In the context of fast depletion of soil fertility and high prices of chemical fertilizers, it has become imperative to use biofertilizers as a pollution-free low-cost input in agricultural production. Presently, the medium and low land rice fields around the urban and industrial areas are being polluted at an alarming pace not only due to domestic waste but also by industrial effluents. This monograph is the first of its kind on highlighting the dual role of the water fern Azolla in sustainable rice farming as well as decontaminating the polluted environment. Endowed with a high nitrogen fixing cyanobacterial endosymbiont Anabaena azollae, the fern acts as an efficient biofertilizer especially for waterlogged rice fields; besides being a suitable waste disposer because of its ability of hyperaccumulating heavy metals from its aquatic environment. This book is specially designed to motivate the marginal rice- growers of the developing countries in adopting Azolla agrotechnology for sustainable agriculture as well as to develop a working strategy towards effectively protect agricultural fields from domestic and industrial pollutants.