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Food security, one of the basic human rights, seems to be ever eluding the people of sub-Saharan Africa. With each occurrence of crop failure, agriculturalists around the world reawaken to the challenge of ensuring sta ble, adequate food production in the tropical African environments. The International Fertilizer Development Center (IFDC), with its mandate of alleviating food shortages through judicial use of fertilizers, formulated a program to study fertilizer use strategies for sub-Saharan Africa. With gener ous financial assistance from the International Fund for Agricultural Devel opment (IFAD), IFDC, in collaboration with the International Crop Re search Institute for the Semi-Arid Tr...
This publication provides information on the impact of animal feeds on food quality, food safety, and the environment, and thus improves the basis for managing such risks. The book brings together in printed form six reviews from the FAO electronic journal AGRIPPA (available online).
The formation of roots is in some respects one of the least fundamentally understood of all plant functions. Propagation by cuttings is the aspect that will occur first to most gardeners and horticulturists, and it is certainly the most useful application. But any observant traveller in the tropics can notice that some trees have the habit of forming roots in the air. Climbers like Cissus bear long fine strings of roots hanging down. Pandanus trees tend to have stout aerial roots issuing from the bases of the long branches, while the tangle of roots around the trunk of many of the Ficus species is characteristic. In Ficus bengalensis, in particular, stout cylindrical roots firmly embedded in the ground from a height of 3 to 5 meters give support to the long horizontal branches, enabling them to spread still further. In the big old specimen at Adyar near Madras, the spread of these branches all around the tree, each with a strong root growing out every few meters, makes a shaded area under which meetings of almost 5000 people are sometimes held. The history of how the formation of roots on stem cuttings was found to be under hormonal control is worth repeating here.
The sustainability of both natural and managed ecosystems is strongly influenced by soil biological processes. A major question in soil biology and ecosystem ecology is the extent to which these processes are affected by the function and structure of the soil's biotic community. The Significance and Regulation of Soil Biodiversity presents the discussions of a group of soil biologists and ecosystem ecologists in which they synthesize available information, present innovative methodologies, and develop cross-taxa and cross-habitat collaborations to advance our understanding of soil biodiversity. The volume addresses the extent and regulation of soil biodiversity and describes initial approaches to the linking of soil biodiversity and ecosystem function. Audience: Researchers and students in a wide range of environmental scientific disciplines.
This book contains the proceedings of the `8th Nitrogen Workshop' which was held at the University of Ghent, Belgium, from 5 to 8 September 1994. Although nitrogen dynamics in different ecosystems have been studied for several decades, new orientations and other emphases have recently emerged. Previously, nitrogen was considered as an essential element mostly in terms of productivity, but now, more emphasis is attached to environmental consequences. More than 100 contributions in this book tackle recent developments within the fields of nitrogen advice systems, plant response to fertilization, immobilization and mobilization, nitrification, denitrification, leaching, ammonia volatilization and biological nitrogen fixation. A large number of papers is devoted to the formation of gaseous nitrogen compounds, while mineralization-immobilization is another topic of important interest. The book also contains the reports of discussion groups on different aspects of the nitrogen cycle.
In the 100 years since the legume-Rhizobium symbiotic nitrogen fixation interaction was first described, interest in this field has grown rapidly. The types of studies have been cyclical in nature, involving a cross-section of disciplines. The availability of cheap nitrogenous fertilizers caused much of the biological nitrogen fixation research to become more theoretical in the developed world. The high cost of energy, coupled with environmental concerns and the interest in sustainable agriculture, has stimulated research in symbiotic nitrogen fixation. The development of modern genetic techniques has resulted in interdisciplinary research on plant-microbe interactions controlling nitrogen fixation. This has resulted in a better understanding of environmental factors influencing the nodulation process, chemical signalling between the symbiotic partners and the nature of the specificity between host plant and microsymbiotant. This volume summarizes the diverse research efforts in biological nitrogen fixation by presenting a collection of papers in the areas of physiology and metabolism, taxonomy and evolution, genetics and ecology.
Integrated studies on the assessment and improvement of soil and water quality have to deal almost inevitably with issues of scale, since the spatial support of measurements, the model calculations and the presentation of results usually vary. This book contains the selected and edited proceedings of a workshop devoted to issues of scale entitled: `Soil and Water Quality at Different Scales', which was held in 1996 in Wageningen. It is intended for environmental researchers, scientists and MSc and PhD students. Part 1 covers current issues and methodologies with scale related soil and water quality research. Part 2 covers agroecological and hydrological case studies in which scale transforms form an important part of the research chain. Part 3 consists of papers focusing on methodologies and up and downscaling. Part 4 contains review papers based on modellers' and statisticians' considerations as well as the papers and posters presented during the workshop. Part 5 consists of short research notes.
Plant adaptation is a fundamental process in plant breeding. It was the first criterion in the initial domestication of plants thousands of years ago. Adaptedness is generally a quantitative complex feature of the plant, involving many traits, many of which are quantitative. Adaptation to stresses like cold, drought or diseases are among the most central problems in a world grappling with global food security. Modern plant breeding, based on mendelian genetics, has made plant improvement more effective and more precise and selective. Molecular genetics and genetic engineering has considerably increased this selectivity down to single genes affecting single traits. The time has come when plan...
This book begins with an overview of current thinking on bioavailability, its definition, cutting-edge research in speciation and advancement in tools for assessing chemical bioavailability in the terrestrial environment. The second section of the book focuses on the role of chemical speciation in bioavailability. Section three addresses bioavailability and ecotoxicity of contaminants and leads into the next section on bioavailability of nutrients and agrichemicals. Subsequent sections provide an overview of tools currently being used and new cutting-edge techniques to assess contaminant bioavailability. The last section of the book builds on previous sections in relating bioavailability to risk assessment and how this could be used for managing risks associated with contaminated land. - Provides the latest information on developing concepts and definitions of bioavailability - Includes a discussion of bioavailability and ecotoxicity of contaminants and bioavailability of nutrients and agrichemicals for applications in agriculture - Analyzes tools for assessing bioavailability and the role of bioavailability in risk assessment and remediation