Substantial K in rainforest through fall.

[Stone]

These two studies show a significant amount of potassium in rainfall but especially throughfall during rainy season in New guinea and Yunnan.
Ammonium was also much higher than nitrate. (in the chinese paper)
New Guinea montane forest (abstract only) The ratio of K relative to other nutrients leaching from the canopy is high:

http://www.jstor.org/discover/10.2307/2260106?uid=3737536&uid=2&uid=4&sid=21103677463083

China:

http://als.xtbg.ac.cn/files/1981-2011/[SCI]2002-Nutrient%20fluxes%20in%20bulk%20precipitation,%20throughfall%20and%20stemflow%20in%20montane%20subtropical%20moist.pdf

Nutrients returned as litter differ in composition. It may be that if most of these minerals are taken directly as disolved ions from rainwater throughfall (very likely) we may need a re-think on the ratios of N P K Ca and Mg available?

Malaysia:

http://www.cabdirect.org/abstracts/19810673259.html;jsessionid=4CA8C81B53780ED5D20B08C2B38FFCC7

Panama:

http://cimad.org/publicaciones-MAJ/Cavelier_et_al_1997.pdf

 

[Trithor]

Some very interesting abstracts. (I was unable to open the Chinese paper). The K is very high, way higher than I would have expected. I eagerly await the discussion that this should generate.

 

[limuhead]

This is VERY interesting; I have no clue what it means though...

 

[Stone]

(I was unable to open the Chinese paper).

Yes I have google it too:
Nutrient fluxes in bulk precipitation, throughfall and stemflow in montane subtropical forest on Ailao Mountains in Yunnan, south-west China

 

[quietaustralian]

I have a copy of the Chinese paper.
I'll drop it here: www.dropbox.com/sh/jga4jd7koz9t28x/uh_wOoCsOs

 

[cnycharles]

Pollution from industrial areas?


Sent from my iPhone using Tapatalk

 

[gonewild]

Just reading the first abstract very quickly...

The amounts of minerals are reported in kg per hectare per year.
When you consider that a hectare receives 40,000,000 liters of water per year that makes the K content less than 2ppm in the water.

Maybe my fast math is incorrect?

 

[gonewild]

It seems that from what the through fall content applies to plants it indicates that through fall is not the source of nutrition for orchids. It certinly plays a roll but probably a small part. The results in the Panama study show K as being higher but in reality it is not much K applied to the environment.
It comes to an amount of about 136 mg per 15cm pot per year.

N is low in the through fall content but we know there are organisms that provide N for plants in addition to what comes with rain.

So if through fall is a significant source for K in the plants nutrition these studies actually support the low potassium theory. ??

 

[Ray]

Just a couple of obervations:

Those numbers are showing REALLY small loadings of mineral content. If I assume that a plant has 5 square feet of territory to absorb from, 100 kg/hectare/year (the units described in the Cambridge paper abstract) is equivalent to about one-eighth of a microgram per day for the plant.

One of the things were have not really discussed much is the relative rates of capture and absorption of the ions.

 

[Trithor]

I accept that the actual quantities are very small, but that is to be expected on a water source as being rain, with mineral pick-up as it passes through foliage etc, but what is interesting is the ratio of one mineral to the next. Or not? What it does support is the practice of reducing feeding way down, but are the ratios of various macros correct. It is interesting to see how consistent the Ca:Mg ratios are. Or am I just being simplistic in looking at it from a ratio perspective?

 

[gonewild]

The low content of the through fall and stem flow can not be considered as the main source of nutrients for orchids, there simply is not enough content.

The plants have to be foraging nutrients directly from soil, organic matter, or other sources such as moss, lichen, bark, ect......
For this reason I think we can not use the through fall content to predict the correct nutrient ratio the plants need and use.

 

[Secundino]

Prediction is for weather-forecasts...
I still don't understand why the action of micorrhiza is constantly ignored. It is irrelevant of how low (IF they are low) the contents are in rain, 'through fall' (what a wonderful occurence!) and stem flow, micorrhiza traps most of it. It is not that a single plant has 'a few' micorrhiza- threads 'hanging around' its roots - the whole epiphytic community is interconnected with multiple types of miccorhizal fungi which as a whole act like an immense trap for all nutrients; over time the concentrations increase as the biomass of a given epiphytic community increases, too.
If the epiphytes were not able to retain the nutrients, in regions with constant all-day moisture (cloud-forests) the effect would be a constant loss of minerals and biomass in the canopy. This is not what we can see in situ.

It seems to me like comparing the root system of an adult tree to the artificially reduced one of a Bonsai. Of course a Bonsai needs specific nutrition in its tiny pot! Feeding an epiphytic orchid in a 15cm pot with just plain bark does not compare to the the orchid growing on a tree.

 

[Rick]

I accept that the actual quantities are very small, but that is to be expected on a water source as being rain, with mineral pick-up as it passes through foliage etc, but what is interesting is the ratio of one mineral to the next. Or not? What it does support is the practice of reducing feeding way down, but are the ratios of various macros correct. It is interesting to see how consistent the Ca:Mg ratios are. Or am I just being simplistic in looking at it from a ratio perspective?

These papers are only looking at bulk precip and throughfall

As already noted when converting from kg/hectare/year to the ppm per watering we apply to plants we are talking about tiny amounts.

As per ratios, I have presented other throughfall and net flux papers from tropical forests that show more Ca than K (especially in karst forrest).

Now if you look at leaf nutrition and plant physiology documents, then the above documents don't really change the whole low K thing.

 

[Rick]

I still don't understand why the action of micorrhiza is constantly ignored. It is irrelevant of how low (IF they are low) the contents are in rain, 'through fall' (what a wonderful occurence!) and stem flow, micorrhiza traps most of it. It is not that a single plant has 'a few' micorrhiza- threads 'hanging around' its roots - the whole epiphytic community is interconnected with multiple types of miccorhizal fungi which as a whole act like an immense trap for all nutrients; over time the concentrations increase as the biomass of a given epiphytic community increases, too. .

Micorrhriza fungi only transfer nutrients from dead plant material to living plants. In the epiphytic system it has been shown that retained leaf litter is very low (except for places built up by ant nests). So the fungal component of nutrient recycle for adult orchids is not high either. Although as Lance points out there is significant trapping and transfer of (mostly nitrogen, but potentially all mineral nutrients) via associations of lichens/mosses/blue green algae.

Although one could also argue that lichens are already combinations of fungi and BG algae.

 

[Rick]

I accept that the actual quantities are very small, but that is to be expected on a water source as being rain, with mineral pick-up as it passes through foliage etc, but what is interesting is the ratio of one mineral to the next. Or not? What it does support is the practice of reducing feeding way down, but are the ratios of various macros correct. It is interesting to see how consistent the Ca:Mg ratios are. Or am I just being simplistic in looking at it from a ratio perspective?

Just looking through the abstract of the New Guinea paper that despite the higher ratio of K to Ca in the throughfall water, the ratios in the standing leaf litter crop were completely reversed, indicating a greater amount of Ca that is being recycled through the system.

 

[Stone]

Ok so you all seem to be missing the point here. Forget about the low consentrations....thats a given. What I'm talking about is the ratios relative to each other. AT THE VERY LEAST this shows that if for example you are growing Phals or Dends on cork slabs and using Klite, you are depriving them of the potassium (RELATIVE TO NITROGEN!!!!!) they are getting in the habitat. Remember that we should always look at plant nutrients in relation to N otherwise they have no meaning.

If you look at page 541 of the Chinese data, it mentions that K is the most easily leached element. This may account for the relativly low amount found in leaf litter...trees may be hoarding as much K as possible to compensate.

It also says that deposition RATIOS of K (from throughfall) is high in ALL forests.

 

[Rick]

Remember that we should always look at plant nutrients in relation to N otherwise they have no meaning.

Not true at all. Plants (not just orchids) pick up K independently of environmental N and actively (not passively) from the environment.

The inorganic constituents of plants (NPKCaMg.....) comprise less than 1% of the wet mass of the plant so applying a squirt of fert, regardless of ratios of K lite or MSU is generally overkill to what most plants pick up during active growth.

My epiphytes (of which I have a bunch of species phalaenopsis, and almost all are mounted) are doing better than ever on low K high N diet. So empirically low K holds up fine too.

 

[Stone]

The low content of the through fall and stem flow can not be considered as the main source of nutrients for orchids, there simply is not enough content.

Most of the orchids we grow are epiphytes. They (and any mycorrhiza) rely ENTIRELY on rainfall and mainly what washes down to them along the branches. There is nowhere else they can go. Yes the bryophytes etc may play a role but they also rely on the same nutrient imput.

Table 4 (Annual Stemflow Yunnan), Look at the ratios!! Total N 2.3 (NH4-1.4- NO3-0.42) P 0.11- K 3.91 (!)- Ca 2.01- 0.92.

If you want to grow Phalaenopsis, feed them these type of ratios. The consentration is up to you.

The plants have to be foraging nutrients directly from soil, organic matter, or other sources such as moss, lichen, bark, ect......
For this reason I think we can not use the through fall content to predict the correct nutrient ratio the plants need and use.

As Paphs are basically terrestrial they may have access to slightly different ratios than epiphytes but remember that they get the same as the rest of the epiphytes from throughfall. Also many Paphs grow in trees so are seeing the same nutrients as anything else growing with them. I doubt whether there is a huge difference in the end. The tremendous amount of rain will heavily dilute the consentrations in whether on a tree on or in the humus layer on the ground but ratios don't change much.

 

[Stone]

Not true at all. Plants (not just orchids) pick up K independently of environmental N and actively (not passively) from the environment.

When formulating a feeding program, it is very true. Thats why billion dollar enterprises spend a fortune developing the correct nutrient ratios for their crops. After countless studies NO Hydrponic formulation (and there are thousands) that I have seen has a K content much lower than 3/4 of the N whether that be for tomatoes or indoor plants (many of which come from the same rainforests that our orchids do) or anything else. But you are saying that all those trials are wrong?

The inorganic constituents of plants (NPKCaMg.....) comprise less than 1% of the wet mass of the plant so applying a squirt of fert, regardless of ratios of K lite or MSU is generally overkill to what most plants pick up during active growth.

That may very well be true but has nothing to do with this discussion


I'm am not saying that these plants will necessarily suffer on k-lite as they may very well be able to scrounge enough to get by. However neither can you say that a plant fed with a 50/50 N to K (as mine always have been) leads some sort of retardation in growth or whatever.

 

[Rick]

http://www.google.com/url?sa=t&rct=...VtFf-6afvtx9bHQ&bvm=bv.62578216,d.eW0&cad=rja

Here's a link to yet another paper on nutrient flux in rainforest. A high K to Ca ratio in rain water is not universal, and it is a very small part of the picture with regard to total nutrient flux.