Soil degradation is clearly one of the most pressing problems facing man­ kind. A continuation of soil degradation will eventually lead to a loss in crop productivity even though fertilizers and other inputs often result in increased yields in the short term. Soil degradation also leads to environ­ mental pollution. A decrease in soil quality invariably leads to a decrease in water quality, and often in air quality. While there is a clear consensus that soil degradation is a major problem, the literature on this subject leaves numerous baffling questions. If statis­ tics on land degradation are correct, there is a definite cause for concern, and present a mammoth challenge for agricultural scientists. There are those that say the scientific community has over dramatized this issue, and created a credibility problem. Consequently; Volume 11 of Advances in Soil Science was organized by Dr. Rattan Lal who is recognized as a lead­ ing authority on the subject. The objective of Volume 11 was to assess the types and processes of soil degradation and establish some of the major cause-effect relationships. Volume II documented the seriousness of soil degradation in many parts of the world. Therefore, it seemed immediately important to devote a volume to the principles and technologies for restor­ ing degraded soils to a productive status. While the land resources are limited, world population is rapidly increasing, particularly in developing countries. Dr.

Need for Land Restoration.- I. Introduction.- II. Basic Concepts of Land Restoration.- III. Global Extent of Soil Degradation.- IV. Land Hunger.- V. Need for Soil Restoration.- VI.Conclusion.- References.- Reclamation of Chemically Degraded Soils.- I. Introduction.- II. Principles of Soil Reclamation.- III. Conclusions.- References.- Soil Fertility Restoration and Management for Sustainable Agriculture in South Asia.- I. Introduction.- II. Soils, Climate, and Crops of South Asia.- III. Soils Under Shifting Cultivation.- IV. Soils Under Intensive Cultivation.- V. Soils Under Salinity or Sodicity.- VI. Summary and Conclusions.- References.- Reclamation of Acid Sulphate Soils.- I. Introduction.- II. Previous Reviews and Major Sources.- III. Formation and Characteristics of Acid Sulphate Soils.- IV. Alternative Strategies for Reclamation.- V. Minimum-Disturbance Strategies.- VI. Reclamation by Leaching and Liming.- VII. Summary and Conclusions.- References.- Restoring Land Degraded by Gully Erosion in the Tropics.- I. Introduction.- II. Mechanisms of Gully Formation and Advance.- III. Factors Affecting Gully Erosion.- IV. Anthropogenic Causes Responsible for Gully Erosion.- V. Watershed Factors in Gully Erosion.- VI. Measurement and Evaluation of Gully Erosion.- VII. Gully Erosion Control.- VIII. Conclusions.- References.- Reclamation of Indurated, Volcanic-Ash Materials in Latin America.- I. Introduction.- II. Nomenclature.- III. Genesis of Indurated, Volcanic-Ash Materials.- IV. Classification of Indurated Materials.- V. Properties of Indurated Materials.- VI. Distribution and Extent of Indurated Materials.- VII. Soil Erosion on Indurated Materials.- VIII. Reclamation of Exposed Indurated Materials.- IX. Summary.- References.- Soil Faunal Degradation and Restoration.- I.Introduction.- II. The Composition of the Fauna.- III. Influence of Fauna on Soil Fertility.- IV. Land Disturbance and Faunal Degradation.- V. Restoring Soil Fauna.- VI. Faunal Indicators and Biological Monitoring of Soil Quality.- VII. Conclusion.- References.- Creation and Restoration of Wetlands: Some Design Considerations for Ecological Engineering.- I. Introduction.- II. Wetland Design.- III. Summary.- References.- Bioremediation of Soils Contaminated with Selenium.- I. Introduction.- II. Geochemistry.- III. Deficiencies and Toxicity of Selenium.- IV. Vegetation Uptake.- V. Microbial Transformations.- VI. Bioremediation of Selenium Contaminated Soils: San Joaquin Valley, California-A Case History.- VII. Remediation of Seleniferous Sediments and Water.- VIII. Conclusions.- References.- Reclamation of Mine Tailings.- I. Introduction.- II. Distribution of Tailings.- III. Environmental Consequences.- IV. Limitations to Tailings Reclamation.- V. Mine Tailings Reclamation.- VI. Summary.- References.- Reclamation of Mine Land Using Municipal Sludge.- I. Introduction.- II. Review of Land Reclamation Projects Using Municipal Sludge.- III. Summary.- References.- Researcher and Development Priorities for Soil Restoration.- I. Introduction.- II. Approaches to Soil Restoration.- III. Strategies and Policies.- IV. Conclusions.- References.