For centuries, rice farmers in China & Vietnam have been using azolla as a green manure in their wetland fields. The aquatic fern fixes nitrogen directly from the atmosphere (with the help of blue-green algae called Anabaena azollae which lives symbiotically in the leaf cavities of the floating plant) and nourishes the fields. The protein content of azolla is about 20-30% of dry weight making it a good feed supplement for cattle, poultry & fish. The tiny plants are used to purify and recover nutrients from waste water. Azolla requires zero agricultural land and less water compared to terrestrial crops.
Recent studies show that azolla can generate biomass upto165 ton/hectare/year dry matter which is many times higher that can be achieved in the case of popular energy crops and azolla biomass yields high amounts of methane (480 l/kg) - which is equivalent to natural gas, besides giving us speciality chemicals, jet fuel and bioplastic.