An appraisal of an IBP experiment on nitrogen fixation by nodulated legumes

Summary Two field experiments on symbiotic nitrogen fixation by nodulated legumes are described, one relatively complex in design and the other very simple. An appraisal has been made of the feasibility of each experiment as a model for world-wide trials intended to provide data about the contribution to nitrogen fixation by useful legumes that can be made by indigenous strains of Rhizobium. It is concluded that more extensive use will be made of the trial and the necessary information secured if the model is of simple design.