute in the papers I looked at.

I wasn't able to get the whole paper of something I was recently trying to get hold of, but it quantified the amount of leaf litter accumulated in a canopy (available as a nutrient sink for epiphytes) and found that only about 1% of total leaf fall actually stayed in the trees.


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## ChrisFL (Oct 19, 2012)

Any papers you'd like full copies of, pm me. I likely have access.


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## gonewild (Oct 19, 2012)

Ray said:


> Plants exude all sorts of nutrients through their leaves, and a heavy rainfall may actually leach more, even thought the plants have mechanisms that try to slow that.



Just throwing out thoughts about this......

Perhaps plants exude nutrients through their leaves in an effort to get rid of internal excesses?

Any exuded nutrient washed from the leaves to the root zone would /could be reabsorbed by the roots if needed. But the "if needed" assumes plants know what they need to absorb and are selective. More likely the roots absorb the maximum possible and then the leaves throw off the excess.


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## Rick (Oct 19, 2012)

At least with regard to K there is no excess.

If you recall the paper on uptake of K by bromiliads, this was an energetic process to capture small amounts of K from "very dilute sources".

There already is a link on this forum to a paper on Panamanian epiphyts that shows that lots of the nutrients in leaves is reabsorbed by the plant before leaf drop.


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## bullsie (Oct 24, 2012)

Seems to me that the natural areas of these plants have some of the greatest numbers of 'high' dwelling critters of all shapes and sizes. How do orchids react to a 'windfall' of fertilizer passing through every now and again? Not that I can see this as a daily regimen but in a week or month or year everyone surely must get this fertilization.


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## Rick (Oct 24, 2012)

bullsie said:


> Seems to me that the natural areas of these plants have some of the greatest numbers of 'high' dwelling critters of all shapes and sizes. How do orchids react to a 'windfall' of fertilizer passing through every now and again? Not that I can see this as a daily regimen but in a week or month or year everyone surely must get this fertilization.



The only significant imput from aboreal critters appears to be ants that nest around some orchid species (like Gongoras, Coryanthes, and some Catesetum). In these cases the ants are bringing/trapping leaf debris and mulching it in the form of their nest around the roots of the plants.

But things like monkey bird or frog poop wash out pretty fast with the heavy rains noted in a rain forest. And poop from random critters is also a pretty rare and random event given amount of plant density in the forest.


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## gonewild (Oct 24, 2012)

Rick said:


> And poop from random critters is also a pretty rare and random event given amount of plant density in the forest.



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".


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## Cheyenne (Oct 24, 2012)

I remember seeing pictures of cattleya and pictures of paphs(I think lowii) in a tree, both from different parts of the world. The plants leaves were so covered in bird or some other animal droppings that they didn't even look green. They looked like there was paint dripped on them. Both the plants were huge. I am sure alot of this runs to the roots when it rains. Especially since most plants are designed in structure to sent water to the roots. If it does was off I am sure it doesn't take that long to accumulate again. In the rainly season the concentration might be less and stronger in the dry. This was one of the reasons I started adding some organic fertilizers like bat guano and worm tea. Plants did great but the smell was a little much indoors.


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## Rick (Oct 24, 2012)

Cheyenne said:


> I remember seeing pictures of cattleya and pictures of paphs(I think lowii) in a tree, both from different parts of the world. The plants leaves were so covered in bird or some other animal droppings that they didn't even look green.



Granted there's not a ton of insitu pics out there, but at least 9 of 10 of the pics of epiphitic plants I see have pretty clean leaves.

I promise I'll dig it out later, but the washdown water data is pretty dismal in terms of finding large concentrations of nutrients.

As noted from much of the leaf tissue and leaf litter data, epiphytic plants are masters of conservation and recycling because the total nutrient availability is so low (certainly compared to domestic agricultural crops).


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## Rick (Oct 24, 2012)

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.


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## Ray (Oct 25, 2012)

Rick said:


> 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?


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## Rick (Oct 25, 2012)

Ray said:


> 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.


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## gonewild (Oct 25, 2012)

The pdf loads for me OK by clicking the link.


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## Rick (Oct 25, 2012)

gonewild said:


> 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.


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## gonewild (Oct 25, 2012)

Rick said:


> 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.


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## Rick (Oct 25, 2012)

gonewild said:


> 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.


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## gonewild (Oct 25, 2012)

Rick said:


> 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?


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## Rick (Oct 25, 2012)

gonewild said:


> 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.


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## Rick (Oct 25, 2012)

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


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## Stone (Oct 25, 2012)

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.


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## Rick (Oct 25, 2012)

Stone said:


> 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.


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## Rick (Oct 25, 2012)

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.


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## Rick (Oct 26, 2012)

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.


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## bullsie (Oct 26, 2012)

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!


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## ChrisFL (Sep 20, 2017)

Or this thread?


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## Happypaphy7 (Sep 22, 2017)

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.


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## StreetVariety (Sep 23, 2017)

Have anyone tried growing orchids with leaf litter?


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