The World Reference Base for Soil Resources (WRB) is an international framework for soil classification, correlation, and communication. This second edition, published by the Bundesanstalt für Geowissenschaften und Rohstoffe (BGR) in collaboration with the Food and Agriculture Organization of the United Nations (FAO), presents the current state-of-the-art of the WRB after eight years of extensive global testing and data collection. The WRB aims to harmonize and correlate technical languages used in soil science, contributing to a better understanding of soil science in public debates and the scientific community. The WRB consists of two levels: 1. **Level 1**: 32 Reference Soil Groups (RSGs) defined by diagnostic horizons, properties, and materials. 2. **Level 2**: Combinations of RSGs with qualifiers, further specifying the properties of the RSGs through a series of defined prefix and suffix qualifiers. Key features of the WRB include: - **Diagnostic Horizons**: These are diagnostic layers that reflect specific soil-forming processes and are used to define RSGs. - **Properties and Materials**: These are characteristics and materials that influence soil formation and are used to define diagnostic horizons and properties. - **Qualifier System**: The qualifier system includes prefix and suffix qualifiers, which are used to specify the properties of RSGs. Prefix qualifiers are typically associated with RSGs and include transitional forms to other RSGs, while suffix qualifiers cover various aspects such as chemical, physical, and mineralogical properties. The WRB is designed to be used for soil correlation, harmonization, and communication, as well as for global soil data compilation, inventory, and monitoring. It is not intended for soil mapping but can be used for small-scale soil maps if the qualifier lists are appropriately adjusted. The WRB has been widely adopted and used in various countries and regions, including Europe, Africa, Asia, and the Americas. It has been translated into multiple languages and is supported by organizations such as the International Soil Reference and Information Centre (ISRIC) and the Food and Agriculture Organization of the United Nations (FAO). This edition includes updates and corrections from the 2007 electronic version published by FAO, reflecting changes in diagnostic criteria, definitions, and qualifier lists. The WRB is a valuable resource for soil scientists, policymakers, and researchers, providing a standardized framework for soil classification and management.The World Reference Base for Soil Resources (WRB) is an international framework for soil classification, correlation, and communication. This second edition, published by the Bundesanstalt für Geowissenschaften und Rohstoffe (BGR) in collaboration with the Food and Agriculture Organization of the United Nations (FAO), presents the current state-of-the-art of the WRB after eight years of extensive global testing and data collection. The WRB aims to harmonize and correlate technical languages used in soil science, contributing to a better understanding of soil science in public debates and the scientific community. The WRB consists of two levels: 1. **Level 1**: 32 Reference Soil Groups (RSGs) defined by diagnostic horizons, properties, and materials. 2. **Level 2**: Combinations of RSGs with qualifiers, further specifying the properties of the RSGs through a series of defined prefix and suffix qualifiers. Key features of the WRB include: - **Diagnostic Horizons**: These are diagnostic layers that reflect specific soil-forming processes and are used to define RSGs. - **Properties and Materials**: These are characteristics and materials that influence soil formation and are used to define diagnostic horizons and properties. - **Qualifier System**: The qualifier system includes prefix and suffix qualifiers, which are used to specify the properties of RSGs. Prefix qualifiers are typically associated with RSGs and include transitional forms to other RSGs, while suffix qualifiers cover various aspects such as chemical, physical, and mineralogical properties. The WRB is designed to be used for soil correlation, harmonization, and communication, as well as for global soil data compilation, inventory, and monitoring. It is not intended for soil mapping but can be used for small-scale soil maps if the qualifier lists are appropriately adjusted. The WRB has been widely adopted and used in various countries and regions, including Europe, Africa, Asia, and the Americas. It has been translated into multiple languages and is supported by organizations such as the International Soil Reference and Information Centre (ISRIC) and the Food and Agriculture Organization of the United Nations (FAO). This edition includes updates and corrections from the 2007 electronic version published by FAO, reflecting changes in diagnostic criteria, definitions, and qualifier lists. The WRB is a valuable resource for soil scientists, policymakers, and researchers, providing a standardized framework for soil classification and management.