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.

Sustainability has a major part to play in the global challenge of continued development of regions, countries, and continents all around the World and biological nitrogen fixation has a key role in this process. This volume begins with chapters specifically addressing crops of major global importance, such as soybeans, rice, and sugar cane. It continues with a second important focus, agroforestry, and describes the use and promise of both legume trees with their rhizobial symbionts and other nitrogen-fixing trees with their actinorhizal colonization. An over-arching theme of all chapters is the interaction of the plants and trees with microbes and this theme allows other aspects of soil microbiology, such as interactions with arbuscular mycorrhizal fungi and the impact of soil-stress factors on biological nitrogen fixation, to be addressed. Furthermore, a link to basic science occurs through the inclusion of chapters describing the biogeochemically important nitrogen cycle and its key relationships among nitrogen fixation, nitrification, and denitrification. The volume then provides an up-to-date view of the production of microbial inocula, especially those for legume crops.

Biological nitrogen fixation (BNF) - the conversion of molecular nitrogen into ammonia - is one of the most important reactions in ecology and agriculture. It is performed exclusively by microbes (prokaryotes) that live in symbiosis with plants. This book summarizes the latest research on this reaction, the participating microbes and the genetics of how their relevant genes could be transferred into the plants. In the light of a more sustainable and less ecologically damaging agriculture, this is becoming an increasingly pressing issue.

The most up-to-date reference on phytomicrobiomes available today The Plant Microbiome in Sustainable Agriculture combines the most relevant and timely information available today in the fields of nutrient and food security. With a particular emphasis on current research progress and perspectives of future development in the area, The Plant Microbiome in Sustainable Agriculture is an invaluable reference for students and researchers in the field, as well as those with an interest in microbiome research and development. The book covers both terrestrial and crop associated microbiomes, unveiling the biological, biotechnological and technical aspects of research. Topics discussed include: Developing model plant microbiome systems for various agriculturally important crops Defining core microbiomes and metagenomes in these model systems Defining synthetic microbiomes for a sustainable increase in food production and quality The Plant Microbiome in Sustainable Agriculture is written to allow a relative neophyte to learn and understand the basic concepts involved in phytomicrobiomes and discuss them intelligently with colleagues.

Reprinted from Plant and Soil, v.174, nos.1-2 (1995), this volume is devoted to discussions on the role of biological nitrogen fixation (BNF) in agricultural sustainability. Papers presented on BNF in crop forage and tree legumes are augmented with discussion of integrated farming systems involving BNF, soil and N management, and recycling of legume residues. BNF by non-legumes is discussed and attempts to transform cereals into nodulating plants are critically reviewed. Also described are advances in the development of new methodologies to understand symbiotic interactions and to assess N-2 fixation in the field; means of enhancing BNF through plant and soil management; breeding and selection; problems encountered in exploiting BNF under farmers' field conditions; and promising approaches to improve BNF exploitation. Lacks a subject index. Annotation copyright by Book News, Inc., Portland, OR

Nitrogen is the most yield-restraining nutrient in crop production globally. Efficient nitrogen management is one of the most important factor for improving nitrogen use efficiency, field crops productivity and profitability. Efficient use of nitrogen for crop production is therefore very important for increasing grain yield, maximizing economic return and minimizing nitrous oxide (N2O) emission from the fields and nitrate (NO3) leaching to ground water. Integrated nitrogen management is a good strategy to improve plant growth, increase yield and yield components, grain quality and reduce environmental problems. Integrated nitrogen management (combined use of chemical + organic + bio-fertilizers) in field crop production is more resilient to climate change.

Poverty is a severe problem in Africa, Asia, South America and even in pockets of the developed world. Addressing poverty alleviation via the expanded use of biological nitrogen fixation in agriculture was the theme of the 15th International Congress on Nitrogen Fixation. Because nitrogen-fixation research is multidisciplinary, exploiting its benefits for agriculture and environmental protection has continued to attract research by diverse groups of scientists, including chemists, biochemists, plant physiologists, evolutionary biologists, ecologists, agricultural scientists, extension agents, and inoculant producers. The 15th International Congress on Nitrogen Fixation was held jointly with the 12th International Conference of the African Association for Biological Nitrogen Fixation. This joint Congress was hosted in South Africa at the Cape Town International Conv- tion Centre, 21–26 January 2007, and was attended by about 200 registered participants from 41 countries world-wide. During the Congress, some 100 oral and approximately 80 poster papers were presented. The wide range of topics covered and the theme of the Congress justifies this book’s title, Nitrogen Fixation: Applications to Poverty Alleviation.

Review of the principles and management implications related to nitrogen in the soil-plant-water system.

During the past three decades there has been a large amount of research on biological nitrogen fixation, in part stimulated by increasing world prices of nitrogen-containing fertilizers and environmental concerns. In the last several years, research on plant--microbe interactions, and symbiotic and asymbiotic nitrogen fixation has become truly interdisciplinary in nature, stimulated to some degree by the use of modern genetic techniques. These methodologies have allowed us to make detailed analyses of plant and bacterial genes involved in symbiotic processes and to follow the growth and persistence of the root-nodule bacteria and free-living nitrogen-fixing bacteria in soils. Through the efforts of a large number of researchers we now have a better understanding of the ecology of rhizobia, environmental parameters affecting the infection and nodulation process, the nature of specificity, the biochemistry of host plants and microsymbionts, and chemical signalling between symbiotic partners. This volume gives a summary of current research efforts and knowledge in the field of biological nitrogen fixation. Since the research field is diverse in nature, this book presents a collection of papers in the major research area of physiology and metabolism, genetics, evolution, taxonomy, ecology, and international programs.

Nitrogen (N) is potentially one of the most complex elements on the Earth. It is necessary for all biological activity, but creates negative impacts on water and air quality. There is a balancing act between deficiency and surplus and the forms of N available further complicate our understanding of the dynamics. Biological fixation provides some plants with N supply while others are totally dependent upon N being available in the soil profile for the roots to extract. Nevertheless, the demand for N will increase because the human population with its increasing growth requires more protein and thus more N. Understanding the global N cycle is imperative to meeting current and future nitrogen demands while decreasing environmental impacts. This book discusses availability, production, and recycling of N in air, water, plants, and soils. It features information on N impacts to soil and water quality, management of N in agroecosystems, and techniques to maximize the use efficiency while minimizing the risks of leakage of reactive N into the environment. This volume in the Advances in Soil Science series is specifically devoted to availability, production, and recycling of N with impact on climate change and water quality, and management of N in agroecosystems in the context of maximizing the use efficiency and minimizing the risks of leakage of reactive N (NO-3, N¬2O) into the environment.