Mushrooms as Rainmakers

posted in: Champions, Research | 0

By Tree Farmer and Soil Health Champion Carl Struck

Mushroom releasing spores. Photo by Carlos Andrés Reyes CC BY 2.0

The full title of the research abstract is “Mushrooms as Rainmakers: How Spores Act as Nuclei for Raindrops”—Wow…really? If you’re a fungi enthusiast like me, this statement is as irresistible as honey to a bear.

I’m assuming here that many of us in the arid and semi-arid Southwest might be interested in how and why precipitation occurs and how we might support an increase in these mechanisms.

I’ve spent a fair amount of time looking into the “cloud seeding” controversy whereby various devices deliver nano-particles, usually silver iodide, into the atmosphere helping to trigger a small increase in precipitation, so I was familiar with the concept of water molecules forming around micro-particles.

I knew that the “alternative” analogues to silver iodide, an inorganic mineral some folks consider toxic even in minute quantities, were micro-particles (or aerosols as scientists refer to them) that find their way into the upper atmosphere through volcanic eruptions, wind erosion, forest fires, industry and other forms of pollution as well as vegetation.

The inorganic aerosols of all these micro-particles form precipitation at very cold temperatures and therefore only effect cumulonimbus clouds at high altitude in most cases. Organic aerosols however form water droplets at much warmer temperatures and therefore effect the nimbostratus as well as cumulonimbus clouds at a much lower altitude.

This is a fairly complicated cause and effect cycle explained beautifully in this presentation on YouTube by Cindy Morris with Montana State University: Biological Rainfall Triggers. Suffice it to say that the organic aerosols formed by vegetation—what I understood to be mostly in the form of bacteria from the surface of plants—are extremely important to the water cycle all of us farmers, ranchers, foresters and gardeners depend on in the dry Southwest.

This is one of the lesser known reasons why plant bio-diversity and living ground cover is so important to the regenerative agriculture movement.


Inky Cap mushrooms (Coprinus atramentarius). Photo by Bryant Olsen CC BY 2.0

But I wasn’t aware of the role mushrooms and their spores play for this important local water cycle. The study I refer to in the title suggests that fungal spores from many of the mushroom species familiar to us here in Northern New Mexico also waft up into the atmosphere and form a significant source of biological aerosols that contribute to our annual precipitation.

It is this finding that has far reaching implications for all of us concerned with soil health. It is already remarkable that saprophytic fungi decompose organic matter forming the backbone of nutrient recycling and mycorrhizal fungi help deliver those nutrients and water to the roots of our plants and trees—but now we learn that fungal spores help trigger the very precipitation that the fungi and our plants and trees depend on!

Apparently there are some 16,000 species of fungi that are capable of literally blasting their spores, with the help of other forces as well, to an altitude of 30,000 feet! Who knew?


The author with Lepiota rachodes. Photo by Johanne Riddick.

What this suggested to me is that with this new bit of knowledge all of us with any access to soil health management, i.e. anybody owning or managing land has the ability to be part of the answer to one of the most threatening aspects of global climate change for those of us in the Southwest… drought.

It gives us even more reason to support our fungal communities by making sure our soils have sufficient organic material and cover to help retain moisture.

Any action we take that results in the growth of mushrooms, like creating a compost pile that produces inky cap (Coprinus atramentarius) or shaggy parasol (Lepiota rachodes) mushrooms, is to be celebrated!

But it may be what we DON’T do that is even more important. To avoid compacting or disturbing our soils so that our resilient fungal communities can thrive. To not add chemical fertilizers, herbicides, pesticides and fungicides to our soil that might kill or severely hamper the biological processes at work beneath our feet.

So fellow soil health enthusiasts… let’s get to work! Supporting fungi supports the rain and snow! But don’t take my word for it… check out the links below!


References

Mushrooms as Rainmakers: How Spores Act as Nuclei for Raindrops, Authors Maribeth O. Hassett, Mark W. F. Fischer, Nicholas P. Money, Published: October 28, 2015


Biological Rainfall Triggers Presentation by Cindy E. Morris, French National Agricultural Research Institute and Montana State University

It’s Raining Cats and Dogs… and Mushrooms, Arizona State University Blog


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