Lecture Notes on the Major Soils of the World

World Soil Resources Reports 94 ISSN 0532-0488 LECTURE NOTES ON THE MAJOR SOILS OF THE WORLD Catholic University of Leuven World Soil Resources Reports 94 LECTURE NOTES ON THE MAJOR SOILS OF THE WORLD Edited by: Paul Driessen, Wageningen Agricultural University, International Institute for Aerospace Survey and Earth Sciences (ITC), Jozef Deckers, Catholic University of Leuven Otto Spaargaren, International Soil Reference and Information Centre Freddy Nachtergaele, FAO FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS Rome, 2001 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 status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. ISBN 925-104637-9 All rights reserved. Reproduction and dissemination of material in this information product for educational or other 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 the Chief, Publishing and Multimedia Service, Information Division, FAO, Viale delle Terme di Caracalla, 00100 Rome, Italy or by e-mail to copyright@fao.org © FAO 2001 Preface After endorsement of the World Reference Base for Soil Resources (WRB) as a universal soil correlation tool by the International Union of Soil Sciences (IUSS), the Reference Base (RB) working group has endeavoured to promote, test and improve the system further . The aim of this publication is to make the WRB available to young scientists at an affordable price. This text is published in conjunction with a CD-ROM that contains additional sample profiles, analytical data and virtual field excursions. The document and the CD-ROM are produced jointly by the Wageningen Agricultural University (Wageningen, The Netherlands), the International Institute for Aerospace Survey and Earth Sciences (ITC, Enschede, The Netherlands), the International Soil Reference and Information Centre (ISRIC, Wageningen, The Netherlands), the Faculty of Agricultural Sciences of the Katholieke Universiteit Leuven (Belgium) and FAO. This publication succeeds the Lecture notes on the major soils of the world by P.M. Driessen and R. Dudal, eds. (1991) which were based on the Legend of the FAO Soil Map of the World. For convenience, all WRB Reference Soil Groups are assembled in ten ‘sets’, each characterized by ‘dominant identifiers’, i.e. soil forming factor(s) which most clearly condition soil formation. Each Reference Soil Group is discussed with due attention to diagnostics, regional distribution, association with other Reference Soil Groups, genesis, characteristics (morphological, hydrological, physical and chemical), land use and management. iv Acknowledgements The editors wish to acknowledge the invaluable help of all individuals who participated in WRB field testing or contributed critical comments and suggestions. The following persons contributed to the text of these Notes (in alphabetical order): Berding, F.R. Gleysols, Umbrisols, Arenosols, Regosols, Andosols, Gypsisols, Calcisols, Durisols, Podzols , Qualifyer categories and their ranking Blume, H.P. Gleysols Brahy, V. Alisols Buurman, P. Podzols Deckers, J. A. Vertisols, Luvisols, Albeluvisols Delvaux, B. Alisols Driessen, P.M. Introduction, Histosols, Arenosols, Leptosols, Regosols, Cambisols, Plinthosols, Ferralsols, Nitisols, Acrisols, Lixisols, Solonchaks, Solonetz, Gypsisols, Calcisols, Chernozems, Kastanozems, Phaeozems, Planosols, final editing of all chapters Dudal, R. Critical review of the entire text, with special attention for Luvisols Langohr, R. Albeluvisols Mensvoort, M. van Gleysols, Fluvisols Nachtergaele, F. O. Qualifyers, maps, critical review of the entire text Spaargaren, O. C. Anthrosols Tarnocai, C. Cryosols Tebbens, L. All chapter on Major Landforms Veldkamp, T. All chapters on Major Landforms. Messrs J. P. Lesschen and N. Witte produced the CD-ROM. These lecture notes will be progressively improved. Suggestions for amendments or additions are most welcome. Rome, June, 2001 Lecture Notes on the Major Soils of the World v Contents page PREFACE INTRODUCTION 1 THE WORLD REFERENCE BASE FOR SOIL RESOURCES 11 The WRB as a soil correlation system 13 Rules for identifying soil units 13 Ranking qualifiers in soil unit names 14 Polygenetic and buried soils 15 REFERENCE SOIL GROUPS 17 SET 1. ORGANIC SOILS 19 Histosols 21 SET 2. MINERAL SOILS CONDITIONED BY MAN 35 Anthrosols 37 SET 3. MINERAL SOILS CONDITIONED BY PARENT MATERIAL 43 Major landforms in volcanic landscapes 45 Andosols 51 Major landforms in landscapes with sands 59 Arenosols 65 Major landforms in landscapes with expanding clays 73 Vertisols 75 SET 4. MINERAL SOILS CONDITIONED BY TOPOGRAPHY 89 Major landforms in alluvial lowlands 91 Fluvisols 105 Gleysols 115 Major landforms in mountains and formerly glaciated regions 121 Leptosols 125 Regosols 131 SET 5. MINERAL SOILS CONDITIONED BY LIMITED AGE 135 Cambisols 137 vi SET 6. MINERAL SOILS CONDITIONED BY A WET (SUB)TROPICAL CLIMATE 141 Major landforms in the (sub-)humid tropics 143 Plinthosols 149 Ferralsols 155 Alisols 163 Nitisols 171 Acrisols 177 Lixisols 181 SET 7. MINERAL SOILS CONDITIONED BY A (SEMI-)ARID CLIMATE 185 Major landforms in (semi-)arid regions 187 Solonchaks 191 Solonetz 201 Gypsisols 207 Durisols 211 Calcisols 215 SET 8. MINERAL SOILS CONDITIONED BY A STEPPIC CLIMATE 221 Major landforms in steppe regions 223 Chernozems 227 Kastanozems 233 Phaeozems 237 SET 9. MINERAL SOILS CONDITIONED BY A (SUB)HUMID TEMPERATE CLIMATE 241 Major landforms in (sub-)humid temperate regions 243 Podzols 247 Planosols 253 Albeluvisols 259 Luvisols 265 Umbrisols 271 SET 10. MINERAL SOILS CONDITIONED BY PERMAFROST 275 Cryosols 277 REFERENCES 285 ANNEXES 291 Annex 1. Key to Reference Soil Groups 293 Annex 2. Diagnostic horizons, properties and materials 299 Annex 3. Qualifiers (formative elements for naming soil units) 317 Annex 4. Suggestions for ranking qualifiers in soil unit names 329 Lecture Notes on the Major Soils of the World 1 Introduction The FAO-Unesco Soil Classification System The World Reference Base for soil resources Diagnostic horizons, properties and materials Lecture Notes on the Major Soils of the World 3 Introduction Soil is a 3-dimensional body with properties that reflect the impact of (1) climate, (2) vegetation, fauna, Man and (3) topography on the soil’s (4) parent material over a variable (5) time span. The nature and relative importance of each of these five ‘soil forming factors’ vary in time and in space. With few exceptions, soils are still in a process of change; they show in their ‘soil profile’ signs of differentiation or alteration of the soil material incurred in a process of soil formation or ‘pedogenesis’. Unlike plants and animals, which can be identified as separate entities, the world’s soil cover is a continuum. Its components occur in temporal and/or spatial successions. In the early days of soil science, soil classification was based on the (surmised) genesis of the soils. Many ‘traditional’ soil names refer to the soil forming factor considered to be dominant in a particular pedogenetic history, for instance ‘desert soils’ (climate being the dominant factor), ‘plaggen soils’ (human interference), ‘prairie soils’ (vegetation), ‘mountain soils’ (topography), or ‘volcanic ash soils’ (parent material). Alternatively, soil names referred to a prominent single factor, for instance ‘Brown Soils’ (colour), ‘alkali soils’ (chemical characteristic), ‘hydromorphic soils’ (physical characteristic), ‘sandy soils’ (texture) or ‘lithosols’ (depth). The many soil classification schemes developed over the years reflect different views held on concepts of soil formation and mirror differences of opinion about the criteria to be used for classification. In the 1950’s, international communications intensified while the number of soil surveys increased sharply both in temperate regions and in the tropics. The experience gained in those years and the exchange of data between scientists rekindled interest in (the dynamics of) the world’s soil cover. Classification systems were developed, which aimed at embracing the full spectrum of the soil continuum. In addition, emphasis shifted away from the genetic approach, which often contained an element of conjecture, to the use of soil properties as differentiating criteria. By and large, consensus evolved as to the major soil bodies which needed to be distinguished in broad level soil classification although differences in definitions and terminology remained. THE FAO-UNESCO SOIL CLASSIFICATION SYSTEM In 1974, the Food and Agriculture Organization of the United Nations (FAO) published its Soil Map of the World (SMW). Compilation of the SMW was a formidable task involving collection and correlation of soil information from all over the world. Initially, the Legend to the SMW consisted of 26 (‘first level’) “Major Soil Groupings” comprising a total of 106 (‘second level’) ‘Soil Units’. In 1990, a ‘Revised Legend’ was published and a third hierarchical level of ‘Soil Subunits’ was introduced to support soil inventory at larger scales. Soil Subunits were not

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