The papers collected in this book were given and discussed at the symposium on "Soil water physics and technology", which was held in Rehovot, Israel, from August 19th-September 4th, 1971. It was sponsored by the International Society of Soil Science (1.S.S.S.) through its Commissions I (soil physics) and VI (soil technology), and organized by the Israeli Soil Science Society. Thanks are due to the Editors for having assembled contributions and discussion remarks into a well-rounded, coherent book. The subjects covered in this book are the theoretical and practical aspects of the following topics: water movement in soils, soil-water interactions, evaporation from soil and plants, water requirements of crops, ion activity and migration in soils, soilwater management and salinity. In as much as these contributions were not solicited, they represent ideas and subjects considered important by the authors and debators. In science, one often finds a gap between basic research and practical application. If reading this book creates a feeling of an apparent lack of balance between theory and practice, this represents the state of our science today, and the thoughtful reader can and will recognize that much remains to be done. W. R. GARDNER T.]. MAR5HAL President, Commission I President, Commission VI 1.5.5.5.

The papers collected in this book were given and discussed at the symposium on "Soil water physics and technology", which was held in Rehovot, Israel, from August 19th-September 4th, 1971. It was sponsored by the International Society of Soil Science (1.S.S.S.) through its Commissions I (soil physics) and VI (soil technology), and organized by the Israeli Soil Science Society. Thanks are due to the Editors for having assembled contributions and discussion remarks into a well-rounded, coherent book. The subjects covered in this book are the theoretical and practical aspects of the following topics: water movement in soils, soil-water interactions, evaporation from soil and plants, water requirements of crops, ion activity and migration in soils, soilwater management and salinity. In as much as these contributions were not solicited, they represent ideas and subjects considered important by the authors and debators. In science, one often finds a gap between basic research and practical application. If reading this book creates a feeling of an apparent lack of balance between theory and practice, this represents the state of our science today, and the thoughtful reader can and will recognize that much remains to be done. W. R. GARDNER T.]. MAR5HAL President, Commission I President, Commission VI 1.5.5.5.

The unsaturated zone is the medium through which pollutants move from the soil surface to groundwater. Polluting substances are subjected to complex physical, chemical and biological transformations while moving through the unsaturated zone and their displacement depends on the transport properties of the water-air­ porous medium system. Pollution caused by human activities, agriculture, and industry, has brought about a growing interest in the role of the unsaturated zone in groundwater pollution. Due to the complexity and the multidisciplinary nature of the subject, it is being investigated by specialists from various scientific disciplines, such as soil physicists, chemists, biologists, and environmental engineers. This state of affairs has motivated the initiative taken by the Water Quality Commissions of IUPAC (the International Union of Pure and Applied Chemistry) and IAHS (the International Association of Hydrological Sciences) to convene an international workshop, which was organized and hosted by the Institute of Soils and Water of the Agricultural Research Organization in Bet­ Dagan, Israel in March 1983. The lecturers at the workshop were an invited group of specialists who are engaged in studying the many facets of the unsaturated zone, and the present book is a selection of their presentations. Each chapter of the book relates to a different aspect of the unsaturated zone.

The papers collected in this book were given and discussed at the symposium on "Soil water physics and technology", which was held in Rehovot, Israel, from August 19th-September 4th, 1971. It was sponsored by the International Society of Soil Science (1.S.S.S.) through its Commissions I (soil physics) and VI (soil technology), and organized by the Israeli Soil Science Society. Thanks are due to the Editors for having assembled contributions and discussion remarks into a well-rounded, coherent book. The subjects covered in this book are the theoretical and practical aspects of the following topics: water movement in soils, soil-water interactions, evaporation from soil and plants, water requirements of crops, ion activity and migration in soils, soilwater management and salinity. In as much as these contributions were not solicited, they represent ideas and subjects considered important by the authors and debators. In science, one often finds a gap between basic research and practical application. If reading this book creates a feeling of an apparent lack of balance between theory and practice, this represents the state of our science today, and the thoughtful reader can and will recognize that much remains to be done. W. R. GARDNER T.]. MAR5HAL President, Commission I President, Commission VI 1.5.5.5.

The papers collected in this book were given and discussed at the symposium on "Soil water physics and technology", which was held in Rehovot, Israel, from August 19th-September 4th, 1971. It was sponsored by the International Society of Soil Science (1.S.S.S.) through its Commissions I (soil physics) and VI (soil technology), and organized by the Israeli Soil Science Society. Thanks are due to the Editors for having assembled contributions and discussion remarks into a well-rounded, coherent book. The subjects covered in this book are the theoretical and practical aspects of the following topics: water movement in soils, soil-water interactions, evaporation from soil and plants, water requirements of crops, ion activity and migration in soils, soilwater management and salinity. In as much as these contributions were not solicited, they represent ideas and subjects considered important by the authors and debators. In science, one often finds a gap between basic research and practical application. If reading this book creates a feeling of an apparent lack of balance between theory and practice, this represents the state of our science today, and the thoughtful reader can and will recognize that much remains to be done. W. R. GARDNER T.]. MAR5HAL President, Commission I President, Commission VI 1.5.5.5.

The unsaturated zone is the medium through which pollutants move from the soil surface to groundwater. Polluting substances are subjected to complex physical, chemical and biological transformations while moving through the unsaturated zone and their displacement depends on the transport properties of the water-air­ porous medium system. Pollution caused by human activities, agriculture, and industry, has brought about a growing interest in the role of the unsaturated zone in groundwater pollution. Due to the complexity and the multidisciplinary nature of the subject, it is being investigated by specialists from various scientific disciplines, such as soil physicists, chemists, biologists, and environmental engineers. This state of affairs has motivated the initiative taken by the Water Quality Commissions of IUPAC (the International Union of Pure and Applied Chemistry) and IAHS (the International Association of Hydrological Sciences) to convene an international workshop, which was organized and hosted by the Institute of Soils and Water of the Agricultural Research Organization in Bet­ Dagan, Israel in March 1983. The lecturers at the workshop were an invited group of specialists who are engaged in studying the many facets of the unsaturated zone, and the present book is a selection of their presentations. Each chapter of the book relates to a different aspect of the unsaturated zone.