FAO-UNESCO Soil Map of the World, 1:5000000. Vol. 6: Africa
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FAO -Unesco Soilmap of the world Volume VI Africa FAO - Unesco Soil map of the world 1 : 5 000 000 Volume VI Africa FAO - Unesco Soil map of theworld Volume I 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 Southeast Asia Volume X Australasia FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS UNITED NATIONS EDUCATIONAL, SCIENTIFIC AND CULTURAL ORGANIZATION FAO-Unesco Soilmap of the world 1: 5 000 000 Volume VI Africa Prepared by the Food and Agriculture Organization of the United Nations Unesco-Paris 1977 The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations or theUnited Nations Educa- tional, Scientific and Cultural Organization con- cerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. 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 Publishedin 1977bytheUnitedNations Educational,Scientific and Cultural Organization Place de Fontenoy, 75007 Paris © FAO/Unesco 1977 Printed in Italy PREFACE The project for a joint FAo/Unesco SoiI Map of maps and text.FAO and Unesco shared the expenses the World was undertaken following a recommen- involved in the realization of the project, and Unesco dation of the International Society of Soil Science. undertook publication of its results.For the prepa- It is the first attempt to prepare, on the basis of in- ration of the Soil Map of Africa and its explanatory ternational cooperation, a soil map coveringall text, the services of experts were made availabie by the continents of the world in a uniform legend, the Governments of Belgium, France and the Nether- thus enabling the correlation of soil units and com- lands to work on the project. parisons on a global scale.The project, which started The present volume, covering the soils of Africa, in 1961, fills a gap in present knowledge of soil po- is the sixth of a set of ten which make up the complete tentialities throughout the world and provides a publication of the Soil Map of the World.The useful instrument in planning agricultural and eco- first volume records introductory information and nomic development programmes. presentsthedefinitions of the elements of the The project has been carried out under the scien- legend which are used uniformly throughout the tific authority of an international advisory panel, publication. Each of the nine following volumes within the framework of FAO and Unesco pro- comprises an explanatory text and the correspond- grammes.The different stages of the work included ing map sheets covering the main regions of the comparative studies of soil maps, field and laboratory world. work, and the organization of international expert FAO and Unesco wish to express their gratitude meetings and study tours. The secretariat of the joint to the governmental institutions, the International project, located at FAO Headquarters, was vested Society of Soil Science, and the many individual soil with the responsibility of compiling the technical scientists who have contributed so much to this in- information, correlating the studies and drafting the ternational project. CONTENTS Preface 6. Landuse and soil suitability 200 Acrisols 201 Cambisols 202 Summaries Rendzinas 204 Ferralsols 205 English Gleysols 206 French Phaeozems 207 Russian Lithosols 207 Spanish Fluvisols 207 Kastanozerns 207 Luvisols 208 Nitosols 208 Introduction 1 Histosols 209 Podzols 209 Arenosols 210 Regosols 210 Acknowledgements 3 S. Solonetz 211 T.Andosols 211 Vertisols 212 Planosals 212 The map 6 X.Xerosols 213 Y.Yermosols 213 Topographic base 6 Z.Soloncha ks 213 Map units and cartographic representation 6 Conc/usions 214 Sources of information 7 Appendix Environmental conditions 18 Morphological, chemical and physical proper- ties of African soils: data from typical pro- Climate 18 files . 218 Vegetation 25 Geomorphology 32 Figures (at back of volume) Geology and Ethology 42 Climatic regions Broad vegetation regions Geomorphological regions The soils of Africa 62 4.Geological regions 5.Broad lithological regions Distribution of major soils 62 6.Broad soil regions Broad soil regions 62 7.Population distribution SUMMARY This volume describes the African section of the Climate is discussed in terms of 12 broad climatic FAo/Unesco 1: 5 000 000 Soil Map of the World. regions.The climatic map which supplements the In 1964, the Commission for Technical Cooperation soil map should be consulted for the transfer of in Africa South of the Sahara (Commission de coo- crop information from one part of the world to peration technique en Afrique au Sud du Sahara - another (Fig. 1). CcrA) produced and published a 1: 5 000 000 map of Africa and an explanatory monograph.However, Vegetation is divided into nine broad vegetation recent surveys and the need to correlate all existing regions and 38 subregions distinguished according maps and make a uniform legend compelled FAO to the physiognomy and structure of the plant cover. to entirely redesign the CCTA map within the frame- The subregions are outlined on a small-scale map work of the Soil Map of the World. (Fig. 2). Geomorphology is examined in terms of 18 regions, each of which is divided into a number of subregions. The maps The various regions and subregions are shown on a small-scale map (Fig. 3). The three map sheets composing the Soil Map of Africa are drawn on topographic base maps Geology andlithologyare considered together of the 1: 5 000 000 series of the American Geo- under 30 regions.Two small-scale maps outline graphical Society.The map units are associations the geological regions and lithology of Africa (Figs. 4 of soil units divided into texture and slope classes. and 5, respectively). They are marked on the maps by symbols, letters and figures.Dominant soils are shown by colours SOILS AND LAND USE while phase differences are shown by overprints. A small inset map shows the three soil information Chapter 5 outlines the soils of the continent ac- reliability classes. cording to 53lat oad soil regi ons and contains an Detailed definitions of the soil units and full descrip- extensive table of soil associations.Chapter 6 treats tion of all the terms used may be found in Volume I. the soils in depth, discussing distribution, climate, plant covet, land use and soil suitabilities for agri- culture. The text The table of soil associations lists all the map units in alphabetical order of symbols.Other col- The first chapter describes the development of umns show associated soils, inclusions, phases, area the project in Africa and gives some notes on uses of units in thousands of hectares, climate symbols, of the map.The second acknowledges the cooper- countriesof occurrence, vegetation symbols, and ation of the agencies and individuals who contrib- lithology or parent materials. uted to the maps and text, and the third gives a The distribution of major soilsis discussed on summary of the material in Volume I on the maps the basis of 53 broad soil regions outlined on a and legend.The fourth, fifth and sixth chapters small-scale map (Fig. 6). deal with environmental conditions, soils and land use. Present land use and suitabilities for agriculture are discussed at first in general with a small-scale ENVIRONMENTAL CONDITIONS map of population distribution (Fig. 7) and an ac- Chapter 4 deals with the environmental factors count of the different farming systems used in Africa. that are important in the development of soils: The main soils are then considered separately in climate,vegetation,geomorphology, geology and terms of their present use and their suitability for lithology. both traditional and modem farming. viii SOIL MAP OF AFRICA Only a small area of Africa is at present under poorly drained, and Arenosols in Senegal, Niger cultivation.Huge regions have yet to be exploited, and Chad often lack nutrient elements and water- and some of them probably never will be owing to absorbing capacity and occur with very poor paleosol the large area occupied by desert regions.The ironpans (Ferralsols and Acrisols).Extensive live- land under cultivation is generally managed by tradi- stock raising is a solution, although cultivation may tional methods and yields are only slightly over those be feasible in rich valleys put under supplementary of a subsistence economy.Agricultural production irrigation. can be substantially increased if the unexploited land Highlands such as those in Ethiopia and Lesotho resources are utilized and better use is made of land often have a basement of volcanic rock, and if not already under cultivation by increasing yield without eroded have fairly favourable humus soils such as causing soil degradation. Andosols, Ferralsols and Nitosols.The climate is also more temperate. The Mediterranean 1 zones of northern and southern CONCLUSIONS Africa have rich soils (Luvisols, Chromic Cambisols, Calcaric and Eutric Cambisols and Kastanozems) Agriculture in Africa is affected by a number of and are generally more suitable for cultivation, but limitations.Vast regions in the Sahara, in Somalia erosion is severe and often produces Lithos°ls. and in the Namib and Kalahari deserts suffer from Steeplands are not numerous in Africa.They a deficiency of water.Even if underground water often coincidewith therichestsoils(Andosols, resources are utilized or recourse is had to sea water Eutric Nitosois and Eutric Cambisols) but are dif- distillation, the irrigated areas wilI always be small ficult to reclaim. in relation to the total land area, especially as the Extensive areas with poor drainage occur in the soils in these regions are often too stony, sandy or Niger and Congo basins and in the Sudd region saline foragriculture.