PUBLICATION N° 93 SOIL MAP OF AFRICA SCALE 1 TO 5000000 Explanatory monograph by J.L. D'HOORE Joint Project no. 11 LAGOS 1964 Commission for Technical Co-operation in Africa YF Commission for Technical Co-operation in Africa PUBLICATION No. 93 SOIL MAP OF AFRICA SCALE 1 TO 5 000 000 EXPLANATORY MONOGRAPH BY J.L. D'HOORE Chargé de cours associé at the Catholic University of Louvain Formerly Director of the Inter African Pedological Service General co-ordinator of Joint Project no 11 Scanned from original by ISRIC - World Soil Information, as ICSU World Data Centre for Soils. The purpose is to make a safe depository for endangered documents and to make the accrued information available for consultation, following Fair Use Guidelines. Every effort is taken to respect Copyright of the materials within the archives where the identification of the Copyright holder is clear and, where feasible, to contact the originators. For questions please contact soil.isriöiawur.nl indicating the item reference number concerned. Joint Project no. 11 LAGOS 1964 PREFACE It is indeed a privilege for me to write the preface to this invaluable work which was begun ten years ago as Joint Project No 11 of the Commission's activities. Over the years, Member Governments repeatedly confirmed their intention to reach agreement on the classification and definition of soils in Africa, and to present the assembled details as an atlas which, like the climatological atlas which has been published recently, would provide the necessary information for land use planning in development programmes. Thus the idea for the pedological map of Africa ivas born. It took some time to prepare the first, second and third drafts of this map, and in 1961 the fourth draft was completed by Dr D'Hoor e with the assistance of correspondence exchanged as a result of a meeting held in 1959 at Dalaba. It then became necessary to meet again in order to consider the abovementioned draft. At a meeting in Paris, therefore, in September, 1961, eleven countries and three organisations participated in three days of technical discussions after which unanimous agreement was reached on all points as to what was to appear on the map and on definitions which had previously been the subject of certain differences. This agreement deserves special emphasis in that, several years ago, few people believed that agreement would ever be reached by pedologists from opposed schools of thought. Thus we have yet another pillar of support for the theory that African governments must agree to act in concert if they are to surmount the many obstacles on the way to attaining their goal : a better Africa for all. The fifth and last version of the map was prepared during the months which followed and now the publication of this valuable work has been made possible by a grant from the US AID. Our deep gratitude therefore goes to the U.S. govern- ment for having appreciated and considered the endeavour valuable enough for financial support. This work covers the entire continent of Africa, including North Africa, and consists of seven maps on a scale of 115,000,000, utilizing the base maps supplied by the Inter-African Correspondent for Cartography under another of the Com- mission's Joint Projects (No. 7). I would like to avail myself of this opportunity to join others in the many tributes that have been paid to the outstanding work of Dr D'Hoore, whose authority and competence have aroused great admiration with pedologists throug- , PREFACE hout Africa. The tireless devotion of Dr D'Hoore to the completion of this project should be noted with gratitude by all who will be using this very fundamental device for future planning inlthe development of Africa. His contribution to the advan- cement of scientific progress in Africa will remain as a monumental proof of what can be achieved when the finest minds are united to search for the solution to a given problem. RICHELIEU MORRIS Secretary General a.i. C.C.T.A. LIST OF CONTENTS FOREWORD 9 GENERAL INTRODUCTION. 11 A'— Origin of the Project 11 B — General Approach and Methodology 11 C — Scientific Value of the Map . 14 PART ONE — THE AFRICAN ENVIRONMENT 17 INTRODUCTION. 19 Chapter 1 — BROAD GEOLOGICAL FEATURES 20 Chapter 2 — GENERAL LANDFORM 24 Chapter 3 — CLIMATE 28 Chapter 4 — VEGETATION : 39 Chapter 5 — PARENT MATERIALS OF THE SOILS 42 PART TWO — THE MAPPING UNITS 47 INTRODUCTION 49 Chapter 1 — RAW MINERAL SOILS 50 A — ROCK AND ROCK DEBRIS 50 1. Rocks rich in ferromagnesian minerals 51 2. Ferruginous cuirasses and calcareous crusts 52 3. Rocks, not differentiated 55 B — Desert detritus 56 1. Sands (ergs) 56 2. Clay plains 57 3. Desert pavements (regs) •• 58 4. Desert detritus, not differentiated 59 Chapter 2 — WEAKLY DEVELOPED SOILS 59 A — Lithosols (skeletal soils) and lithic soils 60 1. On lava 60 2. On rocks rich in ferromagnesian minerals 61 3. On ferruginous crusts 61 4. On calcareous crusts . ' 64 5. Not differentiated 65 B — Sub-desert soils 67 C — Weakly developed soils on loose sediments not recently deposited . 68 D — Juvenile soils on recent deposits 69 1. On volcanic ash 69 2. On riverine and lacustrine alluvium 70 3. On marine alluvium (mangrove swamps) 72 4. On wind-borne sands 73 5. Soils of oases 74 LIST OF CONTENTS Chapter 3 — CALCIMORPHIC SOILS, VERTISOLS AND SIMILAR SOILS 74 A — Calcimorphic soils 74 1. Rendzinas and brown calcareous soils 75 2. Soils with calcareous pans 76 3. Soils containing more than 15% gypsum 77 B — Vertisols and similar soils 77 1. Lithomorphic vertisols derived from rocks rich in ferromagnesian minerals 78 2. Lithomorphic vertisols derived from calcareous rocks 80 3. Vertisols of topographic depressions 81 Chapter 4 — PODSOLIC SOILS AND SOLS LESSIVÉS OR HIOHVELD PSEUDO-PODSOLIC SOILS 83 A — Podsolic soils 83 B — Sols lessivés or Highveld pseudo-podsolic soils 84 Chapter 5 — BROWN AND REDDISH-BROWN SOILS OF ARID AND SEMI-ARID REGIONS . 85 A — Brown soils of arid and semi-arid tropical regions 86 1. Brown soils of arid and semi-arid tropical regions on loose sediments 86 2. Brown soils of arid and semi-arid tropical regions, not differentiated 87 B — Brown and reddish-brown soils of arid and semi-arid Mediterranean regions 88 Chapter 6 — EUTROPHIC BROWN SOILS OF TROPICAL REGIONS 89 1. Eutrophic brown soils on volcanic ash 90 2. Eutrophic brown soils on rocks rich in ferromagnesian minerals . 91 3. Eutrophic brown soils on alluvial deposits 92 4. Eutrophic brown soils, not differentiated 92 Chapter 7 — RED AND BROWN MEDITERRANEAN SOILS 93 A — Red Mediterranean Soils 93 B — Brown Mediterranean Soils 94 Chapter 8 — FERRUGINOUS TROPICAL SOILS 95 1. Ferruginous tropical soils on sandy parent materials 97 2. Ferruginous tropical soils on rocks rich in ferromagnesian minerals 98 3. Ferruginous tropical soils on crystalline acid rocks 99 4. Ferruginous tropical soils , not differentiated 100 Chapter 9 — FERRISOLS 102 1. Humic ferrisols 103 2. Ferrisols on rocks rich in ferromagnesian minerals 104 3. Ferrisols not differentiated 105 Chapter 10 — FERRALLITIC SOILS 107 1. Yellowish-brown ferrallitic soils on loose sandy sediments .... 108 2. Yellowish-brown ferrallitic soils on more or less clayey sediments . 109 3. Yellowish-brown ferrallitic soils not differentiated 110 4. Red ferrallitic soils on loose sandy sediments 112 5. Red ferrallitic soils on rocks rich in ferromagnesian minerals . ... 112 6. Red ferrallitic soils not differentiated . 113 7. Humic ferrallitic soils 114 8. Ferrallitic soils with dark horizon 115 9. Yellow and red ferrallitic soils on various parent materials 116 LIST OF CONTENTS Chapter 11 — HALOMORPHIC SOILS 117 1. Solonetz and solodized solonetz 117 2. Saline soils, alkali soils and saline alkali soils 118 3. Soils of sebkhas and chotts 119 4. Soils of lunettes 120 5. Halomorphic soils, not differentiated 120 Chapter 12 — HYDROMORPHIC SOILS, ORGANIC NON-HYDROMORPHIC SOILS AND • COMPLEX OF VOLCANIC ISLANDS 121 A — Hydromorphic soils 121 1. Mineral hydromorphic soils 121 2. Organic hydromorphic soils 123 B — Organic non-hydromorphic soils 124 C — Complex of volcanic islands 125 PART THREE — CHARACTERISTIC PROFILES AND ANALYTICAL DATA . 127 PART FOUR — THE MAP 179 INTRODUCTION 181 Chapter 1 — THE LEGEND 181 Chapter 2 — REPRESENTATION OF THE UNITS ON THE MAP 185 Chapter 3 —TERRITORIAL DISTRIBUTION OF THE UNITS 186 Chapter 4 — SURFACES COVERED BY EACH OF THE UNITS AND ASSOCIATIONS ... 190 FOREWORD The soils map of Africa was constructed with the direct collaboration of the following authors : GENERAL LEGEND: : G. Aubert, H. Greene, J.V. Botelho da Costa. AFRICA OCCIDENTAL ESPANOLA : P. Dutil. ALGÉRIE : J. Boulaine, J. Durand, P. Dutil. ANGOLA : J.V. Botelho da Costa, A.L. Azevedo, R. Pinto Ricardo, È.P. Cardoso Franco, E.M. Silva da Camara. BASUTOLAND : C.R. Van der Merwe, R. F. Loxton. BECHUANALAND : J. S. De Beer, R. F. Loxton, C. R. Van Straten, C.R. Van der Merwe. BURUNDI : A. Van Wambeke, R. Frankart. CAMEROUN : P. Segalen. CONGO (BRAZZAVILLE) : J. M. Brugière, G. Bocquier. CONGO (LÉOPOLDVILLE) : K. Sys, R. Frankart, P. Jongen, A. Van Wambeke, P. Gilson, J. M. Berce, A. Pecrot, M. Jamagne. CÔTE D'IVOIRE : N. Leneuf, B. Dabin, G. Riou. CÔTE FRANÇAISE DES SOMALIS : H. Besairie, J. Boulaine. DAHOMEY : R. Fauck, P. Willaime. ETHIOPIA : R. E. G. Pichi-Sermolli, Anonyme Doc. F.A.O. GABON : Y. Chatelin. GAMBIA : M. Brunt. GHANA : CF. Charter, H. Brammer. GUINÉE : R. Maignien. GUINEA CONTINENTAL ESPANOLA : A. Hoyos de Castro, W. Kubiena. GUINÉ PORTUGUESA : P. J. da Silva Teixeira. HAUTE VOLTA : R. Mäignien, M. G. Gaveau. KENYA : G. H. Gethin Jones, R. Scott, C.G. Trapnell, J. Thorp. LIBERIA : W. Reed. LIBYA : P. Dutil. MADAGASCAR : J.