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...

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...

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,...

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...

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...

Five years have now passed since the first symposium on frankiae was held at Harvard Forest, Petersham, Massachusetts, USA and the inauguration of the term actinorhiza. Many advances have been made during these five years in our understanding of the actinorhizal symbioses. Evidence for this was provided by the papers presented at the Wageningen Workshop on Frankia symbioses, held in Wageningen at the Department of Microbiology of the Agricultural University. Most of these papers are now published in this volume of PLANT AND SOIL. We kindly acknowledge the assistance of Anton Houwers, editor...

The large and rapidly expanding body ofliterature related to nitrogen cycling in both managed and native terrestrial ecosystems reflects the importance accorded to the behaviour of this vital and often limiting nutrient. Research at the organism, ecosystem and landscape levels commonly addresses questions concerning nitrogen acquisition, internal cycling and retention. Goals for this research include increased agricultural productivity and a better understanding of human impact on local, regional and global nitrogen cycles. Nitrogen cycle research in tropical regions has a long and...

Thisbook isabout ions, about variable-chargesurfacesand about models. Jti about ions because most of the substances in which soil scientists are interested occur in the soil solution as ions. This applies to both plant nutrients and pollutants. Thus the, reilction between soil and say phosphate does not involve a substance called "phosphate"; it involves phosphate ions. Ions are charged particles. When these charged particles react with charged surfaces, the outcome of the reaction is affected by both the charge on the particles and the charge on the surfaces. Hence we also need to understand...

The steadily increasing cost of nitrogen fertilizer has resulted in more emphasis on basic and applied studies to improve nitrogen use efficiency in lowland rice. The efficiency of fertilizer nitrogen in farmers' fields is shockingly low a luxury resource-scarce farmers in tropical Asia can ill afford. We believe it is critical to quantify the basic transformation processes and develop management practices for higher N use efficiency for two reasons. They are: 1. Nitrogen fertilizer together with water management is a key factor for achieving the yield potentials of modern rices. 2....

It has long been recognized that soil organic matter is the key to soil fertility. As a nutrient store it gradually provides essential elements which the soil cannot retain for long in inorganic form. It buffers growing plants against sudden changes in their chemical environment and preserves moisture in times of drought. It keeps the soil in a friable, easily penetrated physical condition, well-aerated and free draining, providing young seedlings with an excellent medium for growth. But it has another property, the nature and extent of which have been the subject of argu ment and controversy...