The 15th Latin American Symposium ''laS held in Brasilia (FD) on J1UY 18-22, 1977, on a topic of great interest for agriculture, especially in the tropics. Many new developments have taken place in the field of research in N2 fixation during the last few years. They "Tere made possible by the improved methods of measuring of nitrogenase activity, progress in genetic engineering fields and the increased interest in taking advantage of natural sources for biological nitrogen fixation. The approach used in this Symposium together with the one held four months earlier in Brookhaven on ;'Genetic Engineering for Nitrogen Fixation" gives an interesting picture of the present status of nitrogen fixation from two diverse approaches. This is my 20th year visiting Latin i'-J11.erica. I am most impressed with the tremendous development which has taken place during these years in Latin American science. I want to congrat ulate our Brazilian colleagues for arranging this excellent and timely symposium and its excellent organization. These symposia are a cooperative effort between our Latin colleagues and scientists allover the world. They are made possible by excellent local support and support by a number of international agencies and several groups in the United States. Earlier symposia in this series are listed on pp. viii-x. Alexander Hollaender vii viii PREFACE I. International Symposium on Tissue Transplantation--Santiago, Vifia del Mar, and Valparaiso, Chile. Published in 1962 by the University of Chile Press, Santiago; edited by A. P. Cristoffanini and Gustavo Hoecker; 269 pp.

The International Workshop on Biological Nitrogen Fixation for Increased Crop Productivity, Enhanced Human Health and Sustained Soil Fertility was held in June 2002 at ENSAM-INRA, Montpellier, France. The main goal of the workshop was to define research strategies for a Challenge Program initiative on Biological Nitrogen Fixation, and develop a pre-proposal based on the concept note submitted and approved by the CGIAR iSC. More than 35 participants from various scientific disciplines, research institutions and from four different continents (Africa, Asia, Americas and Europe) attended the workshop. This book, based on the proceedings of the workshop, takes a holistic approach to harnessing legume BNF technologies, starting from a socioeconomic perspective, and progressing to agronomic and genetic options, and bringing together innovative aspects and participatory research strategies.

Biological nitrogen fixation in tropical agrosystems: twenty years of biological nitrogen fixation research in Africa; Sustainable agriculture: definition and measurement; Biological nitrogen fixation systems in tropical ecosystems: an overview; A protocol for screening legumes as soil-improving crops; The sustenance of tropical agriculture with multipurpose azolla; Facteurs pedoclimatiques limitant la lixation biologique l'azole; Response of some tropical nitrogen-fixing woody legumes to drought and inoculation with mycorrhiza; Improvement to the Phaseolus/Rhizobium symbiosis, with particular reference to the Caribbean region; Effect of pest management systems on biological nitrogen fixation; Agronomic evaluation of a rock phosphate as a phosphorus source for Leucaena leucocephala grown on an utisol; Nodulation of soybean grown under field conditions and inoculated with Bradyrhizobium japonicum strains; Effect of fertilization and Rhizobium inoculation on the growth of Leucaena and Gliricidia on an alfisol in south-western Nigeria; Early growth and nodulation in Leucaena and Gliricidia and the effects or pruning on biomass productivity; Comparative stude on the growth and productivity of Sesbania and Leucaena in the Central Plateau region, Rwanda; Supernoculation and non-nodulation mutants of soybean; Genetically improved rhizobia and their use in agriculture; Sustainability of nitrogen-fixing cropping systems: Nodulation and nitrogen fixation and transfer in a cowpea/rice cropping system; The role of legumes in sustaiing soil productivity and controlling soil erosion; Fitting soil-improving legumes into inland valley rice-baes cropping systems in West Africa; Herbage yield and soil fertility restoration potential of some tropical forage legumes.