Land husbandry - Components and strategy http://www.fao.org/docrep/T1765E/t1765e00.htm#Contents Originated by: Agriculture Department Title: Land husbandry - Components and strategy... Français More details Land husbandry - Components and strategy Table of contents by Eric Roose 70 FAO SOILS BULLETIN Director of Soils Research ORSTOM Montpellier, France Food and Agriculture Organization of the United Nations Rome, 1996 Soil Resources Management and Conservation Service Land and Water Development Division, FAO 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 concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. M-57 ISBN 92-5-103451-6 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying or otherwise, without the prior permission of the copyright owner. Applications for such permission, with a statement of the purpose and extent of the reproduction, should be addressed to the Director, Information Division, Food and Agriculture Organization of the United Nations, Viale delle Terme di Caracalla, 00100 Rome, Italy. © FAO 1996 Contents Foreword 1 van 4 8/01/2007 17:25 Land husbandry - Components and strategy http://www.fao.org/docrep/T1765E/t1765e00.htm#Contents Acronyms and abbreviations Acknowledgements Introduction Part one: Erosion control strategies and the concept of land husbandry Chapter 1. Definitions: words conceal a philosophy Erosion Soil loss tolerance Erosion varies according to place: different agents, two perspectives Erosion varies according to time Soil degradation Factors in the water balance Chapter 2. History of erosion control strategies Soil erosion and population density Traditional erosion control strategies Modern strategies for developing rural water infrastructures Land husbandry Chapter 3. Some social and economic aspects of erosion Erosion crisis diversity Who is concerned by erosion control? The importance of exceptional rainstorms Erosion effects in different regions Effects of erosion on the eroded site: loss of productivity Negative off-site effects of erosion The economic rationale for land husbandry Criteria for the success of soil conservation projects Morroco case study: socio-economic study of erosion control in the Loukkos Basin Part two: Erosion control as a response to various erosion processes Chapter 4. Dry mechanical erosion Definition, forms, dynamics Causative factors Erosion control methods Chapter 5. Sheet erosion: the initial phase of water erosion Forms and symptoms of sheet erosion Cause and dynamics of sheet erosion Wischmeier and Smith's Empirical Soil Loss Model (USLE) Soil erodibility The topographical factor Effects of plant cover Influence of cropping techniques Erosion control strategies 2 van 4 8/01/2007 17:25 Land husbandry - Components and strategy http://www.fao.org/docrep/T1765E/t1765e00.htm#Contents Erosion control practices The P factor in Wischmeier's equation Erosion control structures as related to water management methods Variability of erosion factors Conclusions on the applicability of the USLE in Africa Implementation of Wischmeier's erosion forecast model Chapter 6. Linear erosion Forms of linear erosion The cause and processes of linear erosion Factors in runoff Controlling runoff and linear erosion Cost effective gully treatment Chapter 7. Mass movement Forms of mass movement Causes and processes of mass movements Risk factors Mass movement control Chapter 8. Wind erosion Processes Forms of wind structures Effects of wind erosion Factors affecting the extent of wind erosion Wind erosion control Part three: Case studies Chapter 9. The wide range of erosion control strategies in West Africa: from subequatorial forest to Sudano-Sahelian savannah Erosion control in the subequatorial forest zone of the Abidjan region of southern Côte d'Ivoire Erosion control in the humid, tropical, Sudanian savannah of Korhogo in northern Côte d'Ivoire Erosion control in the tropical savannah environment of the Koutiala region of Mali: strictly rainfed farming Erosion control in the Sudano-Sahelian savannah of the Ouahigouya region of north-western Burkina Faso: runoff farming Erosion control in the northern Sahelian zone around the Doti marches in Burkina Faso: valley farming Chapter 10. Development of the Bamiléké bocage The situation Diagnosis: relatively fragile environments Effective traditional techniques Hazards Some suggested improvements Chapter 11. Agroforestry, mineral fertilization and land husbandry in Rwanda 3 van 4 8/01/2007 17:25 Land husbandry - Components and strategy http://www.fao.org/docrep/T1765E/t1765e00.htm#Contents The situation Analysis of local conditions Traditional techniques Suggestions for managing surface water Suggestions for managing soil fertility Chapter 12. A new approach to erosion control in Haiti The situation Analysis of local conditions Farmers' traditional strategies and their limitations Control measures Chapter 13. Agricultural erosion in the Ecuadorian Andes The situation Soil erosion: diagnosis and source Hazards: the impact of erosion on the agricultural environment Suggested improvements Chapter 14. The Mediterranean Montane Region of Algeria The situation Diagnosis: trial conditions Hazards Suggested improvements: influence of the farming system Chapter 15. Pays de Caux: a temperate, field-crop region in north-western France The situation Local conditions Hazards: the erosion process and its negative effects Solutions and measures adopted Prospects and orientations Land husbandry: a new philosophy Land husbandry: a strategy for action References Further reading 4 van 4 8/01/2007 17:25 Foreword http://www.fao.org/docrep/T1765E/t1765e01.htm#foreword Originated by: Agriculture Department Title: Land husbandry - Components and strategy... Français More details Contents - Next Foreword Since the 1939 work of Bennett, the father of soil conservation, the world has seen a host of erosion control manuals, most of them in English or Spanish and describing practical experience, technical principles, mechanical (and sometimes biological) methods to be used, and a series of practical recipes that have been adopted with varying degrees of success in specific regions. However, there have been few authors who, having seen at first hand the relative ineffectiveness of the generally recommended techniques, have been ready to re-examine the erosion control principles that Bennett developed for the very specific environmental, social and economic conditions of the large-scale, mechanized cropping of groundnut, cotton, tobacco and cereals, all providing little ground cover, that the European immigrants introduced into the semi-arid Great Plains of the United States of America during the Great Depression of the 1930s. Bennett's approach to soil conservation (based on draining runoff water from cultivated fields along gently sloping channels to designated outlets) was then applied, with no prior testing, in totally different circumstances (for example among small subsistence farmers in tropical upland areas)... with the very indifferent results that have been seen by all. Science has made giant strides since Bennett's day. Firstly, it has been discovered that the kinetic energy of raindrops can lead to degradation of cultivated soils. Risks of runoff and erosion can therefore be cut by introducing production systems that provide better ground cover (Ellison 1944, Stallings 1953, Wischmeier and Smith 1960 and 1978, Hudson 1973, Roose 1977a, etc.). Secondly, people have realized that there are many different processes in soil degradation and erosion, with a variety of causes - and a similar variety of sometimes contradictory factors involved in any action to alter them. Treatment of sheet erosion has, for instance, sometimes increased the risk of landslides (as can happen with marls). Thirdly, differences in physical landscapes and in the social and economic conditions of effective application of erosion control methods are better analysed today. The erosion crises facing large-scale, modern landowners in temperate zones are no longer treated in the same way as the subsistence problems of poor, densely-populated communities clinging to tropical hillsides. Instead of simply describing schemes that have worked in one specific place, today one has to learn to assess different conditions and work with, rather than against, the forces of nature; for example, by progressively modifying the slope of a hillside by slowing down sheet runoff and using farming techniques that will gradually terrace the land, instead of tearing at mountains with powerful bulldozers to produce often unstable and expensive-to-maintain infrastructure. The author would like to remind agricultural experts that erosion control is not the exclusive domain of specialists working to rehabilitate land degraded because it has been more mined than farmed, but must incorporate the viewpoints of the land-use planner responsible for water and soil fertility management in the development of cropping systems that are profitable, sustainable, and safe for rural and urban environments. Since the 1980s there has been much criticism of the failure rate of most programmes incorporating 1 van 2 8/01/2007 17:26 Foreword http://www.fao.org/docrep/T1765E/t1765e01.htm#foreword erosion control. It is now recognized that there are two spheres in erosion control: • The State sphere, with the government responding to disasters and sending in engineers to stop landslides, control torrents, replant mountains with trees, or harness watercourses that threaten structural works, lines of communication, inhabited areas, irrigation schemes and dams through siltation. In the public interest, representatives of the central authorities insist on water control in the rural environment. It is expensive and upsets the farmers, but is the only way of controlling the quality of water supplies (the off-site perspective), and only the State is in a position to engage in such large-scale mechanical undertakings. • The farming sphere of land protection (the on-site perspective), which can be assured only by the rural community, so long as it is helped in making a correct diagnosis of the causes of the erosion crisis and the best ways of improving environmental protection, biomass production and living standards. It is essentially on this latter sphere - that of water, soil fertility and biomass management (GCES), or land husbandry - that this work would like to focus, taking stock especially of research by French-speaking soil, agricultural and geographical experts (particularly from ORSTOM and CIRAD), who have worked mainly in Africa, where problems develop much faster than in Europe. After all, the work of English-speaking experts in this sphere is already well known (Wischmeier and Smith 1978, Hudson 1992). The author presents a personal and intentionally confrontational point of view, offering a new and more constructive approach to the problems small farmers face in their battle with the degradation of their land. This is not a manual with clear-cut remedies for each and every erosion problem, but a work that should allow research experts, teachers and agronomists in the field to appreciate differences in situations, diagnose the causes of crises, and propose a range of technical solutions from which a small rural community (a family, a ward, a village, a slope, a hillside or a micro-watershed) can choose the technological package best suited to its particular needs. Rather more "instruction-oriented" material for training extension agents (Dupriez and De Leener 1990, Inades 1989) and more technical manuals on torrent control and landslides (Heusch 1988, CEMAGREF documentation) or improving soil fertility (Pieri 1989) are available elsewhere. This document has been used for eight years as a basis for courses on "Land Husbandry as an Instrument in Land Management" given to 700 agricultural or forestry engineers at CNEARC and ENGREF in Montpellier, in France, and ANDAH in Haiti, as well as 50 senior water technicians at ETSHER in Ouagadougou, in Burkina Faso. It is hoped that future editions will be enriched with readers' comments and details of new experiences. It will have met its aim if it provides large numbers of land-use planners and agronomists with pointers for developing intensive and sustainable farming systems suited to specific environmental situations and social and economic contexts. Contents - Next 2 van 2 8/01/2007 17:26 Acronyms and abbreviations http://www.fao.org/docrep/T1765E/t1765e02.htm Originated by: Agriculture Department Title: Land husbandry - Components and strategy... Français More details Contents - Previous - Next Acronyms and abbreviations ANDAH Association Nationale des Agronomes Haïtiens AREAS Association Régionale pour l'Etude et l'Amélioration des Sols (France) CEMAGREF Centre National du Machinisme Agricole, du Génie Rural, des Eaux et Forêts (France) CIRAD International Cooperation Centre on Agrarian Research for Development CNEARC Centre National d'Etudes en Agronomie des Régions Chaudes (France) CTFT Centre Technique Forestier Tropical (CIRAD) DRSPR Division de la Recherche sur les Systèmes de Production Rurale de l'Institut d'Economie Rurale de Bamako (Mali) EC European Community ENGREF Ecole Nationale du Génie Rural et des Eaux et Forêts (France) ESAT Ecole Supérieure d'Agronomie Tropicale (France) ETSHER Ecole de Techniciens Supérieurs en Hydraulique Rurale (France) ICRAF International Center for Research in Agroforestry ICRISAT International Crops Research Institute for the Semi-Arid Tropics IITA International Institute of Tropical Agriculture INRA Institut National de la Recherche Agronomique (France) INRF Institut National de Recherches Forestières (Algeria) IRA Institut de Recherche Agronomique (Cameroon) IRAZ Institut de Recherche Agronomique du Zaire IRFA Institut Français de Recherche Fruitière Outre-mer (CIRAD) IRHO Institut de Recherche sur les Huiles et Oléagineux (CIRAD) ISAR Institut Supérieure Agronomique du Rwanda ISCO International Soil Conservation Organisation ITCF Institut Technique des Céréales et des Fourrages (France) LH land husbandry NGO non-governmental organization ONTF Office Nationale du Travaux Forestière ORSTOM Institut Français de Recherche Scientifique pour le Développement en Coopération PRATIC Projet de Recherche appliquée à l'Aménagement intégré des Terroirs Insulaires Caraibes RML rehabilitator of mountainous land SPR soil protection and restoration SWC soil and water conservation 1 van 2 8/01/2007 17:26 Acronyms and abbreviations http://www.fao.org/docrep/T1765E/t1765e02.htm USDA United States Department of Agriculture USLE Universal Soil Loss Equation Contents - Previous - Next 2 van 2 8/01/2007 17:26 Acknowledgements http://www.fao.org/docrep/T1765E/t1765e03.htm Originated by: Agriculture Department Title: Land husbandry - Components and strategy... Français More details Contents - Previous - Next Acknowledgements First of all I should like to express my gratitude to ORSTOM, which encouraged me to put to good use the knowledge French-speaking research experts have gained over the past thirty years in the field of soil conservation, water management and fertilization. Next, I should like to thank David Sanders and Jean Claude Griesbach of the FAO Soil Resources Management and Conservation Service for their encouragement throughout the preparation of this work. A dozen or so colleagues agreed to read the first draft, and I am particularly grateful to them for encouraging me to revise it in order to complete, correct and expand it. They all provided me with major ideas: - Jacques Arrivets, CIRAD agricultural scientist, for his thoughts on the aim and presentation of the work; - Christophe De Jaegher, a young agricultural scientist working in Peru under an external aid programme, for details of traditional Peruvian soil preparation methods; - Georges De Noni and Marc Viennot, my colleagues at ORSTOM, for a whole chapter on erosion in the Ecuadorian Andes; - Jean-Marie Fotsing, a Cameroonian geographer, lecturer at Yaoundé University, for a chapter on Bamiléké hedge systems (bocage); - Bernard Heusch, agricultural scientist, for his vast experience of soil conservation problems throughout the world; - Charles Lilin, forestry expert at the French Ministry of the Environment, for a chapter on sociological aspects of erosion crises; - Raymond Mura, forestry expert with CEMAGREF, for his experience of rehabilitation strategies for mountainous terrain; - Jean François Ouvry, agricultural scientist and director of a regional association for land improvement, for a summary of the work of a whole INRA team on large-scale agricultural planning in northern France; - Chris Reij, geographer at the Free University of Amsterdam, for many ideas on traditional methods of water management and soil conservation; - Bernard Smolikowski, agricultural expert working in Haiti under an external aid programme, and Michel Brochet, Director of ESAT in Montpellier, for a whole chapter on Haiti; - Christian Valentin, of ORSTOM, for details of soil surface structures; - François Ségala, agricultural scientist, and Jean Claude Griesbach, geographer, technical 1 van 2 8/01/2007 17:26 Acknowledgements http://www.fao.org/docrep/T1765E/t1765e03.htm officers in FAO's Soil Resources Management and Conservation Service, for constructive criticism and invaluable support in completing the work. I should also like to acknowledge my debt to the young research scientists who have carried out their thesis work under my direction or verified certain land husbandry ideas in the field François Ndayizigiyé, Vincent Nyamulinda and Leonard Sekayange in Rwanda, Vincent Ngarambé and Théodomir Rishirumuhirwa in Burundi, Mourad Arabi, Morsli Boutkhil, Mohammed Mazour, Rachid Chebbani and other colleagues from the INRF erosion team in Algeria, F.X. Masson, Djamel Boudjemline, Marie Antoinette Raheliarisoa in France, and Zacheé Boli and Bep Aziem, IRA soil and agricultural scientists in Cameroon. I cannot close these acknowledgements without recalling all I owe to the "elders" who patiently initiated and guided me throughout my career: in France, Bernard Heusch, Frederic Fournier, Claude Charreau and Georges Aubert; in the English-speaking world, Norman Hudson, Walter Wischmeier, Donald Meyer and William Moldenhauer. Finally, my thanks go to Mme Rigollet and Chrissi Smith-Redfern for tirelessly typing, correcting and editing the manuscript, and Mr Mazzei for drawing the figures so well. Most of the photographs have been taken from my own collection. Other sources have been cited in the text, and I am grateful for their assistance. Ideas do not belong to any one person, but are the fruit of a long period of gestation and the encounter between people and a range of environments and socio-economic conditions. May all those who have played a part in this long labour be included in this expression of gratitude. Contents - Previous - Next 2 van 2 8/01/2007 17:26