Developments in Plant and Soil Sciences

The production of rice has increased considerably in recent years due to the release of improved varieties and the adoption of better fertilization practices. Nevertheless, the production and use of inorganic N fertilizer involves costly investments in terms of energy and transport, the need for complex manufacturing plants, as well as the potential for environmental pollution. The use of agricultural systems that include dinitrogen fixing organisms appears to be an economically sound cultural practice. In the particular case of rice, biological nitrogen fixation by Azolla, blue-green algae (BGA), and heterotrophic microorganisms has long been recognized, in southeast Asia, as a fertilizer for rice culture. The Azolla-Anabaena association has the unique property of being able to retain a significant amount of nitrogenase activity in the presence of combined nitrogen, making the system compatible with inorganic nitrogen fertilization. Researchers working with Azolla (N fixation) are dispersed in 2 countries of southeast Asia, Africa, Europe and Latin America, making it difficult to share ideas, concepts and research results on a more personal basis. Considering the potential positive impact of growing rice in association with Azolla, and the lack, to date, of an international gathering of scientists dedicated to Azolla research, the First International Workshop on "Practical Applications of Azolla for Rice Production" was organized by the University of Puerto Rico-Mayaguez Campus.