The Azolla Fern

by Paul Gaylon

A green swath of growing Azolla ferns
Azolla ferns

Of its 80-million-year history, about 49 million years ago, the aquatic Azolla fern (Mosquito fern) has had a dramatic effect upon the planet. Originally found in the Arctic, Azolla grew in a dense mat which filled in a huge amount of the Arctic Circle. In about one million years, the ferns moderated and cooled the Arctic temperatures to current conditions today. The Azolla fern is found in tropical and temperate areas on nearly every continent.

Azolla fern is the smallest of the fern species. This floating plant requires water while also helping to clean and purify stagnant and wastewater. It fixes nitrogen, releases oxygen, and sequesters carbon dioxide from the air. It prefers aeration and partial shade (shade cloth can be used). Azolla biomass can be used for biofuel, soil amendments, fertilizers, biochar, and agriculture and building products. Harvesting can be done by hand, with a scoop, net, start tray, or any method that collects this floating material.

The Azolla fern contains phosphorus and potassium as well as amino acids, lipids, polyphenols, anthocyanins (especially the reddish leaves), tannins, plant sugars, and caffeic acids. It provides food for animals, particularly farm animals such as cows, pigs, ducks, and chickens as well as freshwater fish including tilapia and even manatees. It has great nutritional potential for the human diet.

Azolla surrounded by Duckweed

Like Blue-Green algae, Azolla ferns greatly enhance soil biology. The decomposition of Azolla results in a sugar–carbon exchange in the root exudates which swap vitamins and minerals with soil or water. In fact, some Azolla species found in Asia contain Anabaena Azollae Cyanobacteria related to Aphanizomenon Flos-aquae (AFA).

In Asia, Azolla ferns are used to feed nutrients into rice ponds. Decomposition accelerates rice growth with a yield that is approximately twice as high as normal. Additionally, as it grows, the Azolla fern helps control algae growth which permits the crops to thrive. This repeatable phenomenon of increased rice field growth in areas where the Azolla fern is present has been well-researched and documented in China, Japan, Thailand, India, Malaysia, Indonesia (including Bali), and Burma. The Azolla fern can double its biomass in a few days which could create an excessive amount. Carbon sequestration produces more soil carbon capture than most plants.

Growing Azolla ferns have been increasing in popularity in recent years. Many people are growing them in small rectangular ponds for use on their farms, particularly in the Phillippines, India, Bali, and Thailand. The Azolla fern is truly a marvel waiting to be developed in as many ways as possible.

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