Geologia

ISSN 0532-0488

WORLD SOIL RESOURCES REPORTS

103

World reference base for soil resources 2006
A framework for international classification, correlation and communication

International Union of Soil Sciences

Cover photograph: Ferralsol (Ghana), Cryosol (Russia), Solonetz (Hungary), Podzol (Austria), Phaeozem (USA), Lixisol (Tanzania), Luvisol (Hungary). Compiled by Erika Michéli.Copies of FAO publications can be requested from: SALES AND MARKETING GROUP Information Division Food and Agriculture Organization of the United Nations Viale delle Terme di Caracalla 00100 Rome, Italy E-mail: publications-sales@fao.org Fax: (+39) 06 57053360 Web site: http://www.fao.org

World reference base for soil resources 2006
A framework for international classification, correlationand communication

WORLD SOIL RESOURCES REPORTS

103

2006 edition

FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS Rome, 2006

The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations concerning the legal or developmentstatus of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. IUSS Working Group WRB. 2006. World reference base for soil resources 2006. 2nd edition. World Soil Resources Reports No. 103. FAO, Rome. ISBN 92-5-105511-4 All rights reserved. Reproduction and dissemination of material in this information product for educational orother non-commercial purposes are authorized without any prior written permission from the copyright holders provided the source is fully acknowledged. Reproduction of material in this information product for resale or other commercial purposes is prohibited without written permission of the copyright holders. Applications for such permission should be addressed to: Chief Publishing ManagementService Information Division FAO Viale delle Terme di Caracalla, 00100 Rome, Italy or by e-mail to: copyright@fao.org © FAO 2006

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Contents

Foreword Acknowledgements List of acronyms and abbreviations 1. Background to the world reference base for soil resources
History From its beginnings to the first edition in 1998 From the first edition in 1998 to the second edition in 2006 Basicprinciples Architecture Key to the Reference Soil Groups The qualifier level Principles and use of the qualifiers in the WRB The geographical dimension of WRB qualifiers – match to mapping scale The object classified in the WRB Rules for classification Step one Step two Step three Example of WRB soil classification

vii viii ix 1
1 1 2 3 4 4 6 6
7

7 8 8 8 8 9

2. Diagnostic horizons,properties and materials
Diagnostic horizons Albic horizon Anthraquic horizon Anthric horizon Argic horizon Calcic horizon Cambic horizon Cryic horizon Duric horizon Ferralic horizon Ferric horizon Folic horizon Fragic horizon Fulvic horizon Gypsic horizon Histic horizon Hortic horizon Hydragric horizon Irragric horizon Melanic horizon Mollic horizon Natric horizon Nitic horizon

11
11 11 12 12 13 1516 17 17 18 19 20 20 21 22 23 23 24 24 25 25 26 28

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Petrocalcic horizon Petroduric horizon Petrogypsic horizon Petroplinthic horizon Pisoplinthic horizon Plaggic horizon Plinthic horizon Salic horizon Sombric horizon Spodic horizon Takyric horizon Terric horizon Thionic horizon Umbric horizon Vertic horizon Voronic horizon Yermic horizon

29 30 30 31 32 32 33 34 35 35 36 37 38 38 39 4041

Diagnostic properties Abrupt textural change Albeluvic tonguing Andic properties Aridic properties Continuous rock Ferralic properties Geric properties Gleyic colour pattern Lithological discontinuity Reducing conditions Secondary carbonates Stagnic colour pattern Vertic properties Vitric properties Diagnostic materials Artefacts Calcaric material Colluvic material Fluvic material Gypsiric...