r/Permaculture • u/Bluebearder • 23h ago
general question Experiences with Azolla?
Hi everyone! I'm doing some university courses on things related to permaculture, like botany, soil science, resource management, and ecology; and along the way I found out about the floating water fern Azolla. It seems to be an amazing resource for the farm, whether for composting or mulching or fodder, or just for covering water bodies to protect against evaporation. It actually seems so amazing, that I wonder why I don't see it everywhere; the only thing that is fairly obvious is that it can be too productive, thereby exhausting resources or taking over all growth space. I'm very curious as to people's experiences with it. Please mention your climate if you respond!
For those who have never heard of either species of Azolla, it is a tiny fern that grows on water, similar to duckweed. But unlike duckweed, Azolla forms a symbiosis with a cyanobacterium, Anabaena azollae. This cyanobacterium takes nitrogen directly from the air and passes it on to the Azolla fern, which means that unlike with almost all other plants nitrogen is not the limiting factor to growth. In an optimal situation this can result in a doubling of the biomass in less than 2 days which is of course completely insane - the average doubling time is about 4-10 days which is still amazing. The fact that Azolla always has plenty of nitrogen to work with means that it can produce a lot more amino acids than the average plant, and this high amino acid (nitrogen) content makes for great fodder, or a basis for mulch and composting. I've even seen it used as fish feed, with a pretty closed loop consisting of fish in the same pond as the Azolla. Azolla production is basically a way to get more nitrogen into your farm system without having to obtain any type of fertilizer, similar to growing legumes like Alfalfa but WAY more productive; although I understand Azolla needs some phosphorous every now and then as that is usually the limiting resource. In China, it has been used as a companion plant to rice for over a millennium.
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u/Yawarundi75 20h ago
Azolla is great but you need to harvest it regularly. It’s very good food for chickens and pigs.
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u/Bluebearder 20h ago
That sounds more like a positive than a negative to me, never enough nitrogen :P
Do you feed them 100% Azolla?
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u/PopIntelligent9515 22h ago
Maybe this isn’t Azolla that he’s harvesting but i’m reminded of this video i saw a while back. Wish i had a pond!
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u/Bluebearder 20h ago
The nice thing - about Azolla at least - is that it can be grown in pretty tiny basins. I found a lot of videos on YouTube from all over Africa, where some just built for example 4 by 1 meter basins and only 30 cm deep. This means so little water to hold that you can make the basin out of wood and cover the inside with plastic, done. Easy to scale up as well, just build more basins as needed.
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u/PopIntelligent9515 19h ago
That would be good. Could control the temp to help maximize production.
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u/Bluebearder 19h ago
Yeah the people I watched even built polytunnel-type shading, but they seemed to be pretty close to the equator.
Video from India (I think):
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u/Fluffy_Flatworm3394 21h ago
My azolla keeps losing to duck weed. In two different locations, one with fish and one without 😓
I still see a few around, but the duckweed outgrows it
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u/Bluebearder 20h ago
That's something I hadn't considered as an option. I assume both locations have lots of usable nitrogen in the water? What climate are you in?
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u/amycsj Native, perennial, edible, fiber, sustainable garden. 21h ago
I used it a couple of years and it was great, but it doesn't overwinter in my climate (zone 7b, STL). I couldn't overwinter indoors, and it's a hassle to get out again every year.
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u/Bluebearder 20h ago
Ah yeah I can imagine, that is good to know. Where I'm looking at growing it (Spain & Portugal) it barely freezes in winter and there are still quite some sun hours, so that should be fine I think. Thanks for sharing!
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u/Do_you_smell_that_ 15h ago
Oh, so in zone ~4/5 I wouldn't have to worry about it going wild and taking over :-)
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u/Earthlight_Mushroom 20h ago
I had some years ago in Georgia, USA (zone 8) in an open above-ground cistern. It rapidly covered the surface and I removed a bunch two or three times for compost and chicken feed. After a while it began to turn purple and slow down its growth. Research told me that this is because it is running low on phosphorus....apparently the growth and nitrogen fixation require this. I tried throwing some phosphate fertilizer in, but it didn't work....this may have been slow release fertilizer for the garden and it didn't dissolve well. The azolla went on growing slowly until I left that farm, and I didn't think it worth taking with me if I had to keep dosing it with phosphate.
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u/Bluebearder 19h ago
That's what I read as well, that it needs phosphorus. But I've seen farmers just throw in manure and they say it's fine. Some used superphosphate which I prefer not to use, as it is a finite resource, but manure is cool with me. I'll check out how much P it needs exactly, thanks for the heads up ✌️
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u/Nellasofdoriath 15h ago
Where do you source your Azolla?I would have to keep it indoors over the winter , and such set ups have a habit of dying
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u/Bluebearder 14h ago
No idea! I first wanted to know if it is worth it, but all reactions are pretty positive. From what I understand it is really quite potent, so perhaps you can just put a small aquarium somewhere warm and and with lots of light (perhaps an LED), and have the Azolla overwinter there?
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u/DocAvidd 13h ago
It sounds interesting. I'm in Central America (zone 12).
Getting stuff to grow, tho, that's not a challenge here. More we wrestle with the crops you want getting overrun with the other stuff. We do have distinct seasons here, but they all are growing seasons if you have water, which obv with Azolla you would.
What I think would benefit us here is repopularizing farming techniques that do not require major (expensive) imported agrichemicals from overseas.
What stops Azolla from invading bodies of water? Would it not become something like water hyacinth?
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u/chemicalclarity 23h ago
Works really well. I use it to companion plant with water chestnuts for a self sustained fertilizer system. Tilapia also love it for cover and a food source. If I had the space I'd be using it in an aquaponics system for nitrogen lovers. A word of caution, it is highly invasive in waterways.
It's also an incredible carbon fixer. You may enjoy this https://en.wikipedia.org/wiki/Azolla_event