Co-utilization or blending of residuals offers a unique opportunity to develop products with particular characteristics that are able to target specific customer needs. The very notion of deliberately blending by-products suggests that the recycling and beneficial reuse industries are taking a quantitative step forward towards developing products rather than simply reusing residuals. At the same time that this step provides unique opportunities, it also presents unique challenges. The science associated with the beneficial use of one product may not apply when that product is mixed with another residual. Blending of materials may alter the chemistry of the components of the mixture. This may offer additional benefits, as in the case of disease suppression in composts, or present unexpected problems, as the use of lime-stabilized biosolids has done in Maryland. This book consists of the proceedings of the Beltsville Symposium. The organizers of the Symposium attempted to structure a meeting that would outline both the potential benefits of co-utilization as well as concerns. The editors have divided the proceedings into sections that describe the practical basis for co-utilization of residuals as well as the potential benefits. Specific considerations are described. Finally, case studies include descriptions of successful operations and data that detail results of research involving co-utilization materials. Blending of materials for specific objectives needs to be the focus of any successful co-utilization effort. The scientific implications of the mix need to be determined before a product can be used properly.

With an ever-increasing demand for more food supply, agricultural scientists will have to search for new ways and technologies to promote food production. In recent decades, plant growth regulators (PGRs) have made great strides in promoting plant growth and development. PGRs are organic compounds which have the ability to dramatically affect physiological plant processes when present in extremely low concentrations (in the range of micro-to picograms). Although all higher plants have the ability to synthesize PGRs endogenously, they do respond to the exogenous sources most likely due to not having the capacity to synthesize sufficient endogenous phytohormones for optimal growth and development under given climatic and environmental conditions. In recent years, PGRs have established their position as a new generation of agrochemicals after pesticides, insecticides and herbicides. Interest in the commercial use of PGRs for improving plant growth and crop yields is also increasing because of their non-polluting nature. The use of PGRs in the post-harvest technology is well established and many new breakthroughs have recently been revealed.

Playing a critical role in both influencing climate change and mitigating its impacts, the world's diverse wetlands have become one of the world's most threatened ecosystems as unsustainable land-use practices coupled with irrational use of water have already resulted in large-scale wetlands loss and degradation. To develop sound management and conservation schemes to assure wetlands sustainability in the long term requires long-term understanding of wetlands ecology. Yet until now, long-term interdisciplinary research into these systems has been limited to only a few systems from tropical or temperate climates (such as the Florida Everglades, and Czech biosphere reserve). This new book adds to the existing wetlands literature, providing a unique reference in basic and applied Mediterranean wetland ecology, based on results from long-term interdisciplinary research at the RAMSAR and UNESCO Biosphere site, of Las Tablas de Daimiel, Spain. Dating back to the early 1990s the research highlights changes in the biotic and abiotic environment in response to cumulative anthropogenic stressors, and provide guidance on applying this understand to sound management and conservation. With particular relevance to researchers dealing with semi-arid wetlands in the Mediterranean and elsewhere, as well as to resource managers, the book discusses the complexity of the interacting abiotic and biotic environment across different spatial and temporal scales and across various levels of biological hierarchy is highlighted, and reveals how management based on poor knowledge causes more damage than repair. The book will be of interest to researchers interested in freshwater ecology, hydrobotany, hydrology, geology, biogeochemistry, landscape ecology and environmental management.

The study of soil nitrogen has long been an active field, but it was generally pivoted on agricultural and forestry production, and animal husbandry. With the rapid increase in the use of fertilizer nitrogen, more attention has been paid to the relationship between nitrogen management and environmental quality and human health. In addition, the study of soil nitrogen has become more comprehensive with the development of related sciences. The quantitative study of the processes of nitrogen cycling and their interrelationships has been an important part of this project and has attracted the attention of scientists all over the world. Nitrogen is one of the most important nutrients for plant growth and the application of fertilizer nitrogen is playing an important role in agricultural production. The annual consumption of fertilizer nitrogen in the world has reached 70 million tons, and China has an annual consumption of more than 15 million tons and is the largest fertilizer nitrogen consumer in the world. However, the efficiency of fertilizer nitrogen is low and losses are large. It is estimated that nitrogen losses from agriculture in China can be as high as 40-60% of the nitrogen applied. Some of the lost nitrogen enters the atmosphere and contributes to the greenhouse effect and some enters water bodies to pollute the water. Consequently, it is important for scientists all over the world to improve the efficiency of use of fertilizer nitrogen, to promote the biological fixation of nitrogen and to increase the nitrogen-supplying potential of soils.

The economic significance of boron (B) in agriculture, horticulture, and forestry has been beyond dispute for several decades. Even in the last two decades, the areas where B deficiency limits plant production has grown with increased reports from China, south Asia and southeast Asia. The present volume is reflective of the growing awareness of the significance of low soil B with reports from Australia, Bangladesh, Brazil, north, central and southern China, India, Nepal, and the North West Frontier Province of Pakistan contained herein. Boron deficiency also continues to be a problem for crop yield and quality in areas where B deficiency has been known for some time, for example in Germany and the USA. The problem of low soil B is not limited to effects on field crop yield, with papers reporting on depressed wood yield and quality in timber trees (Lambert et al. ), and depressed fruit quality (Dong et al. ; Smith et al. : Zude et al. ) also appearing in the present volume. Globally, Shorrocks (1997)1 estimates that ?? tonnes of B fertiliser is applied annually in agriculture. The economic benefits from the use of B fertiliser have not been quantified but are clearly enormous. Paradoxically, the clear economic imperatives for using B fertiliser on low B soils are not matched by a similar clarity of understanding of the role and functions of B in plants.

Over forty years ago, concern was first focussed on cadmium contamination of soils, fertilisers and the food chain. Adverse effects on human health were first highlighted nearly 30 years ago in Japan with the outbreak of Itai-itai disease. Since then, substantial research data have accumulated for cadmium on chemistry in soils, additions to soils, uptake by plants, adverse effects on the soil biota and transfer through the food chain. However, this information has never been compiled into a single volume. This was the stimulus for the Kevin G. Tiller Memorial Symposium "Cadmium in Soils, Plants and the Food Chain", held at the University of California, Berkeley, in June 1997 as part of the Fourth International Conference on the Biogeochemistry of Trace Elements. This symposium brought together leading scientists in the field of cadmium behaviour in soils and plants, to review the scientific data in the literature and highlight gaps in our current knowledge of the subject. This series of review papers are presented here and deal with the chemistry of cadmium in soils, the potential for transfer through the food chain and management to minimise this problem. We hope this information provides a sound scientific basis to assist development of policies and regulations for controlling cadmium in the soil environment.

Modeling and simulation were introduced to the earth sciences about four decades ago. Modeling has proven its worth and now it is an accepted procedure for analyzing and solving geological problems. The papers in this collection are focused on modeling sediment deposition and sedimentary sequences and have a decidedly practical flavor. Some of the leading simulation packages, such as CORRELATOR, SEDFLUX, SEDpak, SEDSIM, STRATA, and STRATSIM are applied to problems in hydrocarbon exploration, oil production, groundwater development, coal-bed appraisal, geothermics, and environmental diagnosis. All of these subjects fall under the broad heading of sedimentary basin analysis. The fifteen papers in this volume are written by internationally recognized experts from academia and industry. The contributions represent the status of geologic modeling and simulation at the start of the 21st century, and will give the reader an insight into current research problems and their possible solutions.

The frrst attempts to use physical methods in agriculture can be found in nineteenth century as a necessary component of farm and food machinery. There were mechanics, electricity and physical chemistry that were the first physical disciplines used in agriculture and food industry. In the same time period the studies on physical properties of soils started to be one of main topics of soil science. The twentieth century was a century of research on physical properties of agromaterials. The physical properties of agromaterials have been studied e. g. in the USA, where a big role has been played by ASAE (1907), and in the Soviet Union where the special Institute of Agrophysics was founded (1932) by Academician Ioffe. The ASAE's activity was enlarged in 1960s and 1970s, especially with the role playing by the Mohsenin's group and its followers. At that time the Institute of Agrophysics of Polish Academy of Sciences was founded in Lublin and conferences on physical methods in agriculture began to be organised. The participants of the last conference - "Physical Methods in Agriculture - Approach to Precision and Quality," held on August 27-30, 2001, have prepared the basis for this book. Part of the conference participants decided to enlarge their conference papers to be more general and more instructive in relation to further development of the science. New papers prepared under this deciSion were reviewed, discussed and revised, repeatedly, to be presented in this book.

B. A. ROBERTS&J. PROCTOR The term 'serpentine' referring to rocks and min- of each of the polymorphs. These conditions in- erals, can be traced back to the ancient Roman clude temperatures of generally less than 530 C, era of Dioscorides (A. D. 50) (Faust & Fahey and fluid pH's in excess of 10 with low pC02* Serpentine protoliths are essentially ultramafic 1962) and they suggest that the speckled colour of serpents and the fact that Dioscorides recom- rocks which fall into a number of categories: (a) mended it for the prevention of snakebite as two stratiform complexes, (b) concentrically zoned complexes, (c) ophiolite complexes and, (d) high- of many origins of the name. It is well known that the use of serpentinized rocks by sculptors temperature peridotite complexes. The most and carvers since ancient times is a tradition that commonly recognized are generally assigned to the ophiolite suite (Malpas, Ch. 2, this is still carried on today (Fig. 1). The differences in chemical composition of serpentinized rocks volume) and occur in most fold-mountain belts are many and specimens come in a wide range of of the world. Serpentinized ultramafic rocks attractive solid and mixed colours, e. g. , red, "H4(MgFe hSi20 9, approximate composition) green, blue and black.

This volume is one outcome of the 6th International Conference on Paleoceano graphy (ICP VI). The conference was held August 23-28, 1998 in Lisbon, Portugal. The meeting followed the traditional format of a small number of invited oral presentations complemented by a large number ofcontributed posters. Over 550 participants attended, representing thirty countries and nearly 450 posters were presented. The invited speakers addressed the main themes of the 5oral sessions. The session topics were: Polar-Tropical and Interhemisphere Linkages; Does the Ocean Cause, or Respond to, Abrupt Climatic Changes?; Biotic Responses to Major Paleoceanographic Changes; Past Warm Climates; and Innovations In Monitoring Ocean History. This is the first time in ICP history that the Conference Proceedings are published. The aim of the organisers with the publication of this book is two-fold: to provide a useful review of the field and to document the ideas/controversies raised during the con ference that may stimulate future work. The book reflects the initial intentions of the conference, but it is not a conven tional conference proceedings, given that the papers have been reviewed by formal exter nal referees. Each of the conference topics is introduced by a review article designed to summarize the state of the art in each theme followed by articles prepared by the invited speakers. As with most conference proceedings, each theme is covered heterogenously. Some topics have all the expected contributions, others are less well covered."

This volume comprises the proceedings of the First International Rehovot Conference on Modem Agriculture and the Environment, held at the Rehovot Campus of the Faculty of Agriculture, the Hebrew University of Jerusalem, Israel, 2-6 October 1994. The conference, first in a series intended to be convened in Rehovot at 4-5 year intervals to address various aspects of the interaction of agriculture and the environment, was initiated, organised and carried out under the auspices of the Faculty of Agriculture, the leading academic institution in agricultural and environmental studies in Israel. It featured four keynote addresses, 39 invited lectures, 40 submitted papers, and 62 posters. Of these, 51 articles, written by 122 contributing authors from 14 countries, were selected by the editors to be presented in this book. All through the twentieth century, and especially ever since the advent of the Green Revolution, modem agriCUlture has been striving to feed and clothe the ever increasing multitudes of the human species through improved technology, relying heavily on tremendous inputs of fertilisers, pesticides, and various other agrochemicals. Undoubtedly, this has been a great blessing to mankind, and enormous strides have indeed been made in the never-ending struggle against starvation, but these have been achieved at a very steep price of increased environmental deterioration. In fact, modem agriculture has become one of the major factors contributing to the degradation of the world's fragile biosphere.

James O. Leckie Environmental Engineering and Science Program, Department of Civil and Environmental Engineering, Stanford University, Stanford, California 94305-4020, USA Nearly 10 years have passed since the beginning of the systematic studies of the Lerma-Chapala Basin coordinated by the Instituto Mexicano de Tecnologia del Agua. Although many public and private institutions, universities and research centers have conducted studies on the Lerma Chapala Basin over the last two decades, the need for a comprehensive summary of the findings of those studies has become increasingly obvious and important for this critical water resource. The Lerma-Chapala Basin is located in the central part of Mexico, and partly occupies five states. The watershed comprises the Lerma river and Lake Chapala. With a length of over 700 km, the tributary watershed covers 2 approximately 54,000 km . The basin accounts for more than one-third of the country's economic activity, one-fifth of all commerce and one-eighth of the nation's agricultural land. The watershed receives 3% of the country's total rainfall, less than 1 % of the runoff, and accounts for 13% of the total groundwater.

Nitrogen is the most limiting element for crop production. Traditionally, expensive commercial fertilizers are used to correct soil nitrogen deficiencies. Indeed, 50% of the increase in rice yields after World War II can be attributed to increased fertilizer nitrogen use. Although an increased rate of fertilizer nitrogen application has been advocated to meet the growing demand for food, it is unrealistic to advise the farmers to apply fertilizers they could hardly afford, and whose prices are likely to escalate in the years ahead. In addition, when they are not applied judiciously there are problems of environmental pollution as plants are capable of taking up only a relatively small portion of the applied nitrogen, a substantial amount being lost through various chemical and biological processes. The exploitation of cheaper alternatives or supplements to fertilizers have therefore gained much interest in recent years. Our increased interest in biological nitrogen fixation as a supplement or alternative to nitrogen fertilizers led to the convening of a consultants' meeting on `The Role of Isotopes in Studies on Nitrogen Fixation and Nitrogen Cycling by Blue-Green Algae and the Azolla-Anabaena azollae Association', in Vienna from 11--15 October 1982. The consultants' group recommended that the Joint FAI/IAEA Division of Nuclear Techniques in Food and Agriculture embark on a coordinated research programme in this field and that initial emphasis should be placed on Azolla-Anabaena symbiosis. As a result, such a programme was initiated in 1984, which was concluded in 1989. The results and conclusions reported here are those that were generated during the five years of its operation.

A knowledge of clay is important in many spheres of scientific endeav our, particularly in natural sciences such as geology, mineralogy and soil science, but also in more applied areas like environmental and mater ials science. Over the last two decades research into clay mineralogy has been strongly influenced by the development and application of a num ber of spectroscopic techniques which are now able to yield information about clay materials at a level of detail that previously would have seemed inconceivable. This information relates not only to the precise characterization of the individual clay components themselves, but also to the ways in which these components interact with a whole range of absorbate molecules. At present, however, the fruits of this research are to be found principally in a somewhat widely dispersed form in the scientific journals, and it was thus considered to be an appropriate time to bring together a compilation of these spectroscopic techniques in a way which would make them more accessible to the non-specialist. This is the primary aim of this book. The authors of the various chapters first describe the principles and instrumentation of the individual spectro scopic techniques, assuming a minimum of prior knowledge, and then go on to show how these methods have been usefully applied to clay mineralogy in its broadest context."

The Fifth International Symposium on Nitrogen Fixation with Non-legumes was held in Florence (Italy) on 10-14 September, 1990. Earlier Symposia of this series were held in Piracicaba (Brazil), Banf Alberta (Canada), Helsinki (Finland) and Rio De Janeiro (Brazil). The Symposium's main objectives were to bring together scientists working in many different fields of nitrogen fixation, to stimulate discussion on this important process and to have an appraisal of the most recent studies concerning nitrogen fixation with non-legumes. The Symposium was attended by 230 scientists from 32 different countries. This volume collects the contributions of 65 lectures and 87 posters, which are an up-to-date account of the state of knowledge on biological nitrogen fixation with non-legumes. The book provides a valuable reference source not only for specialists in nitrogen fixation, but also for researchers working on related aspects of agronomy, biochemistry, genetics, microbiology, molecular biology and plant physiology. It is with great pleasure that we aknowledge the contributions of the authors in assuring the prompt pubblication of this volume. We would also like to express our thanks to Kluwer Academic Publishers B.V. for the publication of these Proceedings. M. Polsinelli R. Materassi M. Vincenzini ORGANIZING COMMITTEE President M. Polsinelli M. Vincenzini Secretary F. Favilli Treasurer E. Galli E. Gallori L. Giovannetti R. Materassi M.P. Nuti M.R. Tredici SCIENTIFIC COMMITTEE M. Bazzicalupo Florence, Italy H. Bothe Cologne, West Germany R.H. Burris Madison, U.S.A.

The International Society of Root Research sponsored the Symposium "Root Demographics and Their Efficiencies in Sustainable Agriculture, GrassLands and Forest Ecosystems," July 14-18, 1996, at the Madren Conference Center, Clemson University, Clemson, South Carolina, USA. The conference was a continuation of a series of international symposiums on root research held every three to four years. Symposiums have also been held twice in Vienna, Austria, and once in Uppsala, Sweden, and Almaty, Kazahkstan prior to the meeting at Clemson University. The sponsoring society has made a particular effort in these symposia to include root scientists from the former Soviet Union because of the importance of exchanging information on a worldwide basis. This symposium continued and promoted that effort by providing travel grants to several scientists from that region; however, funds for that purpose were limited. Therefore, in compiling these proceedings, a number of papers from scientists from the former Soviet Union and former Warsaw Pack countries have been included even though the scientists were not actually present for the SymPOSIum.

Sedimentation and Tectonics in Rift Basins: Red Sea - Gulf of Aden presents new case studies and synthesises the results of recent research on the sedimentological evolution of the Red Sea - Gulf of Aden rift system. This rift basin is generally regarded as the best natural geological laboratory in the world in which to study the processes of rift formation. Uplift of the rift margins in an arid climate results in extensive three-dimensional exposures of pre- and syn-rift strata and associated structures. These serve as analogues for the understanding and hydrocarbon exploration of deeper buried rift-systems on continental margins such as the North Sea and the Atlantic margins. The Red Sea - Gulf of Aden rift is also exceptional in that its stratigraphy spans all stages from pre-rift environments, syn-rift continental to marine environments through the rift to drift transition to post-rift sea-floor spreading. The work is arranged in eight sections: following a review of the sedimentology and stratigraphy of rift basins, the magmatism and structural evolution of the Red Sea - Gulf of Aden rift is reviewed. Subsequently, new case studies are presented of the early rifting environment, syn-rift sedimentation, tectonics and diagenesis, evaporites and salt tectonics. Post-rift sediments of the axial trough are then discussed along with studies of reefs, coastal zone and shelf sediments, and the tectonic geomorphology of the rift margin escarpment. This work results from extensive new research in the rift basin largely carried out under collaborative research projects by European and Middle Eastern geologists. It will be an invaluable reference work for geoscientists in the hydrocarbon, groundwater and mineral extraction industries, as well as for researchers in university departments of earth sciences, mining and physical geography.

The first edition of Practical Sedimentology contained dis ACKNOWLEDGMENTS cussions of principles and techniques that could be applied to the analysis of sediments in the field and in laboratories sup Colleagues at the University of Canterbury and the Univer plied with inexpensive and commonly available equipment. sity of New England, Lismore, have helped with practical When considering a revised edition, we felt that it was inap advice on their experiences with various methodologies dis propriate to restrict consideration to the simple and common cussed in this volume. At the University of Canterbury, we techniques because so many modern analyses of sediments are particularly grateful to K. Swanson for advice on prepar use sophisticated and often expensive equipment to examine ing materials for scanning electron microscopy and paleonto sediments and sedimentary rocks. A review of the wide range logical specimens; to G. Coates (working at the university at of available techniques and equipment was not feasible in the the time of the first edition of Practical Sedimentology) for same volume as a review of principles. The original intent to compilation of, and additions to, the procedures for textural analysis and some tables and sketches; to Ted Montague for produce a concise summary of practical sediment studies in an inexpensive format was maintained, but now in the form the bulk of the chapter on borehole sedimentology; to Dr. J.

Selenium is a naturally occurring trace element that can become concentrated and released by industrial, agricultural, petrochemical and mining activities. At concentrated levels it is toxic and has polluted ecosystems around the world. This book will serve as a comprehensive practical handbook for everyone dealing with selenium in aquatic environments. It offers field-tested approaches and methods for assessment and water quality management. Using his twenty-year experience, the author discusses the effects of selenium on fish and bird populations and presents guidelines for identifying sources of pollution, interpreting selenium concentrations, assessing hazardous conditions, setting water quality criteria and ecosystem loading limits (TMDLs). He also includes a procedure for setting environmentally safe limits that ensure compliance with EPA regulations. Selenium Assessment in Aquatic Ecosystems will interest field scientists, natural resource managers, risk assessors and environmental planners.

Regenerative practices for the farm, garden, orchard, forest, and landscape Mycorrhizal fungi have been waiting a long time for people to recognize just how important they are to the making of dynamic soils. These microscopic organisms partner with the root systems of approximately 95 percent of the plants on Earth, and they sequester carbon in much more meaningful ways than human "carbon offsets" will ever achieve. Pick up a handful of old-growth forest soil and you are holding 26 miles of threadlike fungal mycelia, if it could be stretched it out in a straight line. Most of these soil fungi are mycorrhizal, supporting plant health in elegant and sophisticated ways. The boost to green immune function in plants and community-wide networking turns out to be the true basis of ecosystem resiliency. A profound intelligence exists in the underground nutrient exchange between fungi and plant roots, which in turn determines the nutrient density of the foods we grow and eat. Exploring the science of symbiotic fungi in layman's terms, holistic farmer Michael Phillips (author of The Holistic Orchard and The Apple Grower) sets the stage for practical applications across the landscape. The real impetus behind no-till farming, gardening with mulches, cover cropping, digging with broadforks, shallow cultivation, forest-edge orcharding, and everything related to permaculture is to help the plants and fungi to prosper . . . which means we prosper as well. Building soil structure and fertility that lasts for ages results only once we comprehend the nondisturbance principle. As the author says, "What a grower understands, a grower will do." Mycorrhizal Planet abounds with insights into "fungal consciousness" and offers practical, regenerative techniques that are pertinent to gardeners, landscapers, orchardists, foresters, and farmers. Michael's fungal acumen will resonate with everyone who is fascinated with the unseen workings of nature and concerned about maintaining and restoring the health of our soils, our climate, and the quality of life on Earth for generations to come.

The majority of this book was written in 1983-84 while the senior author was a Visiting Scientist at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee. We believe that the approach to the problem of acid deposition effects on soils and waters developed during this collaboration contains ele ments that are significantly different from most prior work in this area. Some of the material and the software used in the development of these concepts stem from earlier individual efforts of the authors. However, what we believe to be the more significant concepts concerning the processes by which alkalinity may be developed in acid soil solutions, and by which acid deposition may contrib ute to the loss of this alkalinity, were the result of this collaboration. The ultimate usefulness of these concepts in understanding and dealing with various aspects of the problems associated with acid deposition cannot be adequately gauged at the present time. They must first withstand tests of con sistency with available observation, and of direct experimentation. It is our hope that dissemination through this book will facilitate this process within the scientific community. The authors wish to thank the administration of the Environmental Science Division at ORNL, and the College of Agricultural Sciences at Colorado State University for their support in arranging this collaboration. We also wish to express our appreciation for the financial support provided by EPA. Personal thanks are due to Dr."

The increasing global demand for food and other agricultural products calls for urgent measures to increase water use efficiency which is, with plant nutrient availability, one of the two main limiting factors in crop production. Although only 20% of all cultivated land in the world is under irrigation, it provides 35-40% of all crop production. Because of higher yields under irrigated agriculture, investments for irrigation are usually a top priority. However, it has become a matter of serious concern in recent years that, despite their high co~ts, the performance of many irrigation projects has fallen short of expectations as a result of inadequate water management at both farm and system levels. Crop production increase has been well below the project targets. The greatest potential for increasing food and other agricultural products is the more efficient use of naturally occurring precipitation in conjunction with improved soil fertility management. Until recently, regardless of the amounts and distribution of rainfall, irrigation practices were used almost exclusively to supplement the amount of soil water stored in the root zone to such an extent that the available soil water never allowed the crop to suffer from water stress throughout the growing season. As a result, even today farmers still tend to over-irrigate to ensure a bountiful amount of water stored.

In this study, an overview is presented of agricultural policies on manure and minerals, relating to the Nitrate Directive to remedy excessive surface- and groundwater contamination from intensive agricultural practices. Six countries belonging to the European Union were studied: the Netherlands, Belgium, Denmark, France, Germany and the United Kingdom. The policies and their legal incorporation were related to agricultural and environmental conditions in each country. In addition, an inventory was made of agricultural mineral poli cies in the United States and Canada. Conditions for livestock farming in North America differ considerably from those in Europe, but their solutions shed a different light on European policies. Research has shown that there are still very considerable mineral surpluses in many countries and regions. In both the Netherlands and in the Flemish part of Belgium, existing problems due to very high levels of manure production are structural rather than local and cannot easily be solved by transport of manure to other regions. To a lesser extent. Germany, Denmark and relatively small parts of France (Brittany) and the United Kingdom, still exceed the norms for an equilibrium fertilization. In Denmark, existing problems can probably be solved within the existing legislative framework. The Netherlands, Flanders. several German Lander (Nordrhein-Westfalen and Schleswig-Holstein) and Brittany.

Bioremediation - the use of microorganisms for environmental clean-up - is a technology that is experiencing a rapid phase of development. From the opening chapter of Perspectives in Bioremediation, on the nature of environmental site assessment, on to the genetic manipulation of native soil microorganisms, the international collection of authors provide an understanding of the current progress and limitations of technologies that are designed to help nature herself. The book draws together many different aspects of environmental remediation: the environmental engineer is introduced to the bacteria of contaminated environments and the ideas developing from genetic engineering; the environmental microbiologist can grasp site assessment and the predictive kinetic analysis of potentials. The book provides a clear and concise introduction to the nature of and potential for bioremediation to contribute to a critical global effort in eliminating contamination of the world's resources and to start to reverse decades of environmental mismanagement and neglect.

In the Netherlands the Institute for Soil Fertility Research plays a major role in soil biological, soil physical and plant nutritional research on the availability of nitrogen to crops. Main subjects of research are nitrogen turnover in the crop-soil ecosystem through biological transformations, nitrogen transport through the soil and nitrogen losses by leaching, denitrification and volatilization, and nitrogen use efficiency of various crops and cropping systems. The current knowledge in the different fields of research is integrated in simulation models. Simulation models not only make it possible to summarize and structure knowledge, but also, after verification, to extra- late the knowledge to situations different from the situations that have actually been studied. Such research is also carried out in other European and non-European countries. To compare the various simulation models currently in use, a workshop was organized by the Institute for Soil Fertility Research on 5-6 June 1990 on the occasion of its centennial. The title of the workshop was 'Nitrogen turnover in the soil-crop:: cosystem: modelling of biological transformations, transport of nitrogen and nitrogen use efficiency'. The 40 Jarticipants, who came from Canada and various European countries, were requested to run their model with data Jrovided by the Institute prior to the workshop. Data from 18 cases were made available to the participants: three ocations, three treatments, and two seasons.