Thu, 23/08/2012 – Michel Fanton
Azolla, a fern like floating algae, doubles in size every five days under warm conditions. In addition to its traditional cultivation as a bio-fertiliser for wetland paddy (due to its nitrogen fixing ability), azolla is becoming very popular in the sustainable production of livestock feed and general organic farming or market gardening. Azolla is rich in proteins, essential amino acids, vitamins and minerals that few feed supplements can claim. Studies describe feeding azolla to dairy cattle, pigs, ducks, and chickens, with reported increases in milk production, weight of chickens and topping quality egg production of layers. Compare this with conventional feed that most often comes from unknown sources (think GM maize arriving on your plate via your backyard chicken feed?!). One FAO study describes how azolla integrates into a tropical biomass agricultural system, reducing the need for inputs. ( T.R. Preston and E. Murgueitio. “Sustainable intensive livestock systems for the humid tropics”. FAO. 2011-09-28)
Azolla has been recorded as a companion plant to rice for more than two thousands years both because of its ability to fix nitrogen, and to assist in weed control. Rice seedlings are transplanted when they are tall enough to protrude above the water surface; azolla surrounds them, blocking out light, thus preventing competition from weeds. Later, as the rice needs extra fertility, the paddies are drained, leaving on the mud a layer of azolla that quickly turns to compost. This is repeated several times.
Larvicide As an additional benefit to its role as a paddy biofertilizer, Azolla spp., and there are many, have been used to control mosquito larvae in rice fields. The plant grows in a thick carpet on the surface of the water, making it difficult for the larvae to reach the surface to take in air. Azolla starves the larvae from oxygen.
Where to find Azolla? How to recognise it? Azolla is present on many natural water surfaces, such as lakes, creeks and slow waterways. It is a small fern-like algae, reddish in colour, each apparent “leaf” about twenty mm in diameter.