Volcanic ashes as nutrition-source for andean orchids ?!
 

Hi,
at the moment, I have a lot of free time, and after my time at university (mechanical engineering) I like it to dive deep in topics I like.

At the moment, I have a new flow in the topic "orchids".

First, there was the thing with the light, I think, I have a good feeling about my Setup.

Next thing, plant-nutrition, fertilizer, antagonisms between different elements and so on.

And every time, there is the question, where did the plants get the needed elements from.

Rainwater is almost pure, maybe some dust from sandy deserts, some bird-poop and so on, but then a friend and I had the idea, what is with volcanic ash ?

The andes are a region with activ volcanos, the ash is a mineralic mix with almost all needed elements. And it sets these free over a long time when it rains.

So I started with some research and found this article.
Does the Mineral Composition of Volcanic Ashes Have a Beneficial or Detrimental Impact on the Soils and Cultivated Crops of Ecuador? - PMC

Short: Allmost all required elements are in these ashes, it depends on the mass, if it is beneficial or toxic.

Than I looked at the correlation between Orchids and Volcanoes, and even this was already part of some studys like "Species Richness and Cover of Orchids and Bromeliads on an Active Volcano"

Than there is my personal observation:

I use Orchiata for my potting-media, if the pots/plants become bigger, I use 50% of lava-rocks (6-18mm). The Only Reason was to make the pots heavier and reduce media-compression over time in the center of the pot by rotting of the bark.

Plants in my mixed potting-medium hava a better root-growing, the green tips are arround 25% longer, than in pure bark.

The reason could be the PH, Orchiata has dolomit-lime, but maybe the lava-rocks support the PH ?
Or, the additional minerals from the lava supports the growing.

I don't know, but i think, that volcanism is part of orchid nutrition as well.

What do you think and maybe you know papers, where someone looked at it more precise

Nutrition is a minor aspect of orchid culture.

In order to add about 1 kg of mass (think about how long that takes), any plant needs to take up and process roughly 1 gram of NPK fertilizer ions, with nitrogen (not provided by lava rock) being about 90% of that.

I suspect that the improved growth you see in the blended potting mix is related to the improved water retention of the lava rock.

Water is the true driving force for growth. In addition to that gram from nutrients, to add that kg of mass, the plant must absorb and process something in the neighborhood of 200 kg of water, and if you add transpiration losses, that may be more on the order of 2 MT required to be taken up.

Hey Kosmo!

I have seen first hand some of the Ecuadorian lava flows. One relatively new one, documented at 300 years old (best I can remember) was blanketed with orchids. In this case I believe that orchids are colonizers of the rock, not because it is nutrient rich, but because orchids do no need nutrient rich environments, and they also do not need soil. That makes them very well adapted to grow on bare rock, but when soil starts to form, they quickly get outcompeted.

With that said I'm sure you are right that volcanic lava and ash contribute a lot of fertility to volcanic areas. Are you suggesting that ash in the air is dissolved into falling rain? Ash in the soil? How many plants did you test with your 25%?

It is only an anecdotal count of a hand full Cattleyas, so no scientifical count