Limitations And Potentials For Biological Nitrogen Fixation In The Tropics

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 symposium's objectives included an appraisal of the most recent studies relating to microbiological nitrogen fixation in tropical soils, consideration of aways and means of improving management of soils and crops in tropical farming systems to increase biological nitrogen fixation, of exploring ways of concurrently improving both legumes and other hosts and their symbionts to enhance nitrogen fixation, and of recommending the research needed and means of collaborating in the research effort.

This volume discusses the most recent advances in biological nitrogen fixation, with chapters written by experts on the ecology, physiology, biochemistry and genetics of biological nitrogen fixation.

Microorganisms have simultaneously served and assaulted man throughout history. Man is totally dependent on some microbes for life processes, while remaining subject to the destructive capacities of others in diseases not yet conquered.Microbes can be marshaled to aid in solving many important global problems including food shortages, resource recovery and reuse, energy shortages, and pollution. Microbiology is particularly suited to make important contributions to human needs in developing countries, yet it has received comparatively little attention. The range of possible applications covers uses by individuals and industries in rural settings, villages, and cities.This book covers examples of microbial processes that may be useful in developing countries. Although many of these processes may not have a direct and immediate use, their scope and diversity should serve to indicate the strong potential for microbial applications.

Chemical fertilizers have had a significant impact on food production in the recent past, and are today an indispensable part of modern agriculture. On the other hand, the oil crisis of the 1970s and the current Middle East problems are constant reminders of the vulnerability of our fossil fuel dependent agriculture. There are vast areas of the developing world where N fertilizers are neither available nor affordable and, in most of these countries, balance of payment problems have resulted in the removal of N fertilizer subsidies. The external costs of environmental degradation and human health far exceed economic concerns. Input efficiency of N fertilizer is one of the lowest and, in turn, contributes substantially to environmental pollution. Nitrate in ground and surface waters and the threat to the stability of the ozone layer from gaseous oxides of nitrogen are major health and environmental concerns. The removal of large quantities of crop produce from the land also depletes soil of its native N reserves. Another concern is the decline in crop yields under continuous use of N fertilizers. These economic, environmental and production considerations dictate that biological alternatives which can augment, and in some cases replace, N fertilizers must be exploited. Long-term sustainability of agricultural systems must rely on the use and effective management of internal resources. The process of biological nitrogen fixation offers and economically attractive and ecologically sound means of reducing external nitrogen input and improving the quality and quantity of internal resources. In this book, we outline sustainability issues that dictate an increased use of biological nitrogen fixation and the constraints on its optimal use in agriculture.

The first book bearing the title of this volume, Inorganic Plant Nutrition, was written by D. R. HOAGLAND of the University of California at Berkeley. As indicated by its extended title, Lectures on the Inorganic Nutrition of Plants, it is a collection of lectures - the JOHN M. PRATHER lectures, which he was invited in 1942 to give. at Harvard University and presented there between April 10 and 23 of that year - 41 years before the publication of the present volume. They were not "originally intended for publication" but fortunately HOAGLAND was persuaded to publish them; the book appeared in 1944. It might at first blush seem inappropriate to draw comparisons between a book embodying a set of lectures by a single author and an encyclopedic volume with no less than 37 contributors. But HOAGLAND'S book was a compre hensive account of the state of this science in his time, as the present volume is for ours. It was then still possible for one person, at least for a person of HOAGLAND'S intellectual breadth and catholicity of interests, to encompass many major areas of the entire field, from the soil substrate to the metabolic roles of nitrogen, potassium, and other nutrients, and from basic scientific topics to the application of plant nutritional research in solving problems encountered in the field.