Nitrogen fixation occurs in root nodules of Casuarina after infection with the fungus Frankia. In this project scientists sought to identify strains of Frankia most suited to different species of Casuarina under a variety of soil and climatic conditions in Australia and partner countries. Studies included development and application of inoculation technology, and the search for methods of introducing better strains of Frankia into soils containing inferior strains. Other experiments quantified the amounts of nitrogen fixed in the field by different strains of Frankia.