cigr handbook vol 3

8/15/2019 Cigr Handbook Vol 3

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CIGR Handbookof Agricultural Engineering

VolumeIII

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CIGR Handbook of Agricultural Engineering

VolumeIIIPlantProductionEngineering

EditedbyCIGR—TheInternationalCommissionof Agricultural Engineering

VolumeEditor:Bill A. Stout

TexasA& M Universi ty, USA

Co-Editor:BernardCheze

M inistr y of Agriculture, Fisheri esand Food, France

PublishedbytheAmericanSocietyofAgricultural Engineers

iii

Front Matter

Table of Contents


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Copyright c 1999 by American Society of Agricultural EngineersAll rights reserved

LCCN 98-93767 ISBN 1-892769-02-6

This book may not be reproduced in whole or in part by any means (with the exceptionof short quotes for the purpose of review) without the permission of the publisher.

For Information, contact:

Manufactured in the United States of America

The American Society of Agricultural Engineers is not responsible for statements andopinions advanced in its meetings or printed in its publications. They represent the viewsof the individual to whom they are credited and are not binding on the Society as a whole.

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EditorsandAuthorsVolume Editor

B. A. Stout Agricultural Engineering Department, Texas A&M University, College Station,Texas 77843-2117, USA

Co-Editor

B. Cheze MAPA/DEPSE 5, 78 Rue de Varenne, 75349 Paris SP 07, France

Authors

P. F. J. AbeelsProfessor Em., Univ. Catholique de Louvain, Faculte des Sciences Agronomiques, Department of Environmental Sciences and Land Management, Agricultural and Forest Engineering, Place Croix du Sud 2, Box 2, B 1348 Louvain La Neuve, Belgium

H. Auernhammer Institut f ¨ ur Landtechnik, der TU M ¨ unchen, Am Staudengarten 2,85350 Freising-Weihenstephan

P. BalsariUniversit ´ a degli Studi di Torino, Dipartimento di Economia e Ingegneria Agraria,Forestale e Ambientale, Grugliasco, Italy

J. F. BillotTMAN CEMAGREF, Parc de Tourvoie, 92160 Antony, France

D. Blary M ́ ecanisation agricole, CIRAD-CA Programme GEC, BP 5035 34090 Montpellier Cedex 1, France

E. H. Bourarach Institute of Agronomy and Veterinary Medicine, Hassan II, Department of Agricultural Engineering, B.P. 6202 Rabat Instituts, Rabat, Morocco

A. G. CavalchiniUniversit à Degli Studi, Istituto di Ingegneria Agraria, 20133 Milano—ViaG. Celoria, 2, Italy

W. Chancellor Biological and Agricultural Engineering Department, University of California Davis, Davis, California 95616-5294

B. Cheze MAPA/DEPSE 5, 78 Rue de Varenne, 75349 Paris SP 07, France

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vi Editors and Authors

B. Fritz Agricultural Engineering Department, Texas A&M University, College Station,Texas 77843-2117, USA

C. E. Goering

Agricultural Engineering Department, University of Illinois, Urbana, Illinois 61801, USA

R. HahnStandards Coordinator, American Society of Agricultural Engineering,2950 Niles Road, St. Joseph, MI 49085-9659, USA

M. HavardCIRAD-SAR, BP 5035, 73, Rue J.F. Breton, 34090 Montpellier, Cedex 1, France

H. J. HeegeChristian-Albrechts-Universit ¨ at Kiel, Institut f ¨ ur LandwirtschaftlicheVerfahrenstechnik, Max-Eyth-Strasse 6, 24118 Kiel, Germany

R. O. Hegg Agricultural and Biological Engineering Department, Clemson University, McAdams Hall, Box 340357, Clemson, South Carolina 29634-0357, USA

J. W. Hofstee Department of Agricultural Engineering and Physics, Wageningen AgriculturalUniversity, Agrotechnion Bomenweg 4, 6703 HD Wageningen, The Netherlands

D. R. Hunt

University of Illinois, Agricultural Engineering Department, University of Illinois,Urbana, Illinois 61801, USA

H. D. Kutzbach Inst. F. Agrartechnik -440-, Universitaet Hohenheim, Garbenstr. 9, D-70599 Stuttgart,Germany

P. S. Lammers Institut f ¨ ur Landtechnik, Universit ¨ at Bonn, Postanchrift: 53115 Bonn, Nussallee 5,Germany

A. Lara LopezConsul for Science and Technology, State of Guanajuato, Mineral de Valencia No. 20, Marl, Guauajuato, Mexico

E. ManfrediUniversita degli studi di Bologna, Dipartimento di Economia e Inegneria Agrarie,Via Zamboni, 1, 40126 Bologna, Italy

R. ObertiUniversit ´ a degli Studi di Milano, Istituto di Ingegneria Agraria, Milano, Italy


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Editors and Authors vii

E. U. OdigbohUniversity of Nigeria, Faculty of Engineering, Nsukka, Enugu State, Nigeria

J. Ortiz-Canavate

E.T.S.I.AGRONOMOS, Dpt. Ing. Rural, Universidad Polit ´ ecnica de Madrid,Ciudad Universitaria s/n, 28040—Madrid, Spain

C. B. Parnell Department of Agricultural Engineering, Texas A&M University, College Station,Texas 77843-2117, USA

R. PetersKTBL-Versuchsstation Dethlingen, Diethlingen 14, D-29633 Munster, Germany

R. Pirot M ́ ecanisation agricole, CIRAD-CA Programme GEC, BP 5035 34090 Montpellier Cedex 1, France

G. Quick Department of Agricultural and Biosystems Engineering, Iowa State University, Davidson Hall, Ames, Iowa 50011-3080, USA

K. T. Renius Institut fur Landmaschinen, Technical University of Munich, Arcisstr. 21,80333 Munchen, Germany

A. G. Rijk Asian Development Bank, P.O. Box 789, Manila 0980, Philippines

M. Ruiz-Altisent E.T.S.I.AGRONOMOS, Dpt. Ing. Rural, Universidad Polit ´ ecnica de Madrid,Ciudad Universitaria s/n, 28040—Madrid, Spain

J. SakaiKyushu University, Agricultural Machinery Laboratory, Department of Agricultural Engineering, Hakozaki. Higashi-ku. Fukuoka, 812 Japan

B. Scheuer Amazonen Werke H. Dreyer, Postfach 51, D-49202 Hasbergen-Gaste, Germany

J. K. Schueller Department of Mechanical Engineering, University of Florida, P.O. Box 116300,Gainesville, FL 32611, USA

B. Shaw Agricultural Engineering Department, Texas A&M University, College Station,Texas 77843-2117, USA


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viii Editors and Authors

L. Speelman Department of Agricultural Engineering and Physics, Wageningen AgriculturalUniversity, Agrotechnion Bomenweg 4, 6703 HD Wageningen, The Netherlands

T. Tanaguchi

Obihiro Univ. Of Agr. & Vet. Med., Department of Agro-Environmental Science, Inada-ohou Obihiro Hokkaido 0808555, Japan

H. J. Tantau Institute of Horticultural and Agricultural Engineering, University of Hannover, Herrenhaeuser Str. 2, D-30419 Hannover, Germany

A. A. Wanders IMAG-DLO, Mansholtlaan 10-12, P.O. Box 43, NL-6700 AA, Wageningen,The Netherlands

G. H. Weise

Institut f ¨ ur Landtechnik der Justus-Liebig-Universit ¨ at Giessen, Braugasse 7, D-35390 Giessen, Germany

R. Wilkinson212 Farrall Hall, Department of Agricultural Engineering, Michigan State University, East Lansing, Michigan 48824, USA


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Editorial BoardFred W. Bakker-Arkema, Editor of Vol. IVDepartment of Agricultural EngineeringMichigan State UniversityMichigan, USA

El Houssine Bartali, Editor of Vol. II (Part 1)Department of Agricultural EngineeringInstitute of AgronomyHassan II, Rabat, Morocco

Egil BergeDepartment of Agricultural EngineeringUniversity of Norway, Norway

Jan DaelemansNational Institute of Agricultural EngineeringMerelbeke, Belgium

Tetuo HaraDepartment Engenharia AgricolaUniversidade Federal de Vicosa36570-000 Vicosa, MG, Brazil

Donna M. HullAmerican Society of Agricultural EngineersMichigan 49085-9659, USA

A. A. JongebreurIMAG-DLOWageningen, The Netherlands

Osamu Kitani, Editor-in-Chief and Editor of Vol. VDepartment of Bioenvironmental and Agricultural EngineeringNihon UniversityKameino 1866

Fujisawa, 252-8510 Japan

Hubert N. van Lier, Editor of Vol. IChairgroup Land Use PlanningLaboratory for Special Analysis, Planning and DesignDepartment of Environmental SciencesAgricultural UniversityWageningen, The Netherlands

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x Editorial Board

A. G. Rijk Asian Development Bank P.O. Box 7890980 Manila, Philippines

W. SchmidO.R.L. Institute, E.T.H.Z.HongerbergZurich, Switzerland

The late Richard A. SprayAgricultural and Biological Engineering DepartmentClemson UniversityClemson, South Carolina 29634-0357, USA

Bill A. Stout, Editor of Vol. IIIDepartment of Agricultural EngineeringTexas A & M UniversityTexas, USA

Fred W. Wheaton, Editor of Vol. II (Part 2)Agricultural Engineering DepartmentUniversity of MarylandMaryland, USA


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ContentsForeword xxvPreface xxvii

1 Machines for Crop Production 1

1.1 Power Sources 1

Human-Powered Tools and Machines 11.1.1 Technical Characteristics of Human Power 1

Introduction 1Power Production and Consumption by Humans 1Human Work Output 3Some Compensating Attributes of Human Labor 3Importance of Human-Powered

Agricultural Tools/Machines in the LDC’s 41.1.2 Human-Powered Tools and Machines for Field Operations 5

Denitions 5Classication by Field Operations 5Hand-Tools for Land Preparation 5Manual Planting Tools and Machines 6Manual Weeding Tools and Machines 8Manual Harvesting Tools and Machines 11Economics of Human-Powered Tools/Machines

for Field Operations 131.1.3 Human-Powered Tools and Machines for

Post-Harvest Operations 15Denitions and Some General Remarks 15Some Common Tools for Crop Processing by

Peasant Farmers 15Some Common Human-Powered Processing Machines 17

1.1.4 The Sociology and Future of Hand ToolTechnology in LDC’s 19

References 21

Animals 221.1.5 Efcient Use of Energy Potential by a

Draft Animal Power Unit 221.1.6 Control of Animal’s Energy Potential 24

Environmental Conditions 24Choice of Animals 25Use of Animals 26Livestock Management 28

1.1.7 Farm Equipment for Transport, Tillage, SecondaryCultivation and Sowing 29

Equipment for Transport 29

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xii Contents

Equipment for Tillage 31Sowing 35Secondary Tillage Operations 37

1.1.8 Use of Draft Animals 381.1.9 Conclusion 39References 40

Engines 411.1.10 Types of Engines Used in Agriculture 411.1.11 Fuel Injection in CI Engines 431.1.12 Engine Performance Parameters 431.1.13 Turbocharging and Intercooling 491.1.14 Engine Performance Maps 511.1.15 Engine Utilization 521.1.16 Engine Design Goals 53

1.1.17 Engine Selection 53

Tractors: Two-Wheel Tractors for Wet Land Farming 541.1.18 The Role for Small Scale Farms 541.1.19 Differences of Farming Principles Between Upland

Fields and Paddy Fields for Tractors 55Plow Pan Layer 55Depth of Plowing 56Flatness and Size of a Field Lot 56Planting Systems and the Principle of a Transplanting

System in Paddy Cultivation 561.1.20 Types and Durability of Two-Wheel Tractors 57Types of Two-Wheel Tractors 57Durability Classication of Two-Wheel Tractors 58

1.1.21 Principles of Mechanisms and Mechanics 59Engines on Two-Wheel Tractors 59Engine-base Assembly 61Handle Assembly 62Power Transmission Mechanisms 62Front and Rear Hitches and Hitch-pins 64Wheels and New Wheel Dynamics 65Two-Wheel Tractors with the Plow and Plowing 70Two-Wheel Tractors with Rotary Tillers 77

References 93

Tractors: Two-Wheel Tractors for Dry Land Farming 951.1.22 Description and Types of Two-Wheel Tractor Designs 951.1.23 Production and Concentration of Two-Wheel Tractors 1011.1.24 Mechanics of Two-Wheel Tractors 1031.1.25 Field Operations with Two-Wheel Tractors 105


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Contents xiii

1.1.26a Management of Two-Wheel Tractors 1101.1.26b Trends in the Development of Two-Wheel Tractors 114References 114

Tractor: Two Axle Tractors 1151.1.27 History, Trends, Concepts 115

Tractor: Denition, History and Trends 115Tractor Concepts 115

1.1.28 Tractor Mechanics 118Single-Wheel and Tire Mechanics 118Soil Compaction under Tires 120Mechanics of Two-Axle Tractors Pulling

Implements or Trailers 122Mechanics of Hillside Operation and Overturning Stability 125

1.1.29 Chassis Design 127

Traction Tires: Requirements, Design, Specications 127Chassis Concepts, Four-wheel Drive 129Brakes 131Steering 134Track Width and Wheel-to-hub Fixing 136

1.1.30 Diesel Engines and Fuel Tank 137Development Trends 137Motorization Concept 138Diesel Engine Installation 139Practical Fuel Consumption and Fuel Tank Size 139

1.1.31 Transmissions 139Introduction 139Requirements 140Fundamentals of Speeds and Torque Loads 141Rear Power Takeoff (Rear PTO) 143Symbols for Transmission Maps 144Stepped Ratio Transmissions 145Continuously Variable Transmissions (CVTs) 148Master Clutch and Shift Elements 151

1.1.32 Working Place 153Introduction: Role of Comfort, Health and Safety 153Work Load on Machine Operators 153Technical Aids for the Operator: Survey and

Related Standards 154Operator’s Seating Accommodation and Access 155Tractor Ride Dynamics (Vibrations) 157Tractor Noise Control 161Tractor Safety 163

1.1.33 Implement Control and Hydraulics 165Beginnings of Implement Control by Hydrostatic Hitches 165


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xiv Contents

Concept and Dimensions of the Three-point Hitch 166Kinematics and Forces of the Three-point Hitch 168Control Strategies for Three-point Hitches 169Fluid Power Systems: Symbols and Vocabulary 172Hydraulic Circuits: Basic Systems 174

References 176

1.2 Tillage Machinery 1841.2.1 General Importance of Tillage Operations 184

Appropriate Tillage According to Soil Conditions 185Socio-Economical Aspects of Tillage 187

1.2.2 Soil Engaging Components 188Basic Elements and Materials of Tillage Tools 188Drawn Implements 190PTO-Driven Implements 193

1.2.3 Tillage Systems 193Conventional Tillage System 193No-Tillage System 210Tillage Systems for Special Conditions 211

References 215

1.3 Seeders and Planters 2171.3.1 Introduction 2171.3.2 Seeders 217

Seed-Spacing and Seeding-Depth 217

Precision Drilling 218Bulk Seeding 2261.3.3 Planters 235

Potato Planters 236Transplanters 238

References 239

1.4 Fertilizer Distributors 2401.4.1 Introduction 2401.4.2 Fertilizer Distributor Types 241

Spinning Disc Spreaders 241Oscillating Spout Spreaders 248Boom Spreaders 252Aerial Spreaders 255Liquid Fertilizer Spreaders 256

1.4.3 Particle Trajectories 2581.4.4 Spread Pattern Analysis 2611.4.5 Developments 266

Multiple Hoppers 266


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Contents xv

Site Specic Spreading 267Electronics 267

References 268

1.5 Pest Control Equipment 269

1.5.1 Pest Control Methods 269Non-Chemical Methods 269Chemical Control Methods 269

1.5.2 Non-Chemical Techniques 269Mechanical Weeding 269Thermal Treatments 271Vacuum 272Biological Pest-control Equipment 272

1.5.3 Chemical Control Methods 273Formulations 273

Characteristics of Droplets 275Methods of Application 276Meteorological Constraints 280

1.5.4 Spraying Equipment 281Hand Sprayers 281Power Equipment 283Air-assisted Spraying 284Aerial Application 285

1.5.5 Sprayer Components 286Pumps 286

Sprayer Tanks 290Agitation 290Strainers and Screens 292Plumbing and Controls 293Nozzles 295

1.5.6 Choice of Equipment 300Work Rate 300Fans and Capacity 301Crop Spraying 301Orchard Spraying 302

1.5.7 Spraying Techniques 302Drift reduction 302Chemical Mixing and Disposal of Excess

Pesticide 303Cleaning Equipment 303Closed-Transfer Systems 303Ergonomics and Operator Safety 304

1.5.8 Sprayer Calibration 304Sprayer Ground Speed 304


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Timed-ow Method for Calibrating Boom Sprayers 304Calibration Flow Check 305

1.5.9 Granular Applicators 306Metering Devices 306Calibrating and Using Granular Applicators 307Application Rate 307

1.5.10 Future Trends 308Developing Countries 308Developed Countries 308

1.6 Harvesters and Threshers 311

Grain 3111.6.1 Functional Components of Combine Harvesters 3111.6.2 Threshing and Separation 312

Tangential Threshing Unit 312Straw Walker 314Rotary Separators 315Rotary Combines 315Comparison of Tangential and Axial

Threshing Units 317Separation Theory 317Cleaning 319Cleaning Theory 322

1.6.3 Combine Harvester Performance 323

Work Quality 323Crop Properties and Harvest Conditions 325Combine Type and Design 326Engine Power 326Harvest Management 327Combine Testing 327

1.6.4 Information and Control Systems 328Cabs and Controls (Operator Compartment) 328Information Systems 328Control Systems 330

1.6.5 Combine Attachments and Variants 331Header 332Chopper 333

1.6.6 Rice Harvesting 333Rice Combines: Why a Rice Combine? 333Custom-Made Rice Combines 334Combine Categories 335Red and Green Dominate 335Stripper Fronts Gaining on Rice Fields 336


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Contents xvii

Traction and Flotation Assistance for Combinesin Rice Fields 337

A Question of Teeth 339Rice Combines in Asia 340Chinese Combines 340Combines in Southeast Asia 340Summary 341

1.6.7 Power Threshers as Precursors of Mechanization 341Other Countries in Asia 343Chinese Threshers 343IRRI Axial-Flow Thresher Developments 343Throw-in Threshers That Chop the Straw for Stockfeed 344A Quantitative Assessment of Power Threshers 345Summary 346

References 346

Forage Crops 3481.6.8 Foreword 3481.6.9 Meadow-Type Forages 349

Harvest, Treatment and Storage Methods 350Machines and Equipment 357

1.6.10 Forage Cereals 374The Methods 374Machines and Equipment 376

Root Crops 381

1.6.11 Sugar Beet Harvesting 381Main Stages of Mechanical Harvesting 381

1.6.12 Potatoes 397Lifting 397Sieving 400Haulm, Clod, and Stone Separation 400Hoppers/Discharge Elevators 402Single-row, Two-row and Four-row Harvesters 403Self-propelled Harvesters 404Two-Stage Harvesting 404

Damage to Potato Tubers 407Bibliography 408

Fruits and Vegetables 4081.6.13 Introduction 4081.6.14 Harvesting Functions 4091.6.15 Principles and Devices for the Detachment 410

Low-height Herbaceous Structures(Vegetables, Strawberries, etc.) 410


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Bushy Structures (Small Fruits, Wine Grapes) 416Tree Structures (Fruits, Nuts) 419

1.6.16 Complementary Operations 4251.6.17 Mechanical Aids to Manual Harvest 4261.6.18 Electronic Sensors and Robotic Harvesting 428List of Symbols 429References 430

Tropical Crops 4311.6.19 Introduction 4311.6.20 Sugar Cane 431

Whole-stick Harvesting 432Self-propelled Full Stick Harvesters 433Harvest of Chopped Cane 437

1.6.21 Cotton 438

Defoliation 438Desiccation 438Actual Harvest 439

1.6.22 Groundnuts 441Lifting 441Uprooting 442Drying on the Soil 444Threshing 444

1.6.23 Tropical Tubers 446Cassava 446

Yam 4491.6.24 Millet 4501.6.25 Coffee 452References 453

1.7 Transportation 4551.7.1 Introduction 4551.7.2 Powered Farm Vehicles for Use in the Field 455

Monowheelers 455Tri-wheelers 456Four-wheel Carriers 457Multiwheel Carriers 457Crawler-type Carriers 458

1.7.3 Motor Trucks (Used for Local andLong-distance Transport) 460

Subcompact Trucks 460Farm Trucks 461

1.7.4 Trailers 463Trailers for Use with Walking Tractors 463Trailers for Use with Four-wheel Tractors 463


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Contents xix

Trailers with Hydraulic Tippers 464Grain Trailers 464Trailers Used for Transporting Combine Harvesters

and Heavy Equipment 4651.7.5 Loaders 465

Hoist and Truck Loaders 465Universal Elevators 465Tractor-mounted Loaders 465Self-propelled Loaders 466Forklifts 466

1.7.6 Monorails 468References 468

1.8 Specic Equipment Used for CultivationInside Greenhouses 469

1.8.1 Introduction 4691.8.2 Seeders and Seeding Lines 469

Requirements 470Principles of Operation 470

1.8.3 Transplanters 4711.8.4 Transportation 4721.8.5 Benches 4721.8.6 Irrigation Systems 472

Overhead Irrigation 473Drip-and-Trickle Irrigation 473

Subirrigation 474Soil-less Culture 4751.8.7 Articial Lighting 4761.8.8 Greenhouse Climate Control 477

1.9 Forest Engineering 4801.9.1 Harvesting in General 480

Tree Harvesting 480Processing Techniques 480Handlings and Maneuvers 481

1.9.2 Felling 481Felling Process 481Felling Tools 482Mechanical Tree Fellers 484Ergonomics 485

1.9.3 Delimbing 4851.9.4 Additional Interventions 4861.9.5 Topping, Bucking 4861.9.6 Debarking 4861.9.7 Wood Comminution 487


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1.9.8 Harvesters 4871.9.9 Operation 4871.9.10 Security and Safety 4871.9.11 Timber Transportation 488

Log Extraction 488Skidding 488Winch Skidding 490Grapple Skidding 491Forwarding 492Locomotion 492

1.9.12 Special Logging 494Semiaerial Systems 494Aerial or Off-the-Ground Systems 497Water Transportation 498

1.9.13 Forest-Stand Maintenance 498

Special Comments 498Cleaning and Thinning of Young Stands 498Pruning 498Fertilization 498Fire Protection 498Soil Restoration 499

1.9.14 Forest-Stand Establishment 499General Comments 499Site Preparation 500Planting 500

1.9.15 Forest Roads 5011.9.16 Forest Regulations 502Ordering Forest Machines 502Machines and Environment 502Best Management Practices 502Techniques and Future 502

References 502

1.10 Standardization 5031.10.1 Standardization on Workplace Health and Safety in

the European Union 5171.10.2 Relationships Between European and

International Standardization 5191.10.3 E.U. Standards for Environmental

Protection 5191.10.4 Other Directives for Machinery 5201.10.5 National Standards Development 5201.10.6 Standards Searches 520References 520


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Contents xxi

2 Mechanizations Systems 5212.1 Systems Engineering, Operations Research, and

Management Science 5212.1.1 Optimization 522

Linear Programming 5222.1.2 Time and Project Management 525

CPM 525PERT 527

2.1.3 Queuing Theory 528Single-server M/M/1 528Multiple-Server Systems 530Queuing-Theory Example 531

2.1.4 Simulation 532Random Numbers and Random-Number

Generation 533

Uniform Distribution 533Exponential Distribution 534Triangular Distribution 535

References 536

2.2 Agricultural Mechanization Strategy 5362.2.1 Denitions 5362.2.2 Introduction 5372.2.3 Need for Mechanization and

Productivity-enhancing Technology 538

2.2.4 Adoption Process for Mechanization and LaborProductivity–Enhancing Technology 5392.2.5 Basic Guidelines and Principles

for Strategy Formulation 5412.2.6 The AMS Formulation Process 542

Who Should Formulate the Strategy? 543How to Proceed with Formulation? 543Composition of the Strategy Formulation Team 544Outline of the Strategy Document 545Implementation of the Strategy 546

2.2.7 Some Frequently Raised Issues 5462.2.8 Key Policy Instruments for Formulation of an AMS 547

Subsidies 548Credit for Agricultural Machinery 548Taxes and Duties 549Private, Cooperative, or Government Ownership 550Input and Output Prices 550Public Investments 550

References 553


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2.3 Transfer of Technology 5542.3.1 Introduction 5542.3.2 TT in Industrialized Countries 5542.3.3 TT in Less Industrialized Countries 556

Prerequisites and Constraints Connected withTT in the Rural Areas 557

Steps and Structure of TT 558The Role of Farmers 558The Role of Farm Machinery Industries for

Local Manufacturing 558Facilities for TT 560Examples of TT Successfully Carried out inDeveloping Countries 561The Role of Organizations and Associations 562The Role of Farm-Machinery Institutes 562

The Role of Education and Training 563The Role of the Government 563The Protection of Intellectual Property and the

Risk of a Possible Misuse of Know-how 564References 564

2.4 Field Machinery Management 5652.4.1 Field Operations 5652.4.2 Field Patterns 5672.4.3 Calibration 570

2.4.4 Loss Determination 5722.4.5 Field Adjustments 5732.4.6 Repair and Maintenance 573

2.5 Cost Analysis 5742.5.1 Field Capacity of Machines 5742.5.2 Costs of Operation 5762.5.3 Machinery Selection 5782.5.4 Replacement Policies 582References 584

3 Trends for the Future 5853.1 Sustainable and Environmental Engineering 585

3.1.1 Denition and Background 5853.1.2 Policy 5893.1.3 Social, Economic, and Regional Differences 589

India 589Chile 590Philippines 590


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Contents xxiii

3.1.4 Components 590Soil 591Water 591Air 593Nutrients 593Plant Base 594Integrating Plant and Animal Systems 594Energy 595

3.1.5 Summary 597References 598

3.2 Precision Farming 5983.2.1 Introduction 5983.2.2 Positioning in Precision Farming 600

Satellite Navigation Systems 600

Other Location Systems 6023.2.3 Concepts of Precision Farming Systems and Required

System Elements 602Map-Based Systems 603Real-Time Systems 603Real-Time Systems with Maps 604

3.2.4 Yield Mapping 604Grain Combine Harvester Systems 604Other Continuous Crops 605Non-Continuous Yield 607

Data Storage and Mapping 6073.2.5 Soil and Weed Mapping 608Soil Sampling 608Weed Mapping 609Remote Sensing 610

3.2.6 Control of Field Operations 610Requirements and System Components 611Fertilization 611Pesticide Application 612Other Controller Operations 612

3.2.7 Information Management 613BUS Systems on Mobile Equipment 613Data Transfer to and from Farm Management 614Data Management and Geographic

Information Systems 614Decision-support Systems 615

References 616

Index 617


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ForewordThis handbook has been edited and published as a contribution to world agriculture atpresent as well as for the coming century. More than half of the world’s population isengaged in agriculture to meet total world food demand. In developed countries, theeconomic weight of agriculture has been decreasing. However, a global view indicates

that agriculture is still the largest industry and will remain so in the coming century.Agriculture is one of the few industries that creates resources continuously fromnature in a sustainable way because it creates organic matter and its derivatives byutilizing solar energy and other material cycles in nature. Continuity or sustainabilityis the very basis for securing global prosperity over many generations—the commonobjective of humankind.

Agricultural engineering has been applying scientic principles for the optimal con-version of natural resources into agricultural land, machinery, structure, processes, andsystems for the benet of man. Machinery, for example, multiplies the tiny power (about0.07 kW) of a farmer into the 70 kW power of a tractor which makes possible theproduction of food several hundred times more than what a farmen can produce manu-ally. Processing technology reduces food loss and adds much more nutritional values toagricultural products than they originally had.

The role of agricultural engineering is increasing with the dawning of a new century.Agriculture will have to supply not only food, but also other materials such as bio-fuels,organic feedstocks for secondary industries of destruction, and even medical ingredients.Furthermore, new agricultural technology is also expected to help reduce environmentaldestruction.

This handbook is designed to cover the major elds of agricultural engineering suchas soil and water, machinery and its management, farm structures and processing agri-cultural, as well as other emerging elds. Information on technology for rural planningand farming systems, aquaculture, environmental technology for plant and animal pro-duction, energy and biomass engineering is also incorporated in this handbook. Theseemerging technologies will play more and more important roles in the future as bothtraditional and new technologies are used to supply food for an increasing world popula-tion and to manage decreasing fossil resources. Agricultural technologies are especiallyimportant in developing regions of the world where the demand for food and feedstockswill need boosting in parallel with the population growth and the rise of living standards.

It is not easy to cover all of the important topics in agricultural engineering in alimited number of pages. We regretfully had to drop some topics during the planningand editorial processes. There will be other requests from the readers in due course. We

would like to make a continuous effort to improve the contents of the handbook and, inthe near future, to issue the next edition.

This handbook will be useful to many agricultural engineers and students as well asto those who are working in relevant elds. It is my sincere desire that this handbook willbe used worldwide to promote agricultural production and related industrial activities.

Osamu Kitani Editor-in-Chief

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PrefaceEffective crop production requires machines—hand tools, animal-drawn implementsand engine-powered equipment. This volume presents the fundamentals of various agri-cultural tools and machines and describes the types most commonly used for variousoperations. The scope of crop production is dened rather broadly to include green-

house production and forestry in addition to eld crops. Important peripheral top-ics also are covered, such as transport machines, machine systems, and technologytransfer.

Since machines for crop production represent a substantial capital investment forindividual farmers, principles and guidelines are given for proper selection and machinemanagement to achieve the greatest return. On a broader scale, policies and strategies aregiven for effective national or regional mechanization programs. Transfer of technologyfrom industrialized to developing countries is also discussed.

Standards are crucial in the design, testing, marketing and use of agricultural ma-chines. Globalization of the agricultural machinery manufacturing industry requires thatmachines builtby one manufacturer operate effectively with power units built by another.Also, safety issues require standards to assure protection of the operator and the generalpublic.

The future is always hard to predict, but one thing is certain: If humans are to surviveand thrive on planet Earth, agricultural practices must be sustainable over the long term.Machines and associated farming practices can have a profound impact—both positivelyand negatively—on soil erosion, precise chemical application, air quality and otherenvironmental aspects. Precision farming techniques are designed to vary the fertilizerand chemical application rates in accordance with the crop needs and thereby save moneyand help maintain the environment.

Many individuals and agencies have contributed to this handbook. The various chap-ters were written by 41 individuals—all of whom are experts in their particular area of specialization. These authors are from 12 countries and represent many languages otherthan English. Although every effort was made to standardize the format of each chapter,it is hoped the reader will overlook minor variations in format and terminology resultingfrom the broad authorship.

It is notpossible to acknowledge individually thehundreds of authors of the referencescited, although their work contributed signicantly to this volume.

The chapter manuscripts were reviewed by two world renowned experts in the eldof agricultural mechanization. Their questions and comments were considered by thechapter authors and resulted in substantial improvement in the manuscripts. In addi-

tion, all the chapter manuscripts were reviewed by Ms. Lynette James, Department of Agricultural Communications at Texas A&M University, a very capable editor whohelped standardize the format and make the volume more readable.

xxvii


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xxviii Preface

A project of this type would have been impossible without many competent anddedicated research assistants, typists, reviewers and other helpers. The editors extend asincere thanks to everyone who contributed to this volume.

B. A. Stout, Editor Volume IIIB. Cheze, Co-Editor Volume III


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1Machinesfor CropProduction

1.1. Power Sources

Human-Powered Tools and Machines E.U. Odigboh

1.1.1. Technical Characteristics of Human Power

IntroductionTo mechanize means to use machines to accomplish tasks or operations. A machine

may be as simple as a wedge or an inclined plane, or as complex as an airplane. Agricul-tural mechanization, therefore, is theuseof any machine to accomplish a task or operationinvolved in agricultural production. It is clear from this denition that agriculture any-where has always been mechanized, employing a combination of three main sources of power: human, animalandmechanical/engine, giving rise to three broad levels of agricul-tural mechanization technology classied as hand-tool technology (HTT), draft-animaltechnology (DAT) and mechanical-power or engine-power technology (EPT).

Hand-tool technology is the most basic level of agricultural mechanization, wherea human being is the power source, using simple tools and implements such as hoes,machetes, sickles, wooden diggers, etc. A farmer using hand-tool technology can cul-tivate only about one hectare of land. He cannot do more than that because of certainscientically established facts.

Power Production and Consumption by HumansAs a source of power, the human being operates essentially like a heat engine, with

built-in overload controls or regulators. Chemical energy input in the form of food isconverted into energy output, some of which is useful for doing work. On the average, ahealthy person in temperate climates consumes energy at a sustainable rate of only about300 W, while in tropical climates, as a result of heat stress the rate is reduced to onlyabout 250 W. Many tasks for agricultural production can be performed only at higherrates of energy consumption, however, as shown in Table 1.1. Some actual manual work rates for certain eld operations are presented in Table 1.2.

The fact that many primary agricultural production operations demand higher rates of energy than themaximum sustainable rate of energy consumption by humansnecessitates

1


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Power Sources 3

Figure1.1. SustainablePhysical orPower OutputbyHumans(Inns, p. 2).

Human Work Output

Only about 25 percent of the energy consumed when handling relatively easy taskssuch as pedaling, pushing or pulling is converted to actual human work output. Undermore difcult work conditions, the efciency of converting consumed energy to physicalwork may be as low as 5 percent or less. This means that, at the maximum continuousenergy consumption rate of 0.30 kW and conversion efciency of 25 percent, the phys-ical power output is approximately 0.075 kW sustained for an 8–10 hour work day.Naturally, higher rates can be maintained for shorter periods only, as shown in Fig.1.1[2].

Some Compensating Attributes of Human LaborThe discussion thus far and the facts given in Tables 1.1 and 1.2 make it abun-

dantly clear that power is the major limitation to increasing the area cultivated by thehand-tool farmer. It should be noted that the problem is not necessarily with the toolsused, especially for primary production operations, since efforts made to redesign themhave yielded no signicant improvements [3, 4]. The toil, drudgery, and severe powerconstraint on timely eld operations, which limit production and earning capacity, arethe inherent characteristics of peasant farmers using hand-tool technology; change thetechnology and you change the farmer’s status [5].

Still, the peasant farmer and his hoe and machete are efcient companions in cropproduction at the subsistence level where he operates. This is so because of certain human


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4 Machines for Crop Production

attributes that compensate signicantly for the limited physical power that the farmercan generate. The relevant human attributes are exhibited when the farmer:

• Adopts a working mode that incorporates appropriate rest periods.• Makes instantaneous decisions as to how much force to exert to accomplish a task,

thereby conserving energy.• Chooses the most appropriate tools for a given production unit operation.• Changes from one task to another readily and rationally, exhibiting a versatility that

no other power source is capable of.In spite of the inherent compensating characteristics, however, the power needed

to operate any human powered tool or machine should not be more than the farmercan potentially supply; the farmer should employ the preferred modes of human powerapplication such as pedaling or simulated walking.

Importance of Human-Powered Agricultural Tools/Machines in the LDC’sAll three levels of technology, HTT, DAT and EPT, are used in the mechanization of

agriculture in most countries of Africa and the other less developed countries (LDC’s)of the tropical world. But HTT predominates, especially for production eld operationssuch as land preparation, as shown in Table 1.3.

Table 1.4 also shows that for overall agricultural production, human power accountsfor the lion’s share of work in most African and Latin American countries. It has beensuggested that a power-use intensity of 0.4 kW/ha is required for effective levels of agricultural mechanization. While that gure may well be controversial, the facts andgures presented in Tables 1.3 and 1.4, and especially those in Table 1.5, show that thepower-use intensity in Africa is so low that it should be of serious concern to all. Consid-ering the natural limitations of human powered tools and machines, their predominancein the agriculture of developing countries is an important factor to address when dealingwith overall economic development of those countries.

Table 1.3. SourcesofPower forVariousPrimaryLandPreparationOperationsinVariousCountries

% of Total Land Cultivated Draught EngineCountry Human animal (Mech.)

Nigeria 86 4 10Botswana 20 40 40Zimbabwe 15 30 55Tanzania 80 14 6Kenya 84 12 4Ethiopia 10 80 10Zambia 55 15 30Swaziland 15 35 50Uganda 70 20 10China 22 26 52India 18 21 61

Source: [6].


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Power Sources 5

Table1.4. SourcesofPower forOverallAgricultural Productionin Latin Americaand

Africa(%Share)

LatinSourceof Power America Africa Nigeria

Human power 59 89 90Animal power 19 10 8Enginepower 22 1 2

Source: [7, 8].

Table1.5. EnginePower AvailableforAgriculturein DifferentCountriesandContinents

Country/Continent W/ha (Hp/acre)

USA 783 (0.430)Europe 694 (0.340)Latin America 201 (0.110)China 142 (0.080)Africa 37 (0.020)Nigeria 18 (0.008)

Source: Adapted from [9].

1.1.2. Human-Powered Tools and Machines for Field Operations

DenitionsThedescription of a machine in theintroductionto Section 1.1, which grouped a wedge

together with an airplane, may be valid only at a certain level of conceptualization. Butin a more formal sense, a machine is a device or mechanical contrivance consisting of two or more relatively constrained components which is energized by a power source totransmit and/or modify force and motion to accomplish some desired kind of work. Incontrast, a tool is a human powered instrument or implement usually without parts that move relative to one another , like a hoe, a dibber, or the like, used to facilitate mechanicalmanual operations.

Classication by Field OperationsField operations are tasks performed in the eld at different phases of crop produc-

tion. The major operations include land preparation, planting, weeding, and harvesting.Based on these operations, the tools/machines used are classied into: land prepara-tion tools/machines; planting tools/machines; weeding/cultivation tools/machines; andharvesting tools/machines.

Hand-Tools for Land Preparation

HoesNaturally, soil preparation is usually the rst task in crop production, undertaken

to achieve a variety of basic interrelated objectives such as seedbed preparation, weed


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control, soil and water conservation, soil compaction amelioration, etc. In peasant agri-culture, soil or land preparation to achieve a combination of these objectives usuallyinvolves tilling with a hoe, and constitutes the most signicant characteristic of thehand-tool (mechanization) technology.

Curiously, no manually operated machine for land preparation is commonly avail-able. The hoe is the most popular and most versatile tool used in developing coun-tries of the world, where peasant farmers account for close to 90 percent of the areaunder cultivation. The hoe is the tool used almost exclusively in land preparation of peasant agriculture, for combined primary and secondary tillage, and for land-formingoperations such as ridging, bedding, mounding, bunding, ditching, etc. Hoes for landpreparation come in different sizes, weights and peculiar shapes, having evolved overthe years to suit widely varying crops and conditions of soil, farming culture, farmers’physiques and temperaments. Describedgenerallyas long-handled implements with thin,at blades set transversely, common technical features of hoes include long handles andheavy heads carrying the cutting blades or shares. Handles vary a great deal in length,

shape and curvature. Blades also vary a great deal in shape, size and curvature, lead-ing to an intriguingly varied world of hoes, as illustrated by the small sample given inFig. 1.2. Wide-bladed hoes are used for digging, ridging and mounding under normalsoil conditions; narrow-bladed ones are used for hard soil conditions; while tined hoes,which are not very common, are used for stony conditions.

Machetes/SpadesOther hand tools used to complement the hoe in land preparation under peasant

agriculture include machetes, axes, spades, forks, and rakes, which also vary in sizesand shapes, as illustrated in Fig. 1.2. Next to the hoe, the machete is one of the mostimportant tools in peasant agriculture, where it is indispensable in land clearing and ahost of other crop production operations.

Manual Planting Tools and Machines

HoesThe hand hoe of appropriate size and shape is the most versatile tool used by the

peasant farmer in planting cereals, root crops and other crops. The farmer with the handhoe can use his judgment and experience to place the seeds or planting materials atoptimum depths and appropriate spacings within and between rows, and provide justthe right rming pressure to achieve good yields. Hoes used for planting, while varyinggreatly according to diverse cultural preferences, usually are lighter and smaller than

those for primary tillage or ridging, mounding, bedding or ditching operations, becauseless energy is demanded (see Table 1.1) and closer attention required.

Manual PlantersUnlikethecase for land preparation, there aremany hand-operated machines available

for planting and sowing, often with improved results in terms of uniformity of plantspacing and row conguration. The manual planters may be as simple as dibbers, whichare pointed instruments made of steel or wood tipped with steel, used to place seeds inthe ground. Or they may be as sophisticated as the various types of jab planters or pushed


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Power Sources 7

Figure1.2. AVarietyofHandToolsforLandPreparation.A- Hoes;B- Machetes;C - Shovels,spades, forksandrakes.


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or pulled seed drills with more complex seed metering devices. In this case, differentmetering mechanisms give rise to such planter types as seed-roller, uted-roller, slide-roller and chain- and- sprocket driven seed drills/planters. Illustrations of some of themajor types of manual planting tools and machines are given in Fig. 1.3.

It is important to state here that the more sophisticated pushed or pulled planters,which usually are equipped with seed coulters or other furrow openers, do require well-prepared seed beds, which a typical peasant farmer usually is not able to provide. Infact, a peasant farmer, whose only or major means of land preparation is the hand hoe,is not likely to prepare enough land area to make the ownership or use of the moresophisticated hand-operated planters economical. As a result, adoption of these pushedor pulled planters by peasant HTT farmers is very limited indeed.

Manual Weeding Tools and Machines

HoesWhat is said about the hand hoe with respect to planting applies to weeding and

cultivation. Generally speaking, in peasant agriculture, the heavy work of land prepara-tion using big hoes is handled by the men while subsequent eld operations, especiallyweeding, are undertaken by women and children, using the smaller and lighter hand hoesthat come in three major types: digging hoes, chopping hoes and pushing/pulling hoes.Most peasant farmers own only the digging hoe type, which they use for different tillageoperations, often with designs that are peculiar to certain traditional communities, suchas the design called ikeagwu-agadi (literally meaning “exhaustion free for the aged”) byIgbo-speaking people of Nigeria, which is a very popular hoe (see Fig. 1.4) for weedingunder all soil conditions, soil topography and cropping patterns.

By implication, the chopping hoes, used to chop the weeds and soil, though suitable

under hard or friable soil conditions and all conditions of soil topography and croppingpattern, are much less popular. Still less popular are the pushing/pulling hoes, used tocut weeds under the soil surface but suitable only under friable soil conditions. Someexamples of weeding hoes are given in Fig. 1.4.

Rotary Hoes and Wheeled CultivatorsHuman-powered rotary hoes for weeding do exist but are mainly used for row cropped

paddy rice or upland crops in friable soils. Also, many designs of human-poweredwheeled cultivators, with different kinds of weeding shares (tines, hoes, etc.) are avail-able but are suitable only for row crops in friable soils. Some examples of rotary hoesand wheeled cultivators are given in Fig. 1.4. Naturally, use or ownership of these more

sophisticated human-powered weeders is very much restricted, thereby severely lim-iting their impact on the activities of peasant or small-holder farmers of the tropicalworld.

SlashersFor completeness, human-powered slashers, most commonly in the form of machetes

or cutlasses, should be mentioned as important human-powered weeding tools used bypeasant farmers. Slashers are used to cut down above-ground parts of weeds and areespecially useful in controlling weeds in plantations or perennial crops.


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Figure1.4. SomeExamplesofWeedingToolsandMachines. A- Weedinghoes(Ikeagwu-agadi); B - Improvedweedinghandhoe;C - Hand-pushedriceweeder; D -

Wheeledhand-pushedweeder; E - Hand-pushedridge-proleweeder.


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Power Sources 11

Manual Harvesting Tools and MachinesFrom discussions thus far, it is evident that tools and machines for eld operations

used by peasant farmers have retained their pristine forms and sizes as developed bytheir ancestors centuries ago. This is particularly true of harvesting operations for whichthe hoe, various diggers, machetes and knives, sickles and scythes, persist as the majortools available to peasant farmers of the developing countries of the world. A few man-ual harvesting machines have been developed here and there, but they cannot competefavorably with the manual harvesting tools in terms of cost and efciency.

HoesIf the hoe is thought ubiquitous in peasant agriculture, well so it is. It is the principal

tool used by small holder farmers to harvest root and tuber crops (yams, cocoyams,potatoes, corn, cassava, etc.) as well as all crops that develop underground, such asgroundnuts. Of course, the type of hoe used depends on the crop, the topography (at,beds, ridges or mounds) and the soil type or condition (hard or friable, plastic or muddy).Happily, in most cases, a suitable hoe is always available.

Diggers and LiftersA variety of simpletools consisting of long-handleswith sharpenedor speared digging

tips made wholly of wood, wooden with steel tips, or made wholly of steel, form a secondgroup of tools known as diggers, which are used toharvest rootand tuber crops, especiallyyams. Often they are used together with hoes to deal with roots and tubers that developat considerable depths in the ground. Sometimes, shovels and forks, where available, areused in place of wooden diggers. There are also a number of designs of hand tools calledlifters, used for root crops, especially cassava, as illustrated in Fig 1.5.

Machetes and Knives

For harvesting cereals (millet, corn, rice, sorghum) peasant farmers use various typesof machetes or knives developed over the centuries to cut the plant stalk or grain heads, ina once-over operation or selectively, with the special advantage that shattering losses areminimized. Another advantage is that inclusion of unnecessary vegetation is drasticallyreduced, making for lower transport costs and safer storage. The main disadvantage isthe inherently high labor requirements, which can be considerably higher than those forsickles, especially for heavy crops. Special knives have been developed for some crops,such as sugar cane and oil-palm.

SicklesA sickle is a peculiarly shaped knife, very popular in the harvesting of cereals, con-

sisting of a curved metal blade with a sharpened edge and a wooden handle tted onto a shank known as the tang. The length of the blade and its curvature, as well as theshape of the handle and its angle of attachment, varies a good deal from one culture tothe other, as illustrated in the sample presented in Fig. 1.5. Typical specications of asickle also are shown.

ScythesA scythe is a variant of a sickle, composed of a long, curving blade with a sharp edge,

made fast at one end to a long, bent shaft with a handle forming a unit called the snath.


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Figure1.5. SomeExamplesofHarvestingToolsother thanHoesandMachetes. A- Differenttraditional sickleshapes;B - SomeNigeriansickles;C - Variousharvestinghooks; D - Scythe

handles; E - Differentscytheblades; F- Sickledimensions; G - Cassavalifter.


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Power Sources 13

The curved lengths of scythes vary quite considerably, with the shorter bladed ones beingmore suitable for difcult terrains such as hill slopes. The lengths and curvatures of thesnaths also vary a good deal as they are designed to permit users of various statures tooperate with both hands and outstretched arms. Specications for scythes are similar tothose for sickles. Samples of scythe blades and snaths are shown in Fig. 1.5.

Harvesting HooksThe cereal or grass harvesting tool called the reaping hook was developed as a sort

of hybrid or cross between the sickle and the scythe. Reaping or harvesting hooks,like sickles and scythes, come in varying sizes and traditional shapes as illustrated inFig. 1.5. They have short handles and very sharp blades, so that a user crouches to cut thefree standing crop without supporting or holding it. Preference for the harvesting hooksappears to be a cultural trait.

Economics of Human-Powered Tools/Machines for Field OperationsThe discussions so far have shown that human-powered tools/machines for eld

operations are quite limited, consisting essentially of hoes, machetes, knives, hooks anddiggers, virtually preserved in their pristine shapes and sizes by the peasant farmerswho inherited them from their great ancestors of many centuries ago. The overridingcharacteristics of these implements are their relatively low energy demand, low laborproductivity, low technology, low output and inherently high laboriousness and tedium,all of which have direct and indirect relevance to the economics of hand-tool technology(HTT), over and above the purely capital cost considerations.

The low-technology characteristic is important because it implies that these imple-ments can be, and generally, are fabricated by the farmers themselves, as well as by localartisans and blacksmiths, so that their supply is largely in response to their demand. Al-

though local manufacture in itself is a good thing and should be encouraged for variouseconomic reasons, it must be noted that, given the intrinsically low-volume, the lack of formal scientic basis, and the absence of quality control in the production process, theproducts generally are of low quality.

In addition to artisans and blacksmiths, some urban-based companies in some devel-oping countries manufacture the hand tools of interest, as shown in Table 1.6. But suchcompanies often have to contend with many local problems, such as: lack of the right kindof steel locally; inimical or non-conducive manufacturing environment; poor technologi-cal support institutions, infrastructure and superstructure; stiff or unfair competition withdirectly imported alternative goods; and unrealistic excises and sometimes discouragingduties on imported raw materials. Additionally, the companies face the serious problemof low or uncertain volume of sales arising from the fact that their customers, the peasantfarmers, who are usually among the poorest of the poor in their country, have limitedcapacity to invest in new implements, even when the implements they use are too oldand or worn out and require replacement. As a result of these severe local problems, thefew existing companies lack the requisite incentives to invest in the improvement of theproducts or expansion of their operations, all with predictable consequences. This meansthat needs for most of these implements are usually satised by importation from thedeveloped countries, such as Austria, Belgium, Germany, Spain, the United Kingdom,and the United States.


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Table1.6. SomeFormal CompaniesinSomeDevelopingCountriesthatManufactureSomeHumanPoweredImplementsforProductionFieldOperations

H M R W S R F M P S S G P CCountry Company K H H T K Y H L L

Brazil Azotupy Ind. Met. Ltd ∗ ∗Bangladesh Zahed Metal Ind. ∗Cameroon Tropic ∗ ∗ ∗ ∗ ∗Chile Famae ∗ ∗China ChinaImp/Exp Corp ∗India Kumaon Nursery ∗ ∗

Kumar Ind. ∗ ∗ ∗ ∗ ∗Yantra Vidyalaya ∗ ∗ ∗Bharat Ind. Corp ∗Cossul & Co. Ret. Ltd ∗

Kenya Datini MercantileLtd ∗ ∗Oyani Rural Centre ∗

Malawi Chillington AgricLtd ∗ ∗ ∗

Nepal Agric.ToolsFac. Ltd ∗ ∗ ∗ ∗Niger A.F.M.A. ∗Nigeria CrocodileMatch. Ltd ∗ ∗

W.Nig. Tech Ibadan ∗Zartech, Ibadan ∗

Peru FahenaS.A ∗ ∗ ∗HerramieutasS.A ∗ ∗ ∗ ∗ ∗ ∗ ∗Herrandina ∗ ∗

Phillipines Agric. Mech. Dev. Pro ∗Sri Lanka Kanthi Ind. ∗

Agric. Impl. Factory ∗Tanzania SarvudayaKandy ∗

Ubongo Farm Imp/ ∗ ∗ZanaZa KilimoLtd ∗ ∗Uganda Chillington Tool Ltd ∗Zimbabwe Bulawayo Steel Prod. ∗

GarbaInd. (Pvt) Ltd ∗ ∗Temper Tools” Ltd ∗ ∗ ∗ ∗Tool making Eng’g.

Note: H - hoes; M/K - machetes/knives; RH - rotary hoes; WH - wheeled hoes; S - spades/shovels; R -rakes; F - forks; MT - mattocks; P- picks/axes; SK - sickles; SY- scythes; GH - grasshooks; PL - jab/rollerplanters; CL - cassavalifters.

It is clear that there are many factors that combine with capital cost considerationsto make the economics of hand-tool technology in developing countries quite intrigu-ing. With small and usually irregularly shaped plots planted with a mixture of crops,a cropping system that tolerates the feasible use only of primitive hand-tools that maybe old and worn out, leading to poorly cleared land, poorly tilled soils and poor plant-ing in irregularly formed rows, the outcome is inevitably a poor harvest. Under thesecircumstances, with low cost advantage and low productivity, the economics of peasantagriculture using HTT, exhibits the vicious cycle of poverty-begetting-poverty.


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1.1.3. Human-Powered Tools and Machines for Post-Harvest Operations

Denitions and Some General RemarksPost-harvestoperations refer to those activities undertaken to transport, process, trans-

form, preserve or store harvestedagriculturalproducts in order to enhance their economicvalue by increasing their nutritional value and availability over time and space and there-fore, their price or market value. The relevant activities include such unit operations asthreshing, cleaning, sizing, shelling, peeling, grating, cutting, slicing, chipping, grind-ing, milling, comminuting, cooking, drying, pasteurizing, fermentating, handling andtransporting. Although some authorities treat threshing together with harvesting (of ce-reals especially), at the level of operation of small-holder farmers it is considered moreappropriate to treat threshing as a post-harvest operation because the two activities arequite separate.

Tools and machines retain the denitions given in the introduction. Therefore, we areconcerned here with tools used, and machines powered by human beings to perform theindicated post-harvest unit operations. Naturally, small-holder or peasant farmers formthe majority of those who use the human-powered tools and machines, especially thetools for post-harvest operations. Some post-harvest unit operations for certain crops,such as peeling of cassava or extraction of melon ( egusi ) seeds from the pod, can beperformed using only hand tools because viable machines for them, human-powered orotherwise, simply do not exist. In such cases, there is really no choice but to live withthe inherent tedium and low efciency.

Butbecause of thenatureof themajority of post-harvestoperations involved, small-to-medium-scale commercial farmers, and even non-farmers, also use the human-poweredtools and especially, machines, to some advantage. Nevertheless, the fact of the situationis that, given the natural limitations of human-powered machines (tedium, low power,

low capacity, and low efciency), most human-powered machines for post-harvest unitoperations have motorized counterparts, powered by electric motors or internal combus-tion engines. Of course, motorized machines are preferred by small-scale commercialfarmers, or by non-farmers who use them mostly to serve peasant farmers, who naturallyprefer the custom services to the tedium of manual operation.

Nevertheless, there are literally hundreds of food products processed by peasant farm-ers using hand tools and human-powered machines not found in the literature. Many of them are specic to certain localities outside of which they may not be known evenin the same country. As already stated, manual processing of these products is time-consuming and tedious; the conditions prevalent at this level of operation generally are

unsanitary and inherently unhygienic, with little attention paid to quality control, makingthe wholesomeness and quality of the products, perforce, variable and uncertain.

Some Common Tools for Crop Processing by Peasant Farmers

KnivesMany post-harvest unit operations for processing of agricultural products by peas-

ant farmers are performed with the group of tools classied as knives. For example,cutting, peeling, slicing, chipping and many size-reduction operations are carried out


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Figure1.6. WorldofKnivesandCuttersforTraditional CropProcessing.

using knives, which come in numerous sizes and shapes, as shown in Fig. 1.6. Knivesare as indispensable and ubiquitous in post-harvest crop processing operations by peas-ant farmers as hoes and machetes are in their eld operations for primary agriculturalproduction.

Mortar and Pestle SystemsNext to knives, mortars and pestles are the next most commonly used tools in peasant

crop processing operations. They are used for threshing, grinding, milling, size reductionand all unit operations that can be performed by pounding or rubbing. A mortar is a strongvessel, usually of wood in this context, in which materials are pounded or rubbed witha pestle. The popularity of the mortar-and-pestle system derives from the fact that thepeasant farmers are able to produce the tools for themselves. Mortars are produced fromtrunks and pestles from appropriately sized branches of hard or high-density wood of trees such as the iroko, oil-bean trees, etc. Naturally, mortars and pestles vary a greatdeal in size, shape and weight, depending on the intended applications, as illustrated inFig. 1.7. A mortar may be large enough to admit six to eight persons, standing, with longpestles to pound its contents together/simultaneously, to macerate parboiled palm fruitsin peasant palm-oil processing operations, or, in the preparation of yam foo-foo or fufu


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Power Sources 17

Figure1.7. Mortar andPestleSystems.

(Sierra Leone), for communal work-team feeding. Or the mortar/pestle system may be just large enough to grind a few grains of pepper for a small pot of soup for a bachelor.

Miscellaneous Processing ToolsThere are, of course, many processing unit operations by peasant farmers that cannot

be carried out with knives or mortar/pestle systems but require unique tools such as:shellers for maize, groundnuts or such prodded crops; graters for cassava and other rootsand tubers; sifters for meals and ours; and winnowers for grain. Some of these tools areillustrated in Fig. 1.8 without further comments, since they generally are very simple inform and construction.

Some Common Human-Powered Processing Machines

Manual Machines That Can Replace the KnifeFor a limited number of unit operations for which the peasant farmer uses a knife, there

exist some human-powered machines or equipment. Such machines that can replace theknife in traditional or peasant processing operations include roller root cutters, cassavagraters, vegetable cutters/slicers, etc. Some of the machines are illustrated in Fig. 1.9. Onthewhole, such machines do not make a signicant impacton thepost-harvestprocessingoperations of peasant farmers.

Manual Machines That Replace the Mortar/Pestle SystemIt is perhaps correct to state that formost mortar/pestle systems in peasant or traditional

operations, there are viable human-powered machines as alternatives. The machines are


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Figure1.8. SomeMiscellaneousManual ProcessingToolsandMachines. A- Differenttypesofhandtoolsforshellingcorn;B - Gari fryingmachinewithmanual operationarrangement; C - Manual

Bitter-leaf processingmachine.


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Figure1.9. SomeManual ProcessingMachinesThatCanReplacetheKnife.A- Roller rootcutter;B - Disk vegetablecutter/slicer;C - Pedal-assisted

manual cassavagrate.

either hand- or foot-operated, and commonly include grinders, mills, hullers, decorti-cators, shellers, crushers, presses and winnowers/separators, as illustrated in Fig. 1.10.Their impact on peasant farmers’ operations is quite signicant, especially in terms of the custom services that small-scale non-farmer operators of these machines provide, asmentioned earlier.

1.1.4. The Sociology and Future of Hand Tool Technology in LDC’s

In Section 1.1.1, the predominance of HTT in the agriculture of LDC’s was identied asan important factor in the overall economic development of the countries. The sociology


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of HTT thus becomes an important subject to consider in discussing its present or itsfuture in LDC’s.

The man with the hoe , a title credited to Edwin Markham [10], still remains an aptdescription of the peasant farmer in developing countries of Africa, even on the vergeof the 21st century. In spite of decades of enormous expenditures and investments inagriculture, the peasant farmer using HTT remains an indigent serf, regarded by today’syouths as a dreadful anachronism. With HTT the prevalent technology, the agriculturalindustry in those countries has degenerated into a world for and of losers [11], populatedby aged and aging peasants, whose precarious hand-to-mouth existence seems to standlike a huge signboard screaming to the youths: KEEP AWAY!

As such, HTT curiously is no longer sustainable in many of the LDC’s because,frozen as it is in its pristine stages of hoe-and-machete or mule-and-oxen technologies,it leads to the prevalence of mass poverty, which the young people of the LDC’s abhorand roundly reject [12].

It ought to be appreciated by all actors involved that the continuing policy of near

exclusive advocation or promotion of HTT in the LDC’s is becoming counterproductive.Therefore, it has become necessary and urgent to reduce the undue emphasis on HTTas a conceptual and psychological point, and to begin to change the undignied imageof peasant farmers, thereby make farming more attractive to the youths. An ofcialpolicy to deemphasize HTT and promote or encourage higher levels of engine powermechanization technology (EPMT) is necessary to rejuvenate the agricultural industryand foster some hope of a better future for the industry in the LDC’s of Africa.

References1. Anazodo, U. G. N. (1976). A eldstudy and analysisof problemsof and prospects for

mechanization of family farms in Anambra and Imo States of Nigeria: A ResearchReport. Department of Agricultural Engineering, University of Nigeria, Nsukka.

2. Inns, F. (1992). Field Power. In Tools for Agriculture, Fourth Edition IntermediateTechnology Publications Ltd., London.

3. Odigboh, E. U. (1991). Continuing Controversies on Tillage Mechanization inNigeria. J. Agric. Sci. Technol. 1(1): 41–49.

4. Makanjuola, G. A., Abimbola, T. O. and Anazodo, U. G. N. (1991). AgriculturalMechanization Policies andStrategies in Nigeria. In Mrema,G. C. (Ed.) AgriculturalMechanization Policies and Strategies in Africa: Case Studies from CommonwealthAfrican Countries. Commonwealth Secretariat, London.

5. Odigboh, E. U. (1996). Small-Medium-Scale Farmer Oriented Mechanization Strat-egy for Energizing Nigerian Agriculture. Proceedings of the 1996 National Engi-neering Conference of Nigerian Society of Engineers , pp. 96–115.

6. Mrema, G. C. and Mrema, M. Y. (1993). Draught animal technology and agriculturalmechanization in Africa: its potential role and constraints. Network for Agricultural Mechanization in Africa (NAMA) Newsletter 1(2): 12–33.

7. Comsec (1990). Report of expert consultation on agricultural mechanization inCommonwealth Africa. Commonwealth Secretariat, Malborough House, Pall MallLondon SW1Y 511X: 83.


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8. Anazodo, U. G. N., Opara, L., and Abimbola, T. O. (1989). Perspective plan for agri-cultural development in Nigeria (1989–2004). Agricultural Mechanization StudyReport, Fed. Agric. Coordinating Unit (FACU), Ibadan.

9. Anazodo, U. G. N., Abimbola, T. O. and Dairo, J. A. (1987). Agricultural machineryuse in Nigeria: theexperience of a decade(1975–1985). Proc.Nigerian Soc. of Agric. Engineers ( NSAE ) 11: 406–429.

10. Gunkel, W. W. (1963). Nigerian Agriculture. Paper No. NA 63–107, prepared fordistribution at North Atlantic Section Meeting of American Society of AgriculturalEngineers. University of Maine, Orono, Maine, August 25–28, 1963.

11. Wainan, S. (1990). “Major Agricultural Reforms Needed”, Experts say. AfricanFarmer 3: 34.

12. Odigboh, E. U. and Onwualu, A. P. (1994). Mechanization of Agriculture in Nigeria:A Critical Appraisal. A Commissioned feature article. Journal of Agricultural Tech-nology, JAT 2(2): 1–58.

13. FAO (1988). Agricultural Mechanization in Development: Guidelines for Strategy

Formulation. FAO Agricultural Services Bulletin 45, FAO, Rome.

Animals M. Havard and A.Wanders

Animalpoweraccounts forabout 20 percent of agriculturalmechanization in develop-ing countries; human power accounts for 70 percent, mechanical power 10 percent. Theworld number of draft animals has been estimated to about 400 billion head, mainly inAsia. Cattle, buffaloes, horses, donkeys and mules are the main draft animals. Camels,elephants, llamas and yaks also may be used. The factor limiting the use of animals

for work is their reduced energy potential, which is determined by characteristics andworking ability of the species.

1.1.5. Efcient Use of Energy Potential by a Draft Animal Power Unit

Several parameters such as energy, power, draft force, etc. are used to dene the work performed by animals. Energy is provided to animals from feeds previously metabolizedinto fats and carbohydrates, and then assimilated in muscles. The energy output requiredfor such processing is not well known.

A draft animal power (DAP) unit (i.e., animal plus equipment), which exerts a tractiveforce, can be compared with a system consisting of a resistant part (equipment) and apower unit (animals). The energy accumulated by animals is partially released in amechanical form when pulling equipment or carrying a load.

Work W is the energy required to move an object with a draft force F through adistance L: W = Fx L . The power P of a DAP unit is the work performed per unit of time T : P = W / T . The example given hereafter refers to pulling a plow (Fig. 1.11).

Draft resistance Fr is a downward diagonal. On a well-adjusted plow that the operatorcan easily hold straightward, Fr consists of three forces:

• Force exerted by soil on the working parts Fs• Implement weight P which in fact does not affect the resistance effort signicantly


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Table 1.7. Effortsandenergyexpendituresforsomedraft animal species ∗

LiveWeight Forcepc of Speed Work Time DEAnimals (LW) kg LW m/s h (MJ)

Donkey 100–150 10–16 0.7–0.9 3.0–6.0 5–8Horse 200–300 10–16 0.9–1.0 4.5–6.5 16–24Zebu 300–450 9–15 0.6–0.8 4.5–6.5 24–40

WhereDE, energy expenditureat work = DE horizontal displacement +DE pull output + De transport + DE vertical displacement [6].

∗ In India [15], similar forces in percent of live weight have been recordedwith camels (15–16 pc) and buffaloes(10–12 pc).Source: [18].

Figure1.12. Trendofcurvesofthedistancetravelledandpull

outputin termsoftractiveforce.

Selecting the most suitable parameter for characterizing team capability is difcult.Available power and energy vary with the mean pull required per day. Capability dependson the direction of the line of draft and ground surface conditions. Efciency decreasesfrom 1 in straight-line work to 0.8 in circular work (capstan). Tillage in dry soils causeshigh frequencies and a wide range of variations in forces. This results in pronouncedvibrations and greatly affects the animal’s comfort. Working in loose soils limits theanimal’s draft capability because of the sinking effect.

1.1.6. Control of Animal’s Energy PotentialIn-depth knowledge of the factors inuencing the work achieved by animals is re-

quired. Some of these can be controlled by farmers, others cannot (Fig. 1.13).

Environmental ConditionsEnvironmental factors (soil and climate) that dene working conditions are uneasy

to control. Farmers can improve such conditions but to a small extent. They may preferto work their animals at the beginning or end of the day, when heat is acceptable. Thisis protable in terms of animal capabilities and endurance.


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Figure1.13. Factorsinuencingthecapabilitiesof animal teams.

Choice of AnimalsThe characteristics of animals (breed, species, sex, age, temperament) determine their

working abilities. Farmers cannot control these. Their only room for maneuver is in thechoice they can make between the various species locally available or affordable. Heavyand slow species (e.g., elephants, buffaloes, bovine crosses) must be preferred for hardwork. Light and fast species (e.g., donkeys, horses, camels) are particularly suited forlight work such as sowing, weeding and transport. Whatever the species, local breeds


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are preferable. In terms of draft, the cows potentialities are almost the same as those of oxen. Nevertheless, cows are less convenient for high draft forces.

Use of AnimalsTeam composition and the choice of implements and harnessing systems depend on

the farmer’s decisions. They are key factors for transforming the energy accumulated byanimals into mechanical power. With current yokes and harnessing, pooling two animalsor more in a team results in a reduced efciency at an individual level. If the availablepower is 1 with one animal, it is only 1.85 with two animals, 3.10 with four, and 3.80with six [12]. Choosing the more suitable harnessing system, equipment and number of animals depends on local availability and cost, but may rapidly enable signicant energygains.

The main harnessing systems have been largely described in many manuals and books[3, 4, 6, 9, 10, 16]. A harnessing system is a set of elements involving a harness, drivingttings (steering ropes, bridles) and single or multiple hitching systems (abreast or intandem). For carting, additional ttings can be used to assume other functions such asthe cart balance (back strap, belly strap), braking, and reversing (breeching strap).

The harness is the main part of a harnessing system. It makes it possible to optimizethe energy potential provided by an animal to exert a force for pack transport, pullinga cart or a farm implement, or driving an animal-powered gear. There are various typesof harnesses that can be classied according to the point where they apply work to theanimal, e.g., before the shoulders (collar), on the withers (withers yoke), just behind thehorns on the neck (neck yoke) or on the breast (breast band or breast strap) (Fig. 1.14).

The collar generally is the most suitable harnessing system. A collar includes a framefor tting on the animals, padding for protection and comfort, and a device for hitchingan implement. There are several points to apply a collar to the animal, which results ina better distribution of forces. Collars are not as widely used as expected because theyare relatively difcult to make, and therefore expensive.

Breast bands are lighter and simpler harnesses, widely used with horses and mulesbecause of their simplicity and low cost. They prove well-suited to the conformation of such animals because of their ample breast.

Yokes are mainly used with bovines. They take power from points higher on theanimals than collars and breast bands. According to the number of animals harnessed,yokes can be single with a single animal, double with a pair of animals, or sometimestriple for training a young animal between two older ones.

Head yokes described as forehead yokes are tied in front of the horns, and are rather

uncommon. They were known in Spain and largely popularized in Switzerland andGermany. Head yokes described as neck yokes are tied just behind the horns. They werewidely used in Europe before the introduction of power-driven equipment. Mainly usedwith humpless cattle ( Bos taurus ) with strong necks and horns, their form varies fromthe simplest uncarved wooden pole to yokes shaped into more or less pronounced bows.Padding is required between the yoke and the animal’s neck. Incorrectly shaped or ttedneck yokes, with excessively loose or thin securing ropes, provoke injury, horn wearingand sawing. This results in reduced power from the draft animals harnessed.


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Figure1.14. Differenttypesofharnessingsystems.

27


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In Burkina Faso [9] and India [15], the use of improved yokes has made it possibleto achieve respective energy gains of 15% and 15%–25% as compared with traditionalyokes.

Withers yokes apply on the withers, in front and over the shoulders. They are naturallysuited to hump cattle ( Bos indicus ) such as zebus. They can also be used with taurinesas N’Damas. Withers yokes are predominant in Africa.

Whatever the type of yoke, lowering the attachment point also requires lowering theapplying points towards the points of the shoulders. This reduces the slope of the line of draft (an angle of 15 ◦ is suitable).

Livestock ManagementThe components of livestock management (i.e., feeding, training, care, and watering)

depend entirely on the user. They determine the conditions and steadiness of the workinganimal, resulting in the actual energy accumulated and available for working with respectto the energy potential of the species.

Feeding must cover the nutritional expenditures that allow animals to maintain theirweight. To produce work, milk or meat, and for their maintenance, animals require en-ergy, proteins, minerals, vitamins and water. The energy contained in feeds is called grossenergy, 25%–55% of which is lost in feces. The remaining energy is called digestibleenergy. This undergoes losses as gas, urine and heat, and leads to the net energy usedby animals for their maintenance, for working and sometimes also for other produc-tion.

Stock watering is of prime importance to counterbalance the water losses inducedthrough the respiration and transpiration processes occurring when an effort is exerted.Water quantities must be determined according to the work required and climatic con-ditions. They can easily double. The minimum is 15 liters of water for an ox weighting300 kg, performing a light work, in the rainy season, and a daily feed ration of DM (drymatter) 4–5 kg [3].

Timeliness in vaccinations and other health treatments (e.g., parasite control) are alsobenecial, although farmers can only use the products available locally.

The training level will affect animal performance at work. Docile animals, whichprove easy to handle and steady in the force required, will be more efcient. A trainingprogram consists of a succession of stages based on repeated commands and constraintsto one or several animals, so as to achieve a docile and rm behavior at work. Trainingwill preferably be done before the agricultural campaign, when animals are about threeyears old. Duration depends widely on the animals’ age and temperament, and on the

trainer’s skill as well. Training time ranges from one month with already familiar animalsto more than two months with animals not used to human company.

There are three methods for training cattle:1. Hitching two young bulls together with the same yoke. This is the most common,

but the more difcult, method.2. Training a young animal with an older one for one or two weeks before they are

yoked together. The advantage is reduced stress for the young animal because of the example offered by the older one.


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3. Yoking three animals together, with the young animal between two already well-trained animals. This is certainly the most rapid training method with vicious,nervous and restive cattle. It is widely employed in southeast Africa.

The future user must train draft animals personally, or at least take an active part inthe training. The rst stage is a mutual familiarization. The trainer must show patience,calm, sympathy and rmness. Further stages involve putting the yoke on the animal andmaking it accept the yoke, and training the animal to walk and pull a light load, exert atractive force, pull farm implements and work alone.

1.1.7. Farm Equipment for Transport, Tillage, Secondary Cultivationand Sowing

This chapter has voluntarily been limited to the most common mechanized operationssuch as transport, tillage, secondary cultivation and sowing. Nevertheless, animal poweralso can be used for water-lifting or harvesting (e.g., groundnut lifting). For furtherdetails on the mechanization of such operations, see the many manuals available [1–4,6, 13].

Equipment for TransportIn rural and urban areas, the daily transport of people and goods is a highly important

activity. Various means are used: riding, pack and cart transport (two-wheeled carts orfour-wheeled trailers), and sledges.

Riding donkeys, horses and camels is common throughout the Mediterranean andsub-Saharan areas. Riding donkeys without any harnessing system is predominant be-cause of their high hardiness. Oxen also may be employed, as in Mauritania and Chad.Camels and horses are more prestigious. They are harnessed with specic saddles locally

manufactured.Carrying loads on the back of animals is very common throughout all the tropi-cal areas. Loads vary between 80 and 100 kg in weight for donkeys, to 300 kg fordromedaries. Three methods can be applied: bulky loads are directly placed over theanimal’s back and held in place with ropes; rigid materials (stones, rewood, watercontainers) are transported on pack saddles with a wooden frame tting on protectivepaddings; and in-bulk products are placed in symmetrical pannier baskets over the ani-mal’s back (Fig. 1.15).

In certain areas of southern and eastern Africa and Madagascar, artisan-made woodensledges are used. Their main advantage is that they are cheap, being easy to makeand maintain. They are narrower than carts, have a low center of gravity, and can beused on steep, wet, or unbearing ground. Nevertheless they cannot be recommended ontracks because the tractive force required is higher than for a cart, and repeated passagesaccelerate erosion. That is why they have been banned in some hilly countries such asLesotho and Zimbabwe. Using a sledge, a pair of oxen can carry a load of about 200 kg,at 0.8 m per second, over several kms.

In the tropics, animal-drawn carts are the most widely used equipment for transport.In rural areas, farmers, artisans and traders employ carts for domestic needs (water andrewood), agriculture (seeds, fertilizers, manure, harvest), trade and social purposes.


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Figure1.15. Usinghorsesanddonkeysforcarryingaloadorcarting. Sour ce: [11].

The load capacity of a cart (the load a cart can carry across country without distortionor breaking) is 500 kg with a donkey and 1,000 kg with a pair of oxen. The tractiveforce Tr required to move a cart is the product of the total weight P of the load (loadcapacity + dead weight), by the rolling coefcient K (which varies with the soil surfacestate) and the slope i (slope coefcient in percent), that is: T r = Px (K + i), where T r


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Power Sources 31

and P are in kg. A braking system is required in hilly areas. Carts may be tted withwooden or steel wheels. But wheels tted with pneumatic tires–similar to those on lightpower-driven vehicles–are becoming increasingly common.

In the past, wheels with wooden spokes and metal rims were used on all carts. Madetoday in Northern Africa, Egypt and Madagascar, this type of wheel is rather uncommonin other countries.

Metal wheels are being abandoned in many areas. They have been introduced fortransport purposes in the sub-Saharan wet areas (having high ground clearance, well-suited to negotiate ruts and holes), and are still used in the sandy areas where spikybushes can cause problems of punctures with pneumatic tires.

Two-wheeled carts with pneumatic tires are the best suited to satisfy the varied needsand situations. Tired wheels require a minimum tractive force as their rolling coefcientis optimum–above 35% on dry track and up to 64% on muddy ground.

Tip-carts with tip-up boxes facilitate the unloading of materials such as earth ormanure but are little used because of their high manufacturing cost.

Four-wheeled carts (trailers) can be found in southern African countries, in urbanareas and near cities (Bamako, Cairo). They also are used on some plantations. Theyallow heavy loads up to 3 tons because the animals only support a very small part of theload weight.

Equipment for Tillage

Under Dry ConditionsUnder dry conditions tillage objectives are as follows:• To loosen the soil for creating conditions conducive to in-depth aeration and

water movement, which promotes root growth, facilitates rain water inltration,

and achieves convenient conditions for germination.• To control weeds by uprooting, burying, or even promoting weed emergence forlater destruction.

• To plow in fertilizers and soil improvers and mix them with soil.Choosing a tillage method depends on the type of soil, ground moisture, and on the

cultivation system applied. For cultivation in at ground, tined implements are suitableon dry sandy soil, while plowing is essential on wet, silty soils. For bedding or ridgecultivation, the use of a plow or a ridger is essential.

There are four main categories of operational sequences to be performed prior toplanting:

• Tine tillage on dry soil (subsoiling) which can be done before surface tillage andplowing operations. Currently tested in tropical areas.

•

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