FA 0-Unesco S oilmap f the world FAO - Unesco Soil map of the world 1: 5 000 000 Volume IV South America FAO - Unesco Soil map of the world Volume I Elements of the legend Volume II North America Volume III Mexico and Central America Volume IV South America Volume V Europe Volume VI Africa Volume VII South Asia Volume VIII North and Central Asia Volume IX South East Asia Volume X Australasia FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS CvS UNITED NATIONS EDUCATIONAL, SCIENTIFIC AND CULTURAL ORGANIZATION FAO-Unesco Soilmap of the world 1: 5 000 000 Volume IV South America Prepared by the Food and Agriculture Organization of the United Nations Unesco- Paris 1971 Printed by Tipolitografia F. Failli, Rome for the Food and Agriculture Organization of the United Nations and the United Nations Educational, Scientific and Cultural Organization Published in 1971 by the United Nations Educational, Scientific and Cultural Organization Place de Fontenoy, 75 Paris-7e © FAO/Unesco 1971 Printed in Italy PREFACE The project for a joint FAo/Unesco Soil Map of Foundation; furthermore, the services of associate the World was undertaken foliowing a recommen- experts were made available by the Governments of dation of the International Society of Soil Science. Belgium andtheNetherlands to work on the It is the first attempt to prepare, on the basis of in- project. ternational cooperation, a soil map covering all The present volume, covering the soils of South the continents of the world in a uniform legend, America, is the fourth of a set of ten which make up thus enabling the correlation of soil units and com- the complete publication of the Soil Map of the World.. parisons on a global scale.The project, which started The first volume records introductory information in 1961, fills a gap in present lmowledge of soil po- and presents the definitions of the elements of the tentialities throughout the world and provides a legend which is used uniformly throughout the pub- useful instrument in planning agricultural and eco- lication. Each of the nine following volumes com- nomic development programmes. prises an explanatory text and the corresponding The project has been carried out under the scien- map sheets covering the main regions of the world. tific authority of an international advisory panel, FAO and Unesco wish to express their gratitude within the framework of FAO and Unesco program- to the governmental institutions, the International mes. The different stages of the work included com- Society of Soil Science, and the many individual soil parative studies of soil maps, field and laboratory scientists who have contributed so much to this in- work, and the organization of international expert ternational project. meetings and study tours. The secretariat of the joint The designations employed and the presentation project, located at FAO Headquarters, was vested of the material in this publication do not imply with the responsibility of compiling the technical the expression of any opinion whatsoever on the information, correlating the studies and drafting the part of the Food and Agriculture Organization of the maps and text. FAO and Unesco shared the expenses United Nations or the United Nations Educational, involved in the realization of the project, and Unesco Scientific and Cultural Organization concerning the undertook publication of its results. For the prepa- legal or constitutional status of any country, terri- ration of the Soil Map of South America, additional tory or sea area or concerning the delimitation of financial support was received from the Rockefeller frontiers. CONTENTS Preface y 6. Land use and soil suitability 107 109 Summaries A. Acrisols B. Cambisols 110 English vn F. Ferralsols 110 French a G. Gleysols 113 Russian XI H. Phaeozems 114 Spanish mu I.Lithosols 115 Fluvisols 115 Kastanozems 115 1. Introduction 1 L. Luvisols 116 Nitosols 117 Histosols 117 2. Acknowledgements 4 Podzols 118 Arenosols 118 R. Regosols 119 3. The map 6 S.Solonetz 119 Topographic base 6 T. Andosols 119 120 Map units 6 V. Vertisols W. Planosols 121 Cartographic representation 7 X. Xerosols 121 Sources of information 8 Yermosols 122 Solonchaks 122 4. Environmental conditions 13 Conclusions 123 CLIMATE 13 Climatic factors 13 Appendix Climatic regions 20 Morphological, chemical and physical proper- VEGETATION 21 ties of South American soils: data from se- The broad vegetation regions 21 lected profiles 124 GEOMORPHOLOGY 35 LITHOLOGY 42 Geotectonic regions. 42 Figures 1.Sources of information 9 5. The soils of South America 55 2.Climatic map of South America 17 3. Broad vegetation regions of South America 23 Distribution of major soils 55 4.Geomorphological map of South America 37 Soil regions of the lowlands 89 5.Geotectonic regions of South America... 45 Soil regions of the uplands 94 6.Lithological map of South America 46 Soil regions of the Andean mountain 7.Broad soil regions of South America 91 ranges 102 8.Population distribution, South America.. 108 SUMMARIES This volume describes the South American section soil map in the transfer of crop information from of the 1: 5 000 000 Soil Map of the World.The one part of the world to another.Here only the compilation of the Soil Map of South America was highercategoriesarediscussed.The maincli- started by FAO in the 1950s and was continued and matic regions are outlined on a small-scale map completed by FAO and Unesco in a joint project (Fig. 2). initiated in 1961. Vegetation is discussed on the basis of ten broad vegetation regions distinguished on the basis of the habitat (either climatic or edaphic), the physiognomy The maps and the structure of the vegetation.These regions are then subdivided into 42 subregions which are The two map sheets which make up the Soil Map outlined on a small-scale map (Fig. 3).The text of South America are drawn on topographic base gives some brief notes on each region and on the maps of the 1: 5 000 000 series of the American location and nature of its subregions. Geographical Society. The map units are associa- Geomorphology and landscape development are then tions of soil units divided into texture and slope treated in terms of three main groups of regions: classes. They are marked on the maps by symbols. the Precambrian shield areas on the east of the con- The dominant soils are shown by colours while tinent, the Andean mountain ranges on the western phase differences are shown by overprints. margin and, between these, the basins of the Orinoco A small inset map shows three grades of reli- and Amazon rivers and the Chaco and pampa plains. ability of soil information from which the map was A small-scale map shows the different relief elements compiled. (Fig. 4). Detailed definitions of the soil units and full de- Lithology is considered under the broad headings scriptions of all the terms used may be found in of shields,Andes andbasins.Two small-scale Volume I of the set. maps (Figs.5 and 6)areincluded, one of geo- tectonic regions, which are considered region by region in the text, and the other of lithology.The The text text outlines the geological origins and nature of The first chapter describes the development of the main surfaces at present exposed. the project in South America and gives some notes on uses of the map.The second acknowledges the SOILS AND LAND USE cooperation of the agencies and of the large number of people who contributed to the maps and text, Chapters 5 and 6, describing the soils of the con- and the third gives a summary of the material in tinent, contain an extensive table of soil associa- Volume I on the maps and legend. tions, an account of the distribution of the main The main chapters of this volume deal with envi- soils, and a discussion of land use and soil suitabil- ronmental conditions and use of soils and land. ities for agriculture. The table of soil associations lists all the map units in alphabetical order of symbols.Other columns ENVIRONMENTAL CONDITIONS show; Chapter 4 contains brief accounts with maps of Associated soils the four factors of the environment that have close Inclusions relationships with the pattern of soils: climate, veg- Phases etation, geomorphology and lithology. Areas of units in 1 000 ha Climate is discussed on the basis of seven broad Climate symbols climatic subdivisions.Since the criteria used in de- Countries of occurrence limiting units are those that are important to crop Vegetation growth, the climate map is supplementary to the Lithology or parent materials viii SOIL MAP OF SOUTH AMERICA The distribution of major soils is discussed on the irrigation hazardous or impossible.The soils are basis of 27 broad soil regions grouped into lowlands, mainly Yermosols, Xerosols, Regosols, LithosoIs, uplands and mountains, and outlined on a small- salt-affectedsoilslikeSolonchaks and Solonetz, scale map (Fig. 7).The main soils of each region Ferric Luvisols and Chromic Luvisols. are discussed in relation to factors of the environ- There are also extensive areas with poor drainage, ment, and their important characteristics are noted. which make up about 10 percent of the continent. Present land use and suitabilities for agriculture Here soils are mostly Gleysols, Plinthic Acrisols, are discussed at first in general, with a small-scale Vertisols and Planosols. map of population distribution (Fig. 8) and an ac- The large areas of steeplands in the Andes make count of traditional and modem farming systems. up about 10 percent of the continent.Apart from Then the main soils are considered separately.Their Lithosols, which are dominant, Dystric Cambisols, present use is described, and the suitability of the Andosols and Orthic Acrisols are important, their land for both traditional and modem farming is occurrence being dearly related to altitude and parent outlined.