Azolla

It's silly really, but growing azolla fills me with such satisfaction. Today, I'm here to spread that joy.

So what is azolla? Bizarrely, it's an aquatic fern that grows floating on the surface of pond water like duckweed. As far as I'm concerned, its humble appearance hides a spark of magic. 

Although unrelated to legumes such as beans and peas, like them, azolla can fix nitrogen from the air. Nice! Azolla achieves this by forming a symbiotic relationship with the cyanobacterium Anabaena azollae. Anabeana fixes nitrogen sharing it with the azolla while in return the azolla houses and protects the anabeana in special egg shaped cavities in its scale looking leaves.  If that isn't magic, I don't know what is.

If that isn't enough for you, just listen to this. Paleoclimatologists have discovered that during the middle Eocene, approximately 40 million years ago, giant rafts of azolla grew on the surface of the Arctic Ocean, a tropical environment back then. These azolla rafts absorbed so much atmospheric carbon dioxide, they contributed to the global cooling event that created the relatively colder climate we live in today. Are you beginning to understand why I enjoy growing azolla so much?

At this point you might be thinking, wow, why don't we turn our efforts to cultivating vast oceanic rafts of the stuff to stem the tide of today's human induced climate change? Unfortunately, as you might expect, it isn't as simple as that. In the Eocene, for complex reasons you can read about in this article, the ocean had a thin layer of freshwater on its surface. In the salty depths below, a unique set of circumstances lead to an environment that sequestered the carbon dioxide absorbed by the azolla rafts rather than recycling it back into the atmosphere.

Now to an entirely different point, in the vegetable patch, azolla isn't just a carbon absorbing rather picturesque talking point. It can serve the practical purpose of feeding your veg too. Remember what I said earlier about the nitrogen fixing prowess of azolla's partner anabeana? You can skim azolla off the surface of your pond and add it to your compost bin. Azolla grows so quickly, you can do this every couple weeks with ease. Fabulous, free, nitrogen rich fertilizer for leafy green growth.

Using azolla as fertilizer has been practiced in parts of Asia, such as Vietnam, for centuries. Farmers cultivate it between crops of rice and then us it to fertilize the rice paddies themselves. Many parts of the world even go one step further and produce azolla as livestock fodder due to its naturally high protein content. In Japan, Dr Takao Furuno has developed a method of organic farming that integrates rice, duck, azolla, and fish production eliminating the need for chemical fertilizers, pesticides, and herbicides. Maybe I can get out to Japan one day to see this in practice. Holistic forms of agriculture like this must be the way of the future.