Tropical Ecology Support Program (TÖB)

Soil Fertility

Options for Soil and Farmer Friendly Agriculture in the Highlands of Northern edited by

Koen Van Keer J.D. Comtois Francis Turkelboom Somchai Ongprasert

Eschborn 1998 TÖB publication number: TÖB F-I/4

This publication is a final output of the SOIL FERTILITY CONSERVATION PROJECT (SFC), a collaborative research project between the Laboratory of Soil Fertility and Soil Biology, Katholieke Universiteit Leuven (K.U. Leuven), Belgium and the Department of Soils and Fertilizers and Department of Agronomy, Maejo University (MJU), Thailand.

The project was established under the auspices of the Flemish Inter-University Council (VLIR) and the National Research Council of Thailand (NRCT) and sponsored by the Belgian Agency for Development Cooperation (BADC) and the Flemish Organisation for Development Cooperation and Technical Assistance (VVOB).

Additional financial support for this publication was provided by the K.U. Leuven Interfaculty Council for Development Cooperation (IRO) and by GTZ-TÖB.

SFC realised the following objectives:

· installation of a lab for soil, plant and water analysis at Maejo University · strengthening of Maejo University staff through training and exchange programs · implementation of research on soil issues linked to highland farming under land pressure

During a first project phase (1989 - 1992) SFC studied soil dynamics under various soil conservation cropping systems. This research was conducted on station-based experiments of the Department of Land Development (DLD), the International Board of Soil Research and Soil Management (IBSRAM), the Thai-German Development Project (TG-HDP) and the Thai-Australian Highland Agricultural and Social Development Project (TA-HASDP). During a second project phase (1993 - 1995) SFC focused on research in farmers’ fields. This research was conducted in 3 highland villages, in collaboration with local farmers and two Thai NGOs, the Hill Area Development Foundation (HADF) and the Hill Communities Education and Development Project (HCEDP).

Published by: Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) GmbH Postfach 5180 D-65726 Eschborn

Responsible: Tropenökologisches Begleitprogramm (TÖB) Dr. Claus Baetke

Editors: Koen Van Keer, J.D. Comtois, Francis Turkelboom, Somchai Ongprasert

Authors: Koen Van Keer, Francis Turkelboom, Somchai Ongprasert, Apichai Thirathon

Contributors: Pathipan Sutigoolabud, Katelijne Rotschild-Van Look, Anan Pintarak, Josianne Pelletier

Layout: Koen Van Keer, J.D. Comtois, Stefanie Eißing

Illustrations: concepts: Koen Van Keer, Francis Turkelboom first drafts: Daranee Danwandee final illustrations: Filip Le Roy

Photos: Koen Van Keer, Francis Turkelboom, Josianne Pelletier

ISBN: 3-9806467- 0 - X

Produced by: TZ Verlagsgesellschaft mbH, D-64380 Rossdorf

This publication is not copyrighted. The editors encourage the translation, adaptation and copying of materials for non-commercial use, providing a reference to this publication is included. Dedicated to the memory of Boonlert Koomnok and Awhu Poti in acknowledgement of their contribution to the Soil Fertility Conservation Project Forewords

Tropical ecosystems are the essential base of life for the majority of the world’s population. Growing degradation of natural resources and the destruction of fragile ecosystems increasingly jeopardise efforts towards sustainable development and effective poverty reduction.

The Tropical Ecology Support Program (Tropenökologisches Begleitprogram, TÖB) wants to contribute to an effective analysis, utilization and implementation of know- how and experiences made in this regard within the scope of development cooperation.

TÖB is a supraregional service project conducted by the Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) GmbH on behalf of the Federal German Ministry for Economic Cooperation and Development (BMZ).

On request, the program flanks specific projects with studies focusing on issues relevant to tropical ecology. TÖB wants to contribute to further develop concepts and approaches aimed at the conservation and sustainable use of tropical ecosystems. The analysis and evaluation of the research work provides the basis for designing innovative instruments that will facilitate ecologically-sound development cooperation.

By translating scientific results into action at the extension level, TÖB supports other projects in the implementation of international agreements, in particular Agenda 21 and the Biodiversity Convention, to which the BMZ attaches great importance.

Key element of the program concept is the joint conduction of applied research by German and local scientists. The Tropical Ecology Support Program is thus making an important contribution to the practice-oriented upgrading of counterpart experts and the consolidation of tropical-ecology expertise in partner countries.

This series of publications has been produced in a generally comprehensible form with the specific aim of presenting the results and recommendations of the studies to all organisations and institutions active in development cooperation, and also to those members of the general public who are interested in environmental and development- policy issues.

Dr. H. P. Schipulle Dr. J. Friedrichsen

Head of Division Environment Head of Department Resource Protection and Rural Development

Federal German Ministry for Economic Deutsche Gesellschaft für Cooperation and Development Technische Zusammenarbeit (GTZ) GmbH Here is a book that is a credit to the authors. What started out as an extended academic and research exercise has come full circle. A round of fieldwork, scientific reports, meetings and discussions is appropriately completed by this publication. Here are the results of seven years careful research work, unpretentiously pared down to essential findings, and presented as a practical guide to better management.

So much to praise. Here is a book which acknowledges in a substantial way those whose lives are most directly and profoundly affected by the way in which the highlands of Thailand and beyond are farmed. Here is a book prepared in a form that will make translation easy. The illustrations in Options for Soil and Farmer Friendly Agriculture in the Highlands of encourage the reader to enjoy the experience of becoming better informed. Important sections of text are placed in boxes which are easy to find. Indigenous knowledge is given a proper place alongside information gleaned from the meticulous procedures of modern agricultural and soil science.

Who will benefit? A few farmers may read it in Thai and none at all in English but this is not the point. The text has the look and feel of a presentation negotiated with farmers or those who know farmers well enough to recognise illustrations that appeal to the eye and make it easy to see what is being represented. The immediate beneficiaries of this book will be agricultural extension workers, and field people working with NGOs, development projects and the like who, for the first time find themselves working with farmers. Here is text, drawings and explanations that can be taken aboard and distributed to farmers at the appropriate time and place and in appropriately sized morsels. It lends itself to translation into many languages.

In an ideal world perhaps the highlands of Thailand and the Upper Mekhong ecoregion should not be farmed at all, especially not by farmers who till the soil but we do not need to be reminded that the world is far from perfect. The implementation of utopian policies that would attempt to clear the highlands of farmers would be disastrous. Millions of mountain people distributed throughout Thailand and stretching north to the mountains of Guizhou, will, at least until the end of the first century in the next millennium, if not longer, rely on these soils for a large proportion of their food needs. The beauty of this book is that it acknowledges this reality without claiming more than that ”the content may have relevance for much of the Upper Mekhong ecoregion. And a portion of it, at least the basic ideas and concepts, might hold in highland areas in other parts of the tropics”.

So muted. This modest book is an important contribution to the amelioration of a huge challenge: how to make use of highland soils in such a way as to optimise returns and minimise damage. It shows us how useful researchers and academics with a social conscience can be. It deserves to be circulated widely. The authors deserve a medal - make that several medals.

Dr. John McKinnon

Convenor Development Studies Institute of Geography, Victoria University of Wellington, New Zealand Acknowledgements

First of all we want to address warm words of gratitude to all farmers who generously shared their time, knowledge, friendship, houses and meals with us.

We sincerely thank Dr. Karel Vlassak (KULeuven), Dr. Ahnon Tiangtrong, Dr. Nalinee Roongruangsree, Dr. Songvut Phetpradap (MJU) for setting up and supervising the Soil Fertility Conservation Project.

We recognise the institutions that provided administrative and financial support to the SFC-Project. A special word of thanks goes out to BADC representatives Dr. Jean- Yves Standaert and Dr. Eddy Tessens and to VVOB representatives Dr. Jacques Lenvain, Mrs. Mireille Swinnen and Mr. Jan Van Lint. We also acknowledge the organisations which provided funding to publish this book, the KULeuven Interfaculty Council for Development Cooperation and GTZ-TÖB, as well as their respective representatives Mr. Roland Vanermen and Mrs. Kirsten Hegener.

We are grateful to the staff members of several organisations, for the collaboration opportunities they offered us: Dr. Chayasit Anecksamphant, Mr. Sawatdee Boonchee, Mr. Pitag Inthapan and Mr. Samran Sombatpanit (DLD), Dr. Adisak Sajapongse (IBSRAM), Mr. Christoph Backhaus (TG-HDP), Mr. Terry Bull (TA-HASDP), Mrs. Tuenjai Deetes (HADF) and Mr. Wiroot Kantasuk (HCEDP).

We appreciate the expertise provided by many colleague-researchers: Dr. Roel Merckx, Dr. Seppe Deckers, Dr. Jean Poessen and Dr. Eric Tollens (KULeuven); Dr. Benjawan Rerkasem, Dr. Amphan Bhromsiri and Dr. Jitti Pinthong (Chiang Mai University); Dr. Guy Trébuil (CIRAD, seconded to IRRI); Dr. Thomas George (NIFTAL, seconded to IRRI); Dr. Cyril Ciesiolka (Department of Primary Industries, Queensland, Australia) and Dr. Eelko Bergsma (ITC, the Netherlands).

We thank the staff of the Department of Soils and Fertilizers (MJU) and all other people of Mae Jo University for the nice cooperation. We would like to thank in particular Mrs. Lut Ooms and her laboratory team, all SFC field assistants and all Thai, Belgian and other students for their thesis contributions.

A special word of thanks goes to the many people who provided valuable review comments on this book. First of all to ad hoc editor J. D. Comtois, without whom this book would never have seen the daylight. Further also to Mr. Klaus Prinz (McKean Rehabilitation Center, Chiang Mai), Mr. Jerry Duckit (GDS, Thailand), Mr. David Bluhm (Peace Corps, Thailand), Mrs. Madeleine Dunphy (writer, USA), Mr. William Kenneth Fox III (MJU), Mr. Hans Carlier (Project Earth, the Netherlands), Dr. Sam Fujisaka (CIAT, Colombia), Dr. Rudy Dudal and Dr. Jean Poessen (KULeuven).

Last but not least we thank all our relatives and friends for their continuous support.

The SFC team Table of contents

About this book vii

Part I: The highlands of northern Thailand: agriculture, people and soils

Chapter 1: Highland agriculture in transition 1.1. Agroecosystems in northern Thailand 1 1.2. Highland farming systems 3 1.3. The highland dilemma: development or conservation? 5

Chapter 2: Solving problems together with farmers 2.1. Reflections on sustainable agricultural development 9 2.2. Participation in development 12 2.3. Participatory methods for farmer-led development 17 2.4. So far the theory, what about the practice? 23

Chapter 3: Characteristics of highland soils 3.1. What is soil and how is it formed? 25 3.2. What determines the fertility of soils? 27 3.3. How can we evaluate the fertility of soils? 30 3.4. Are highland soils suitable for agriculture? 35 Conclusion: Highland soils are suitable for agriculture 38

Part II: The management of highland soils: an integrated vision

Chapter 4: Lessons from the forest 4.1. Why are forests soil-friendly agroecosystems? 41 4.2. The forest as a model for soil-friendly farming 42 4.3. Agroforestry, a compromise between forests and farming 42

Chapter 5: Fallow management 5.1. What is a fallow? 45 5.2. What are the functions of a fallow? 45 5.3. Fallow degradation: the start of a crisis 46 5.4. Away with fallow-based farming systems? 47 5.5. Fallow management options 50 Conclusion: Don’t neglect the fallow 52

Chapter 6: The management of plant residues 6.1. General overview of residue management options 55 6.2 Management based on burning of plant residues 56 6.3. Management based on non-burning of plant residues 64 Conclusion: Plant residues are resources that should be judiciously managed 67

Chapter 7: Soil erosion control 7.1. What is soil erosion? 69 7.2. Is soil erosion a problem typical of only subsistence farming in the tropics? 71 7.3. Is soil erosion a problem in northern Thailand? 71 7.4. Is soil erosion a problem in the village where you are working? 73 7.5. When should erosion control measures be taken? 73 7.6. Basic principles of soil erosion control 74

i Table of contents

7.6. Erosion control strategies and methods 76 Conclusion: Soil conservation should be an integral part of a comprehensive 94 strategy

Chapter 8: Soil nutrient management 8.1. Why do we need to manage plant nutrients? 96 8.2. How can we diagnose plant nutrient problems? 96 8.3. Nutrient management strategies and methods 97 Conclusion: Nutrient cycling and balanced fertilisation are the key- 102 components of sound nutrient management

Chapter 9: Weed control 9.1. The burden of weeding 103 9.2. What is the purpose of weed control? 103 9.3. Weed control and soil conservation: irreconcilable objectives? 104 9.4. How can we diagnose weed problems? 104 9.5. Weed control strategies and methods 105 Conclusion: Weeds are a huge challenge to the development of 109 sustainable highland farming

Chapter 10: The management of soil-borne pests 10.1.What are soil-borne pests? 111 10.2.How can we diagnose soil-borne pests? 111 10.3.Methods to control soil-borne pests 112 Conclusion: Rotate and mix to avoid problems with soil-borne pests 113

Part III: The future of highland agriculture

Chapter 11: Diversification, of species and activities 11.1.Upland rice: a dead-end street? 115 11.2.Highland paddy rice farming: a sustainable alternative? 116 11.3.Other field crops: limited possibilities 118 11.4.Home gardening: a small activity with big advantages 118 11.5.Fruit trees: a secure investment? 118 11.6.Commercial high-input horticulture: risky but very attractive 120 11.7.Alternative low-input agriculture: adopt as much as feasible 122 11.8.Livestock and/or fish raising: the more the merrier? 122 11.9.Collection of forest products: OK but don’t exaggerate 123 11.10.Off-farm activities: unavoidable... 123

Concluding remarks 125

Photographs 129

Notes on photographs 137

Appendices

Appendix 1: Diagnostic methods and tools 1.1. Basic principles of PRA-PLA 143 1.2. Some concrete PRA-PLA techniques 144 1.3. Some limitations and dangers of PRA-PLA 148 1.4. General tips for field experiments with farmers 149 ii Table of contents

1.5. Conducting your own soil survey 150 1.6. Tips for adequate soil sampling 151 1.7. Soil fertility evaluation with pot experiments 153

Appendix 2: Some recommendations 2.1. Fallow improvement 155 2.2. Suggestions for better fire control 155 2.3. Suggestions to improve burning practices 157 2.4. Some guidelines for decision making on burning vs. non-burning 159 2.5. Suggestions to improve vegetative contour strip systems 161 2.6. Some general recommendations for appropriate fertiliser use 163

Appendix 3: Useful addresses 165

Appendix 4: Selected references and further reading 169

Appendix 5: Glossary 175

List of tables

Table 1:Description of the SFC on-farm research sites 4 Table 2:Overview of the characteristics of the major highland soil types 35 Table 3:Historical profile of Mae Haeng 146 Table 4:Historical profile of Pakha Sukchai 147 Table 5:Factors to be considered in decision making on burning vs. non-burning 159 Table 6:Types of organic soil amendments potentially available in Thailand 163

List of text boxes

Box 1: Typology of agricultural systems in northern Thailand 3 Box 2: Who are the hill tribes? 6 Box 3: What are external inputs and what are the problems with their use? 10 Box 4: Classification of agricultural systems based on the use of external inputs 10 Box 5: Some tricky questions about sustainability 11 Box 6: Standard recommendation package for soil conservation and sustainable 13 (rice based) highland agriculture in northern Thailand Box 7: What to put in the basket? 15 Box 8: Some shortcomings of indigenous knowledge, farmer experimentation 16 and farmer-to-farmer extension Box 9: Terminology of participatory methodologies 17 Box 10:What is the reason of rice shortage? 18 Box 11:Household typology 20 Box 12:Model farmers 21 Box 13:The construction of an irrigation channel in Mae Haeng village 24 Box 14:The importance of soil organic matter 26 Box 15:Soil acidity (pH) 29 Box 16:Indicator plants for soil quality 31 Box 17:Farmers’ ways of evaluating soils (in northern Thailand) 34 Box 18:Soils in limestone areas 36 Box 19:Valley soils 37 Box 20:What are the mechanisms that make forests soil-friendly ecosystems? 41 Box 21:Agroforestry systems in the highlands of northern Thailand 43

iii Table of contents

Box 22: Some common fallow and forest products 46 Box 23: Are shortening of the fallow period and lengthening of the cropping 47 period one and the same? Box 24: Some issues related to the discussion of fallow-based vs. permanent 48 farming Box 25: Sustainable farming practices of rotational swiddeners 51 Box 26: Some contrasting opinions about fire (in agriculture and/or forestry) 58 Box 27: Who starts the fire? 59 Box 28: Disadvantages of (yearly) in forest and fallow areas 60 Box 29: Effects of burning on soil organic matter 62 Box 30: Effects of burning on living soil organisms (flora and fauna) 62 Box 31: Alternative eco-friendly agricultural systems 65 Box 32: Organic gardening vs. organic farming 66 Box 33: Factors that facilitate and factors that hamper adoption of organic 67 farming Box 34: Negative effects of soil erosion 70 Box 35: Factors that influence soil erosion 70 Box 36: Examples of soil conservation and lack of it in Western Europe 71 Box 37: Other factors that contribute to flooding (or drought) problems in the 72 lowlands Box 38: When does erosion requires drastic action and when can it be tolerated? 74 Box 39: Situations where large amounts of runoff water can accumulate on the 76 slope Box 40: Methods of soil preparation and their effects on soil erosion 79 Box 41: Why different crops receive different tillage treatments 79 Box 42: Why certain crops are mulched and others not 81 Box 43: Ways to mix and rotate crops 84 Box 44: Badly established/maintained erosion control structures can increase 86 erosion damage Box 45: Plants that can be used to establish vegetative contour strips 89 Box 46: Hedgerow systems, seen from a researcher’s and from a farmer’s 91 perspective Box 47: Why is farmers’ adoption of hedgerow systems not very successful? 93 Box 48: Processes that affect the amount/availability of plant nutrients in the soil 95 Box 49: Chemical changes in flooded soils 97 Box 50: Types of organic fertilisers 98 Box 51: Types of inorganic fertilisers 98 Box 52: Common misconceptions about chemical fertilisers 101 Box 53: What kind of weed problems do highland farmers face? 103 Box 54: Salt as a herbicide, an ingenious or noxious indigenous practice? 108 Box 55: Participatory matrix ranking of cropping constraints 144

List of figures

Figure 1: Map of northern Thailand with location of the SFC research sites 2 Figure 2: Can the highlands exert productive and protective roles at the same 5 time? Figure 3: Sustainable agriculture, which way to go? 9 Figure 4: Transfer-of-technology approach 12 Figure 5: Several people still have to get used to farmers’ participation… 13 Figure 6: The basket approach 14 Figure 7: Sustainable agricultural development is the responsibility of everyone 16 Figure 8: Understanding the goals of others 17 iv Table of contents

Figure 9: Whose problem are we talking about? 19 Figure 10: Farmer-to-farmer extension 22 Figure 11: In extension, models can readily portray complex problems 23 Figure 12: Soil is the farmers’ most precious resource 25 Figure 13: A soil profile consists of layers with different colours and properties 26 Figure 14: Soil is a mix of 4 components 27 Figure 15: Physical, biological and chemical soil properties 28 Figure 16: Examining the fertility of a soil 30 Figure 17: Digging soil pits vs. using an auger to study soil profiles 32 Figure 18: Agroforestry is a compromise between forests and fields 43 Figure 19: Fallowing is an integral part of most highland cropping systems 45 Figure 20: Flow-chart of options for plant residue management 55 Figure 21: Is fire a valid and rational farming tool? 56 Figure 22: Most small-scale farmers consider fire as a multi-purpose, cheap, 57 easy and labour-saving practice Figure 23: Uncontrolled burning is the big bad dragon 59 Figure 24: Burning soil is like cooking food 61 Figure 25: Erosion symptoms: rills, gullies and land slides 69 Figure 26: Tillage on steep slopes is almost as controversial as burning 78 Figure 27: Contour mulch lines 85 Figure 28: Declining ditches 87 Figure 29: Terraces 88 Figure 30: Contour hedgerows 90 Figure 31: Nutrient and yield gradients in contour hedgerow systems 94 Figure 32: Balanced use of organic and chemical fertilisers 100 Figure 33: Methods for better fire control 156 Figure 34: Ash fertilisation 158

v About this book

Rationale

Highland agriculture in northern Thailand is undergoing rapid changes, some for better, some for worse. These changes affect the livelihood of highland minority peoples as well as the livelihood of large rural and urban lowland Thai communities. They also affect the ecological balance of the rich but fragile mountain environment. Sustainable highland development is therefore an urgent but very delicate and complicated issue. It requires the acceptance of equal rights for people of different ethnic origins, as well as the need for environmental conservation. It should also try to reconcile age-old traditional farming wisdom with contemporary scientific knowledge. Concerted efforts by highland farmers, extension workers, policy makers and academics are needed to guarantee the future well-being of both the highland peoples and the environment in which they live.

Why this book has been written

The Soil Fertility Conservation (SFC) project was a development-oriented research project that focused on soil issues relative to highland farming under land pressure. The results of 7 years of research have been disseminated to fellow-scientists by means of scientific reports, papers and oral presentations at conferences. The ultimate goal of the research, however, was that the results should reach and benefit the farmers. In the long run, development-oriented research should indeed lead to the implementation of productive, farmer- and eco-friendly agricultural systems and to policy regulations that encourage agricultural production while conserving natural resources.

This book has been written to satisfy the explicit demand for a somewhat easier, more practical presentation of (our) research results. Our major intention is therefore to summarise scientific findings in a less-technical, more understandable manner. Thereby we will introduce elementary background theory and highlight key-issues to facilitate interpretation. Furthermore we will raise questions about several controversial issues in order to provoke critical reflection. Finally, we will also provide some practical tips and sources of further information.

For whom this book has been written

Easily understandable scientific information about soils and highland agriculture is requested by people with various professional backgrounds: extension workers, project co-ordinators, planners, administrators, politicians, economists, teachers, foresters, nature conservationists, etc. It is also requested by the farmers. Unfortunately, the overall majority of the highland farmers is still illiterate. It is our hope, however, that this book will serve the farmers in 2 ways:

vii Options for Soil and Farmer Friendly Agriculture in the Highlands of Northern Thailand

1) by providing relevant and unbiased information to people who make decisions that influence the farmers’ life; 2) by providing information to extension workers, who in turn can offer the information to the farmers.

Although this book primarily caters to a non-scientific audience, we hope that parts of it may also be of interest to scientists, mainly as a guide to help focusing research more on farmers’ needs and priorities. Furthermore we also hope that it will stimulate colleagues to write similar publications on other important highland topics (e.g. water management, pest control, reforestation, non-agricultural economic activities).

How this book has been written

A first draft of this book was prepared (in Thai and English) by all the members of the SFC project, each of them writing contributions in their specific domain of research and/or interest. This draft was used as the core of a 3-day workshop, which was organised in November 1995 in the highland village of Pakha Sook Chai, , Thailand and attended by a group of 30 extension workers from governmental and non-governmental organisations. The different chapters were outlined in brief presentations, which were followed by field visits and exercises. At the end of the workshop participants were asked to read and evaluate the different chapters. This final version includes comments/suggestions which were made during and after this workshop, by workshop participants as well as by other reviewers.

Language

We have tried, as much as possible, to avoid the use of scientific language, without compromising however the essential scientific content. Despite this intention, we still had to use a lot of terms that do not belong to our daily vocabulary. Completely avoiding them turned out to be impossible. Difficult terms, which we think are crucial to understand the information presented in this book, are explained when they are used for the first time. They are also listed in a Glossary, together with other terms that might need more explanation.

At present this book is only available in English. Efforts are being made to also have it translated into Thai.

Geographical scope

The book draws upon research findings from the northern Thai highlands. The reader should be well-aware that most of the statements we make refer to this specific context, and should not be interpreted as general or absolute statements. Given the ecological and cultural similarities of many neighbouring countries, however, the content may have relevance for much of the Upper Mekhong ecoregion. And a portion of it, at least the basic ideas and concepts, might also hold in highland areas in other parts of the tropics. viii Options for Soil and Farmer Friendly Agriculture in the Highlands of Northern Thailand

General content

The focus in this book is on agrotechnical issues related to soil management in highland farming systems under land pressure. Soil is a key natural resource and sound soil management - especially in the highlands - is therefore an absolute prerequisite for sustainable agriculture. We are well aware, however, that sustainable agricultural development requires more than only digging into the soil or looking for merely technical solutions. Non-soil perspectives are equally important and should, ideally, be addressed at the same time. Such perspectives include other biophysical/agronomic issues (e.g. water management, pest control) as well as issues of a more social, political and economic nature.

Given our specific research mandate and limited experience in the other fields, we addressed highland agriculture mainly from a soil scientist’s point of view. Wherever possible and relevant, however, we also made links with the complex realities of everyday farming. Various soil and crop management options are presented as discrete items with some explanatory background. Advantages and limitations of each option are presented in the context of the greater farming system. The advantages are often the perspective of the researcher, extension worker, the head of an NGO or government agency while the limitations are often representative of the farmer’s perspective.

Chapter contents

Part I gives an introduction to the physical and human setting of the northern Thai highlands, as well as to the general issues that will be discussed throughout this book. Chapter 1 presents essential background information about the agroecosystems and farming systems and about the characteristic potentials and constraints of highland farming. Chapter 2 opens with some general reflections about agricultural development. It then argues the need for farmers’ participation in research and development and presents some principles and techniques to achieve this. Chapter 3 starts with a basic introduction to soil science and then discusses the major characteristics of highland soils.

Part II, which is the core of this book, addresses specific agrotechnical issues relative to the soil management of highland agroecosystems. It starts with explaining how an undisturbed forest ecosystem functions and what the consequences are of the conversion of forests into fallows. After that it elaborates on different soil management-related issues (plant residue management, soil erosion control, soil nutrient management, control of weeds and soil-borne pests) during the cropping and fallow periods.

Part III concludes this book by giving an overview of the various agricultural and non-agricultural activities highland people can adopt to provide in their livelihood. It further also contains the concluding remarks.

ix Options for Soil and Farmer Friendly Agriculture in the Highlands of Northern Thailand

Sources of information

The contents are based on 7 years of on-station and on-farm research (complemented with lab and greenhouse experiments) done by SFC; information derived from farmers (by means of PRA, interviews and informal talks); and experiences from other projects, institutions and resource persons. In order to limit the text we did not cite the original source (SFC, farmers or outsiders) every time we made a statement. The names and addresses of resource persons can be found in Appendix 3. The key- reference texts are listed in Appendix 4.

How this book can be read

The book is written in a format that allows ”selective reading”. People who only want to know the basics can find most information in the continuous text. Specific details or examples are presented in numbered text boxes, which are referred to in the text. Drawings are used to illustrate difficult concepts or to emphasise some key messages. Methods for survey and diagnosis, suggestions to improve management practices, useful addresses and references are listed in appendices. The book is organised according to key topics, but many of these topics do overlap. The earlier chapters of this book often refer the reader to topics of later chapters. This was unavoidable as agriculture is a cycle and factors of the last step, of course, influence the first step. We apologise if, on the first reading of this text, you find it necessary to jump back and forth in an effort to fully understand the topics being discussed.

How this book can be used

The information in this book is presented as a basket of options. It is not yet another technical manual on soil conservation and sustainable agriculture that should be rigorously followed, rather this book is an attempt to address highland agriculture in its overall complexity. We will not give advice on which options should be followed but instead outline an inventory of options that can be followed. We try to explain how things work and what the advantages and limitations are of various practices under real farmers’ conditions. Many alternatives are presented and we leave it up to the readers to make their own selection. We suggest to use the samebasket approach when extending the information to the farmers (see Chapter 2.2.).

How this book can be improved

The situation in the highlands, as well as our scientific understanding of agriculture and ecology, is changing rapidly. Much information in this book may become out of date rather quickly. Our writing is furthermore based on the experience of only a small group of people and derived from a small number of locations (see Figure 1). Therefore, we invite readers to offer feedback on this publication by sending comments on the current content or by providing additional information which is not yet included. You can send us your comments by filling in the evaluation form that is attached to this publication. x Part I:

The highlands of northern Thailand: agriculture, people and soils Chapter 1: Highland agriculture in transition

1.1 Agroecosystems in northern Thailand

The northern part of Thailand (see Figure 1) is a (sub)tropical mountain region which covers an area of nearly 100 000 km2. The climate is monsoonal, with 3 distinct seasons: a wet season from May to October, a cool and dry season from November to January and a hot and dry season from February to April. The rainy season accounts for about 90% of the total precipitation, which ranges from 1000 to over 2000 mm/year.

The landscape, climate and culture of northern Thailand are fairly distinct from the rest of the country, but have much in common with mountainous areas in Burma, , Southern China, and Vietnam. Northern Thailand forms, indeed, part of a larger geographic unit which is known as Montane Mainland Southeast Asia or the Upper Mekhong Ecoregion. Economic links between the different subregions have always existed and are nowadays evolving towards the establishment of a new transnational economic growth zone.

Of the total area of northern Thailand, about 20% consists of large river valleys and basins. These lowlands are inhabited by a population of over 5 million ethnic-Thai people, have generally fertile soils and are almost entirely under agricultural land use. Wetland rice cultivation is predominant during the rainy season. A wide range of rainfed crops are grown during the dry period (see Box 1 for more explanations).

At the fringes of the lowlands start the uplands, an ecozone which consists of old river terraces, hills and lower mountain slopes. Quite often these uplands have poor sandy/gravely soils and are covered by deciduous forest types. Their agricultural potential is limited and in the past they were used for forestry rather than for agriculture. Due to land pressure in the lowlands, however, they are nowadays increasingly exploited for rainfed (swidden) farming (see Box 1), fruit production and also as a source of soil and gravel for lowland construction works.

The highlands are somewhat arbitrarily defined as the ecozone above an altitude of 500m. They consist predominantly of hills and mountain ranges of medium altitude (only a few peaks exceed 2000 m) and cover almost 80% of the north. Differences in altitude give rise to distinct variations in climate, soils and vegetation types. The lower areas of the highlands are generally covered by mixed deciduous-evergreen forest types, the higher elevations by evergreen forest types. Most of the highlands are inhabited by non-Thai ethnic minorities, the so-called hill tribes (see Box 2), whose current numbers are estimated to be around one million. Their livelihood depends largely on mountain agriculture, which mainly comprises subsistence swidden cultivation of upland rice but more and more also commercial cultivation of various other crops (see Box 1 and Table 1). Unfortunately, mountain agriculture implies

1 The highlands of norhern Thailand: agriculture, people and soils large scale clearing of the natural vegetation and subsequent cultivation on steep to very steep slopes (30% to 70%).

Figure 1. Map of northern Thailand with locations where SFC has conducted research

Stations (collaborating organisations): 1 Doi Thung (DLD/IBSRAM); 2 Lao Che Guay (TA-HASDP); 3 Doi Yao (TA-HASDP); 4 San Chareun (DLD/TG-HDP); 5 Huai Luk (DLD/IBSRAM); 6 Jabo (DLD/TG-HDP); 7 Mae Sawan Noi (TA-HASDP) Village sites: 8 Mae Sa Mai; 9 Mae Lod (only soil survey); 10 Mae Cha Nua (only soil survey); 11 Mae Haeng; 12 Pakha Suk Chai

2 Chapter 1: Highland agriculture in transition

Box 1. Typology of agricultural systems in northern Thailand

· Rainfed vs. irrigated farming. Farming dependent on natural rainfall vs. farming where water is artificially supplied (by flooding or other types of irrigation). · Dryland (upland, rainfed) vs. wetland (irrigated, paddy) rice. Rice cultivated on non- flooded fields vs. rice cultivated on flooded fields. · Subsistence farming. Farming aiming at food production for own consumption. · Commercial (or cash) farming. Farming aiming at income generation (the farm products are sold at the market). · Swidden farming (, slash-and-burn). Farming based on rotating fields rather than crops. Natural vegetation is cleared (cut, slashed), in most cases (but not always) burned and then cultivated for a period of one to several years. After cultivation the field is left fallow (i.e. uncultivated) for varying periods of time, and then the cycle is repeated. This type of farming may also include the movement of human settlements, although in northern Thailand this is seldom the case nowadays. · Pioneer (primary forest) swidden farming. Swidden farming based on the clearing of mature forest stands, with long cultivation (several years) and very long fallow periods. Formerly practised by several ethnic minorities in northern Thailand (Akha, Lahu, Lisu, Hmong and Yao). At present it is rarely practised in its original form, but many ex-pioneer swiddeners continue fallow-based farming, without however following any regular fallow rotation pattern (see also Chapter 5.5.). · Rotational () swidden farming. Swidden farming based on a regular fallow rotation pattern, with a short (1 year) cultivation period and a medium to long (more than 7 years) fallow period. Still practised by the Karen and Lua in northern Thailand (see also Chapter 5.5.).

1.2 Highland farming systems

Highland agriculture is rapidly changing. Nowadays the term is only a common denominator for a wide range of farming systems in different stages of transition. The degree of transition (from a ”traditional” to a more ”modern” farming system) is mainly dependent on external socioeconomic and political factors. To a lesser extent it is also related to the local physical environment and ethnic differences. Due to the expansion of transport infrastructure, the once relatively isolated highland farming systems are increasingly getting linked to the lowland market economies. Farming communities range nowadays from remote villages still largely dependent on subsistence swidden agriculture to villages which thrive entirely on contemporary commercial agriculture.

Subsistence farming is mainly based on the cultivation of rainfed rice. Irrigated rice, cultivated in narrow valleys and on terraced hill slopes, is less common (compared to other areas in SE Asia) but the practice is gaining popularity these days as a result of the increasing land pressure. A wide range of other crops (maize, pulses, vegetables, spices) are grown in mixed or single stands in swidden fields or home gardens.

3 The highlands of norhern Thailand: agriculture, people and soils

Livestock is always present but seldom the backbone of the farming system. Forests and fallow lands are important resources for supplementary food, water supply, firewood, construction materials, cash products, etc. Off-farm labouring is becoming increasingly important, for some people as a necessary means to make ends meet, for others as a way to satisfy the increasing interest in consumer goods.

Cash farming in the highlands was traditionally based on the cultivation of poppies. After its cultivation was banned by the government, a wide range of alternative cash crops have been introduced. Popular nowadays are the cultivation of various types of temperate and subtropical vegetables, flowers and fruit trees (see some examples in Table 1). Together with these new crops, new farming practices were also adopted, such as the use of agrochemicals and irrigation devices.

Many highland villages or individual households are nowadays managing a mixed subsistence/cash-oriented farming system. For some this is only a transitional phase before complete conversion to cash farming, whereas for others this may be a deliberate strategy to secure at once food production and income generation. The three villages where SFC conducted on-farm research (see Table 1) were representative for the three above mentioned phases of agricultural intensification. Chronological overviews of the changes which took place in the villages of Mae Haeng and Pakha Sook Chai are given in Appendix 1.2.

Table 1. Description of the SFC on-farm research sites (data from 1996)

Village Mae Haeng Pakha Sukchai Mae Sa Mai Province Chiang Mai Chiang Rai Chiang Mai District Mae Ai Mae Chan Mae Rim Elevation 600 - 1200 m 600 - 1200 m 650 - 1250 m Ethnic group Lahu Nyi Loimi Akha Hmong Population dens. 21 people/km2 45 people/km2 62 people/km2 Dominant FS1 subsistence subsistence/cash cash Major crops2 upland rice (s) maize (c/s) cabbage (c) maize (s) rainfed rice (s) litchis (c) litchis (c) irrigated rice (s) strawberries (c) irrigated rice (s) soybean (c) potatoes (c) cabbage (c) carrots (c) ginger (c) salad (c) fruit trees (c/s) ginger (c) flowers (c) red kidney bean (c) sweet pepper (c) irrigated rice (s) upland rice (s) 1 FS = farming system; 2 The crops are ranked (from highest to lowest) according to their importance in the land use (surface area covered) and/or their financial returns; (s)=subsistence crop; (c)=cash crop.

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1.3 The highland dilemma: development or conservation?

growing awareness of the importance of mountainous watersheds

A major debate that has been going on for the last 20 years is whether the envisioned protective functions of the highlands should get priority over (actual and/or potential) productive functions. The increasing importance that is given to the environmental functions is reflected by the official government policies - which often though are unclear, contradictory and therefore of dubious effectiveness - such as the implementation of a nation-wide ban on commercial in 1988, the expansion of forest reserves and the recent large-scale reforestation programs. Some people want to go further and advocate a ban on agricultural activities above a certain (arbitrary) altitude or slope degree. And ultimately there are even radical proponents of the idea that the highlands should become one big national park where agriculture (and highland people) should not be allowed at all.

Figure 2. Can the highlands exert productive and protective roles at the same time?

5 The highlands of norhern Thailand: agriculture, people and soils

Box 2. Who are the hill tribes?

”” is a collective name commonly used to denote various non-Thai and non-Chinese ethnic (minority) groups who populate the highlands of northern Thailand and other areas of Montane Mainland Southeast Asia. In the context of northern Thailand the term is used for people of the following groups (arranged according to decreasing population figures): Karen, Hmong, Lahu, Yao, Akha, H’tin, Lisu, Lua and Kamu. All these groups are linguistically and culturally different from each other, but their exact origins and history (of migration) is still rather vague. For the Lua it is an established fact that they are the descendants of autochthonous valley-dwelling people who lived in northern Thailand already before the arrival of the first Thai immigrants. The Karen, the largest group of tribal people, are residing in the western hills since at least 250 years, probably even longer. The others are more recent immigrants, who have been arriving from Burma and Laos since about 1850.

The fact that we write a book about highland farming reveals automatically to which ”ideological camp” we belong. We think, indeed, that it is not realistic nor socially justified to implement a total ban on highland agriculture (this would require the creation of new employment for nearly a million tribal people and/or their massive relocation). At the same time, however, we do acknowledge the urgent need for environmental conservation. The big challenge will be to find a fair and rational compromise between development and conservation. In order to find such a compromise we should carefully (re)consider the characteristic potentials and constraints of highland agriculture and weigh them against each other:

· Characteristic potentials of highland agriculture: + The highlands are characterised by temperature and moisture regimes that are very distinct from (and often more favourable than) those in the major lowland agricultural areas. This climatic variability allows the cultivation of a wide range of subtropical and temperate zone crops. Many of these crops cannot be grown (in an economically profitable way) in the lowlands, have high commercial value and are in high demand by urban consumers. + Most highland soils have good physical characteristics and, if properly managed, are well-suited for agricultural production (Chapter 3). + With small-scale irrigation development, many highland areas have the potential for a year-round water supply (as water sources are often close-by). + Various opportunities exist to develop non-agricultural activities that can complement and stabilise the farming systems: sustainable timber harvesting, collection of non-timber forest products and eco-tourism (Chapter 11). + Virtually all the arable land in the lowland areas is cultivated and much high- quality agricultural land is increasingly being lost due to urbanisation and industrialisation. If Thailand wants to keep a status quo or even expand its agricultural production, it only has two possibilities: either intensification of lowland agriculture or extensification of slopeland agriculture (upslope movement of Thai lowland farmers is actually already taking place).

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· Characteristic constraints of highland agriculture: - Agriculture on steep slopes inevitably causes soil erosion (Chapter 7). - Mechanisation and transport of agricultural inputs/outputs is difficult. - Most highland soils have limited reserves of plant nutrients (Chapter 3). - Weeds/soil pests are difficult to control on rainfed fields (Chapters 9 & 10). - Much of the land is degraded due to previous unsustainable land use. - Agricultural interests are often in direct conflict with ecosystem and watershed conservation objectives. - Highland farmers have no official landtitles (often even no full citizenship). - A considerable number of highlanders are probably not ”real” farmers at heart, they farm because they have no other alternatives in making a living. - The ethnic diversity complicates extension work and government control. - Extension work, government control, marketing and transport of agricultural products are difficult because of limited accessibility. - Too many government agencies (>90!) are involved in highland development, what jeopardizes coordination and efficiency.

The various potentials and constraints that are listed here will be discussed more in detail in the following chapters. At the end of this book then the reader should have all the background information needed to make his or her own well-balanced judgement regarding this list. The pessimists or radical conservationists among us may argue though that we can stop our discourse right here, because the list obviously shows that the constraints outnumber the potentials. The optimists, on the other hand, may argue that the potentials outweigh the constraints and that furthermore several of these constraints can be alleviated if not eliminated. How this should happen depends on the nature of the constraints. In order to solve those problems that are mainly of an agrotechnical nature (1-5), a sound research-and-extension strategy is needed and that’s what this book will talk about. To solve the problems that are more of a socioeconomic nature (6-11), appropriate policy regulations should be worked out. The latter is not the focus of this book although we largely acknowledge that ultimately the reality of a sustainable agricultural development process lies in politics and macro-economics.

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2.1 Reflections on sustainable agricultural development

The whole issue of sustainable agriculture revolves around the question of how to allocate part of the world’s natural resources to agricultural production, in a way that is ecologically sound, economically viable, socially just, ethically justified and adaptable. Among the various sub-issues that are involved, the use of external inputs (see Box 2) in agriculture is one of the most heavily debated ones. The key considerations here are whether-or-not or to-what-extent external inputs are needed to achieve sustainable agricultural development. Or to state the question more straightforward, should we promote no-external-input (NEIA), high-external-input (HEIA) or balanced-external-input (BEIA) agricultural systems in the highlands (see Box 4)?

Unfortunately we cannot provide clear-cut answers to these questions. What we will try to provide you with is generous background information to help you found your own insightful and balanced arguments The core problem of the whole sustainability debate is, indeed, the fact that “sustainability” can be interpreted from many points of view. Ultimately, sustainability is as much an ideological as a scientific concept (see Box 5) and therefore the debate will probably continue for many more decades - if not centuries - to come.

Figure 3. Sustainable agriculture, which way to go?

9 The highlands of northern Thailand: agriculture, people and soils

Box 3. What are external inputs and what are the problems with their use? · External inputs refer to all types of materials, equipment and technical knowledge that are derived from outside the farm or local community. Very often, however, its meaning is narrowed down to synthetic agrochemicals (fertilisers, pesticides), improved plant materials (through scientific plant breeding or genetic engineering), mechanisation based on fossil fuels and large-scale irrigation infrastructure. · Problems related to the use of external inputs:

· in most cases money is needed to obtain them;

· non-renewable resources (i.e., resources that can be used only once) get depleted;

· their production and use can create environmental pollution;

· their transport creates extra costs and environmental pollution;

· external inputs make farmers dependent on outside-suppliers;

· farmers, consumers and livestock may face health risks if agrochemicals are indiscriminately used;

· indiscriminate use of pesticides may, on the long term, worsen pest problems.

Box 4. Classification of agricultural systems based on the use of external inputs · No-external-input agriculture (NEIA). Refers to farming systems that rely exclusively on local resources. Examples of sustainable NEIA systems are the ancient irrigated rice terraces that can be found throughout Asia and certain agroforestry systems in southern France (see Box 36), northern Thailand (see Box 21) and Indonesia. Unfortunately, there are also NEIA systems where natural resources are overexploited, which can lead to poverty and environmental degradation. Such examples can be found in the ancient Mediterranean and American civilisations and nowadays in many areas of the tropics. The pioneer swidden systems of northern Thailand (see Box 1 and Chapter 5.5.) belong also to this category. · High-external-input agriculture (HEIA). Refers to farming systems that rely on an excessive use of external inputs. Agricultural production is very high but there are several drawbacks (see Box 3). Farmers face high financial risks due to high investments and unpredictable price-fluctuations of the agricultural products. Once introduced, commercial farming systems may seriously widen social and economic disparities between farmers. And last but not least, these systems are facing increasing ethical dilemmas with regard to “modern” ways of animal raising and genetic engineering. Examples are most present-day agricultural systems in industrialised countries and cash-cropping systems in northern Thailand (see Chapter 11.6.). · Low- or balanced-external-input sustainable agriculture (LEISA or BEISA). Is a compromise between the no- and high-input extremes, a “blend” which tries to combine the best of both. It refers to a deliberate farming ideology that emphasises the full and sustainable use of local resources but yet retains the option for an often needed minimum amount of external inputs. Throughout the tropics more and more farmers are using small amounts of external inputs nowadays due to improved communication, transport and marketing facilities. Encouraging and interesting individual examples of BEISA systems can also be found among farmers in the northern Thai highlands. Box 5. Some tricky questions about sustainability

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· What is the best way to conserve the environment: to promote extensive no-input agriculture, thereby altering the ecosystem over large areas, or to promote intensive high- input farming, thereby heavily disturbing small areas but leaving the opportunity to preserve vast tracts of nature as national parks and wildlife sanctuaries? · To what extent should and can we urge developing countries to protect their (primary) tropical forests and other valuable natural habitats? See Box 24. · The world population is increasing swiftly, especially in Asia. Will it be possible to meet the increasing demand for food production without the use of external inputs? · There are several LEISA systems or methods which have proven to be successful. A big problem however is that farmers (subsistence farmers as well as commercial farmers) often do not have the means (savings, labour or equipment) to make the transition to LEISA possible. Moreover it often takes a couple years before such LEISA systems show good results. During the transition period, agricultural production/profit may be temporarily lower than in the previous system. Will, in such cases, government agencies be prepared to support (=subsidise) the farmers to make the transition possible? · A similar question can be formulated with regard to the increasing demand for “organic” (chemical-free, natural) farm products. If these products are more expensive than their “chemical” rivals, will consumers be prepared to pay the farmers higher prices? · The Karen and Lua tribal people of northern Thailand are often praised, rightly, for their eco-friendly, almost idyllic subsistence lifestyle. It is therefore very tempting to propose their farming system as a model for other, more commercially-oriented and less environmentally-concerned ethnic groups. Can we demand that highland people continue to live or return to a life of subsistence, in the name of sustainability? · Most of us will acknowledge that all people in the world should be able to satisfy their “basic” human needs. But what are those needs? Are they identical in industrialised and in developing countries? Are they the same for people living in the city and for people living at the country-side? Should it be that rich people (countries) should use fewer resources and poor people (countries) be allowed to use more resources? If one day non-renewable resources would become really scarce, which economic sectors should receive priority to use them: the agricultural sector, the transport sector, the industrial sector, the entertainment sector? · At present, each of us is “concerned” about the environment, but almost everyone continues to pollute. Farmers are often blamed for the environmental degradation and pollution they cause. It needs to be asked though who is really polluting the most and who should have the greatest “rights” to pollute: farmers who pollute out of necessity, or citizens who pollute out of luxury? · We could continue this list for many more pages, but will end with a few last questions that resume the essence of the whole sustainability debate. Will the earth have the carrying capacity to support ALL people leading the same consumer lifestyle that people in the West and people in big cities take for granted? What are we, as individual people or as part of a larger community, prepared to contribute or sacrifice to the sustainable development of our globe? Are we prepared to stop the problematic demographic growth, or will we better conserve/divide the resources that are available?

2.2 Participation in development

11 The highlands of northern Thailand: agriculture, people and soils

Failure of the conventional transfer-of-technology approach

Until recently, agricultural development generally happened according to a conventional transfer-of-technology (ToT) approach (see Figure 4). This ToT approach has proven to be successful (in terms of agricultural production) when applied to (rich) farmers in areas which are very favourable for agriculture. It is, however, seldom efficacious when applied to poor farmers in less-favourable, fragile or widely varying agroecosystems. The standard extension package for soil conservation and sustainable highland farming in northern Thailand (Box 6), for instance, has barely been adopted by the farmers, due to various agrotechnical and socioeconomic reasons which will be explained in the following Chapters. Briefly summarising, however, we can say that a ToT approach for the highlands is bound to fail because: (1) it does not take account of the diversity nor the dynamics of the biophysical and human environment of a region or a community; (2) it does not properly address the farmers’ needs and priorities; (3) for most farmers it is already difficult to adopt certain individual practices, much less a complete package.

Figure 4. In the transfer-of-technology approach farmers are expected to adopt standard technical packages that were designed and tested by researchers.

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Box 6. Standard recommendation package for soil conservation and sustainable (rice- based) highland agriculture in northern Thailand (the various technical concepts will be discussed more in detail in the following chapters).

· Permanent farming: crop rotation instead of fallow rotation (rice followed by a leguminous crop or rice followed by maize/leguminous relay-crop). · Management of plant residues: no-burning; crop and weed residues to be applied as mulch or to be incorporated into the soil. · Land preparation: no- or minimum tillage. · Erosion control: bench terraces or contour hedgerows (with 3-5 m interval) of nitrogen fixing trees/shrubs (Leucaena leucocephala, Cajanus cajan,…) or fast-growing exotic grasses (Setaria anceps, Vetivaria zizanoides, …); the hedgerows should be cut regularly (every 30-40 days); the cuttings should be applied as mulch or used as livestock fodder. · Planting material: “selected” or “improved” varieties. · Plant arrangement and spacing: the upper part of the slope should remain under forest cover; the annual crops should be arranged in a contour strip cropping system; dense plant (hill) spacing is recommended (10-25 cm x 20-30 cm for upland rice). · Fertiliser application: 50-100 kg N per ha over two applications; 20-40 kg of P and K per ha (for upland rice) · Weed management: 2-3 early manual weedings (between 15 and 60 days after sowing). · Generation of cash-income: by planting perennial cash crops (coffee, tea or various fruit trees) in the contour hedges, by integration of livestock into the system or by selling products derived from vetiver grass.

Figure 5. Several people still have to get used to the idea of farmers’ participation…

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The need for farmers’ participation

Researchers and development workers are increasingly becoming aware of the need to let farmers participate in the processes of learning and action needed to improve the farmers’ situation. This has led to the exploration of participatory methodologies for investigating development problems and for subsequent planning, implementation and evaluation of development activities. These methodologies are currently known under a wide range of names but they all rely on the same key-concepts: indigenous knowledge, farmer experimentation and farmer-to-farmer extension (see 2.3. for more details). Several readers will already be familiar with participatory approaches or, if not, may discover that they are just new and trendy names for methods they have known and used for a long time. For others however, researchers and administrators in particular, “participation” may still be a rather exotic concept...

The basket approach

In line with the need for more farmers’ participation we have previously suggested to use a basket approach in agricultural development. The philosophy behind this is to present farmers a huge basket full of ideas (eventually also tools and inputs if this would be necessary) for farming or non-farming activities, and to let them choose items from this basket according to their own preferences. If farmers are presented a wide range of options and are, at the same time, well-informed about the advantages and limitations of the different options, they will have the greatest chance of improving their situation in a way which fits them best.

If a basket approach is to be utilised the question remains of course what to put in the basket? In this book we will present a wide range of options and discuss these options mainly from an agrotechnical and environmental point of view. We do not dwell at length on other issues of a more human nature, such as the ones addressed in Boxes 5 and 7, but we would like to stress that such issues too should be taken into consideration.

Figure 6. The basket approach: real participation means giving farmers the opportunity to select and combine the building blocks for development in a way that suits them best.

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Box 7. What to put in the basket?

The highlands of northern Thailand, with its “scenic forested mountains” and “idyllic mountain folks”, is an area which is still relatively untouched by modernisation. When we offer certain options, we inevitably start to worry about the possible implications they may have for the environment and the people who will be affected by the development. The more “virgin” the ecosystem and its inhabitants, the more sensitive the issue. Do we have the right to hold back certain options, fearing that they would alter too greatly the unspoiled nature and traditional lifestyles of the local people? Do we have the right to refuse “traditional” people access to the achievements of modernisation or to select for them what they should get or know and what not? Probably not. Given the rapid evolution of communication and transportation, changes are inevitable. And even if we would deliberately hold back certain options from the basket, sooner or later farmers will request them or simply put them in the basket themselves. The least we can do is to help them to raise or sustain their cultural awareness and dignity, so that they can decide for themselves how much of their traditional lifestyle they want to preserve.

Working together for a sustainable agriculture

Being disappointed about the limitations of the purely science-based approach and being excited about the potentials of the participatory approach, one might wonder whether the latter isn’t the one and only way to develop sustainable smallholder farming systems in the tropics? One might even wonder whether researchers, extensionists and other development workers are still needed or should all be retrained to become PLA facilitators (see 2.3.) instead?

Such a vision is tempting though unrealistic. Participatory methods should be seen as a necessary and extra set of tools that can complement but not replace other, more conventional methods of research and development (lab analyses or experiments, station- based research or scientist-managed on-farm trials). If small farmers were able to tackle all problems on their own, they wouldn’t face the situations of poverty and environmental degradation they are facing at present. Peasant farmers who are confronted with rapidly changing conditions (that are mostly beyond their control) cannot be expected to solve all their farming problems with their own knowledge, experiments and communication networks (see Box 8). Outsiders - either local or foreign development workers or scientists - can provide important information and skills needed to widen the farmers’ base for reflection and action.

Concerted efforts of policy makers, researchers, extension workers-facilitators and farmers will be needed to actualise sustainable agricultural development. All parties involved will have to work together and perform their specific duties as best as they are able. How such cooperation should ideally work is represented in Figure 8.

15 The highlands of northern Thailand: agriculture, people and soils

Box 8. Some shortcomings of indigenous knowledge (IK), farmer experimentation and farmer-to-farmer extension (incomplete list, only a few examples are mentioned).

· Indigenous knowledge: farmers do generally not document their knowledge; IK is not uniformly spread throughout a community; farmers are not aware of negative impacts their practices might have beyond the borders of their village (e.g. atmospheric pollution through burning, downstream effects of erosion and pesticide use, etc.); farmers are generally not aware of external policies and market mechanisms and how they may influence their daily life. · Farmer experimentation: technology development may go too slow to cope with rapid changes; it is furthermore limited to problems farmers can directly observe (plant nutrient disorders or nematode problems, for instance, may remain unnoticed). · Farmer-to-farmer extension: is limited by transport problems and inter-ethnic language barriers; as farmers become more commercially-minded, they may no longer be prepared to share their knowledge with other farmers, conceived as “competitors” rather than colleagues.

Figure 7. Sustainable agricultural development is the responsibility of everyone. Politicians should create an institutional environment that stimulates research, agricultural production and environmental protection. Researchers should look, in direct consultation with the farmers or through mediation of extension workers-facilitators, for new productive andeco-friendly items that can be added to the basket of farming options. Farmers should be allowed to choose the building blocks of their own farming systems while taking the responsibility to produce agricultural commodities without damaging the environment.

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2.3 Participatory methods for farmer-led development

Basic principles

PLA (Participatory Learning and Action) refers to a range of methods (see Box 9) that aim to combine the capacities of both farmers and extension workers/scientists to develop (technical) solutions for existing problems. It is however more than merely a set of methods, it is a philosophy that requires a drastic change in attitude, most in particular from the outsiders. The outsiders who initiate a PLA process should in the first place act as facilitators, people who encourage farmers to solve problems on their own. In some (many?) cases, the transfer of problem solving skills may indeed be sufficient to enable farmers to solve problems on their own.

In this section we will give a brief overview of the steps involved in a PLA process. Some practical tips to do-it-yourself can be found in Appendices 1.1.-1.3. For a complete background, we refer to a number of publications listed in Appendix 4.

Box 9. Terminology of participatory methodologies.

· RRA or PRA: Rapid or Participatory Rural Appraisal · PTD: Participatory (or People-centred) Technology Development · RAAKS: Rapid Appraisal of Agricultural Knowledge Systems · FFS: Farmer Field Schools · Agroecosystem Analysis · (P)IPM: (Participatory) Integrated Pest Management

Figure 8. What is required of developers is a strong sense of humility, an awareness of the inherent difficulty in understanding the goals of others.

17 The highlands of northern Thailand: agriculture, people and soils

Identifying problems

What is the problem?

Before rushing to find solutions to existing problems, both farmers and outsiders should have a detailed understanding of those problems. A sound problem analysis is often complex and time-consuming (see example in Box 10) but it is a very crucial step. A wrong or not carefully balanced appraisal can make all the following steps useless or might even worsen the situation of the farmers if inappropriate action is taken.

Box 10. What is the reason of rice shortage?

Farmers often mention that they “have not enough rice to eat". This information is insufficient to start a research or extension project that aims at increasing rice yields. Additional information you need is:

· How significant is the rice shortage? Only 1 month or 11 months? · Is there a lack of farming land? Is there any possibility to extend the cultivated area? · Is there a lack of labour force? If yes, is this due to health problems, migration of the young people to the cities, opium addiction? · Are the yields low and/or extremely variable? Is this due to adverse climatic conditions, poor soil fertility, erosion, weeds, insects, diseases, variety choice or poor management? · Are there important losses during storage of the grains? · Are there irrigated rice fields? If not, are there potentials to establish irrigated rice fields? · Which other crops are grown or can be grown to supplement the shortage in rice? · Do farmers really want be self-sufficient in rice, or would they prefer to earn cash and buy rice?

Where do we get the information?

A first problem assessment should always be based on discussions with the farmers. Other sources of information that can be consulted are: key-informants (village headman, teacher, extension workers, staff of local projects, health worker), regional government officials and staff of research centres or projects (see Appendix 3). If the information gathered in this way would still be inadequate, conducting additional research should be considered.

Who is facing problems?

Before starting any development initiative, you should not only get to knowwhat the problems are, but also who is facing those problems. When identifying problems it is therefore necessary to work with different groups of people. The most obvious divisions that can be made are divisions based on gender (man/women), age (children/adolescents/adults/elderly people) and household type (see Box 11). Making a farmer typology can help to focus the attention on or to provide assistance to those groups that need it most. The basic principle is that the weakest need the most

18 Chapter 2: Solving problems together with farmers attention/assistance, but care should be taken that this happens in a fair way according to the local values. Knowing the problems of different groups can also help to predict whether or not certain farmers will be able to adopt new technologies and what the impact of those technologies will be, i.e. whether a certain group might derive benefits from it or, on the other hand, may get into a situation that is worse than before. There are many examples of projects where the introduction of cash farming, for instance, improved the situation of the men but worsened the situation of the women.

Figure 9. Whose problem are we talking about?

19 The highlands of northern Thailand: agriculture, people and soils

Box 11. Household typology

When entering a highland village for the first time one often gets the impression that all households are equally poor or face the same kinds of problems. This is however seldom the case. In general there are important socio-economic differences between the households, i.e. there aredifferent household types. These differences are related to aspects such as number and age of the household members (labour availability), the number and type of fields owned (steep or flat, rainfed or irrigated, annual crops or orchards, etc.), the social status of the household (headman, priest, blacksmith, vendor, opium-addict), accumulated wealth, farmers’ diligence, etc.

Example: Typology of household strategies in the Akha-village Pakha Sook Chai

The 74 households (hh) of Pakha Sook Chai were ranked on the basis of 3 criteria: rice sufficiency (rs), prosperity (wealth) and engagement in cash farming. Using these three criteria, a seemingly uniform community could be separated into 5 categories.

· Risk Averse: rs for 10-12 months, high prosperity, do not grow cabbage (3hh) · Secure Investors: rs for 10-12 months, high prosperity, grow cabbage (7 hh) · Profit Maximisers: rs for 0-9 months, medium prosperity, grow cabbage (23 hh) · Diversifyers: rs for 0-9 months, low prosperity, grow cabbage, ginger or beans (15hh ) · Survivors: rs for 0-5 months, low prosperity, do not grow cabbage (26hh)

The 5 groups presented here have different resource-bases and follow different household strategies. We will not go further in detail but hope that this example illustrates that important differences exist and that development workers should take account of them.

Discussing the solutions

Once problems are clearly identified, the search for solutions can start. The task of an experienced facilitator is to initiate a thinking-process among people. This happens by presenting the information in a way that facilitates problem-solving. The facilitator should stimulate farmers to present their own solutions first. Only if the “basket of options” would not get filled, should he add his own suggestions. The different solutions can then be screened by the farmers, to see whether they make sense in the given farming system context. Only after that can they be verified in the field.

Verifying the solutions

Field Visits

Some farmers in the village itself or in neighbouring villages might already experiment with a certain technology. Group visits to the fields of such model farmers can be organised. We should however keep in mind that the fact that one farmer is able to adopt a certain practice does not necessarily mean that all farmers are able to do so. Whether or not a farmer can adopt a certain practice is, as previously mentioned, dependent on his

20 Chapter 2: Solving problems together with farmers household situation. Model farmers are often exceptional farmers. They are not only very clever and innovative, quite often they also have the best land, good water supply and/or a lot of labour which make their fascinating results possible (see Box 12). Of course this doesn’t mean that farmers who are facing less favourable household conditions cannot become model farmers. Farmers who have marginal land and little money are sometimes the first ones to adopt a different technology, having little hope any more with their traditional practices or with the practices that were introduced by development workers or by agri-business people.

Box 12. Model farmers

· Lagei Aseu (Mae Haeng village). Lagei was among the first farmers who settled down in Mae Haeng, some 20 years ago. He is the son of the village priest and was the headman of the first settlement. Being among the first settlers, he was able to claim 6 large pieces of favourable agricultural land (3 of the 6 fields have water supply). He has very strong and good ties with his children (4), who all help their father and each other in the field. Lagei and most of his family members are very dedicated to farming. Their fields are always well-maintained and the family is generally self-sufficient in rice. This rice does mainly come from rainfed fields, recently they also started to cultivate a small plot of irrigated rice. Lagei does not (need to) engage in off-farm labour to obtain cash income. The latter is derived from two litchi-orchards, livestock-raising (buffaloes, cows, horses and pigs; corn is grown to feed the livestock and vitamins or medicines are injected if animals are sick), embroidery and from a small grocery shop in the village. · Sala Aja Asorngku (Pakha Sukchai village). It is not the first time that Sala Aja’s name is mentioned in a book or an article. This diligent, innovative and dignified Akha farmer is famous because of his successful implementation of alley cropping (see Chapter 7.7.) and because of his very diversified and integrated farm. As a consequence, he is an eminent model farmer (he has the title of “Sala” what means teacher, expert) and has received hundreds of visitors over the years. Sala Aja was among the first settlers in Pakha Sukchai village. He has only two pieces of farming land, but one of these is really remarkable. It extends from a hilltop to a flatter area and has the shape of a semi-bowl (or amphitheatre). The hilltop is no longer used for the cultivation of annual crops. It is a natural fallow “enriched” (see Chapter 5.5.) by the farmer with various species of useful forest trees and fruit trees. The upper, sloping part of the bowl is used for the cultivation of upland rice and other field crops and also functions as a water catchment area: declining ditches (see Chapter 7.7.) intercept runoff water and sediments and divert these to irrigated rice fields, which are constructed at the lower slopes and flat part of the bowl. In the middle of the flat part there is a kind of “island” with a fishpond and a cute little house surrounded by various fruit trees. Downslope from the bowl starts an immense alley cropping which is permanently farmed following sound crop rotations. Most people only visit Sala Aja’s famous ecological rice-bowl and annex alley-field. It should be mentioned though that he has a second field at the other side of the mountain, in an area which is known as the “cabbage- valley”. On that field he grows cabbages, in a way that is less ecologically but more financially rewarding…

21 The highlands of northern Thailand: agriculture, people and soils

Experiments in farmers’ fields

If a technology is unfamiliar to the farmers, then experimentation is needed for one or more cropping seasons. Some practical tips for setting up experiments together with farmers are given in Appendix 1.4. If you cannot convince any farmer about the potential benefits of a new technology then you should set up your own demonstration trials. Choose a site where most farmers pass every day to provoke curiosity. If it makes sense to some farmers they will certainly come to ask you what you are doing.

Training and extension

If a new technology, crop or cropping system really works well, farmers themselves will take care of the extension. The best example is the present expansion of litchi-cultivation in the highlands (see Box 21 and Chapter 11.5.). In Mae Haeng village, farmers are rapidly adopting the crop, as well as a range of new (and relatively sophisticated) cultural operations that go with it (such as air layering for vegetative propagation, pruning, scoring and the construction of “mini-terraces” around individual trees to facilitate irrigation, fertilisation and weed control). All this is happening without the intervention of extension workers. Farmers exchange information every day on social gatherings, and when they are keen about something, everybody will get to know about it in a very short time. Extension workers can support this farmer-to-farmer extension (if needed) by providing transport to organise field trips or by providing some basic extension tools (blackboard, posters,...) to farmers.

Not everything sells like hot cakes though. If the advantages of an innovation are only visible on the long-term, or if environmental aspects are involved, some more extension efforts will be needed to raise farmers interest for a new technology. During exercises and demonstrations, techniques can be explained by visual means such as drawings, pictures or models (see Figure 11).

Figure 10. Farmer-to-farmer extension: if something works well, farmers will certainly talk about it!

22 Chapter 2: Solving problems together with farmers

Figure 11. In extension, models can readily portray complex problems such as erosion.

Monitoring and adjusting the solutions

Once farmers master the basics of a new technology they will continuously adapt it to their specific conditions. This farmers' experimentation is interesting to follow-up, as it can give new prospects for improvement. Another reason why a new technology needs follow-up after introduction is to check whether there might be negative side-effects which we didn’t foresee during the planning stage. If, after a while it turns out that adoption is poor, the whole participatory process should start all over again.

2.4 So far the theory, what about the practice?

As the SFC-project only had a mandate for doing research, our experiences with participatory methods have been limited to mainly the stage of problem diagnosis. Information gained by means of participatory-methods was used as a starting-point for more in-depth scientific research on topics such as burning, tillage, erosion, weeds, etc. (see Part II). Participatory-methods have further extensively been used to understand why different households use different land management strategies. Concrete tips and suggestions to improve farmers’ participation in research, based on the experiences we gained ourselves, are listed in Appendices 1.1.-1.3. (together with general information we took from the literature).

The only experience we had with participatory technology development (PTD) is related to the construction of a dam for a fishpond and to the construction of an irrigation channel in Mae Haeng village. An outline of the irrigation project is given in Box 13. One important lesson could be drawn from that project. In the initial stage we were only concerned about the technical problems that had to be solved. Later on we experienced that dealing with problems that were of a human nature was much more difficult than solving the technical problems that were linked to the project.

23 The highlands of northern Thailand: agriculture, people and soils

Box 13. The construction of an irrigation channel in Mae Haeng village

· Identifying the problems:

Core problem. The majority of the Mae Haeng households cannot produce sufficient upland rice for the whole year. To tackle this problem, the villagers expressed their will to construct irrigated rice fields, arguing that irrigated rice gives more stable yields than upland rice. This knowledge was based on their previous experience with irrigated rice farming in Burma. Technical problems. What hindered the farmers to construct paddy fields were technical difficulties to build an irrigation channel (distance, land topography and presence of big rocks). SFC therefore decided to provide technical assistance (financed by the Belgian Embassy). Social problems. The farmers proposed a large, gently sloping area near the village as the ideal site to construct irrigated rice terraces. A serious problem however was the fact that this area was claimed by a few influential households (the household of Lagei, see Box 12, among others). SFC made it clear to the villagers that the project would not be supported if only a limited number of households would derive a benefit from it.

· Discussing the solutions:

Technical solutions. To start with, farmers were asked to select a water source and to propose a route for the channel. Field surveys were done by farmers together with project members. An irrigation-engineer was consulted because the technical difficulties appeared to be serious. Plans were made and discussed. The channel would be built in four sections, each section providing technical adaptations to the soil surface state and the topography. Social compromise. SFC did not interfere in the discussions that were held among the villagers. The villagers finally decided that each household would contribute labour to construct the channel. The paddy area would be divided among as many households as possible. The households that would not obtain paddies, would get irrigated orchard land in return for their labour contribution (extra orchard land could be irrigated with the water that would drain out of the rice terraces).

· Testing and implementing the technologies:

Construction happened in different phases. Combining the knowledge and skills of the farmers (with regard to the terrain and the use of local tools and materials) with the outsiders’ expertise and introduced tools and materials, proved to be the only way to get the job done.

· Monitoring the results:

The channel is now in its last phase of construction. Getting the whole village mobilised to finish the job is becoming increasingly difficult however. Most work has to be done during the dry season when farmers are busy in their litchi orchards or out for off-farm labour. Small plots of paddy rice have been planted already and produced very satisfactory yields. Unforeseen problems with land slides (see Chapter 7.1.) along the channel will have to be solved and farmers will have to organise themselves to maintain the irrigation facilities.

24 Chapter 3: Characteristics of highland soils

3.1 What is soil and how is it formed?

Soil is the loose, natural material that covers the earth’s land surface. It is of crucial importance to the earth’s ecosystem and to the existence of human society as being a medium for plant growth, a system for water supply and purification, a recycling system for nutrients and organic wastes and an engineering medium.

Figure 12. Soil is the farmers’ most precious resource. It provides anchorage, water and nutrients to the crops that farmers cultivate.

Before we can discuss highland soils specifically, we must have a good understanding of what a soil exactly is. If we carefully observe a soil profile (a vertical soil section), we will notice that it is composed of several layers, each with different properties (see Figure 13). The uppermost soil layer is called the topsoil or the plow layer, because it is often modified by tillage. It generally has a characteristic dark colour, which is due to the presence of organic residues, the soil organic matter. This soil organic matter is a very essential part of the soil, as is explained in Box 14. The topsoil is of crucial importance to agriculture because it is the major rooting zone of most cultivated crops.

The layers beneath the topsoil are referred to as the subsoil. In tropical highland regions the subsoil generally has a red or yellowish colour and is often - but not always - poor in plant nutrients. The subsoil plays an important role with regard to the storage and movement of soil water.

In the deeper layers of the subsoil we will often encounter stones and boulders. Finally, we may even encounter rock.

40 The highlands of northern Thailand: agriculture, people and soils

Figure 13. If we carefully observe a soil profile we will notice that it consists of layers with different colours and properties. These layers are like chapters in a book: they can tell us how a soil was formed, how it can be classified and how it can best be used.

Box 14. The importance of soil organic matter (SOM).

· SOM is a source of plant nutrients (after decomposition). · SOM helps soil to retain nutrients, or in other words, prevents nutrients from being drained away by rain water to deeper soil layers (a process which is called leaching). · SOM increases the capacity of soil to store water (the water holding capacity). · SOM makes soil softer, easier to cultivate and more resistant to erosion. · SOM encourages the presence and stimulates the activity of soil organisms.

The presence of rock in the lower part and the presence of organic residues in the upper part of soil profiles hint at what exactly constitutes a soil. Indeed soil is a mix of rock residues and organic residues and also water and air (see Figure 14).

How soil is formed under natural conditions and how it gets arranged into characteristic layers is the result of complex interactions between the major soil forming factors: nature of the parent material (source of the rock residues); activity of living organisms; climate; position in the landscape; time and last but not least human influence.

The study of the processes of weathering (the physical and chemical breakdown of rock into inorganic soil particles and soil nutrients) and soil formation belongs to the domain of soil science. It is beyond the scope of this book to go into all the details of soil formation and soil science. We will only present the elementary theoretical background needed to understand the soil issues discussed throughout this book. For a more in-depth understanding of soil science the interested reader should consult more specialised books (see Appendix 4).

26 Chapter 3: Characteristics of highland soils

Figure 14. Soil is a mix of 4 components: rock residues, organic residues, air and water.

3.2 What determines the fertility of soils?

The mix of rock residues, organic residues, water and air - what we call soil - is amazingly complex. Scientists therefore divide the study of soils into 3 broad domains: the study of physical, biological and chemical soil properties (see Figure 15). Each of these properties are equally important for a good crop growth and do very much affect each other.

The combined picture of the physical, biological and chemical soil properties determines what is generally called the fertility of a soil. Very often, however, the term fertility is used in a narrower sense, referring only to the nutrient content of a soil (the chemical fertility). In it’s broadest meaning soil fertility refers to the overall ”quality” of a soil, i.e. the capability to produce a good crop. This agricultural definition of soil fertility comprises, besides inherent soil characteristics, other important factors such as the position of the soil in the landscape and the presence (or absence) of soil-borne pests and weeds. Whenever the term soil fertility is used, it should always be made clear what it is referring to.

In this section we will give a brief picture of the concept of soil fertility. It should provide the necessary background to explore management options that aim to conserve or improve soil fertility.

27 The highlands of northern Thailand: agriculture, people and soils

Figure 15. Soil properties a) Physical soil properties are those characteristics of the soil we can see or feel. b) Biological soil properties relate to the soil organisms, which can be useful partners to crops ... or nasty little parasites. c) Chemical soil properties can be evaluated by means of scientific instruments.

Physical soil properties

The physical properties of a soil are the properties we can see or feel, such as the presence of sand or loam or clay, or how hard or soft a soil is (see Glossary for more details). These properties are important with regard to tillage (soil cultivation, i.e. preparation of the soil with a hoe or plow before planting), resistance of the soil to erosion, root development and - very important - the behaviour of water in the soil.

The physical state of a soil is of more immediate concern to farmers than the biological or chemical state of a soil because it is much more difficult to change (improve). A very sandy or very stony soil, for example, cannot be converted into a clayey soil free of stones, whereas a soil with poor biochemical fertility can in most cases be improved through good management.

Biological soil properties

Biological properties relate to the kind and number of organisms that live below the soil surface. Those living organisms can be several centimetres long or microscopically small. Some of them belong to the animal kingdom while others belong to the kingdom of the plants. In general, soil organisms are very useful to plants (and to the ecosystem), but in some cases they can be annoying parasites that do much harm to cultivated crops.

28 Chapter 3: Characteristics of highland soils

A major role of the beneficial soil organisms is to break down soil organic matter into smaller particles, through a range of processes called soil organic matter decomposition and mineralisation. Some of the particles that result from these processes can be taken up by plants as plant nutrients. Another major role of certain micro-organisms is the natural fixation of nitrogen, a process that is very beneficial to the soil and which will be addressed in a little more detail in Chapter 8.

Like for all living creatures, the well-being of soil organisms is influenced by their environment. The way the soil is managed has important effects on their numbers and activity. To keep a soil fertile we must ”nurture” the beneficial soil organisms while avoiding the build-up of large populations of harmful soil organisms.

Chemical soil properties

Chemical properties relate to the kinds, amounts and availability of substances that are nutrients, non-nutrients or toxins (poisons) to plants. It also relates to the very important concept of soil acidity (see Box 15). The chemical properties of a soil are the ones that are probably most difficult to understand for farmers and laymen, because they cannot be seen or felt. A detailed evaluation of chemical properties cannot be done without scientific know-how and specialised equipment.

Nutrients are elementary chemical ”building blocks” which plants need for their growth. All plants require 13 nutrients from the soil but it is difficult to specify the role and status of each nutrient simply. Certain nutrients (N, P and K) affect the growth of every part of the plant and are therefore required in large amounts. Special efforts are needed to conserve or even increase the soil’s content of those nutrients under systems of continuous cropping. The other nutrients have more specific functions and need to be adjusted only on specific soil types or for specific crops. It is not our aim to go into more detail here. Readers who want more information on soil chemistry should consult the Glossary or specialised books (see Appendix 4).

Box 15. Soil acidity (pH).

· Acids, in a general sense, are corrosive (”biting”) materials. Acidity is the degree to which a material is acid (sour). Scientists have defined an acidity scale that ranges from 0 to 14, and call this scale pH. Pure water is used as a reference of neutral pH (pH = 7). Other neutral fluids are blood and milk. Materials that are more acid than water, are said to have a low pH, i.e. a pH between 0 and 7. Examples of acid solutions are coca cola (pH=2.8), lemon/tamarind juice and vinegar (pH around 2). Materials that are less acid than water, are said to have a high pH, i.e. a pH. between 7 and 14. · Just as for other materials, we can also ascribe a pH value to soil (solutions). The pH of a soil is a key-chemical property which can give us an initial idea about the overall chemical nature of a soil and about the availability of plant nutrients. The pH of natural soils can vary from only 3 to more than 8.5. Optimal pH for the growth of most plants and activity of soil micro-organisms is in the range of 6 to 7.

29 The highlands of northern Thailand: agriculture, people and soils

3.3 How can we evaluate the fertility of soils?

So far we have seen that soil fertility refers to the ability of a soil to provide favourable physical, biological and chemical conditions to plants. Before we can manage fertility, however, we must first be able to assess the fertility of a soil.

Farmers and extension workers, indeed, often want to know whether a certain soil is ”good” or ”bad”. These are very relative concepts though, which depend on 1) the physical, biological and chemical properties of the soil; 2) its position in the landscape; 3) the surrounding (micro-)climate and 4) on the way the soil is going to be ”used”. A good soil which is used in a bad way can become a bad soil, whereas a bad soil might be improved if it is well managed. Or a soil which is considered bad for one type of crop or land use may still be good for an alternative one.

Instead of asking whether a soil is good or bad, it is better to ask how a certain soil can most effectively be used. To answer this question we must do the following:

1) We first have to investigate the nature of the soil, what comprises the specific arrangement of the soil layers as well as the properties of those layers. This step is called soil survey. 2) In a second step we have to interpret the soil data obtained from the survey, i.e. we have to evaluate whether the current or intended use of the soil is suitable (in accordance) with its characteristics. This step is called soil evaluation. For convenience we will discuss soil survey and soil evaluation as two separate and chronological steps, although in reality they often happen simultaneously.

Figure 16. Soil can be considered as a natural and dynamic ”body”. Examining soil to evaluate how it can best be used to produce good yields is very similar to examining the health and physical condition of a child to give advice on selecting a sport in which the child would most likely excel.

30 Chapter 3: Characteristics of highland soils

Soil survey

There are three approaches which can be followed when surveying soils. Which approach to follow depends on your interest, needs, knowledge, time and budget. Ideally, however, we would combine them all.

Observing the vegetation

Before starting to dig soil pits or take soil samples, it is always useful to have a look at the vegetation that covers the soil you want to study.

The type and the appearance of natural vegetation cover can give a first indication of the characteristics of the soil below. In northern Thailand, for instance, extremely shallow and sandy soils are often covered by deciduous forests, whereas deep and clayey soils are more likely covered by evergreen forest types. Weeds grow in abundance on almost any soil type, but their physical appearance can be a sign of soil fertility: broadleaf weeds growing on a fertile soil have thick, ”fleshy” and dark green leaves, whereas weeds growing on a poor soil have thin and light green or yellowish leaves. Some knowledgeable farmers can assess the quality of the soil on the presence or absence of certain indicator plants (see Box 16).

Of course we can also look at the crops which are grown in the area. The types of crops which farmers select can give us a first general idea of the capabilities of the soil (if we have some foreknowledge about these crops). Individual plants can be investigated in detail for the occurrence of nutrient deficiency symptoms. More elaborate crop surveys or experiments can be conducted if this would appear to be necessary (see Appendix 1.7.).

Box 16. Indicator plants for soil quality.

· Some farmers can associate certain plants with soil characteristics such as soil hardness, temperature, moisture and nutrient content. Such plants are calledindicator plants. · Farmers’ knowledge about indicator plants is an interesting topic always worth exploring. It seems however that nowadays (in northern Thailand) it is probably only of secondary importance in decision-making relative to site-selection. Much of the knowledge on indicator plants seems to be related to the - now forbidden - practice of poppy cultivation. Furthermore there is so little fallow land left that many farmers simply no longer have the option to select the best spots. When one asks farmers about (herbaceous or shrubby) plants that can be used as soil indicators many farmers say that ultimately they still prefer farmland with ”many and/or big trees”, nostalgically referring to the good old days when forests were abundant and when there were no restrictions to cut them down… · Examples of indicator plants: Plants generally perceived as ”good”: Eupatorium odoratum (Siam weed), Musa acuminata (wild banana), Alpinia malacensis. Plants generally perceived as ”bad”: Eupatorium adenophorum, Pteridium aquilinum (bracken fern), Ageratum conyzoides (goatweed), Borreria latifolia. Plants sometimes perceived as good, sometimes as bad: Imperata cylindrica, bamboo.

31 The highlands of northern Thailand: agriculture, people and soils

Observing soil profiles

The best way to become familiar with the soils in your area is to carefully observe them in the field. This can be done by digging soil pits (at least 1 m deep), by examining soil cuttings along roads, terraces or even land slides or by using a soil auger (see Figure 17). The basic concepts and methods of soil survey are explained more in detail in Appendix 1.5.

By doing your own soil survey you can learn a lot about soils without the help of a scientist or the need for high-tech equipment. It will give you an initial, basic set of information about the soil’s physical characteristics. For practical interpretation of your observations with regard to agricultural land use, you should only pay attention to observed differences (between soil layers or between soil profiles) which are very obvious. With regard then to possible extreme differences in soil physical characteristics we can make the following generalisations:

Good soils are soils which have a deep profile (at least one meter), no or few stones in their profile, a deep (> 15cm), soft and dark topsoil, a good structure (clumps of soil do not easily disintegrate when fully wet, clumps of dry soil are not hard like stone), a medium to high clay content, many pores, many and deep roots and a good drainage (no signs of water saturation).

Bad soils are soils which have none or only a few of these characteristics.

Figure 17. Digging soil pits to study soil profiles is the best way to become familiar with the soils in your area. It is however back-breaking and time-consuming work which causes some damage to farmers’ fields. A convenient alternative is to use an auger. With such a tool you can do survey work much faster and with minimal disturbance of the soil.

32 Chapter 3: Characteristics of highland soils

Taking soil samples for scientific analysis

Observing vegetation and soils in the field should always be the first thing to do. In many cases however we may also need to know some of the chemical and microbiological soil properties. Unless you have relevant experience, you will always have to rely on outsiders to analyse samples of your soils and interpret the results.

Analysing soil samples, though, is expensive and time consuming and, furthermore, the results are often difficult to interpret. How valid the analysis results are depends very much on how the soil sampling was carried out (see tips in Appendix 1.6.). Subsequent interpretation of (trustworthy) analysis results, in turn, demands extensive background information on the area, on management practices and on crop history. So, although laboratory analysis of soil may seem very sophisticated, it is not a magic tool that will provide answers to all your questions. Taking soil samples and having them analysed should, therefore, be an activity that is well thought out. If this is not the case it may be a loss of time and a loss of money.

Soil evaluation

Once we have completed the soil survey we must now interpret the findings in order to decide how a certain soil can best be used. As hinted earlier there exist many ways in which soil can be used. If, in the end, our soil survey suggests that agriculture is a viable option in the area under question (or if there simply exist no other alternatives for the land owner), then the focus of soil evaluation should be the selection of crops appropriate to that type of soil (crops most likely to grow well) and/or the selection of sound ways to manage that soil. Here we will briefly discuss the issue of appropriate plant selection. The management of soils will be addressed in Part II.

Some farmers (see Box 17), extension workers and agronomists can evaluate soils by drawing on their own previous experience with various crops on a range of soils. People with less experience must seek advice from outsiders or consult specialised literature. Extensive tables exist with information about soil requirements and limiting factors for the major field crops, but generally such information is not easy to read nor easily accessible. Additionally, it is risky to rely exclusively on information derived from literature, as the relevance of this information may be limited to the area where it was collected. Therefore it is useful to set up your own cropping experiments, as this is the most direct and reliable way of soil evaluation.

Briefly summarising the issue of soil evaluation we can state that:

1) On good soils we can grow almost any crop. 2) On soils of medium quality (i. e. soils with some limitations) we should make a careful crop selection. 3) Absolutely bad soils (i.e. shallow, stony and/or very sandy soils) should not be used for agriculture if located on a slope. If located in a valley, they may still have potential for paddy rice cultivation, vegetable production or fruit production.

33 The highlands of northern Thailand: agriculture, people and soils

Box 17. Farmers’ ways of evaluating soils (in northern Thailand)

· Farmers obviously have a lot of practical experience with soils. The way they view soils is in general holistic and deals only to a limited extent with inherent soil properties. If farmers are asked to give their opinion about a certain soil type, their answer is generally based on a wide range of criteria which differ among farmers. Factors that are mentioned are: various physical soil characteristics, the amount of sunlight a soil receives, the topography, the type of rocks, the type of fallow vegetation and indicator plants (see Box 16), the presence of weeds and other pests and the performance of previous crops on that soil. The latter factor is in general of overriding importance for their final evaluation. Sometimes farmers also mention the presence/absence of ”pui” (plant nutrients). Their knowledge about it seems however limited. · Farmers knowledge about inherent (top) soil characteristics is mainly related to physical characteristics: stoniness, soil colour, soil texture, soil structure, soil hardness, soil water content and soil temperature. Often (not always) a dark soil colour is appreciated as ”good”. Clayey soils are differentiated from sandy soils based on their stickiness (the degree to which a soil sticks to your hands or feet). Farmers also have tests to evaluate the structure of soils. They look to see, for instance, whether soil clumps easily break up or not. In another test they look at how soil aggregates that are dug out of a hole fit into the hole when they are placed back. If they do not fit well, then this indicates a good soil (structure). Soil hardness is evaluated based on the resistance of the soil during tillage and on the extent dry soil ”hurts” when walking barefoot. · Do farmers also look at the subsoil? It seems that this is almost never the case. · Which farmers have most soil knowledge? It appears that in general the older farmers have more knowledge about soils than the younger ones. · Soils with specific characteristics often get local soil names. Examples: midza mini (black soil, Akha); miye migo (cool soil, Lahu). · Do farmers use their knowledge about inherent soil characteristics when selecting fields or when deciding which crops to grow on what fields? In the past this seems certainly to have been the case for the cultivation of opium. Today however they don’t seem to be make specific correlations between certain soil types and certain crops. Obviously they have less chance for selecting the best spots because of the lack of agricultural land. For the same reason some farmers are cultivating fields which formerly they would have considered as unsuitable. It seems that today practical considerations (e.g. the presence of a nearby road or water source), economic considerations (crop prices) and the presence/absence of various pests are of major importance for site and crop selection. The increasing use of commercial fertilisers will further reduce the necessity to look for the most fertile soils (or the most appropriate crops). · The current interest in farmers’ local soil knowledge has two main reasons. First of all it is hoped that it might reveal issues that are overlooked by ”conventional” modern soil science. Secondly, if a local classification system exists, it can be of practical use in survey and extension work. Highland farmers of northern Thailand do have local soil knowledge that is worth exploring, but the extent and applicability of this knowledge seem to be limited. It does not give us exciting new insights into the soils of the area but can facilitate soil survey and extension work.

34 Chapter 3: Characteristics of highland soils

3.4 Are highland soils suitable for agriculture?

Now that we have introductory know-how on soil fertility, soil survey and soil evaluation it is time to address the above question. To answer this question we will first have a look at the specific characteristics of highland soils and at the soil forming factors that created these characteristics. After that we will make an overall suitability evaluation of these soils.

Characteristics of highland soils

Although it is always difficult and risky to make generalisations about soils, we made an attempt to group (sloping) highland soils into 4 major types and to present their major characteristics (which are in reality more variable than is presented in Table 2).

Table 2. Overview of the characteristics of the major highland soil types

ROCK TYPE Limestone Shale/Schist Granite Sandstone Cover 1 10% 40% 40% 10% Soil deep mod. deep - mod. deep - mod. deep - depth shallow deep shallow Stoniness few stones many stones few stones many stones Colour dark red red brown - red brown - red brown - subsoil greyish brown yellow red yellow brown Texture clay clay sandy clay sandy loam topsoil loam Texture clay clay clay sandy clay loam subsoil Structure good moderate moderate poor Water (very) good good good poor retention Water high high high very high infiltration pH topsoil 6 - 7.5 5 - 6 5 - 6 5 - 6 pH subsoil 5.5 - 6 4.5 - 6 4.5 - 6 4.5 - 5 Topsoil nutr. high - medium - medium - poor content medium poor poor Subsoil nutr. medium - (very) poor (very) poor (very) poor content poor SOIL very good medium - poor - poor FERTILITY 2 good medium

1 Refers to the approximate percentage of the total highland area that is covered by the different rock types. 2 Rating of the soil’s agricultural potential, based on the overall combination of its various physical, biological and chemical characteristics.

35 The highlands of northern Thailand: agriculture, people and soils

The grouping in Table 2 is based on the rock type as this factor is of major importance to the distribution and properties of highland soils. You don’t need to be an ”expert” to be able to recognise the different rock types. Most easily distinguished are the limestone rocks, which are characterised by irregular and steep rock formations with many and large caves. Shales/shists show characteristic layers, which look like ”slices” pressed upon each other. Massive ”boulders” in and along streams are typical of areas where granite is the parent material. The presence of sandstone is often indicated by extremely rocky and shallow soils with a poor cover of mainly deciduous vegetation. Limestone soils (see Box 18) have by far the highest potential for agricultural use because of both their good physical and chemical characteristics. Second best are the clayey soils derived from shales/shists (when their profile is not too shallow). Granite soils are of lower quality than the previously mentioned types. One positive characteristic however is that they are generally quite deep. If well managed, granite soils can give very satisfactory yields. The sandstone-derived soils are clearly the worst ones, because of their poor physical and chemical qualities. Pure sandstone soils are therefore seldom cultivated.

Box 18. Soils in limestone areas.

· Limestone soils are greatly appreciated by highland farmers. In the past, they were the preferred soils for opium cultivation. Nowadays they are used for a wide range of crops, particularly for commercial production of maize, red kidney beans and vegetables. · The closer the soils are situated to the big limestone outcrops or isolated rocks in the field, the higher their nutrient content. In the immediate vicinity of the outcrops the soils are not cultivated, because this is an area which is believed to be inhabited by ”spirits”. More practical reasons might be that in those zones soils are too rocky, alkaline or dry (they are in the ”rainshadow” of the rocks). · Many farmers claim that limestone soils can be cultivated for up to 10 years before being fallowed, and that they require few fertiliser inputs. · The major drawback of limestone areas is that there are often no rivers in the immediate vicinity, especially on the higher slopes. Agriculture in those areas is, as a consequence, very much dependent on the rainfall. Drought therefore can be a problem and irrigation poses more practical problems than in other mountain areas. · An extreme example of the characteristics of limestone areas is the notorious limestone rock ”Doi Luang Chiang Dao” (> 2000 m altitude) in . This mountain used to be a major area for opium cultivation. Water sources can only be found at the base, on the higher elevations there are no sources.

Besides rock type, there are other factors which influence the soil properties and which may significantly alter them from the general characteristics of their parent material group. One such factor is the position of the soil in the landscape. Extremely shallow soils are most likely to be found on very steep slopes, near big limestone outcrops or on narrow valley bottoms. Soils on the top or along the slope of a hill or mountain will generally reflect the characteristics of the parent material. Valley soils are often very different from what the underlying rock would suggest (see Box 19)

36 Chapter 3: Characteristics of highland soils because they are mostly formed from materials that were transported by erosion processes and/or by rivers.

The altitude is another factor which influences the properties of highland soils (through its influence on climate and vegetation). The higher the altitude, the higher the content of soil organic matter. The soil moisture regime (water content and duration of the moist period) and soil temperature are also more favourable (for certain crops) at higher altitudes. These are important characteristics which give highland soils a relative advantage and specific potential when compared to lowland soils.

A last factor which has an important impact on the properties of highland soils is the history of human activity. How agricultural practices may influence soil properties will be discussed in Part II of this book.

Box 19. Valley soils.

· With the word valley we refer in this text only to relatively small highland valleys and not to large lowland river basins. · The nature of the soils at the bottom of a valley depends on the local landscape and on whether or not the valley is intersected by a river. Narrow valleys without a river often have soils with profiles that are deeper and more fertile than those located along the valley slopes. Narrow valleys with a river often have shallow, rocky and sandy soils. If the valley is somewhat larger, the soils may be deeper, less rocky and more clayey. · An important characteristic of valley soils is that they tend to be more moist than soils on sloping land, even to the extremes of temporary or permanent water saturation. Valley soils are therefore often used for irrigated rice, fruit tree or vegetable cultivation.

Agricultural potential of highland soils

Based on Table 2 we can make some summarising conclusions about the characteristics of highland soils, thereby dividing them into favourable and unfavourable characteristics:

· Favourable characteristics of highland soils:

+ Physical properties are generally good. Most soils have sufficiently deep profiles, have a texture and a structure that are favourable for crop production, are well drained and capable of storing water. + Soil organic matter contents are high (compared to lowland soils). + Soil moisture and temperature regimes allow the cultivation of crops that cannot be cultivated in the lowlands. + Limestone soils are extremely well-suited for agricultural production because of both their favourable physical and chemical soil properties. In the north limestone soils can only be found in the highlands.

37 The highlands of northern Thailand: agriculture, people and soils

· Unfavourable characteristics of highland soils:

- Slope is in general steep to very steep (35% to 70%). - Some soils have shallow, stony and/or very sandy profiles. - Topsoil nutrient contents are medium to low (except for limestone soils). Subsoil nutrient contents are low to very low. The nutrient gradient (difference) between topsoil and subsoil is always drastic. - Topsoils and subsoils are moderately acid (except for limestone soils). In a few cases subsoils may even be strongly acid. Some soils may contain soluble components which are toxic to plants. This toxicity danger however doesn’t seem to be dramatic and affects some crops more than others

The final question which remains to be answered is what can we learn from these characteristics with regard to the agricultural suitability and management of highland soils? An answer can be given based on only (soil) scientific arguments, but any answer is inevitably also subject to ideological, political and socioeconomic considerations (see Chapter 1).

Some people emphasise the unfavourable characteristics of highland soils. They argue that these unfavourable characteristics are so formidable that they cannot be compensated for. They consider highland agriculture, under whatever conditions, as too risky for the soil and the environment and therefore lobby for a ban on agriculture above a certain altitude or slope gradient.

Other people - the authors of this book included - emphasise the favourable characteristics of highland soils and the specific potentials of highland agriculture in general. They furthermore think that the unfavourable characteristics can be countered with ”proper” management. Such a proper management should comprise, in addition to other things, measures to prevent excessive soil erosion and measures to conserve or improve the soil nutrient status (see Part II).

Conclusion: highland soils are suitable for agriculture

This chapter provided a basic introduction to soil science. An elementary knowledge of the nature and properties of soils is indispensable if you want to be able to manage soils properly. To obtain this elementary knowledge, you don’t have to be a specialist or use sophisticated tools. If you have a fair amount of interest and motivation you can learn a lot about the soils in your area by using relatively simple field survey methods. Once you are familiar with the basic characteristics of your soils it is only a small step to learn how to evaluate and properly use these soils. Setting up small experiments will turn out to be the best way to achieve that final goal. You can go through the whole learning process on your own, but it would be much more fun and also much more beneficial if you ask the farmers to join in. If you and the farmers increase your knowledge of the soils in the area this will prove to be a big step forward on the road to sustainable agriculture!

38 Chapter 3: Characteristics of highland soils

If you would survey the highland soils in your area you would probably conclude together with us that the majority of these soils are characterised by good physical properties but medium to poor nutrient contents. You will also notice that if these soils are well-managed they will give very satisfactory yields. Maybe you will come across soil types that are not at all suited for agriculture, i.e. shallow or stony soils or soils that are very sandy. Such soils should, as much as possible, remain under forest cover. If you have the luck to work in an area where there are limestone soils you will find out that these soils are extremely productive over long periods and therefore intensively used by highland farmers. You will probably also come across soils that are located at the bottom of (small) highland valleys. When you look at these soils in detail you will certainly appreciate their generally favourable moisture and/or nutrient status. It will therefore not surprise you that such valley soils are often intensively used for paddy rice, fruit and vegetable production.

39 Part III:

The future of highland agriculture Chapter 11: Diversification, of species and activities

The most promising strategy to achieve sustainable agricultural development in the highlands (and globally) is diversification, i.e. combining a wide range of different crops, cropping practices, cropping systems and non-farming activities, at the household or at the community-level.

11.1 Upland rice: a dead-end street?

Upland rice is the crop that, since ancient times, has been most closely associated with the highland people’s (agri)cultural and religious way of life. On a national level the economic importance of upland rice is negligible, but for the majority of the highland people it remains the major means of subsistence. The cultivation of upland rice, out of cultural desire and/or economic necessity, is probably the single most important reason for continued wide-scale swidden cultivation in northern Thailand.

The problems associated with the cultivation of upland rice are, unfortunately, numerous and severe. The crop appears to be very sensitive to a wide range of environmental stresses, among which soil-borne pests, weeds, drought, erosion and soil physical and chemical limitations are the most important ones. Yields go down (dramatically) if upland rice is grown for 2 or more successive years on the same plot. Only in a few remote and sparsely populated areas, where farmers still can practice long fallow rotations, can upland rice continue to sustain local communities without major environmental impacts. In much of the highlands, however, the production of upland rice is insufficient to feed the population and is furthermore associated with soil degradation and degradation of the remaining forests and surrounding fallow lands. Under the present cultivation practices (short fallow periods and extended cropping periods, uncontrolled burning and limited or no implementation of soil conservation measures) the cultivation of upland rice is undoubtedly a major culprit for the continuing degradation of the highland ecosystem.

Are there any possibilities to stop, alleviate or reverse this process? This is a difficult question. Even today, after decades of agricultural research in the highlands, very little information is available to effectively improve upland rice production under real farmers’ conditions. Lack of detailed on-farm research and severe agroecological and farming systems constraints are at the basis of this failure. It can be seriously questioned whether, under the given constraints, researchers will ever be able to come up with effective recommendations to raise upland rice yields significantly above the current potential maximum yields observed in farmers’ fields (that being 2-3 ton/ha). Based on the past research and extension experiences, it seems doubtful that ”modern” high-input methods, such as improved varieties and use of inorganic fertilisers and pesticides, will bring spectacular solutions.

115 The future of highland agriculture

What seems more needed and feasible though, is to design strategies to ”stabilise” the upland rice production system, i.e. to prevent extreme yield variations, reduce the labour inputs and reduce or stop the negative environmental impacts of upland rice cropping. Many options to achieve this goal are available and have been presented and discussed in the previous chapters of this book: improved fallow management; a more careful and pragmatic use of fire; methods for erosion control that are acceptable by the farmers; improved weed management and judicious crop rotations which take benefit of fertiliser residues from previous cash crops, maintain favourable soil conditions and prevent an accumulation of soil-borne pests.

Besides assisting farmers to stabilise their upland rice production systems, there are yet two other alternatives to solve the ”upland rice problem”. The most sustainable way to produce rice in the highlands is wetland cultivation on terrace systems. Another alternative is to replace upland rice, partly or entirely, with other crops that provide cash to buy lowland rice. Both trends are, at an increasingly large scale, already taking place. It is likely then that upland rice is gradually going to disappear but how long this transition period will take cannot be predicted. For the time being, researchers and extension workers should continue their efforts to design and promote productive and ecologically-sound upland rice systems, in order to alleviate the farmers’ hardship and protect the highlands against further degradation.

· Advantages of upland rice cultivation: + Farmers are familiar with it. + Farmers have planting material that is adapted to the highland environment and to their personal preferences (such as the taste of a given variety of rice).

· Limitations of upland rice cultivation: - Requires much agricultural land. - Upland rice is very sensitive to unfavourable crop environmental conditions. - Yields go down rapidly under permanent cultivation with traditional cropping practices. - The cultivation of upland rice under conditions of land pressure requires high labour inputs for tillage and weeding. - Many ”recommended” soil conservation and organic farming practices appear difficult to be integrated in an upland rice system.

11.2 Highland paddy rice farming: a sustainable alternative?

There are many places in Southeast Asia where irrigated rice terraces have been managed in a sustainable way for ages. In northern Thailand the practice is not widespread, but it is gaining popularity, especially in areas where land pressure is high. The change from rainfed rice cultivation to paddy rice cultivation is a hopeful trend which could (should?) be stimulated by (1) giving farmers more guarantees about land (use) rights and by (2) giving technical assistance where this is needed. The

116 Chapter 11: Diversification, of species and activities constructing of terraces and irrigation-infrastructure (dams, ponds and channels) are indeed difficult technical undertakings which highland communities or individual households are sometimes not able to carry out and/or finance on their own. Wetland rice cultivation has multiple advantages over dryland rice cultivation (see list below). If it is grown under no-input conditions, the potential maximum yields are not higher than for upland rice, but yields are more stable (i.e. they do not rapidly decline over time). With good management and some minimal soil nutrient inputs irrigated terrace systems can remain productive for ages.

When wetland rice is cultivated on steep mountain slopes, however, some potential dangers should be taken into consideration. The first one is the risk of landslides (see Box 44), which actually have been observed in large terraced paddy fields in Mae Salong area. To prevent landslides, appropriate site-selection, appropriate construction techniques and careful water management during periods of high rainfall are critical factors to look at. Another aspect that should be considered is thewater consumption of highland paddy fields, i.e. the possible negative impact of extensive highland paddy rice cultivation on the availability of water in the lowlands. Little research data is available concerning this issue. We can assume, though, that during the rainy season water consumption in highland paddies will not adversely affect the lowlands. This may, on the contrary, even prove to be beneficial (paddies may act as buffers that slow down the drainage of water to the rivers, which is beneficial during periods of heavy rainfall). More critical however would be the use of water during the dry period (if cultivation of an irrigated dry season crop would become widespread). Strict regulations might be needed toavoid water use conflicts.

· Advantages of (terraced) paddy rice cultivation: + Gives a stable rice production. + Provides good erosion control. + Provides good weed control (due to flooding many weeds do not survive). + Flooding improves some of the soil chemical characteristics (see Box 49). + Provides a continuous water supply to the rice plant (no drought stress). + Gives less problems with soil-borne pests. + Flat terrace fields are easier to cultivate then sloping fields. + After the wet season rice crop another (irrigated) crop can be grown. + Provides opportunities for integration of fish and duck raising.

· Limitations of (terraced) paddy rice cultivation: - Requires considerable technical knowledge and investment of labour and/or money for building and maintaining the terraces and irrigation-infrastructure. - Requires sufficient water resources in the vicinity. - Requires deep and clayey soils. - May require land redistribution, so that a maximum number of households from a local community can have access to land that is suitable for paddy field construction (see Box 13). - The possible impact of highland paddy rice farming on water availability in the lowlands is not yet known. Water use conflicts are a potential risk.

117 The future of highland agriculture

- Paddy rice terraces increase the risk of landslides. - Flooding causes the release of certain plant-toxic substances (the amounts depend on the type of soil) and the formation of the greenhouse gas methane.

11.3 Other field crops: limited possibilities

Besides rice, there are various other field crops which can be grown in the highlands. Examples are maize, soybean, peanut, lablab bean and red kidney bean which are often grown as low-input commercial fieldcrops, and wheat and barley grown in some areas as high-input commercial fieldcrops. Maize is after rice perhaps the second most widely cultivated highland crop. It is grown as supplementary human food and as a fodder crop for pigs. Improved varieties are also grown as cash crop. Some farmers specialising in pig raising allocate much of their land to maize. An advantage of maize is that it requires less land preparation and weeding than rice.

11.4 Home gardening: a small activity with big advantages

Home gardens are small (often fenced) pieces of land which are intensively managed for the production of vegetables, herbs and fruits. They are a well-developed, integral part of the farming system of certain minority groups (e.g. the Akha) and only a marginal activity among others (e.g. the Lahu). The prime objective of home gardens is to supply the farm-household with a wide range of foods and kitchen ingredients, but in areas where markets are nearby the surpluses are also sold to get some extra income. Home gardens might offer farmers interesting prospects if in the future the demand for ”organic” products would increase and the marketing better organised.

· Advantages of home gardens: + Require no or few external inputs. + Require little space. + Can serve subsistence as well as cash objectives.

· Limitations of home gardens: - Marketing of the products might be difficult if sales is the objective.

11.5 Fruit trees: a secure investment?

Fruit tree cultivation is currently ”booming” in the highlands. Among the cash- oriented farmers (in particular the Hmong) this started more than 20 years ago, but among subsistence farmers the phenomenon is more recent.

The species grown as well as the way in which they are arranged may vary from farm to farm or from region to region. Especially popular is litchi, but other fruits such as plum and apricot are grown as well. The young tree seedlings are often mixed with

118 Chapter 11: Diversification, of species and activities annual crops, upland rice in particular. Some farmers plant the trees in fallow land, others plant them under a cover of native forest trees or in complex mixtures. All these types of arrangements can be described as ”fruit tree-based (agroforestry) systems”. The combination with annual crops is in most cases only temporary. Single species stands are most common and in many areas entire valleys and hillslopes are being converted into orchards. At present, fruit tree cultivation is bringing prosperity among many highland households, who, until only a few years ago, were still mainly dependent on subsistence cultivation of upland rice. Speaking well for this is the increasing number of households in Mae Haeng village that purchased bicycles and motorbikes after each successful litchi harvest of the past three years.

The conversion of upland rice fields and (degraded) fallow lands into permanent orchards can be seen as a rather beneficial evolution, from an environmental and soil conservation point of view. Somewhat alarming, though, is the fact that fruit tree cultivation, litchi cultivation in particular, is evolving towards yet another large-scale monocropping system. Potential dangers are a ”crash” of the current high market prices of these exquisite fruits or massive pest outbreaks. When we pointed out this danger to some enthusiastic litchi farmers of Mae Haeng, they replied promptly with the following very pragmatic answer: ”If that would be the case we would chop down the trees, burn them and plant upland rice just the way we did before…”.

· Advantages of fruit tree-based systems: + Planting material is easily available because most farmers master the technique to produce their own tree saplings (air layering). + The trees are easily integrated in the upland rice cropping system. + The requirements for external inputs and labour are moderate. + The returns to investment come relatively fast. After 4 to 5 years farmers can start to sell the fruits. + The fruits are easily sold and fetch (very) good prices. + The fruits are a tasty and nutritious extra to the poor diet of some highland minority groups. + Once an orchard is established it requires far less work than the production of annual crops, with much higher financial rewards. + Litchi-farming creates employment opportunities in isolated villages: richer farmers hire other farmers for harvesting and transportation of the crop. + Many farmers see fruit trees as a secure investment for their old days or for their children.

· Limitations of fruit tree-based systems: - To be productive some fruit trees (litchi in particular) need a lot of water during the dry season. On sloping fields this water is not always available. - Heavy rainshowers during the ripening stage of litchis may damage the crop. - Harvesting, storage and transportation of the bulky and fragile products requires a lot of labour and/or good infrastructure. In villages that are not accessible by road this may limit the area that can be harvested (in Mae Haeng

119 The future of highland agriculture

it already happened that farmers lost considerable parts of their yield because of a seasonal lack of labour force). - Price instability, especially if the competition from neighbouring countries (China in particular) would increase. - Pest attacks don’t seem to be a big problem yet but might increase in the future as most farmers plant single species stands.

11.6 Commercial high-input horticulture: risky but very attractive

The commercialisation of agriculture (vegetable, fruit and flower production) has been one of the most spectacular evolutions in the recent history of the northern Thai highlands. In some villages this transition happened gradually whereas in others the switch from subsistence farming to cash farming happened in just a few years.

Whether the commercialisation of highland agriculture is something to be happy about or something rather deplorable, is dependent on who you ask the question to. Outsiders generally emphasise the possible (but so far not clearly documented) negative effects of commercial highland farming on the environment and on the highlanders traditional lifestyle. For farmers, however, commercial agriculture is often the only way out, the last option which can prevent a total breakdown of the traditional agricultural and social system. Adopting (at least some degree of) commercial farming may be the only means to a continued existence as independent farmers in their native village. The alternative might be temporary or permanent migration to lowland cities or even abroad (Malaysia, Taiwan) to become a cheap wage-labourer, or to work as a guide, merchant or as an attraction in the tourist business. In the worst-case scenario it might imply becoming a beggar or getting involved into illegal activities such as logging, drug trafficking, theft, smuggling or prostitution.

It should be emphasised that there are examples of highland farmers who developed commercial and sustainable farming systems. Some farmers can manage to make a fairly good living on a relatively small piece of land. Cash farming often reduces erosion due to many factors that are inherent to the introduction of cash cropping in the highlands - factors such as a reduction of the cultivated area, terracing (to prevent expensive fertilisers being washed from the slope!), ridge tillage, mulching and covering delicate crops with nets or plastic (the latter practice is not intended as a soil conservation measure but has beneficial side-affects as such). Other sustainable practices arising as a side-effect of commercialisation are integration of fruit trees, crop rotations (which might be due to ”market-price rotations”!) and the combined use of chemical and organic fertilisers (chicken manure, for instance).

It should further be stressed that commercial farming can also lead to considerably increased well-being for the farmer and his family. The financial benefits of cash farming can make the highlanders more independent and might even help them to

120 Chapter 11: Diversification, of species and activities conserve part of their traditional lifestyle (traditional costumes and sacrificing large animals are expensive). What cash-farmers obviously enjoy is their increased mobility once they can afford their own means of transport such as motorbikes and pick-up trucks. It makes them less dependent from middlemen because it allows them to market their products themselves. It also allows them to visit relatives more frequently, relatives who often live in villages that are several hundreds kilometres away. Last but not least we should mention that cash cropping opens the potential for education. It is indeed common nowadays to see colourfully dressed hill tribe families at student graduation ceremonies, proudly offering flowers to their children who may go on to life-pursuits that ensure their survival as a people and who will soon return home with state-of-the-art agricultural and commercial knowledge.

Of course cash farming is not just a bed of roses (see list below). The biggest challenge will be to develop effective and environmentally-sound methods to control the extremely versatile army of crop pests. Unfortunately, most farmers are fighting the battle with chemical weapons these days. Although few concrete data are available, there are pertinent concerns about the negative effects of excessive pesticide use on the environment and on the health of producers and consumers.Integrated pest management, i.e. using a maximum of cultural, biological (use of natural enemies) and physical (traps, nets,...) control methods and a minimum of chemicals, would be a much more efficient and eco-friendly alternative. Here, however, we have to refer the reader to more specialised books or resource persons (see Appendices 3 and 4). Another major problem of cash cropping are the financial risks that are involved, risks which are due to unpredictable price fluctuations of the farming inputs, the farm production and the foodstuffs that have to be purchased once subsistence cropping is abandoned. This is something which the farmers will have to learn by bitter experiences. They can suddenly become rich...or loose everything. They can be cheated once by sly businessmen, but usually not twice.

A complete switch towards commercial farming in every highland village of northern Thailand will probably never happen, or at least not in the near future, given the huge investments in transport infrastructure this would require. We have to acknowledge, however, that the commercialisation of highland agriculture has really taken-off. Together with the farmers we will have to look for solutions to the new challenges this will bring along.

· Advantages of commercial highland farming: + Can give high financial returns. + Can reduce soil erosion. + Can solve some soil nutrient problems. + Requires less land than traditional fallow-based farming. + Can be an easy and fast way to more sustainable farming.

· Limitations of commercial highland farming: - Requires high investments from the individual farmer and the public sector.

121 The future of highland agriculture

- Becoming solely dependent on cash farming and buying staple foodstuffs such as rice is a risky situation for smallholder farmers to put themselves into. - Relies heavily on external agrochemicals. - Makes farmers very dependent on timely transport (many crops need to be transported to the market almost immediately after harvest; storage of the agricultural products is difficult and expensive). - Makes farmers dependent on the questionable attitude and the inconsistent standards of the middlemen (especially in the case of contract-farming). - May lead to worsened gender or community relations.

11.7 Alternative low-input agriculture: adopt as much as feasible

We have previously argued (see Chapter 6.3.) that low-input organic farming should be favoured whenever possible, but that adoption of farming systems that are ”100% organic” is very difficult if not impossible.

Because there exists a wide range of organic farming systems which each having their specific philosophies and methods (see Box 31), it would be risky here to make generalisations about the advantages and limitations of these systems as a whole. The advantages and limitations of several specific organic farming practices have been addressed in various chapters throughout in this book. For more information about particular organic farming systems, specialised literature and/or recourse persons should be consulted (see Appendices 3 and 4).

11.8 Livestock and/or fish raising: the more the merrier?

It is generally accepted that mixed or integrated farming systems are the most stable ones. This mixing refers to crop species, crop types (annual and perennial, subsistence and commercial) and also to the broad types of living organisms which are raised to the farmers’ benefit: plants and animals. Bringing livestock or fish into the system creates a range of opportunities to diversify and stabilise the system: linking production chains, recycling or improving nutrient and energy flows and improving transport and mechanisation (based on animal traction).

Almost every highland household raises some livestock (mainly chickens and pigs, the better-off households also cows, buffaloes and horses) but this activity is seldom the backbone of the farming system. Some farmers are engaged in the risky but lucrative smuggling of livestock from Burma and Laos. Fish-raising is only done in some villages where development projects are active. There should certainly be opportunities to improve the efficiency and productivity of livestock or fish raising in the highlands. Large herds of livestock should however be avoided or strictly controlled, because highland farmers often leave their animals roaming in the forest what inevitably leads to forest and soil degradation.

122 Chapter 11: Diversification, of species and activities

· Advantages of livestock and fish raising: + Create new opportunities to diversify and stabilise the farming system.

· Limitations of livestock and fish raising: - Livestock raising is labour intensive (e.g. collecting and preparing food for pigs; guarding buffaloes and cattle). - Animals often give rise to conflicts when they damage crops. - The most frequently heard problems with livestock raising are animal diseases, which are often epidemic and decimate the entire village livestock. - Large herds of animals can damage the forest and/or create erosion. - Highland farmers are traditionally not familiar with fish raising.

11.9 Collection of forest products: OK but don’t exaggerate

Although farming is since time immemorial the mountain people’s main livelihood, hunting and gathering were also and still are providing an important ”extra” (see Box 22). This extra may be less and less essential for those who made a successful switch to more commercial and/or sustainable ways of farming, but may be increasingly important for those who have not yet ”jumped on the bandwagon”.

Sustainable ways of using the forest and fallow areas as a resource for timber and non-timber products should get a place on the agenda of policy-makers, development workers and researchers. Due to the expanding road network in the highlands, the danger of overexploitation of commercial non-timber forest products and of illegal logging and charcoal production is bigger then ever before. A step in the right direction is the growing recognition ofcommunity forests, an ancient tradition of Thai lowland farmers and some highland minority groups.

11.10 Off-farm activities: unavoidable…

A large number of highland farmers, especially those who are dependent on subsistence cropping, are increasingly looking for off-farm labour opportunities to make ends meet. Off-farm labour increases the risk of social and cultural disintegration of highland communities, but is often the only way to survive. It may also be a way to collect some cash to invest in new cropping alternatives. If the ”cultural erosion” associated with off-farm labour is not too bad and if the peoples’ working conditions are humane, the phenomenon can be regarded as a positive evolution stabilising the highland farming systems.

A sector which offers particular opportunities to highland people is the tourist business. Tourists are prepared to pay large sums to ”enjoy the unspoiled nature” and ”get in close contact with the fascinating hill tribe people”. There are individuals and organisations who make sincere efforts to promote sustainable (eco)tourism, i.e. to protect nature and involve highland people as equal partners or at least on a fair basis.

123 The future of highland agriculture

Unfortunately there are others who are only out for quick profits and shamelessly exploit people, animals and nature. There is still a big task waiting to raise the awareness of the public sector, the private sector, highland communities and last but not least the tourists, in order to guarantee that the whole business will contribute to the benefit of the inhabitants and the environment of the highlands.

It is of utmost importance that government and non-government agencies are well- aware of the increasing numbers of highland people who, temporarily or permanently, leave their villages in search for work. Current development programs, which are mainly highland-based and focused on the improvement of the highlanders’ agricultural livelihood, might need to be adapted to the reality of this new, ultimate wave of hill tribe migration. The success or failure of agricultural extension work will, to a large extent, depend on whether at all the target group still aspires a future as mountain farmers…

124 Concluding remarks

Developing ecologically sound, productive and farmer-friendly agricultural systems in its mountainous watershed areas is a huge challenge for present-day Thailand and the entire Upper Mekhong ecoregion. It is part of a greater search for ways to balance economic development with ecological and cultural conservation, a search which is more pressing than ever now that a severe economic crisis is shaking Thailand and the rest of Southeast Asia to its foundations.

Highland development is complicated by the fact that the various projected highland roles fall under either one of two apparently conflicting categories: protective environmental roles vs. productive developmental roles. Further complicating the matter is the fact that Thailand’s major watersheds are inhabited by various non-Thai ethnic minority groups, who farm according to traditional slash-and-burn systems that are generally perceived as destructive and erosive forms of land use. The time that the highlands were economically marginal and an administrative no-man’s land belongs to the past. All-weather roads have penetrated the once isolated mountains and are linking traditional highland subsistence economies with mainstream Thai and transnational market-oriented economies. Government policies, determined by lobbying interests in the lowlands and overseas, are increasingly impinging on the highlands, thereby putting important restrictions on highland agriculture.

Against this background of lowland-highland conflicts and dynamically changing geo-economic and geo-political realities, we have tried to give an objective picture of present-day northern Thai highland agriculture. We have taken this picture from soil- and farmer-centred perspectives, considering these as the hubs of the agroecosystem. A comprehensive understanding of both components and the complex interactions between them is imperative if the ultimate goal is to develop sustainable ways of highland farming. In order to come to such an understanding elaborate scientific studies have to be undertaken based on meticulous research procedures, alongside participatory appraisals based on elementary social consciousness and straightforward common-sense. Once the various essential pieces of information are collected, they should be compiled in an understandable manner and passed on to others. The ultimate goal of development - and specific aim of this manuscript - is, indeed, to provide information, information of a sort that increases the ability to deal with local problems and increases awareness of available options.

In this book we have tried to present anintegrated vision on highland soils and on the various options to manage these soils for agricultural production. Thereby we started from the fundamental but controversial premise that agriculture is a valid land use option for the highlands. Throughout the book we have tried to justify this premise by carefully balancing the characteristic potentials of highland farming against the characteristic constraints, thereby taking hard-headed scientific, economic and practical arguments into consideration along with arguments of a more humane and ethical nature.

125 Concluding remarks

The core problem of highland farming is that agricultural production interests are often in direct conflict with the envisioned protective ecological and watershed roles of the highlands. This is especially the case for some controversial traditional farming practices such as fallowing, biomass burning and soil tillage, as well as for certain contemporary farming practices such as the use of inorganic fertilisers and pesticides. Various people argue that farmers should be persuaded to give up these practices and instead adopt alternative organic and/or agroforestry types of farming, which are generally perceived as the only sustainable options for agricultural land use in a mountainous watershed area. Some people even would like to see agriculture ruled out altogether in the highlands. We do not (entirely) agree with these latter two opinions. Throughout this book we have tried to point out that it is not realistic nor socially justified to advocate an agricultural development approach that is based on the prejudiced exclusion of certain farming options whatsoever, not to mention a radical ban on farming and the massive relocation of tribal people this would imply. We fully acknowledge the pressing need for environmental conservation but think that this can only be achieved by means of a comprehensive approach which tries to find a carefully-balanced and pragmatic compromise between development and conservation objectives.

Finally then, what should such a comprehensive approach look like? Some readers may be disappointed that this book did not offer one or several well-defined blueprints for sustainable highland farming, but instead presented a “basket full of options”. Our reasoning for this is hopefully now quite obvious: any one single agricultural strategy or method is not entirely perfect. We have provided the reader with state-of-the-art listings of the advantages and limitations of various management options and with the necessary background information to interpret these listings with reference to particular situations. Our main conclusion - however trivial this may sound - is that the best approach to sustainable highland farming is to mix and match several of the various options available. We hope therefore that in the long run this basket of information and options, in one way or another, will be passed on to the farmers. Farmers, then, should have the freedom (and the means) to select those options which permit them to tailor unique farming systems that best match their specific conditions and personal preferences. This should empower them with the ability - but also charge them with the responsibility - to engage in agricultural production without inflicting any major on- or off-site environmental damage.

The basket approach was the common thread that ran through our discourse. Other conceptual issues that emerged from this book as being critical components of a comprehensive and successful highland (agricultural) development strategy are communication, participation, facilitation, flexibility, creativity, complementarity, diversification, shared engagement and responsibility. We would furthermore like to emphasise here that, due to the spectacular progress in science, developing technical options for ecologically sound and productive farming is no longer the major bottleneck - an impressive range of options does already exist. The ultimate challenge will be to formulate and implement adequate policies that create a proper political and socioeconomic climate that stimulates and facilitates resource-poor farmers to

126 Concluding remarks adopt sustainable ways of land management. In a world where economics and politics are increasingly globalised, i.e. (forcedly) integrated into mainstream capitalistic production and consumption systems, this is no longer the sole responsibility of local Thai or Asian governments and NGOs, but the responsibility of the entire world community. Ultimately then, sustainable development should be the individual responsibility of all people, not in the least of those who presently live in the most privileged conditions.

Addressing highland soil management the way we have done, i.e. within a complex farming systems perspective, proved more taxing then initially expected. We hope nevertheless that we succeeded in our objective tobetter inform the interested reader, clarify some misconceptions and stimulate critical but well-balanced reflection regarding highland agricultural development issues. We also hope that, at least to a certain degree, we have rendered service to the farmers by bringing their cause into the spotlight, thereby not only highlighting the negative but also the positive changes that are taking place.

Finally, we would like you to see this document only as an uncompleted exercise. The challenge for each of us engaged in highland development is to complete this exercise, not only by providing additional information and options, but ultimately by translating theory and rhetorics into concrete actions.

127 Photographs Photographs

1. Highland nature 2. Karen swidden field and rice paddy

3. Lahu land use 4. Pine trees and cabbages

129 Photographs

5. Changing attitudes 6. Wealth ranking exercise

7. Land use model 8. Who’s finger points?

130 Photographs

9. Poppy plants on limestone soil 10. Soil profile on schist

11. Soil profile on granite 12. Deciduous trees on sandstone soil

131 Photographs

13. Uncontrolled forest fire 14. Controlled field burning

15. Deep tillage after field burning

132 Photographs

16. What is learnt early is learnt well? 17. “Dry” tillage erosion

18. Rill erosion in red kidney bean 19. Land slide in a young litchi plantation

133 Photographs

20. Contour mulch line 21. Contour mulch line with sweet potato

22. Diversion ditch 23. Irrigated terraces

134 Photographs

24. Semi-permanent land use (Chinese and Akha)

25. Integrated highland farm

26. Model example of alley-cropping

135 Photographs

27. Lahu farmer slashing a bush fallow 28. Lahu women weeding upland rice

29. Heavy weed growth in upland rice 30. Lahu farmer spraying salt as herbicide

136 Notes on photographs

Highland land use: protective and productive functions

Plate 1 “Highland nature” (Van Keer; Mae Taeng, Chiang Mai, November 1992). This beautiful waterfall symbolises the conservation-or-development dilemma. Protection of the highlands is needed to guarantee stable supplies of clean water, maintain carbon stocks and biodiversity and conserve aesthetically attractive landscapes. Development is needed to meet the increasing demands - from various groups of people - for food production, wood production, income generation and recreation. The balancing of these protective and productive roles, based on rational and ethical considerations, is a huge challenge for many countries in South East Asia.

Plate 2 “Karen swidden field and rice paddy” (Van Keer; Mae Surin, , February 1993). Characteristic picture of traditional agricultural land use near a Karen village: on the hill slope is a swidden field cut in a healthy secondary forest, on the valley bottom an irrigated rice field. Such traditional rice-based “composite” swidden systems can cover the needs of subsistence-oriented highland communities without inflicting major ecological damage, as long as population pressure is low. In most of the highlands however there is no scope for this type of extensive swidden land use any longer.

Plate 3 “Lahu land use” (Van Keer; Mae Haeng, Mae Ai, Chiang Mai, October 1996). View of the idyllic Red Lahu village Mae Haeng, where SFC conducted 5 years of on-farm research. The village is still largely dependent on the subsistence cultivation of upland rice (the yellow patches are upland rice fields during the ripening stage) but the commercial cultivation of litchis is gaining importance. In this village the litchi orchards have steadily been expanded both up- and down-slope from the original plantations on the flatter lands as evidenced by the decreasing height of the trees (age gradient). If this trend continues, most of the presently denuded slopes will be under litchi “forest” within 10 years. The large gently sloping area above the village, which presently is almost entirely under upland rice, is slated to be converted to paddy fields. Secondary forest, which is mainly found on ridges and hill tops, covers about 25% of the village territory. It is no longer used for cultivation but still important for foraging. If Mae Haeng people will be able to protect the remaining forest, establish their paddy fields and expand and diversify the area under fruit trees (by partial or entire replacement of the upland rice area) while maintaining their still strong cultural integrity, their future appears relatively bright.

Plate 4 “Pine trees and cabbages” (Van Keer; Mae Surin, Mae Hong Son, February 1993). This extreme example of highland “development”, advocated by some as an alternative to swidden cultivation, is the ultimate nightmare for ecologists: pine tree forests on the hill slopes and cabbage fields in the valleys. Note the small “island” of banana trees, which is the only relic of the past vegetation cover.

137 Notes on photographs

Farmers’ participation

Plate 5 “Changing attitudes” (Turkelboom; Pakha Sukchai, Mae Salong, Chiang Rai). Participation requires a drastic change in attitude: outsiders should be prepared to listen and learn, farmers to talk and teach.

Plate 6 “Wealth ranking exercise” (Turkelboom; Mae Haeng, Mae Ai, Chiang Mai, 1994). Lahu women rank village households according to (relative) prosperity. For this and various other PRA exercises photographs turned out to be an excellent tool.

Plate 7 “Land use model” (Turkelboom; Mae Haeng, Mae Ai, Chiang Mai, 1994). This three-dimensional land use model in clay was made by the farmers, reflecting their strong understanding of the land’s physiography. Models like this can greatly facilitate studies and discussions on present and future land use.

Plate 8 “Who’s finger points?” (Turkelboom; Pakha Sukchai, Mae Salong, Chiang Rai 1996). Despite our good intentions, it is not always easy to change our old attitudes…

Characteristics of the major highland soil types

Plate 9 “Poppy plants on limestone soil” (Van Keer; Pai, Mae Hong Son, August 1991). Limestone soils can be easily recognised by their dusky red colour and by the presence of limestone rocks in the immediate surroundings. These soils are among the richest soils that can be found in the highlands and therefore highly preferred for the cultivation of opium-poppies and other cash crops.

Plate 10 “Soil profile on schist” (Van Keer; San Chareun, Mae Suay, Chiang Rai, 1991). Soils developed on schist typically show dark and clayey profiles that are well-suited for agriculture. The only weakness of these soils is their shallow depth (stony parent material encountered at 70 cm in this profile).

Plate 11 “Soil profile on granite” (Van Keer; Lao Che Guay, Mae Chan, Chiang Rai, 1992). The profile shown in this picture is characteristic for much of the cultivated swidden land in the northern Thai highlands. Granite soils are poor in nutrients but they are generally deep and have a reasonably good structure. Their agricultural potential is satisfactory if they are well managed. Here, termite activity - an important factor in soil formation - has resulted in cavities in the subsoil.

Plate 12 “ Deciduous trees on sandstone soil” (Van Keer; Mae Hong Son, February 1993). Soils of this type are not at all suited for agriculture because of their extremely shallow, sandy and nutrient-poor characteristics. They should remain under forest, which on sandstone soils is typically dominated by deciduous trees. Note the very distinct difference in colour between the dark topsoil and the reddish subsoil.

138 Notes on photographs

Biomass burning

Plate 13 “Uncontrolled forest fire” (Van Keer; Mae Rim, Chiang Mai, March 1996). Forest fires are a perennial source of grief. Because of the ecological damage they inflict, they should be prevented by all possible means. This should not, however, lead us to the hasty and emotional conclusion that the use of fire in agriculture - one among many others factors laying at the origins of wildfires - is per se a harmful practice that should be banned.

Plate 14 “Controlled field burning (Van Keer; Mae Salong, Chiang Rai, November 1995). This picture represents a model example of responsible use of fire as an agricultural tool. The field was burned early in the dry season and a fire break was established - two control measures which aim at keeping the fire within the boundary of the field. In the densely populated area of Mae Salong where this picture was taken, farmers are becoming increasingly cautious when using fire. Note that the lower left corner of the field has already been tilled.

Plate 15 “Deep tillage after field burning” (Turkelboom; Pakha Sukchai, Mae Salong, Chiang Rai). Deep tillage immediately after burning is an emerging practice, which aims at preventing the loss of ash-fertiliser through wind and water erosion. Note the large soil clods (aggregates) that result from the tillage operation and which indicate a strong soil structure. If the soil clods remain intact during the beginning of the rainy season, this rough soil surface (on a relatively gentle slope) will decrease rather then increase erosion (because of increased infiltration). If, however, the clods are broken after tillage by subsequent harrowing operations, the deeply loosened topsoil may become more vulnerable to erosion.

Tillage and soil erosion

Plate 16 “What is learned early is learned well?” (Van Keer; Mae Haeng, Mae Ai, Chiang Mai, 1995). This close-up evokes reflection on various issues: 1) In response to increasing weed problems, hoe tillage is becoming a standard “traditional” practice in the cultivation of upland rice. It is a practice, however, almost as controversial as biomass burning. For many farmers it is the only option to control (grassy) weeds. Unfortunately it implies a long-term threat to the soil if done year after year on steep slopes and without any additional soil conservation structures. Note the small soil clods resulting from the tillage operation in this field (see also Plate 17, same field) that is being cultivated for the fourth year in a row (Namoo and her husband Eluka are late comers in the village and have only two fields). Compare this soil surface state with the one displayed in Plate 15. 2) Is this young Lahu girl going to face the same hardship as her mother? Will she harvest sufficient amounts of rice from the recently established paddy fields (see Plate 23, same field), the fruits of the hundreds of litchi-trees (since planted on this field) or the fruits of the education she enjoys at the recently established village school? Will she keep on farming like her diligent parents who are diversifying their farm to secure theirs and her future, or will she choose - or indeed be forced - to

139 Notes on photographs

say farewell to her “chao khao” livelihood to pursue a more urban, commercial livelihood?

Plate 17 “Dry tillage erosion” (Pelletier; Mae Haeng, Mae Ai, Chiang Mai, 1993). Dry tillage erosion, i.e. the downward displacement of topsoil as an immediate result of tillage, makes an important contribution to the overall erosion losses on this field. Note the yellowish subsoil which is getting exposed. Further note that the field is cultivated up to just a few meters from a small stream (the green area at the bottom of the field). When the first rains arrive, much of the soil which has accumulated at the bottom of the field will be carried away by the river, which implies an important loss from the field and a contribution to sediment-loads in the lowland rivers.

Plate 18 “Rill erosion in red kidney bean” (Turkelboom; Mae Haeng, Mae Ai, Chiang Mai, October 1993). In an attempt to diversify their farming system, Mae Haeng farmers have been experimenting with red kidney beans, planted as a cash crop after early maturing rice harvested in August. Unfortunately deep tillage, lack of erosion control structures, poor crop cover and the occurrence of heavy rains during the second half of the rainy season lead to very severe rill erosion, thereby jeopardising the sustainability of this well-intended attempt at diversification.

Plate 19 “Land slide in a young litchi plantation” (Van Keer; Mae Haeng, Mae Ai, Chiang Mai, October 1994). Land slides are the most dramatic indicators of land degradation. The fact that this land slide occurred at the bottom of a bowl-shaped depression in the landscape (where all the runoff-water gets concentrated) underscores the importance of a well-considered spatial arrangement of the land use. Such erosion-prone areas in the landscape should remain under a permanent cover of deep rooting native vegetation. Note the down-slope age gradient of the litchi trees and the depth of the exposedgranitic soil profile.

Indigenous erosion control structures

Plate 20 “Contour mulch line” (Van Keer; Mae Sa Mai, Mae Rim, Chiang Mai, 1995). It is surprising that, so far, contour mulch lines have received little attention from researchers and extension workers, despite their good potential for a wider adoption. Of all the erosion control structures, countour mulch lines are the least labour demanding, are very efficient on moderate slopes if well maintained and do not compete for light and nutrients with the crop. The mulch line displayed here was reinforced during each weeding operation and hence remained intact until the end of the rainy season. Note that the rice plants next to the mulch lines are growing as well as those more removed.

Plate 21 “Contour mulch line with sweet potato” (Van Keer; Mae Haeng, Mae Ai, Chiang Mai, 1994). Sweet potato is an excellent crop to make beneficial use of the area that is occupied by the mulch lines and to reinforce them at the same time. It gives a good and quick soil cover and does not compete too much with the main rice crop (sweet potato is a soil creeping plant).

140 Notes on photographs

Plate 22 “Diversion ditch” (Turkelboom; Pakha Sukchai, Mae Salong, Chiang Rai). Diversion ditches are the most common soil conservation practice implemented by the Akha farmers of Pakha Sukchai. The main advantage of these ditches, just as is the case with contour mulch lines, is the absence of competition effects on the adjacent upland rice plants. Diversion ditches offer good erosion control if well- established and maintained, otherwise they can prove to be a great source of on- and off-site erosion damage.

Plate 23 “Irrigated terraces” (Van Keer; Mae Haeng, Mae Ai, Chiang Mai, 1995). Irrigated rice terraces are a prominent feature of traditional agriculture in upland and highland areas all over Southeast Asia. Well-established and well- maintained terraces provide a good control of weeds and erosion and can sustain long-term stable yields. Until recently they were not prominent in the northern Thai highlands, but due to land pressure farmers are increasingly building terraces in areas where soil and water resources allow their construction. The farmers who work this piece of land (see also Plates 16 and 17) built their first terraces in 1995. They realized an excellent yield which was a stimulus for further expansion in 1996.

(Semi-) permanent land use

Plate 24 “Semi-permanent land use (Chinese and Akha)” (Van Keer; Mae Salong, Chiang Rai, November 1992). Characteristic view of a land use “mosaic” in a densely populated highland area. The forest has virtually disappeared and fallow land is scarce. Many fields are connected with each other along the slope, which increases the risk of erosion. Despite the deforestation and intensive land use one cannot say, however, that at this stage highland agriculture has led to “desertification” or to the generation of “badlands”. What should be stressed here is the need for a careful balance of management techniques under increasing land use intensity. Features worth noting in this picture are the cultivation of subsistence crops (upland rice) as well as cash crops (cabbages), early controlled burning (see field on top of the small hill at the left) and the presence of a land slide adjacent to a road cutting (upper left corner).

Plate 25 “Integrated highland farm” (Turkelboom; Pakha Sukchai, Mae Salong, Chiang Rai, July 1995). This picture gives an overview of the exemplary integrated farm of Sala Adja (see Box 12). On the upper slopes of this remarkable bowl-shaped field upland rice and corn are grown. The lower slopes and centre of the bowl are used for irrigated rice cultivation. At the lowest part are a field hut and a fish pond surrounded by various fruit trees. This integrated farm is a masterpiece of sustainable highland agriculture, made possible by the strong will of a motivated farmer, as well as by the exceptionally favourable physical micro-environment. It would be ideal if all farmers could follow his example, but unfortunately there are few of such favourable locations available in the area.

Plate 26 “Model example of alley cropping” (Van Keer; Mae Salong, Chiang Rai, November 1992). Soy beans intercropped with maize are grown between trimmed hedgerows of Leucaena leucocephala. Owing to the common belief that it

141 Notes on photographs was a stable alternative to shifting cultivation, this type of cropping system has been the focus of research and extension efforts for 20 years. However convincing and aesthetically attractive this example may seem, adoption among highland farmers has been generally disappointing. This poor adoption is not due to the fact that the system per se is not valid, but simply because it is not the ultimate panacea many researchers and development workers had envisioned (due to various reasons that have been extensively discussed in Chapter 7.7.).

The struggle against weeds

Plate 27 “Lahu farmer slashing a bush fallow” (Van Keer; Mae Haeng, Mae Ai, Chiang Mai, 1993). This picture captures what we labelled as “degraded fallow”. This four year fallow, exposed to annual burning, shows a plant succession that has not gone beyond the stage of poor “bush vegetation”, having only bamboo and tiny trees in the upper story and Imperata-grass dominating the lower story.

Plate 28 “Lahu women weeding upland rice” (Van Keer; Mae Haeng, Mae Ai, Chiang Mai, June 1993). The happy smile of this Lahu women distracts our attention from the burden that will keep her busy for many weeks to follow: the manual weeding of upland rice. Luckily she could start with it in time and her efforts were later rewarded with a satisfying rice crop. Note the nice brown colour and crumbly structure of the topsoil in this first-year field, as well as the healthy condition of the upland rice seedlings.

Plate 29 “Heavy weed growth in upland rice (Van Keer; Mae Haeng, Mae Ai, Chiang Mai, June 1993). The first weeding of this field was carried out too late and the damage inflicted on the vulnerable rice seedlings is irreparable.

Plate 30 “Lahu farmer spraying salt as herbicide” (Van Keer; Mae Haeng, Mae Ai, Chiang Mai, June 1995). The heavy weed infestation in this large fourth-year field (same field as in Plate 17) made the farmer so desperate that he saw no other option than eradicating the weeds (mainly Ageratum conyzoides) with chemical means. Just like most of the Mae Haeng farmers, the “chemical” used is ordinary kitchen salt (NaCl) mixed with washing detergent. The efficacy of this method can be clearly seen in this picture: compare the wilting weed plants on the left side of the farmer with the still fresh and green ones on his right side - over a time period of only a few minutes! Further notice the poorly structured reddish surface soil on this heavily eroded field, which is in strong contrast with the brown and crumbly surface soil shown in Plates 28 and 29.

142 Appendices Appendix 1: Diagnostic methods and tools

1.1 Basic principles of PRA-PLA

· You can initiate PRA-PLA activities on your own, but it is often better to work with a multidisciplinary team of facilitators. · At the beginning of any PRA-PLA activity it is very important to make clear to the villagers who you are and what you want. Dubious identity can lead to misunderstandings and wrong expectations: people may mistrust you and think that you are out to make profit or discover illegal activities, or, on the other hand, may hope that you will come with money, presents or a project to improve their living conditions. If you only want to collect information, then tell this straightforward, as well as why you want to collect this information. Be prepared to give the villagers information about yourself (work, funding, family, religion) if they ask for it, because they are often as eager to learn about you as you are eager to learn about them! An excellent way to break the ice is to show pictures of yourself, your family and the place where you live, especially if you come from a foreign country. · Stimulate positive and easygoing relations with the villagers. This can happen in various ways: by playing games, by cooking and eating together, by helping them with work in the field or with other activities at the farm, by taking part in ceremonies and celebrations (if they invite you), by entertaining the villagers with music and dance (if you are capable of doing this), etc. If you have nice pictures of the villagers, make a copy for them too! This is a simple present which is always highly appreciated (unless the people would have objections against being photographed, inform yourself in advance). · It is vital to create a relaxed environment while talking to people: shady place, easy chairs, nice view, some cookies. Meet people when it suits them, not when it suits you. Jokes are often the best means to get a discussion started. Show interest and enthusiasm in learning from people, but stop when you see that people get tired. · PRA-PLA exercises can be done with individuals or with groups. Group exercises have the advantage that people can react on each others information. · Try to make things visual! Drawings or models can facilitate information exchange a lot. Discussions and exercises can get started or animated by means of pictures (from the people, the village, the fields) or a slide show. The latter is a particularly exciting event in villages where there is no electricity yet (in that case you’ll need a portable electricity generator). · Do not try to find out more than what is needed, or do not ask what people do not know. Farmers are good in trends and relative comparisons. If you ask exact numbers, they often make a wild guess. · Cross-check information by doing the same exercise with different people or with the same people but in a different way. · Let villagers themselves present and comment on the results of the exercises. · Write summaries or reports of the activities as soon as possible, when you have the events still fresh in your mind.

143 Appendix 1: Diagnostic methods and tools

1.2 Some concrete PRA-PLA techniques

· Direct observation. By living in a village and participating in the villagers activities you can learn a lot by careful observation. · Transect walks. Cross-sectional walks (alone or together with the villagers) through different land use zones. · Semi-structured interviews by using the six helpers: Who? What? Where?, When?, Why? and How? In this way you avoid leading questions, i.e. questions where you already suggest an answer or your opinion. · Ranking and classification exercises. Various items of interest can be ranked or classified according to certain criteria. For example: households based on their well- being, soils based on their fertility, rice varieties based on their taste, weed species based on their difficulty to control, etc. A particularly interesting ranking exercise is matrix ranking, which allows to make a combined analysis of two related items of interest. For example: crops vs. crop constraints (see Box 55), forest plants vs. their use, soil types vs. soil characteristics, livestock vs. different types of fodder, etc. · Drawings, maps and models. Drawings/maps made by villagers can give you a lot of insight in the functioning of individual households or the village as a whole. 3- Dimensional models are helpful to discuss and plan land use. Such models can be made by the villagers with local materials (clay, stones, wood). More sophisticated cardboard models based on topographic maps can be made by extension people. · Seasonal diagramming, seasonal calendars. It is always useful to know the seasonal dynamics of various issues such as rainfall, pest incidence, on-farm and off-farm labouring, etc. · Historical profile. A chronological outline of key events which took place in the village, based on interviews, secondary data and own observations (see Tables 3-4).

Box 55. Participatory matrix ranking of cropping constraints

By way of illustration we present here the results of matrix ranking exercises that were carried out in the villages of Mae Haeng (MH) and Pakha Sukchhai (PSC) during an initial 4-day PRA workshop (1993 dry season). The results of this workshop were used as guidelines to set the on- farm research priorities for the second phase of SFC.

Method:

· A checkerboard (matrix) was drawn on a large piece of paper. Separate groups of about 10 male and 10 female farmers were asked (1) what they considered as their major crops and (2) what they considered to be the major constraints for these respective crops. The crops and constraints were written down and visualised by using real materials (soil, crops, weeds, insects) or by drawings. · Then the farmers were asked to rank the major constraints for each crop by putting seeds in the corresponding squares: the more serious the constraint, the more seeds should be added. Each farmer added an arbitrary number of seeds according to his own perceptions. · The tables here below show the results of these ranking exercises. The numbers in each cell are the total amounts of seeds put in that cell by all the participating farmers. Row and column subtotals are shown to facilitate global comparison between the constraints and between the different crops.

144 Appendix 1: Diagnostic methods and tools

Box 55 (continued) Examples:

Interpretations (see 1.3. below for methodological problems and interpretation pitfalls)

These 4 simple tables, together with farmers’ comments noted down during the exercise, contain a wealth of information. Here we only highlight a few findings that catch the eye:

4 Soil erosion was never spontaneously mentioned as a crop constraint. 4 The fact that litchis were not mentioned as an important crop by the women of Mae Haeng suggests that they are less cash-oriented then their spouses. 4 According to the row totals, weeds are perceived as the number one cropping constraint, except by the men of Pakha who ranked weeds second. 4 According to the column totals, upland rice is perceived as the crop that experiences the heaviest constraints, except by the women of Pakha. 4 There is a striking difference between paddy rice and upland rice: soil and weeds are seen as no problems at all for the first while as major problems for the latter. The opposite is true for rainfall (without sufficient rainfall the paddies cannot be flooded). 4 Poor soil conditions are in Pakha perceived as a greater constraint than in Mae Haeng, what appears logic given the higher land pressure (and thus shorter fallows) in Pakha. Table 3. Historical profile of Mae Haeng1

145 Appendix 1: Diagnostic methods and tools

Key characteristics and changes Year Biophysical and socioeconomic Cropping and farming systems environment Before Shards of 500-600 years old ceramics found not far from the current village site 1976 suggest human presence since ancient times. Some village elders mention temporary settlements of Wa and before 1976. According an Act from 1964 the area is officially a “National Forest Reserve”. 1976 Foundation of Mae Haeng by 7 Traditional swidden cultivation: upland households arriving from Burma, later rice (subsistence) and opium poppy followed by 30 more households. The (cash). area is still densely forested. 1980 Stricter control of the border area by End of extensive poppy cultivation in the the Thai army. Economic development area, but many MH households retain of the Fang valley and expansion of small poppy fields for cash income and litchi orchards into the uplands. home consumption. 1983 The first Mae Haeng settlement is Some prominent households establish the destroyed by fire and the people move first litchi orchards on flat valley lands to the present village location. around Mae Haeng. 1989 HCEDP2 starts social and agricultural Introduction of alley cropping, which is development activities3. implemented by most farmers. 1992 SFC starts research activities. The Start of massive planting of litchi trees. village consists of 49 households. Farmers experiment with red kidney beans. Still many small poppy fields. 1993 Construction of a village fish pond. Expansion of red kidney beans. Some Only one villager has motorbike. farmers experiment with herbicides in Missionary builds house in MH. upland rice (mainly NaCl - see Box 54). 1994 Start of the construction of an irrigation Many farmers abandon alley-cropping channel. and red kidney beans. Increase of off- farm labouring. 1995 A school is set up in the village and a Red kidney bean growing abandoned. teacher is appointed. The village First terraced paddy fields appear. consists of 57 households. 1996 Drug-warlord “Khun Sa” surrenders to Poppy cultivation virtually abandoned. the Burmese army. Border area under Expansion of terraced paddy fields. complete control of Thai and Burmese Increasing use of herbicides in upland rice army. Already 5 MH households have a (NaCl) and in orchards (commercial motorbike. herbicides). First mechanical weed mower appears (purchased by a farmer). 1998 An increasing number of households gets cash revenues from litchi orchards. Upland rice remains important.

1) Events mentioned in the left and the right columns of thesame year do not necessarily have a causal relationship with each other. 2) Hill Communities Education and Development Project 3) negotiation of a land use agreement with the forestry department (reduction of the cultivation area, protection of the forest and forest tree planting); establishment of a community forest; improved access for motorbikes; drinking water system; rice bank; fruit tree nursery; cow raising; treatment of opium addicts. Table 4. Historical profile of Pakha Sukchai1

146 Appendix 1: Diagnostic methods and tools

Key characteristics and changes Year Biophysical and socioeconomic Cropping and farming systems environment Before Mae Salong area was a major entrance point for various ethnic groups that migrated 1976 into Thailand. At least since the beginning of this century the area has been inhabited. In 1962 Chinese KMT soldiers founded the village of Mae Salong. According an Act from 1964 the area is officially a “National Forest Reserve”. 1977 Foundation of Pakha by 9 families Traditional swidden cultivation of upland coming from Burma. The area is rice, corn and vegetables. covered by Imperata grassland. 1980 Construction of a dirt road (accessible Start of soybean cropping. by 4-wheel drive) to Pakha. The village consists of 30 households. 1984 Road Mae Chan-Mae Salong finished. 1985 Disarmament of KMT soldiers, stricter border control by Thai Army. 1986 Increased control by Thai authorities. Start tomato cropping. A second (administrative) village leader Start fruit tree planting. is appointed. HADF2 starts development activities3. 1988 No special permission needed any More frequent tilling. Use of herbicides longer to enter Mae Salong area. starts. Beginning of paddy construction. Farmers perceive soil productivity Introduction of alley cropping, which is decline. implemented by most farmers. 1989 Establishment of a government-initiated Expansion of planting of commercial “Forest Fire Prevention and Control maize and fruit trees. Start of cabbage, Unit” near the village. ginger and red kidney bean growing. 1991 Road to Pakha improved. A teacher is appointed in Pakha. 1992 Road Thaton-Mae Salong asphalted. SFC starts research activities. The village The village receives electricity and consists of 68 households. 1993 First TV and 2 cars in the village. Expansion of cabbage cropping. 1994 The village consists of 74 households. Start commercial taro cropping. 1995 Start green been cropping. 1996 Reduction of the cultivation area because of reforestation programs initiated by the government. 1997 10 TV’s and 5 cars in the village

1) Events mentioned in the left and the right columns of thesame year do not necessarily have a causal relationship with each other. 2) Hill Area Development Foundation 3) start of Thai education; negotiations on land use with the forestry department; extension on ecological farming; field trips for farmers to other projects/model farmers; (fruit) tree nursery; revolving fund to buy fruit tree saplings and to hire labour to construct irrigated rice terraces. 1.3 Some limitations and dangers of PRA-PLA

147 Appendix 1: Diagnostic methods and tools

· Lecturing instead of listening and learning. Some people cannot avoid it! · PRA-PLA is often a slow process. Some people feel uncomfortable if they do not have a strict, pre-set program. Don’t get impatientor try to rush. · Dominance in group discussions. The powerful dominate the weak, men dominate women, the older dominate the younger. You should try to balance this without offending the local values. It might be necessary to work with separate groups if group domination is too much of a problem. · Matrix ranking exercises. Methodological problems. Although the principles of matrix ranking appear very simple in theory, in reality it takes quite a lot of time, patience and experience to bring such exercises to a good end. Matrix ranking has the advantage of being a very visual way of information exchange, but it is crucial that the visual means (symbols) used are clearly recognised by the farmers. The latter is not always obvious, as was evidenced during the ranking exercise with the men of Pakha Sukchai (see Box 55). Using seeds to quantify the severity of a constraint created confusion among the farmer participants, because a high number of seeds appeared to have a positive connotation of a high yield (the opposite of a constrained yield!). This problem could be easily solved though by replacing seeds with stones. Another practical problem was the number of seeds used for quantification. In the beginning we asked each farmer to put at maximum 10 seeds in one cell (10 seeds = maximum level of constraint) because this would facilitate comparisons afterwards. In reality this turned out to be too difficult for the farmers, especially when due to group interactions farmers changed their minds and added or removed seeds from certain cells. Interpretation pitfalls. The results displayed in Box 55 show that certain trends are quite similar throughout the four different tables, whereas others are very different. This is not surprising as the exercises were done in different villages with different groups of people. Certain observations agree quite well with agricultural theory whereas others are less obvious to explain. We should therefore be careful not to draw overhasty and generalising conclusions that are based on exercises done with only a limited number of people. It may well be that the trends observed are not relevant for the village as a whole because we “sampled” a group quite exceptional farmers (remember Boxes 11 and 12 regarding household typologies). It is, as was previously already mentioned, very essential to cross-check information by repeating the exercise with other people (the more replications, the better), by comparison with secondary data or by applying other more scientific methods of data gathering (experiments and surveys, see further below). · Asking people to talk about their problems is often quite delicate (some people may be too proud or too shy). An elegant way to avoid direct talking about problems is to ask people to talk about (or draw) their aspirations for the future. By knowing these aspirations some household or agricultural problems may be revealed. · Sometimes you get confidential or personal information during the informal discussions. Protect people's identity if necessary.

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· Take care not to “work” all the time when you are at your “research site”. Reserve time to chat with villagers about generalities and participate in their meals and celebrations. · Keep discipline in recording and presenting the information. The fact that much of the data collected is of a qualitative nature should be no excuse to work in a shoddy way! If your notebook is a mess, much of the information might get lost afterwards, which means that you lost your time and that of the villagers. Try to (re)organise your data as soon as possible after (or even during) a fieldtrip. · If you work in a village for a long time, you will inevitably get confronted with the peoples’ health and/or social problems. As you are often in a position that allows you to help at least some people (because of your stronger social and/or economic status) it is very human and tempting to do so. Make sure however that you and your research/extension team are clear on how far these small-scale welfare initiatives can go. If some members of your team are more/less “generous” than others, this can disrupt community respect and the working atmosphere within your team. It is also necessary that the generosity be consistent across households or you may end up doing more damage than good. The same applies topersonal relations. It is very natural that you will develop closer contacts with certain villagers, because your characters or interests may match well together. Take care however that such relationships do not disrupt existing social patterns. Be especially careful in cases of already existing social conflicts or of intimate personal relationships with villagers.

1.4 General tips for field experiments with farmers

· Before setting up an on-farm trial, discuss the issue in detail with the farmers and select the fields of those people who volunteer to participate. Discuss also how to compensate the farmers for eventual crop damage or crop losses. · Keep the trials very simple. Limit the treatments to “with” and “without”. Use bamboo sticks with colour indications to set out squares of at least 5m X 5m. In one square you can observe the “traditional” way of farming, in another square you can try out “the new thing”. The bigger the squares, the better (the effects of the treatments will be more visible) but keep in mind that the risk and disturbance for the farmer should be minimal. In case of an experiment about soil conservation you should reserve a strip of at least 10m meter along the contour line. · Please repeat, in the same field and/or in different fields. One successful observation might be purely accidental. The more replications the better, but discuss with farmers what is feasible. If the cropping season was extremely wet or dry, try again next year. · Setting up a field experiment is useful only if you make regular and detailed observations! Try to involve farmers in this process as much as possible. · Organise farmers’ meetings to compare and evaluate results and to plan for eventual further experimentation. 1.5 Conducting your own soil survey

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· Equipment. To do a basic soil survey you don’t need much high-tech equipment. Your eyes and hands, a spade or hoe (or, alternatively, a soil auger - see Figure 17), a knife, a measuring stick, a spray bottle, a magnifying-glass, a camera, a map (made by yourself, made by the farmers or - if available - a topographic map) and a notebook are the basic instruments. In order to facilitate and organise recording of your observations it is convenient to work with pre-formatted record sheets in stead of a notebook. · Site selection. One of the most characteristic aspects of soils is their variability, i.e. soils differ from place to place, often within very short distances. This variability can be due to variations in the parent material, topography or land use. If you see that there are different rock types in the area, you should look at profiles on each different rock type. In a hilly or mountainous landscape you should observe profiles situated at different positions in the landscape. If you notice distinct differences in land use (e.g. forest vs. agricultural land) or in the growth of agricultural crops (good vs. bad), these differences should be a guide to locate your survey sites. Particularly interesting for soil survey are sites where soil profiles are already exposed (road cuttings, terraces, irrigation channels, rivers, landslides), because such places offer you excellent opportunities for observation and may reduce the number of soil pits or augerings you need to make. Last but not least you should also consult local farmers. Their practical experience with soils in the area can help you to focus your survey work on soil variability that is of particular relevance for agriculture. · Observations. The first thing to look at is the depth of the soil and the presence or absence of rocks and/or stones in the profile, aspects you will instantly notice during the digging of a soil pit or during sampling with an auger. Another important observation is the depth of the top soil. The topsoil can be distinguished from the subsoil by its distinct darker colour. If the colour differences between soil layers are not immediately obvious, clumps of soil can be removed from different depths and placed side by side at the soil surface. Another way to differentiate the different layers of a soil profile is by poking into the soil with a knife, to assess the soil hardness at different depths. Once the different soil layers are determined, you should have a closer look at the soil structure of these various layers by removing large clumps of soil from these layers (with a knife or a spade). If those clumps stay together when removed from the wall you can state that the soil has a strong structure; if, on the other hand, the clumps of soil easily fall apart you can conclude that the soil has a weak structure. To get a general idea of the soil texture without soil analysis, you can conduct a few simple field tests. Spray the soil with enough water to just moisten it and then press the moist soil between your thumb and forefinger. The extent to which a soil “sticks” to your fingers when releasing the pressure gives an indication of the clay content: the more it sticks, the higher the clay content. Another test consists of trying to make a ribbon with the moist soil. Soil which can be squeezed into a ribbon has a high clay content. The longer the ribbon can be made without it breaking, the more clay there is in the soil. A soil which contains much sand will not form ribbons nor stick to your fingers. An additional check for sand content is to take a little bit of soil into your mouth. If the soil “crunches” between your teeth it indicates the presence of sand. Besides

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paying attention to soil structure and soil texture you should also look at soil porosity (the quantity and size of pores, spaces and channels in the soil), which is important for air and water movement in the soil. If you are studying profiles of valley soils you might encounter the soil water table (the depth at which soil is saturated with water), or observe the presence of rust coloured spots, which indicate that in certain periods of the year the profile is saturated with water to the depth of these spots. Last but not least you should have a look at the density and types of roots in the different layers of the soil profile. Their presence (or absence) gives an initial visible account of the suitability (or constraints) of different soil layers/soil types for plant growth. · Soil classification. Based on observations from field surveys and soil analysis, scientists have developed several systems to classify (arrange) soils into different soil types, i.e. groups of soils with a similar set of soil characteristics. Most of these classification systems are too academic to be of practical use for laymen. It can be very useful though to make your own classification system, based on those soil characteristics which show most variability and/or which are of practical relevance to you or to the farmers. Ask farmers whether they have their own names for soil types or soil characteristics. The use of these local names may facilitate future extension work. · Soil mapping. For study, planning or discussion of land use with farmers it is always useful to make a soil map. You can make such a map based on your own survey work (in that case a soil auger will be very useful as a large number of observations has to be made) or you can ask farmers to draw up a soil map. Most interesting is to have both. · Detailed evaluation of soil properties. In some cases more elaborate soil evaluations may be needed than the ones described above. Scientists can be consulted and/or soil samples taken and brought to a lab for analysis (see below). We would like to stress however that extension workers with some experience or a very thorough interest in soils can do many basic soil measurements on their own. Several physical soil properties can be assessed with relatively simple home-made tools or with (simple or very sophisticated) equipment purchased from companies specialising in such equipment. Several chemical soil characteristics can be evaluated in the field by using soil test kits (pH, for instance, can be tested with simple and cheap dye-methods). If you have a good magnifying glass (or even better, a microscope), you can also learn to identify soil pests on your own. For more information about measurement methods, soil survey equipment and laboratories where soils can be analysed we refer to Appendices 3 and 4.

1.6 Tips for adequate soil sampling

Here we will only provide some very general guidelines to give an idea of which factors should be considered when taking soil samples. You should consult more specialised books or ask advice from scientists/lab technicians for more explanations relative to your specific situation and needs.

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· Justification of the sampling. We have mentioned it several times already, but it cannot be emphasised too much that soil sampling is only worth the effort and the money in case (1) detailed soil evaluation is really needed (e.g. to give advise on land use planning if new policies are going to put severe restrictions on agricultural land use in a certain area; to investigate the agricultural and ecological soundness of farmers' practices or proposed alternatives) or (2) for certain practical purposes (e.g. irrigation management; cost-efficient fertiliser application; the cultivation of particularly demanding cash crops such as flowers; control of soil-borne pests). · Selection of the sampling area. Which areas you are going to sample depends on the objectives of your study: you may want to compare soils on different parent materials; good fields with bad fields; zones of good growth with zones of bad growth within the same field; soils on the slope with soils on the valley floor; soils which received different soil management treatments (e.g. burning versus non- burning, tillage versus non-tillage, mulching versus non-mulching). Before starting to take samples, define very clearly what your objectives are and what amount of time and money you want to spend for sample collection and analysis. Make a sketch of the sampling area and try to collect as much secondary information as possible (vegetation, topography, cropping practices, drainage, etc.). · Sampling methods. Before starting the sampling, you should determine whether you need disturbed or undisturbed samples, which depends on the type of soil properties you want to evaluate. Disturbed samples are used for chemical analyses and some physical analyses (soil moisture content and soil texture). They can be taken with a hoe, a spade or an auger and then put into plastic bags. Undisturbed samples are needed for certain physical analyses. Such samples are taken with plastic or metal cylinders to preserve the soil’s structure during sampling and transport. Don’t forget to identify all the samples with clear (water-proof) labels. · Sampling depth. For routine evaluation of the soil nutrient status, samples are taken from the top 15 to 30 cm of the soil. For certain crops or for water management issues the subsoil needs to be sampled also. To sample the subsoil it is most convenient to use a soil auger. · Number of samples. Soils are highly variable and therefore, as a general rule, the more samples you take the better. Because time and budget are generally limited it is common to take mixed samples, i.e. several individual samples are thoroughly mixed in one single bag. Be sure to mix like samples only, i.e. samples from the same field (or part of the field if there are important variations within one field) and from the same soil layer. · Amount of sample. For routine analysis half a kilogram of soil (remove stones and big fragments of organic material if it is a disturbed sample) is sufficient.

1.7 Soil fertility evaluation with pot experiments

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If you are interested in soil fertility evaluation but don't have the budget or tools to have soils analysed, you can use plants as indicators of soil fertility. A direct and relatively simple way to test the chemical fertility status of soils is by means of pot experiments. Pot experiments are experiments in which you grow plants in a limited volume of soil, which allows you to “isolate” the effect various soils have on a given crop by controlling (eliminating) all other factors that affect crop growth under real field conditions (moisture, light, weeds, pests).

1) Take soil samples from the places/fields of interest (see 1.6.) and bring them to a common site (your test area). 2) Put the samples on plastic sheets or in whatever type of large containers. Let them dry if they are very wet. Make each sample homogeneous by thoroughly mixing the sample (don’t mix different samples with each other). 3) Put the soil samples into individual pots or plastic bags. Each field you sampled (or each type of crop you want to test on that field’s soil) is called a treatment. It is best to have more than one pot per treatment (i.e. 2 or 3replications per field or crop). This is a security measure in the case one of your treatments would become damaged. Replications also serve the purpose of ensuring that the results of one treatment did not just happen by chance. 4) In these pots, plant the species you wish to test (test crops). Use crops which the farmers plant or which you intend to grow. Be sure that the seeds or planting materials you use are of good quality. 5) Place the plants in a sunny area and give them water regularly. Take care that light and other conditions are uniform in the testing area. If necessary, fence the area to keep out animals. If possible, locate the test area at a place where farmers pass regularly. Mark the pots/bags so that farmers can easily recognise which ones are from their fields (if the farmers cannot read, you can use colours or pictures of the farmer or of the fields ). 6) Observe the trial regularly and take notes and pictures. Organise group visits with the farmers, to observe and discuss the results. Things that should be observed are plant height, colour of the leaves and stems, development stage (number of leaves, date of flowering, date of grain or fruits formation, date of harvest) and general plant health conditions. At harvest you should evaluate the yield visually, count the numbers of panicles, pods or fruit or even better weigh the harvested products. 7) Finally, how can you interpret and make use of such a trial? If one species of plant grown in pots with different types of soil shows clear differences in growth/yield, you can be confident that there are soil nutrient factors involved. Based on these results, you can find out which soils (fields) are most fertile and/or which crops should best be grown on specific soils. Eventual nutrient problems might be detected by specific nutrient deficiency symptoms exhibited by the plants (consult more specialised books for interpretation). They can be confirmed by new pot experiments that include fertiliser treatments or by soil analysis. Because of the pot testing already done, the number of soil samples and types of analyses can be limited to a few important and/or characteristic situations or soil properties. 8) If you are suspicious of the presence (and harmful influence) of nematodes you can compare pots of soil that received a treatment to kill the nematodes with pots

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containing untreated soils. Nematodes can be killed by letting the soils thoroughly dry in the sun (you can cover them with a black plastic sheet to increase the temperature) or by treating them with a pesticide such as furadan. To have eventual nematodes identified it will be necessary to bring soil samples to a lab.

154 Appendix 2: Some recommendations

2.1 Fallow improvement

· Plants “ideal” for use in improved fallows are plants that: + are easy to get and/or easy to propagate; + are easy to establish (by preference by simple broadcasting of seeds); + are not very demanding on the soil; + show a rapid growth; + give a good and fast soil cover; + can survive long drought periods; + have a deep and extensive root system; + improve the soil during and after the fallow period, i.e. produce a large amount of (nutrient rich) biomass (roots, litter and slashed residues); + are not hosts for crop pests; + are themselves not very sensitive to pest attacks; + are easy to clear and do not regrow after weeding; + have some direct benefit to the farmer (food, cash, ...); + are an excellent fodder for livestock or, on the other hand, are not at all eaten by animals; + are relatively “tolerant” to wildfires; + give a “good” burn after slash (if burning is desired).

· Be careful with exotics! Plants that are introduced for use in improved fallows, hedgerow systems, cover crop systems or green manure systems might be very beneficial, but their introduction is never without risks. Those plants were often selected for their vigorous growth and adaptability and might therefore quickly spread and establish themselves as weeds. They might also bring in new plant pests. Therefore, introducing exotic plants should always be a last-choice option. Only if after “screening” of the local plant resources it would appear that there are no plants available that can do the desired job, one can consider bringing in plant material from outside the system. If this is done, one should be well- informed about the characteristics of that plant and test it out for some time in a small area. Only after confirmation that it is useful and safe it can be extended to the farmers.

2.2 Suggestions for better fire control

· Fire breaks. Fire breaks are the most essential tools in fire control. They are made by simply removing all standing vegetation and/or vegetation residues along the border of a field which is going to be burned. The width of the fire break should depend on the amount of fuel (plant residues) and on the slope of the plot. The greater either of those two are, the wider the firebreak has to be. A rule of thumb is 2 metres wide on flat land and 4 metres minimum on sloping land. Tilling the fire

155 Appendix 2: Some recommendations

break zone (just before burning) will increase its safety (all remaining inflammable materials are worked into the soil). · Timing. Burning should happen by preference in the early dry season, when the surrounding vegetation is still green. In this way there will be less risk of the fire going beyond the boundaries of the target plots. The feasibility of an early burn is of course dependent on the fallow type (time required for drying) and labour availability at that time. · Organisation at village level. Fire control is labour intensive. Instead of burning individually, farmers should burn collectively, helping each other with the establishment of fire breaks and fire fighting. It is very useful to co-ordinate fire control at a village or even higher administrative level, possibly with the help of local governmental authorities. It is even reasonable to fine villagers who cause fire damage because of obvious carelessness. The fine can range from a somewhat symbolic “100 Bath” to much higher amounts in case orchards or property are damaged. · Top-down burning. Usually farmers will light the fire at the lowest part of the field, which makes it very difficult to control because of the speed and heat it generates when moving upslope. A safer alternative is to ignite the top of the field first, as is illustrated in Figure 33. If this is done, the fire will “creep” slope- downwards at a relatively low speed, what makes it more easy to control.

Figure 33. Making a large fire-break, good timing (early in the dry season, when the surrounding vegetation is still green), cooperation between farmers at a village level and top- down burning can help prevent the start of wildfires. With top-down burning fire is lit at the upper part of the field and allowed to go downslope.

156 Appendix 2: Some recommendations

2.3 Suggestions to improve burning practices

· Decreased burning frequency. Instead of burning every year it would be of greater benefit to burn only when there are no other alternatives, i.e. when opening a new field or when pest infestation levels get too high. · Tillage. Considerable amounts of ashes that are left on the soil surface after burning get lost through wind and water erosion. An effective way to prevent loss of ashes after burning is to plow them into the soil as soon as possible after burning. · Ash fertilisation. Besides tillage, there is yet another alternative to prevent loss of ashes and to make more efficient use of the plant nutrients they contain. Ashes can be collected and temporarily stored after burning. When a crop is planted the ashes can be applied as a fertiliser, close to the plant roots (see Figure 34). This principle of ash fertilisation (concentration) is practised by Thai lowland farmers, who use ash from rice stubble to fertilise the individual hills of a following soybean crop. The method would be particularly useful for fields cleared in degraded fallows, which yield low ash amounts upon burning. Besides ashes from field burning, ashes from household kitchen fires can be used as a fertiliser as well. · Chitemene burning. Refers to a burning practice indigenous to northern Zambia, whereby branches of trees are collected over a large area and then piled and burned in a smaller area, in order to obtain “ash circles” or “ash gardens” where crops will be cultivated. These ash gardens are very fertile because of the concentration of ashes into a relatively small area. Vegetative regeneration of the slashed area surrounding the ash gardens happens relatively fast because there was only selective slashing (in fact, it is only trimming) and no burning involved. Creating ash gardens on steep slopes in the highlands of northern Thailand is of course less obvious than creating ash gardens in the flat savannah areas of Africa. On a small scale though, the practice may have applications on gently sloping fields for the cultivation of cash crops or to stimulate a quick establishment of young fruit trees or vegetative buffer strips. · Implementation of soil conservation measures. A major drawback of burning is the removal of a protective soil cover of living or dead plant biomass. The soil remains bare until the cultivated crop and emerging weeds have formed a new vegetation cover. During this period (which can last several weeks to several months, depending on the type of crop grown and on the weed management) serious erosion can take place. If no organic residues are left after the burn, erosion can be reduced by rough tillage, ridge tillage and/or the establishment of declining ditches. If organic materials are still available (due to an incomplete burn or obtainable from neighbouring fallow land) it can be used to establish contour mulch lines or frameworks for erosion control.

157 Appendix 2: Some recommendations

Figure 34. Ash fertilisation. a) Ashes, which remain on the soil after burning a field, are a valuable fertiliser. b) Collecting the ashes in heaps as soon as possible after burning, by using a rake or other device. c) Storing the ashes in a small shelter to prevent losses through wind and rain. d) Using the ash as a fertiliser at the moment of planting or after planting, by applying it individually to each plant or hill. Take care that the ash is mixed with the soil - do not plant seeds directly in the ashes. 2.4 Some guidelines for decision making on burning vs. non-burning

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Table 5.Factors to be considered in realistic and sound decision making about burning vs. non-burning alternatives.

FACTORS TO BE BURNING may be NON-BURNING may CONSIDERED justifiable if be more appropriate if Quality1 and amount of low quality and high high quality and low plant residues amount amount Availability of low high labour/machinery Need for soil conservation low high Need for mulching low high Soil org. matter content high low pH low high N-content high low Pav-content low high Access2 to fertilisers low high Attitude3 towards negative positive fertiliser use Pest infestation level high low Access2 to pesticides low high Attitude3 towards negative positive pesticide use Crop type: . growth cycle annual perennial . economics subsistence cash (with inputs) . pest resistance low high . nutrient demand high low . soil cover 4 high low

Notes:

1) See table 6 below (Appendix 2.6.). 2) With “access” we mean physical infrastructure (transportation and marketing facilities) and financial means and economic incentives. 3) With “attitude” we mean the openness or reluctance to use those inputs. 4) Percentage crop soil cover throughout theentire cropping cycle. A few concrete examples:

· Medium- and long-term fallows vs. short-term fallows.

· When farmers clear a medium term (2 to 5 years) or a long term (more than 5 years) fallow, they are confronted with large amounts of plant residue (from 10 159 Appendix 2: Some recommendations

to more than 30 tonnes per ha), which is very often of a woody nature (shrubs, bamboo, trees). If they want to grow annual crops on the plot, they have no other option than to burn the residues. Non-burning would make tillage and planting virtually impossible.

· When farmers clear a short term fallow (1 year or less; e.g., a dry season fallow) the plant residues are not too bulky and mainly of a non-woody nature. In this case there is no practical need to burn. The plant residues can instead be worked into the soil, used for mulching, used for the establishment of mulch- lines or for making compost. · Natural vs. improved fallows.

· Plant residues from natural fallows consist very often of (woody) materials which decompose slowly. To render the plant nutrients quickly available, burning is the one and only option.

· Improved fallows produce plant residues that have a higher nutrient content (especially N) and that decompose more rapidly. To maximise the benefits of such an improved fallow (especially in terms of organic matter and nitrogen addition) it would be ideal not to burn the residues. If the production of woody biomass is however too abundant to be manageable, farmers may still decide to burn. Despite the losses that will be caused by burning, the overall additions of organic matter and nitrogen from a burned improved fallow may still be higher than those from a burned degraded fallow (due to higher additions through litter fall and root growth during the fallow period; these below ground inputs will be only slightly affected by the burn). · Annual vs. perennial crops.

· When a fallow is cleared to grow annual crops, tillage and planting activities need to take place over the entire plot surface. Besides that, annual crops need a sufficient nutrient supply across a short period (because of their short life cycle). Both factors explain why many subsistence farmers burn their fields for annual crop production.

· When a fallow is cleared to plant perennial crops (trees) or tuber crops that are widely spaced, non-burning becomes a feasible alternative. Tillage and planting activities can happen spot-wise and there is no need for an immediate “injection” of plant nutrients through burning. The residues of the fallow vegetation can be left on the soil as a mulch that protects against erosion, keeps the soil moist and gradually releases its nutrients. Traditional slash- and-mulch systems are actually reported in some of the wetter areas of the tropics, such as Papua New Guinea, Indonesia and Congo. In those systems small patches of forest (0.25 - 0.5 ha) are slashed and various perennial crops are planted in the debris without previous burning. Crops that are grown in such systems are banana, cassava, taro and fruit trees such as durian, jack-fruit, guava, langsat, papaya and lemon. · Orchards. In theory it should be possible (and preferable) to establish orchards in the highlands in similar slash-and-mulch ways as those previously described. Non- burning orchard establishment is however risky in northern Thailand. Because of the long dry season and the yearly occurrence of wildfires, plant residues left on the soil surface in an orchard could catch fire and thereby severely damage or even completely destroy the valuable fruit trees. Eventual non-burn orchard

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management is therefore largely dependent on the success of fire control, which should be guaranteed in the entire village area and beyond (see Appendix 2.2.). It seems that farmers who invest in fruit trees prefer to burn the whole plot before planting (and to burn residues in rows or heaps between the trees once they are established) rather than embracing the possibility of damage through uncontrolled fires from outside their plot. Another practical reason why many farmers still burn the area in between their fruit trees is because of the common (and due to land shortage often necessary) practice of intercropping with rice (or other crops) during the first years of orchard establishment.

2.5 Suggestions to improve vegetative contour strip systems

1) Widening the choice of plants that can be grown in the strips:

· Promoting the planting of crops for contour strip establishment. Probably the easiest way to make vegetative contour strip systems more popular with farmers is to promote crop plants for vegetative strips. The most obvious crops to select for this purpose are those crops which farmers traditionally already mix in their upland fields. The advantage of promoting these crops is that they were already pre- selected by farmers, based on criteria such as usefulness to the farmer, suitability to the cropping environment, availability of planting material, limited competition with the main crop, etc. It shouldn’t be that difficult to encourage a farmer to plant these crops in rows, rather than mixing them “at random” in the field (if it is really at random, because often farmers have very good reasons why they plant crops in specific places). · Widening the choice of non-crop plants for contour strip establishment. There is obviously a need for a wider selection of non-crop plants that produce soil- improving or otherwise beneficial cuttings (as alternatives to the commonly promoted species - see Box 45). Priority should be given to indigenous species (see Appendix 2.1.) and preferably species that the farmers are already using. Only if after a screening of local plant material it appears that there are no interesting possibilities, we might consider to introduce new, promising plants from outside the area.

2) Measures to reduce competition between the main crop and the vegetative strip.

· Increasing strip spacing and decreasing strip width. Given their emphasis on erosion control, most soil conservation manuals and projects recommend very narrow spacing (4m - 6m) and rather wide strips (0.5m - 1m). It seems however that in many cases spacing may be increased (up to 10 m) and that a strip should 161 Appendix 2: Some recommendations

not be wider than 0.5m. If on steep slopes this would still allow too much erosion, the strips can be combined with other erosion prevention measures, in particular mulch lines and declining ditches. · Appropriate strip/crop combinations. More research efforts should be made to find out which types of crops can best be combined with which types of vegetative strips, in order to minimise competition. Prior attention should be given to the rooting patterns of the plants that are grown together. As a general rule (with probably many exceptions) it seems that annual crops are most easily combined with crop strips, whereas perennial crops can be combined with crop as well as non-crop types of strips. · De-synchronising the periods of maximum growth of the main crop and strip plants. This can happen by careful plant selection, by adapting the time of planting of the strips and crops or simply by leaving a field with vegetative strips fallow from time to time (so that the strips can produce biomass during the fallow periods, without competing with a companion crop).

3) Measures to tackle the problem of yield gradients.

· Measures to avoid the formation of yield gradients. There are basically 3 methods to avoid the formation of yield gradients. The first method is moving the strips every year. This method is feasible with annual crop strips and with mulchlines. The second method is to practice no-tillage in between the strips, the feasibility of which depends on the type of crops grown and/or the feasibility and effectiveness of alternative methods to control weeds. The third method is contour tillage, a method that is restricted to slopes that are not too steep. · Measures to counterbalance the yield gradients. Nutrient depletion in the upper part of the inter-strip zone might be counterbalanced by selectively applying fertilisers in that zone (strip cuttings, organic or inorganic fertilisers). · Adapting crop arrangement to the fertility gradients. Crops which have high nutrient demands may be planted in the nutrient-rich lower part of the inter-strip zone or even in the strips themselves. Less nutrient demanding crops may be planted in the nutrient-poor upper part of the inter-strip zone.

2.6 Some general recommendations for appropriate fertiliser use.

· The use of fertilisers that contain easily soluble plant nutrients (inorganic fertilisers, animal manure and ashes) should always be combined with soil conservation measures. · The direct use of commercial fertilisers for subsistence crops (upland rice in particular) is not recommended because this is in general not economically

162 Appendix 2: Some recommendations

profitable. What is very beneficial though is to grow subsistence crops in rotation with cash crops that received fertiliser, so that the first can take advantage of eventual fertiliser residues left by the latter. · In the case of permanent farming without burning or ash fertilisation, the application of phosphorus-fertilisers is unavoidable (heat and ashes spectacularly increase the availability of phosphorus). Phosphorus-fertilisers should by preference be applied in the planting hole (close to the roots) because phosphorus is not very mobile in the soil. · In Table 6 below we roughly classify organic soil amendments that are potentially available in Thailand into different quality groups. The quality refers to the overall NPK-content and to the decomposition rates of the residues (which determines the extent and speed of nutrient release to crops). The main function of low-quality organic soil amendments is to maintain soil organic matter levels and improve the soil structure. They have beneficial effects on the soil nutrient status only in the long term. In the short term they may even provoke a temporary deficiency of plant nutrients (and thus negatively affect crop production), if they are applied in large amounts without additional inorganic fertilisers (this refers in particular to nitrogen-immobilisation - see Box 48). Medium and high quality organic soil amendments are valuable resources for immediate improvement of the soil nutrient content. Whenever they are available and if their application is practically feasible, their use should be preferred over the use of commercial inorganic fertilisers.

Table 6. Types of organic soil amendments potentially available in Thailand

Amendments of low quality rice straw and husks, maize residues, grass residues Amendments of medium quality residues of various legume plants and broadleaf weeds; cow, buffalo, horse and duck manure. Amendments of high quality residues of algae and various types of waterplants; pig, chicken, swallow1 and bat1 manure

1Can be collected in the highlands in limestone areas where caves are abundant

163 Appendix 3: Useful addresses (Thailand)

Here below we provide only a very brief list of useful contact addresses. More complete and updated information can be found on the internet:

: http://www.nectec.or.th/index.html ® extensive information on Thai governmental and academic organisations : http://cmu0.chiangmai.ac.th/~webzone/NGO/ngoindex.html ® listing of NGOs in Thailand and SE Asia : http://www.intanon.nectec.or.th ® general information on Thai highland agricultural development (including, among others, information about the Royal Project and alternative agriculture)

Highland development projects and institutions

Name and address Expertise Contact persons Royal Project horticulture; 65 Moo 1, Suthep Rd., Chiang Mai 50200 plant protection tel.: (053) 277094 Hill Community Education Development highl. social Wirot Kantasuk Project (HCEDP) - NORTHNET development; 255/112 M.Sintana, Mu 2, T. San Pranet, ecol. agriculture; Chiang Mai 50210 marketing of tel/fax.: (053) 380566 organic products Hill Area Devel. Foundation (HADF) highl. social Tuengchai Deetes P.O. Box 11, Mae Chan, Chiang Rai 57110 development; tel./fax: (053) 758266 ecol. agriculture Association for Akha Education and highl. social Culture (AFECT) development 370 Moo 4, T. Rimkok, Chiang Rai 57000 tel./fax.: (053) 714250 Mountain Peoples’ Culture & Developm. highl. social Leo Alting von Geusau Education/Research Project (MPCDE) development 137/1 Nantharam Rd., Chiang Mai 50000 tel.: (053) 236194 Samoeng Highl. Dev. Project (SM-HDP) com. forestry; Samer Limchoowong Huai Keiw Rd, Chiang Mai 50000 soc. development; tel: (053) 217453; fax: (053) 217454 land use planning Karen Baptist Rural Life Project ecol. agriculture; Rupert Nelson P.O. Box 29, Chiang Mai 50000 soil conservation tel.: (053) 243542 Lahu Irrigation Project water resources; Micheal Mann 47 Soi 3, Tung Hotel Rd, Chiang Mai 50000 irrigation tel.: (053) 247139; fax: (053) 247246 Thai-German Highland Development soil conservation; Program (TG-HDP) land use planning; P.O. Box 67, Chiang Mai 50000 highl. social tel.: (053) 217637; fax.: (053) 211780 development

165 Appendix 3: Useful addresses

Research and development centres

Name and address Expertise Contact persons Mae Jo University (MJU) agric. eduction & Mae Jo, Chiang Mai 50290 research MJU Department of Soils and Fertilizers soil survey; Somchai Ongprasert (former headquarter of SFC project) soil analysis; Pathipan Sutigoolabud tel./fax.: (053) 498164 soil conservation MJU Department of Agronomy soil conservation; Anan Pintarak (formerly associated to SFC project) green manures; Apichai Thirathorn tel./fax.: (053) 498168 cropping systems MJU Division of Vegetable Technology horticulture Sathit Wimol Chiang Mai University (CMU) education; Huai Keiw Rd, Chiang Mai 50200 research CMU Department of Soil Science soil survey; Jitti Pinthong tel.: (053) 221699 soil analysis Niwat Hiranburana CMU Multiple Cropping Center cropping systems; Benjavan Rerkasem tel.: (053) 221275; fax.: (053) 210000 GIS; Kanok Rerkasem socioeconomics CMU Tribal Research Institute social research & tel.: (053) 221933; fax.: (053) 222494 development CMU Social Research Institute social research & Chayan Vaddhanaphutti tel./fax.: (053) 211552 development CMU Forest Restoration Research Unit; botany; Stephen Elliot Department of Biology forest regeneration J.F. Maxwell tel.: (053) 221699 ex 3346; fax.: 222268 Royal Forestry Department forestry issues; Huai Keiw Rd, Chiang Mai 50000 watershed tel.: 217847 conservation Payap University R&D Center highl. agriculture; Robert Lamar LPO. 101 (Payap Univ), ChiangMai 50000 socioeconomics; Ken Logsdon tel.: (053) 241255; fax.: (053) 241983 water resources Department of Land Development (DLD) soil survey; Samran Sombatpanit Paholyothin Rd., Bangkok 10900 soil analysis; Pisoot Vijarnsorn tel.: (02 ) 5794775; fax: (02) 5611959 soil conservation DLD, Region 6 soil survey; Sawatdee Boonchee 164 Chiang Mai-Fang Rd, CM 50180 soil conservation Pithag Inthapan tel.: (053) 890109; fax.: (053) 216219 Office of Agricultural R&D, Region 1 cropping systems; Maejo, ChiangMai, 50290 farming systems tel./fax: (053) 498864 Samoeng Upland Rice Exp. Station cultivation of Samoeng, Chiang Mai upland rice and tel./fax: (053) 487016 other cereals Int. Board for Soil Research & soil conservation; Management (IBSRAM) land management PO Box 1, 109 Bangkhen, Bangkok 10900 tel: (02) 5797590; fax: (02) 5611230 Thailand Dev. Research Institute (TDRI) policy research Mingsarn Kaosard 565 Soi Ramkhamhaeng 39, BKK 10310 tel.: (02) 7185460; fax: (02) 7185461

166 Appendix 3: Useful addresses

Development organisations (general)

Name and address Expertise Contact persons Thai Dev. Support Committee (TDSC) social Gothom Arya 409 Soi Rohitsook, Pracharat, Pracharat development (chairman) Bumpen Rd., Huay Kwang, BKK 10310 Project for Ecological Recovery (PER) forestry issues; Witoon same address as TDSC water resources Pungpasacharoen CARE Thailand agr. extension; 185-187 Paholyothin Soi 2, BKK 10500 community dev. tel.: (02) 2795306; fax.: (02) 2714467 Save the Children rural development PO Box 49, Nakhon Sawan 60000 agroforestry; tel.: (056) 221385; IPM CUSO Thailand rural development 17 Phaholyothin Golf Village, BKK 10900 tel.: (02) 5133031; (02) 5135347 FAO Reg. Office for Asia and the Pacific rural development 39 Phra Athit Rd, Bangkok 10200 food security; fax.: (02) 2800445 IPM

Alternative eco-friendly farming

Name and address Expertise Contact persons Mckean Rehabilitation Center green manure; Klaus Prinz PO Box 53, Chiang Mai 50000 improved fallow; tel.: (053) 277049 botan. pesticides Found. for Ed. & Dev. Of Rural Areas vegetable Lawan Chansueberi Wat Pa Daraphirom, Mae Rim, CM 50180 cropping tel.: (053) 297015 Phayao Rural Development Project organic rice 447 Phaholyothin Rd, 56000 Phayao farming tel.: (054) 481364 Technology for Rural Ecolological eco-farming; Decha Siriphat Enrichement (TREE) marketing of (Director) 21 Nenkaew Soi 2, Tha Peeliang, Suphan organic products Buri 72000 tel.: (035) 500803 Alternative Agriculture Network (AAN) eco-farming; Supa Yaimuang 67 Soi Thonglor 3, Sukhumvit 55, marketing of Phrakhanong, Bangkok 10110 organic products tel.: (02) 7126442; fax.: (02) 3911771 policy analysis Green Net marketing of Withoon Panyakul 1108 Soi Sri-on-rod, Sutthisan Rd, organic products; Huaykhwang, Bangkok 10320 policy analysis tel.: (02) 2768023; fax.: (02) 6936622 Appropriate Technology Association botanical 143/172-2 Pinklao Phatthana Village, Bang pesticides; Bamroo, Bangkok Noi, Bangkok 10700 forest tel.: (02) 4343252; fax.: (02) 434 3253 conservation

167 Appendix 3: Useful addresses

Laboratories for soil analysis

Name Address Mae Jo University, Department of Soils and Mae Jo, Chiang Mai 50290 Fertilizers tel./fax.: (053) 498164 Chiang Mai University, Department of Soil Huai Keiw Road, Chiang Mai 50002 Science tel.: (053) 221699 Department of Land Development (DLD) Paholyothin Rd., Bangkok 10900 Soil Analysis Section tel.: (02 ) 5794775; fax: (02) 5611959 DLD, Region 6, Soil Analysis Section Chiang Mai Lampang Highway Amphur Hangchat, Lampang 52190

Companies selling soil and land survey equipment

Name Address Ben Meadows Company, Inc.; Equipment for P.O. Box 80549; Atlanta, G.A. 30366, USA Natural Resource Managers fax.: 1 800 628 2068 e-mail.: [email protected] Eijkelkamp Agrisearch Equipment P.O. Box 4, 6987 ZG Giesbeek, The Netherlands fax.: 31 313 631941 e-mail: [email protected] Palintest Instruments Palintest House, Kingsway, Team Valley, Gateshead, Tyne and Wear, UK, NE 11 ONS fax.: 091 4825372 Forestry Suppliers, Inc. 205 W. Rankin Street, P.O. Box 8397 Jackson, MS 39284-8397, USA ART’s Manufacturing and Supply 105 Harrison, American Falls, ID 83211- 1230, USA

168 Appendix 4: Selected references and further reading

Here below we give only a brief list of selected key-references. More literature on various highland issues can be consulted in libraries of the following Chiang Mai- based institutes (see Appendix 3 for the respective addresses):

& Maejo University Central Library or the specialised library in the Department of Soils and Fertilisers & Chiang Mai University Central Library or the specialised library of the Tribal Research Institute & Payap University Library & Library of the Mountain Peoples’ Culture and Development Education/Research Project (MPCDE) SFC-project

For a complete list of all papers and thesis-reports published by the project we refer to the 1996 Research Highlights, which can be obtained at the Department of Soils and Fertilizers, Mae Jo University.

Anderson M. (1995). Indigenous soil conservation in the highlands of northern Thailand. Training report, Agricultural University of Wageningen, The Netherlands, 145 pages. Bil F. (1992). Indigenous land evaluation: a case study in two hilltribe villages in northern Thailand. M.Sc. thesis, Agricultural University of Wageningen, The Netherlands, 200 pages. Cools D. (1996). Household typology and land use dynamics in a northern Thai highland village. M.Sc. thesis, KULeuven, Belgium, 106 pages. Ongprasert S. (1991). Changes of some physical properties of the soil on sloping land under traditional and conservation farming systems. In: Yoshida T., Yamazaki K. and Nakano M. (eds.) (1991). Dynamics and its control of soils in tropical monsoon regions. Report of soil survey and research in Thailand. Department od Soil Science, Kasetsart University, Bangkok, Thailand, pages 119-135. Ongprasert S. and Turkelboom F. (1996). 20 Years of alley cropping research and extension on the slopes of northern Thailand. In: Proceedings of the Discussion Forum ”Highland Farming: Soil and the Future?”, organised by the SFC project and Mae Jo University, 21-24 December 1995, Chiang Mai, Thailand. Pages 55-71. Ongprasert S. and Prinz C. (1997). Use of viny legumes as accelerated seasonal fallow: an innovation of intensified shifting cultivation in northern Thailand. Poster paper presented at the ”International Workshop on Indigenous Strategies of Shifting Cultivation in Southeast Asia”, organised by ICRAF, 23- 27 June 1997, Bogor, Indonesia,

169 Appendix 4: Selected references and further reading

Pelletier J. (1994). Farmers’ perception of sustainability on their farm: voices from the mountains. Working Report presented to the Technical Section of the Office of Land Development Region 6, Chiang Mai, Thailand. Pintarak A. and Juntorn W. (1996). Improved fallow management. In: Proceedings of the Discussion Forum ”Highland Farming: Soil and the Future?”, organised by the SFC project and Mae Jo University, 21- 24 December 1995, Chiang Mai, Thailand. Pages 177-187. SFC (1992). Research report 1990-1991. SFC, Mae Jo, Thailand, 88 pages. SFC (1993). Research report 1989-1992. SFC, Mae Jo, Thailand, 255 pages. SFC (1994). Research report 1993. SFC, Mae Jo, Thailand, 212 pages. SFC (1995). Research report 1994. SFC, Mae Jo, Thailand, 138 pages. SFC (1996). Research Highlights of the Soil Fertility Conservation Project (1989-1995). SFC, Mae Jo, Thailand, 52 pages. SFC (1996). Proceedings of the Discussion Forum ”Highland Farming: Soil and the Future?”, organised by the SFC project and Mae Jo University, 21-24 December 1995, Chiang Mai, Thailand, 212 pages. Turkelboom F., Ongprasert S. and Taejajae U. (1996). Soil fertility dynamics in steep land alley farming. Paper presented at the ”Seventh Annual Meeting of the Management of Sloping Lands for Sustainable Agriculture in Asia Network” organised by DLD and IBSRAM, 16-20 October 1995, Chiang Mai, Thailand, 15 pages. Turkelboom F., Van Keer K., Ongprasert S., Sutigoolabud P. and Pelletier J. (1996). The changing landscape of the northern Thai hills: adaptive strategies to increasing land pressure. In: Proceedings of the symposioum ”Montane Mainland Southeast Asia in Transition” organised by Chiang Mai University, 12-16 November 1995, Chiang Mai, Thailand, pages 436-461. Turkelboom F., Poesen J., Ohler I., Van Keer K., Ongprasert S. and K. Vlassak (1997). Assesement of tillage erosion rates on steep slopes in northern Thailand. Catena 29 (1997) 29-44. Turkelboom F. and Trébuil G. (1998). An integrative approach to on-farm erosion research: application to northern Thailand highlands. In: Assessing the causes and impact of soil erosion at multiple scales, CABI and IBSRAM (in press). Van Keer K. (1992). Soil variability along steep slopes in the highlands of northern Thailand. M.Sc. thesis, KULeuven, Belgium, 84 pages. (in Dutch with English abstract). Van Keer K., Turkelboom F. and Vlassak K. (1995). Soil conservation and weed control: friends or foes? ILEIA Newsletter ( 1995) 14-15.

170 Appendix 4: Selected references and further reading

Van Keer K., Thirathon A. and Jannsen W. (1996). To burn or not to burn? In: Proceedings of the Discussion Forum ”Highland Farming: Soil and the Future?”, organised by the SFC project and Mae Jo University, 21-24 December 1995, Chiang Mai, Thailand, pages 105-125. Van Keer K., Thirathon A. and Vejpas C. (1996). Weed problems in a transitional upland rice based swidden system in northern Thailand. In: Proceedings of the Discussion Forum ”Highland Farming: Soil and the Future?”, organised by the SFC project and Mae Jo University, 21-24 December 1995, Chiang Mai, Thailand. Pages 161-176. Soils general

Brady N. C. (1990). The Nature and Properties of Soils. Macmillan Publishing Company, New York, USA, 740 pages. Lal R. and Sanchez P.A. (eds.) (1992). Myths and Sience of Soils of the Tropics. Soil Science Society of America Special Publication Number 29. Soil Science Society of America, Madison, Wisconsin, USA, 204 pages. Landon J. (1991). Booker Tropical Soil Manual, A Handbook for Soil Survey and Agricultural Land Evaluation in the Tropics and Subtropics. Longman Scientific and Technical, England, 465 pages. Nye P. H. and Greenland D. J. (1960). The soil under shifting cultivation. Technical Communication No. 51, Commonwealth Bureau of Soils, Harpenden, U. K., 156 pages. Sanchez P. A. (1976). Properties and Management of soils in the tropics. John Wiley & Sons, New York, USA, 605 pages. Highland soils northern Thailand

Hansen P. K. (1991). Characteristics and Formation of Soils in a Mountainous Watershed Area in Northern Thailand. Chemistry Department, Royal Veterinary and Agricultural University, Copenhagen, 38 pages. Hendricks C. A. (1981). Soil-vegetation relations in the north continental highland region of Thailand: a preliminary investigation of soil-vegetation correlation. Technical bulletin No. 32, Soil Survey Division, DLD, Thailand, 112 pages. Kubiniok J. (1992). Soils and weathering as indicators of landform development in the mountains and basins of northern Thailand. Zeitschrift fur Geomorphologie N.E., Suppl.-Bd 91 (1992) 67-78. Yemefak M. (1995). Fertility of Tropical Forest Soils in Relation to Physiography, Parent material and Alternative Land Use. M. Sc. Thesis, ITC, Enschede, The Netherlands, 171 pages.

171 Appendix 4: Selected references and further reading

Fertilisers

Bøckman O. C., Kaarstad O., Lie O.H. and Richards I. (1990). Agriculture and Fertilizers. Agricultural Group, Norsk Hydro a.s., Oslo, Norway, 245 pages. Janssen B.H. (1993). Integrated nutrient management: the use of organic and mineral fertilzers. In: van Reuler H. and Prins W.H. (eds.) (1993). The role of plant nutrients for sustainable food crop production in Sub-Saharan Africa. Dutch Association of Fertilizer Producers (VKP), Leidschendam, The Netherlands, pages 89 - 105. Tisdale S. L., Nelson W. L., Beaton J. D. and Havlin J. L. (1993). Soil Fertility and Fertilizers. Macmillan Publishing Company, New York, USA, 634 pages. Soil conservation

Fujisaka S. (1993). Learning from six reasons why farmers do not adopt innovations intended to improve sustainability of upland agriculture. Agricultural Systems 46 (4):409-425. Sathirathai S. (1995). Roles of Property Rights on the Adoption of Conservation Practices in Northern Thailand. TEI Quarterly Environmental Journal, Vol. 3 No. 2, pages 41 - 54. Soil and Water Conservation Society of Thailand, 1995. Guidelines for Soil Conservation Extension. Department of Land Development, Bangkok, Thailand, 8 pages. Pahlman C. (1990). Farmers’ perception of the sustainability of upland farming systems of northern Thailand. M. Sc. Thesis, University of Canberra, Australia. Watson H.R. (1995). The development of sloping agricultural land technology (SALT) in the Philippines. Extension Bulletin 400, Food and Fertilizer Technology Center, Taipei, Taiwan, 21 pages. Highland issues northern Thailand

McKinnon J. and Vienne B. (eds.) (1989). Hill Tribes Today. White Lotus, Bangkok, Thailand, 507 pages. Grandstaff T. B. (1980). Shifting Cultivation in Northern Thailand. Possibilities for Development. Resource Systems Theory and Methodology Series, No. 3, The United Nations University, Tokyo, Japan, 44 pages. Kunstadter P., Chapman E.C. and Sabhasri S. (eds.) (1978). Farmers in the forest: Economic Development and Marginal Agriculture in Northern Thailand. East-West Center, Hawaii, 400 pages. Lewis P. and Lewis E. (1984). Peoples of the Golden Triangle. Thames and Hudson, London, England, 300 pages.

172 Appendix 4: Selected references and further reading

Rerkasem K. and Rerkasem B. (1994). Shifting cultivation in Thailand: its current situations and dynamics in the context of highland development. IIED, London. Royal Thai Government, Ministry of Agriculture and Cooperatives, Department of Land Development (1985). Thailand Northern Upland Agriculture. Chiang Mai, Thailand, 165 pages. Shubert B., Backhaus C., Humann J., Kleipass L., Michel K., Seyfferth A., Windish P. and Zoumer K. B. (1986). Proposals for Farmings Systems-Oriented Crop Research of Wawi Highland Agricultural research Station in Northern Thailand. Centre for Advanced Training in Agricultural development, Technical University of Berlin, Germany, 322 pages. Suwanarat G. (1996). Tragedy of the commons revisited: the case of the northern Thai highlands. In: Proceedings of the Discussion Forum ”Highland Farming: Soil and the Future?”, organised by the SFC project and Mae Jo University, 21-24 December 1995, Chiang Mai, Thailand, pages 46- 54. Thomas D. E. (1996). Opportunities and limitations for agroforestry systems in the highlands of north Thailand. In: Proceedings of the Discussion Forum ”Highland Farming: Soil and the Future?”, organised by the SFC project and Mae Jo University, 21-24 December 1995, Chiang Mai, Thailand, pages 126-160. Upland/highland issues Southeast Asia

Bass S. and Morisson E. (1994). Shifting Cultivation in Thailand, Laos and Vietnam: Regional Overview and Policy Recommendations. IIED, London, UK. CMU (1996). Proceedings of the symposioum ”Montane Mainland Southeast Asia in Transition” organised by Chiang Mai University, 12-16 November 1995, Chiang Mai, Thailand, 497 pages. FAO and IIRR (1995). Resource management for upland areas in Southeast Asia. Farm Field Document 2. FAO, Bangkok, Thailand and IIRR, Silang, Cavite, Philippines, 207 pages. Smallholder tropical farming systems general

Beets W. C. (1990). Raising and Sustaining of Smallholder Farming Systems in the Tropics. AgBé Publishing, The Netherlands. Kotschi J., Waters-Bayer A., Adelhelm R. and Ulrich H. (1989). Ecofarming in agricultural development. Margraf Scientific Publishers, Weikersheim, Germany, 132 pages. Reyntjes C., Haverkort B. and Waters-Bayer A. (1992). Farming for the Future. An Introduction to Low-External-Input and Sustainable Agriculture, The Macmillan Press LTD, 250 pages.

173 Appendix 4: Selected references and further reading

Forest issues

Durno J. (1994). From Imperata Forest to Community Forest: the case of Pakhasukjai. Unpublished Draft Report, HADF, Chiang Rai, Thailand, 159 pages. Leungaramsri P. and Rajesh N. (1992). The future of forests and people after the logging ban. Project for Ecological Recovery, Bangkok, Thailand, 201 pages. Crops

Anderson E.F. (1993). Plants and People of the Golden Triangle. Ethnobotany of the Hill Tribes of Northern Thailand. Silkworm Books, Chiang Mai, Thailand, 279 pages. Chantaboon Sutthi (1995). (a) Swidden Crop Germplasms Highlander of Thailand. Tribal Research Institute, Chiang Mai, Thailand, 111 pages. (only a listing, no explanations) (b) Non-Swidden Crop Germplasms Highlander of Thailand. Tribal Research Institute, Chiang Mai, Thailand, 149 pages. (only a listing, no explanations) Weeds

Akobundu I. O. (1987). Weed Science in the Tropics: Priciples and Practices. John Wiley & Sons, 522 pages. Harada J., Paisooksantivatana Y. and Zungsontiporn S. (1987). Weeds in the Highlands of Northern Thailand, Botany and Weed Science Division, Department of Agriculture, Bangkok, Thailand, 125 pages. Radanachaless T. and Maxwell J. F. (1994). Weeds of Soybean Fields in Thailand. Multiple Cropping Center, CMU, Chiang Mai, Thailand, 408 pages. Participation in Development

Carlier H. (1996). Working together for a sustainable agriculture: inspiration for development workers. Non-published draft document, Zutphen, The Netherlands, 63 pages. J. N Pretty, I. Guyt, I. Scoones and J. Thompson (eds.) (1995). A Trainer’s Guide for Participatory Learning and Action. IIED, London. Van Veldhuizen L., Waters-Bayer A., Ramirez R., Johnson D. A. and Tompson J. (eds.) (1997). Farmers’ Research in Practice: Lessons from the Field. Intermediate Technology Publications, London, UK, 285 pages.

174 Appendix 5: Glossary (based on references listed in Appendix 4).

Acidification. Gradual decrease of the soil pH as a result of natural or human-induced processes. Acid soils. Soils with a pH value < 7. Agricultural extension. In the ”classical” meaning this refers to activities that disseminate research findings and advice on agricultural practices to farmers. In a more contemporary interpretation it also includes participatory approaches to strengthen farmers’ problem solving and communication skills. Agrochemicals. Chemical substances that are used in agriculture. The term is generally associated with substances that are industrially prepared and commercially marketed (e.g. fertilisers, pesticides, hormones) but any ”home-made” extract that is used for agricultural purposes can be considered as an agrochemical as well (e.g. ash extracts, salt solutions, botanical pesticides). Agroecosystem. An ecological system (ecosystem) modified by people to produce food, fibre, wood, meat and various other agricultural and/or natural products for human use. Agroforestry. An agricultural land use system which deliberately combines trees with arable crops and/or livestock. Alkaline soils. Soils with a pH value > 7. Alley cropping. See contour hedgerow systems. Annual crops/plant. Crops/plants that grow for only one season or year before dying.

Biodiversity. The number of species of living organisms (plants and/or animals) within a certain area. The higher the biodiversity the ”better” the natural condition of that area. Biomass. The organic material produced by living organisms (plants or animals). Botanical pesticides. Plant-derived pesticides.

Canopy. The uppermost layer of a plant community. Cash cropping/farming. See commercial agriculture/farming. Chemical. (a) More or less pure (organic or inorganic) compounds that were formed trough a natural or artificial (industrial) process. (b) In the (non-scientific) agricultural literature, the adjective chemical is often used in the connotative sense of ”artificial” or ”environment- unfriendly” (the opposite of ”natural” or ecological). Chemical fertilisers. See fertilisers. Clay. Inorganic fraction of the soil with a diameter < 0.002 mm Clayey soils. Soils that contain a lot of clay. Commercial agriculture/farming. Farming aiming at income generation (the farm products are sold at the market). Compost. Fertiliser derived from organic matter subjected to an accelerated process of organic matter decomposition. This process focuses on optimising moisture content, temperature, nutrient composition of the final product and species composition of the populations of biodegrading organisms. Contour (line). An imaginary line connecting points of equal elevation on the soil surface. Contour mulch lines. Narrow strips of piled-up plant residues along the contour lines. Contour hedgerow. A closely planted contour strip of shrubs or small trees.

175 Appendix 5: Glossary

Contour hedgerow systems. Soil conservation cropping systems in which annual crops are grown in between contour hedgerows composed of fast-growing nitrogen fixing shrubs or trees. Besides the presence of hedgerows as soil conservation structures, the systems include a range of ”model” practices such as permanent farming with crop rotation, no-burning, no- or minimum tillage and use of the hedgerow cuttings as mulch for the annual crops or as livestock fodder. Hedgerow systems are also known as alley cropping systems. Very similar to hedgerow systems are grass strip systems, in which the vegetative contour strips consist of perennial grasses. Contour planting/cropping/farming. Growing plants in rows parallel to the contour lines. Contour tillage. Tillage done parallel with the contour lines. Cover crop. A close-growing crop grown primarily for the purpose of protecting and improving the soil between periods of regular crop production or between other crops or trees. Cropping system. The cropping patterns used on a farm, which comprises the crop choice, the crop spatial arrangements and rotations, all soil and crop management practices, the technology which is available and the interactions with other activities/resources on the farm. Crop rotation. Changing the crops grown on a particular piece of land from season to season. May also include a fallow period. Crop succession. See crop rotation.

Deciduous forest. A forest composed of trees that shed their leaves every year at a certain season - compare evergreen forest. Degraded fallow. See fallow degradation. Degraded soils. See soil degradation. Dibbling stick. A (long) stick (often of bamboo) used to make holes for planting crops. Diversification. Combining several agricultural (and non-agricultural) activities at the household or at the community level. Diversion ditches. Ditches which run diagonal to the slope, aiming at intercepting and draining runoff water and soil sediments. Drainage. (a) The removal of excess water (from rainfall or irrigation) from the soil, along the surface (external drainage or runoff) or through the soil to deeper soil layers (internal drainage or percolation). (b) Term used to denote a physical state of the soil, i.e. the frequency and duration of periods when the soil is free from saturation with water. The extent in which a soil is drained depends on its inherent physical properties and on its position in the landscape. Drop structures. Structures made to slow down the flow of water in channels. Dryland agriculture/farming. See rainfed agriculture/farming. Dryland rice. See rainfed rice.

Ecology. The science of the interactions between living organisms and between living organisms and their environment. Eco-, Ecological. Prefix and adjective to denote concepts or methods which bear upon ecology. In the (non-scientific) literature about agriculture eco- and ecological are often used in a connotative sense of ”environment friendly” (the opposite ofchemical ). Ecosystem. The communities of all living organisms and their physical environment in a certain area, including all the interactions that exist. Ecoregion (ecozone). A geographic area characterised by one or several specific ecosystems.

176 Appendix 5: Glossary

Erosion. See soil erosion. Evergreen forest. A forest composed of trees that retain their leaves and remain green throughout the year. Eutrophication. The enrichment of water with plant nutrients (mainly N and P) to such an extent that it may cause pollution and massive growth of algae, which on its turn may lead to a depletion of oxygen in the water. Exotic. Introduced (plant or animal species), not native to the area. The opposite of indigenous. Extensive agriculture/cultivation/land use. The management of land for agricultural or other purposes over a large area with very little input per unit of area - compare intensive agriculture. Extensification. See extensive agriculture. Extension. See agricultural extension. Extension worker. A person who carries out agricultural extension.

Facilitator. The contemporary interpretation of an extension worker, i.e. a person who stimulates and teaches farmers how to solve problems on their own. Fallow. A piece of land which is left uncultivated for a certain period, but which has been cultivated before and will be cultivated in the future. Fallow degradation. A deterioration of the quality of the vegetation and the soil of a fallow plot. Fallow period. A period of no-cultivation in between two periods of cultivation. Fallow regeneration. Re-establishment of the fallow vegetation by natural regrowth. Fallow (based/rotation) systems. Cropping/farming systems that are based on the practice of fallowing. Fallowing. The practice of alternating periods of cultivation with periods of no-cultivation. Farming system. A unique arrangement and management of farming (and non-farming) activities, in response to the biophysical, cultural, socio-economic and political environment and in accordance with the household’s goals, preferences and available resources. Fertiliser. Any material which is added to the soil in order to supply one or more nutrients. Flooding. (a) Natural phenomenon (calamity). (b) A type of irrigation whereby water is released from field ditches and forced to flood the land.

Genetic engineering. High-tech methods to change the genetic material of living organisms. Grass strip (systems). See hedgerow systems. Gravely soils. Soils that contain a lot of small stones (gravel). Global change. See greenhouse-effect. Global warming. See greenhouse-effect. Greenhouse-effect. The warming of the earth’s atmosphere as a result of the blanketing of the earth by accumulated gases such as carbon dioxide and methane. Such gases keep earth’s heat from escaping into space. While such an effect is theoretically possible, global warming caused by the greenhouse effect is still under scientific debate. Greenhouse gasses. Gasses that contribute to the greenhouse effect. Green manure. Fresh or dry plant biomass that is applied to the soil as a fertiliser. Gully (erosion). See soil erosion.

177 Appendix 5: Glossary

Gully plug. A pile of plant residues used to (partly) fill up an erosion gully in order to prevent its further incision and expansion.

Herbaceous plants. A non-woody plant. Herbicide. A substance used to control weeds. Hedgerow (systems). See contour hedgerow systems. Hill (planting). The planting (or seeding) of more then one plant in one single planting hole. Hill planting is typically done for rice and often also for maize. Hill tribes. General term used to refer to various ethnic groups that populate the highlands of northern Thailand and other areas of the Upper Mekhongecoregion . Hoe. Traditional tool to cultivate the soil (depicted in various drawings throughout the book). Homegarden. Small, intensively managed piece of land that is used for the cultivation of vegetables, herbs, tuber crops, fruits, etc. Homegardens are generally (not always) located nearby the house and are often fenced. Irrigation and application of animal manure are common practices. Household typology. A classification of households into relatively homogenous groups which have similar resource-bases and follow similar strategies in using these resources for agricultural production and other (non-farming) activities.

Improved varieties. Crop plant varieties that are created by men (through plant breeding and/or genetic engineering) in order to be more suited for agricultural production. Indigenous (knowledge, tools, animals, plants). Concepts, objects or living organisms that have been common to an area for a very long time. Opposite ofexotic . Inorganic compounds/materials. Naturally occurring or industrially prepared compounds which are not organic in nature. Examples are metal, rock, clay, plant nutrients, salt, etc. Inorganic fertilisers. Fertilisers that have an organic nature. Infiltration (of water). The downward entry of water into the soil. Inorganic fertilisers. See fertilisers. Intensive agriculture/cultivation/land use. The management of land for agricultural and/or forestry related activities, concentrated on a small area and with much external inputs and/or labour used per unit area. Intensification. See intensive agriculture/land use. Indicator plants. Plants whose presence (or absence) gives an indication of the quality of the soil. Infiltration. See soil physical properties. Irrigated agriculture/farming. Farming with artificial supply of water - compare rainfed agriculture/farming. Irrigated rice. Rice grown under irrigated conditions (seeflooding ). Irrigation. The application of water to an area to enhance crop production.

Land degradation. A deterioration of the quality of the vegetation, soil and water resources in a certain area. Land evaluation. The interpretation of soil and land survey data with regard to the current or intended use of the land. Land evaluation has a broader scope than soil evaluation, because it considers all possible types of land use, not only agriculture. The evaluation is based on an

178 Appendix 5: Glossary interpretation of the entire biophysical environment, which includes soils, topography, climate, natural drainage systems, vegetation cover, wildlife, etc. Land pressure. At its most basic level, land pressure is simply the demand for land as caused by growth of a population. At a more subtle level, it is a reference to the necessity of using a given piece of land - high pressures occur when there is little land around to choose from. Land slide. The downslope movement of a large piece of land as a result of oversaturation with water. Land use (types/systems). The way the land is used in a particular area. Land can be used for agriculture, livestock raising, forestry, water storage and/or transport, road infrastructure and housing infrastructure. Land use planning. The division and assignment of land to specific uses, generally as the responsibility of a municipal or regional public body. Leaching. The transport (by water) of nutrients or other soil compounds to deeper layers of the soil. Legume. Any plant species belonging to the Leguminosae family. This is a very important plant family because it includes many valuable food (various beans and peas), forage and green manure crops and because the vast majority of legume plants can carry out nitrogen- fixation. Litter. All sorts of plant residues (leafs in particular) that cover soil as a result of natural dy- off processes. Loam. Inorganic fraction of the soil with a diameter between 0.002 mm and 0.05 mm. Loamy soils. Soils that contain a lot of clay. Lodging. Falling over plants, either by uprooting or steam breakage.

Micronutrient. A plant nutrient that is needed in only very small amounts. Micronutrient depletion. A serious decrease of a soil’s micro-nutrient content. Mineralisation. The conversion of an element from an organic to an inorganic form as a result of microbial decomposition. Mixed cropping. The growing of two or more crops simultaneously on the same piece of land. In traditional cropping systems this happens without any regular plant arrangement. Monocropping/culture. The repetitive growing of the same, single crop species on the same piece of land. Monsoon. Periodic wind that determines the wet and dry seasons in Southeast Asia. Monsoonal (climate). See monsoon. Mulch. Plant residues or other materials (e.g. plastic) used to cover the soil surface during or after cropping. Mulch lines. See contour mulch lines. Mulching. See mulch.

NGO. Non-governmental organisation. Nematodes. Microscopic soil animals resembling worms. Many nematode species are crop pests that attack plant roots. Niche. A specific ”portion” or ”area” of the environment occupied by a certain species.

179 Appendix 5: Glossary

Nitrogen (N). An essential plant nutrient that is required in great amounts by most plants. No rock or rock residues contain N, all soil nitrogen is derived from the organic part of the soil. This is, among others, one of the major reasons to conserve or even increase soil organic matter. But even under optimum soil organic matter conditions most (tropical) soils cannot supply sufficient nitrogen if they are continuously cultivated, unless nitrogen-containing fertilisers are applied.

Nitrogen fixation. The biological conversion of elemental atmospheric nitrogen (N2) into organic compounds. This happens by specialised micro-organisms that can ”catch” nitrogen from the air (where it is present abundantly as a gas) and turn it into plant available nitrogen forms. Some micro-organisms can do this on their own, but the most important ones require a close association with the roots of plants (legumes). Nutrient. See plant nutrients. Nutrient deficiency. The lack of one or more plant nutrients, which manifests itself in an abnormal plant growth (discoloration, stunting, no flowering, etc.). Nutrient immobilisation. The conversion of an element from an inorganic to an organic form in microbial tissues - compare mineralisation. Nutrient (re)cycling. The recurrent flow of plant nutrients through a field, farm or larger agroecosystem, such that a major portion of the mobile nutrients are kept within the system and reused.

Off-farm labour. Wage labour activities outside the farm. On-farm research. Research conducted in farmers’ fields. On-station research. Research carried in fields located in an enclosed area that is managed and controlled by scientists. Organic (compounds, materials). In a strict scientific definition this refers to naturally occurring or industrially prepared compounds that contain carbon as their principal element. In a more general sense this refers to all materials that are derived from living organisms. Organic farming. Agricultural systems in which plant nutrient management is based on nutrient recycling through a sound use of organic matter. Organic fertilisers. See fertilisers. Organic matter decomposition. The degradation of organic materials by various types of soil organisms (see also mineralisation).

Paddy rice. See irrigated rice. Parasite. An organism deriving its food from the living body of another organism. Parent material. The unconsolidated and more or less weathered mineral and organic material from which soils are formed. Participatory approaches/methodologies. A set of principles and methods to let farmers participate in the investigation of development problems and in the subsequent planning, implementation and evaluation of development activities. Plant breeding. Men-induced crossing of plants in order to obtain plants that have certain desired characteristics. PLA. Participatory learning and action. PRA. Participatory rural appraisal. See participatory approaches. Percolation. See drainage.

180 Appendix 5: Glossary

Perennial crops/plants. Crops/plants that grow for more than one year - compare annual crops/plants. Pest. Any type of living organisms (animals, insects, fungi, bacteria, viruses, nematodes, weeds, etc.) which people want to control or eliminate because of the harm they can cause to crops. Pesticide. A substance for controlling or destroying pests. Phosphorus (P). An essential plant nutrient, derived from both rock and plant residues. Due to chemical processes, phosphorus is strongly attached to soil particles. Even though a soil may have a high phosphorus content, most of it may be unavailable to plants - a problem that is typical for almost any soil but particularly serious in highly weathered tropical soils. It is very difficult to maintain phosphorus reserves by applying only plant residues. Plant nutrients. Chemical elements (”elementary building blocks”) that plants need for their growth. Plant nutrient availability. The extent to which a nutrient can be readily taken up by plants. Plant residues. Plant material that remains in the field after clearing, pruning or harvest activities. Pioneer swidden cultivation/agriculture/farming. See Box 1 page 3. Potassium (K). An essential plant nutrient, mainly derived from rock residues. In most soils (with the exception of very sandy soils) potassium is present in sufficient amounts to support normal crop production. Potassium uptake by crops is high though, and if soils are continuously cultivated this will eventually lead to depletion of the potassium reserves unless fertilisers are applied. Primary forest. Refers to a natural forest that has never (or at least not since a very long time) been logged or severely disturbed by human activities. See alsosecondary forest.

Rainfed agriculture/farming. Agriculture that is entirely dependent on rainfall for the water supply of the cultivated crops. Rainfed rice. Rice grown under rainfed conditions. Relay cropping. Growing two or more crops simultaneously during part of the life cycle of each crop. The second crop is planted after the first crop has reached its reproductive phase but before it is ready for harvest. Rill (erosion). See soil erosion. Riparian zone. The zone adjacent to a river. Rotational swidden cultivation/agriculture/farming. See Box 1 page 3. Run-off (water). Rain or irrigation water that does not enter the soil but flows across the soil surface. This water will scour loose soil from the surface of the land, especially if the land has no or very little vegetative cover (see alsoerosion ).

Sand. Inorganic fraction of the soil with a diameter between 0.05 mm and 2 mm. Sandy soils. Soils that contain a lot of sand. Secondary forest. Refers to a forest that has been disturbed (by logging, crop cultivation or livestock raising) in the recent past but has since re-established by natural regrowth. Soil acidity (pH). See Box 14 page 29. Soil aggregate. Many small soil particles that stick together in single larger entity (a clod or clump). See also soil physical properties - soil structure. Soil auger. An instrument to take soil samples (see Figure 17).

181 Appendix 5: Glossary

Soil biological properties. Relate to the kind and number of organisms live below the soil surface. Soil chemical properties. Relate to the kinds, amounts and availability of substances that are nutrients, non-nutrients and toxins to plants. Soil-borne pest. Pests which complete at least part of their life cycle in the soil. They damage plants by directly affecting the roots. Nematodes are an example of soil-borne pests. Soil (suitability) evaluation. The interpretation of soil survey/analysis data with regard to the current or intended agricultural use of the soil. The result is a practical classification (and often also a map) of the soils in a specific area, with concrete recommendations for a beneficial and sustainable management of the soils. See also land evaluation. Soil conservation. A combination of all soil/crop management and land use practices that safeguard the soil against degradation. Soil degradation. A deterioration of the quality of the soil due to natural or human-induced degradation processes (erosion, structural deterioration, nutrient depletion, pollution, etc.). Soil erosion. The downslope transport of soil by any means such as plowing or hoeing (dry erosion) or by runoff water (water-induced erosion). Three types of water-induced erosion are generally recognised: Sheet erosion. An erosion process whereby soil is removed more or less uniformly from every part of the soil surface. Such erosion is sometimes evidenced by small ”pillars” left standing on the soil Rill erosion. An erosion process whereby numerous small channels of only several centimetres in depth are formed. Occurs mainly on recently cultivated soils. Gully erosion. An erosion process caused by large amounts of fast moving water, resulting in deep and wide fissures in the soil surface. Soil fertility. In a narrow sense soil fertility refers to the capability of a soil to provide nutrients in quantities and proportions essential to the growth of plants. In a broader agricultural meaning it refers to the capability of a soil to sustain crop production, which is dependent on the overall picture of a soils’ physical, chemical and biological properties and interactions with the larger biophysical environment (landscape position, climate, presence or absence of weed and soil-borne-pests). Soil organic matter. The organic fraction of the soil that includes plant and animal residues in various stages of decomposition, cells and tissues of living soil organisms and substances synthesised by soil organisms. Soil physical properties. The properties of a soil we can see or feel. Important physical properties are: Temperature. Hardness. The resistance of a soil to the penetration force of roots (or tools). Soil depth. The distance from the soil surface to a layer which cannot be penetrated by plant roots, very often a stone layer or rock. Texture. The relative contributions of sand, silt and clay, which are mineral soil fractions with different diameters (sand>silt>clay). The soil texture greatly affects various soil physical and chemical properties. Clayey soils are in general more fertile than sandy soils as clay is able to retain nutrients while in sandy soils, nutrients are easily leached through the soil profile. Soils with an extreme textural composition (extremely sandy, silty or clayey) are often unfavourable for plant growth or difficult to cultivate.

182 Appendix 5: Glossary

Stickiness. the degree to which soil ”sticks” to your fingers, shoes, plow or hoe. The more sticky the soil, the more clay it contains. Structure. Soil is a mixture of particles which may (or may not) bind to each other to form soil aggregates. The type and degree of arrangement (packing) of these particles is called soil structure. A ”good structure” is an arrangement which shows resistance to erosion forces and creates optimum conditions for air and water movement and root development. Soil structure can be greatly influenced (for better or for worse) by cultivation practices Porosity. Refers to the volume of soil which is occupied by spaces (pores) filled with air and/or water. Water holding capacity. The ability of a soil to hold (store) water. Soil moisture content. The amount of water present in the soil. This is dependent on its water holding capacity, the climate, the position in the landscape, the kind of vegetation and the crop and soil management. Water infiltration rate. The maximum rate at which water can enter the soil under specified moisture content conditions. Soil profile. A vertical section of the soil that displays the different soil layers. Soil survey. The systematic examination, description, classification and mapping of soils in an area. Soil toxicity. Soils can have natural concentrations of substances which are toxic (poisonous) to plants. Examples of these substances are aluminium (Al), iron (Fe) and manganese (Mn). Their presence can result in poor growth and in extreme cases in a crop die-off. If toxicity occurs, it is generally most serious in the subsoil. Soil type. A group (family) of soils with a similar set of soil characteristics. Subsoil. That part of the soil below the topsoil. Soil structure. See soil physical properties. Species. A population of living organisms (plants or animals) that can crossbreed and produce fertile offspring. Strip cropping. Several crop species planted in alternating rows (one species per row) simultaneously in one field. Subtropical plants/crops. Plants/crops that are indigenous to subtropical zones. Subtropical zone, subtropics. Climatic zone characterised by one or more months with monthly mean temperatures below 18 °C but all months above 5 °C. Subsistence farming. A farming system whereby production is focused at meeting the food demands of the farming family or community only. Sustainable agriculture. Management of resources for agriculture to satisfy changing human needs, while maintaining or enhancing the quality of the environment and conserving the natural resources. Swidden. An area of cultivated land in a swidden farming system. Swidden cultivation/agriculture/farming. See Box 1 page 3. Also known as shifting cultivation or slash-and burn farming.

Temperate plants/crops/soils. Plants/crops/soils that are indigenous to temperate zones. Temperate zone. Climatic zone characterised by one or more months with monthly mean temperatures below 5 °C.

183 Appendix 5: Glossary

Tillage. The mechanical manipulation (modification) of the topsoil structure for various agricultural purposes such as weed control, improving water infiltration, aeration, loosening the soil for better root development of the cultivated crops, etc. Topography. The general form or relief of the soil (micro-topography) or the landscape (macro-topography). Topsoil. The uppermost part of the soil (0-30 cm), which, under agricultural land use, is generally disturbed by tillage. Tropical plants/crops/soils. Plants/crops/soils that are indigenous to the tropics. Tropical zone, tropics. Climatic zone characterised by monthly mean temperatures that are always above 18°C.

Upland rice. See rainfed rice.

Variety. A population of plants that belong to the same species but share one or more characteristics that distinguish them from the remainder of that species. Vegetative contour strips. A closely planted contour strip of any type of plants (mixed natural weeds, annual or perennial crops, grasses, shrubs or small trees). Volatilisation. The transition from a liquid to a gaseous phase.

Water catchment (area), watershed (area). An elevated area of land that ”catches” rainwater and focuses it to one or several routes for drainage (underground springs or above- ground rivers). The fundamental role of a watershed is to provide a continuous supply of sufficient amounts of clear water to agricultural and urban communities that live downstream of the watershed. Water saturation. The physical state of a soil whereby all soil pores are filled with water. Weathering. The physical and chemical breakdown of rocks into soil particles and soil nutrients. Weed. A plant that grows in a place where it is not wanted by humans. Wetland cultivation/agriculture/farming. Crop production on natural or artificial water saturated soils - see flooding. Wetland rice. See irrigated rice.

184 Part II:

The management of highland soils: an integrated vision Chapter 4: Lessons from the forest

4.1. Why are forests soil-friendly ecosystems?

Anyone who enters an undisturbed natural forest and has a closer look at the soil, will have the impression that the soil is “good”. The topsoil is dark, soft, moist and cool. If you look more in detail, you will notice that the soil is inhabited by a myriad macroscopic and microscopic creatures: the soil is “living”. The reasons why forests are soil-friendly ecosystems are explained in Box 20.

The luxuriant vegetation and dark topsoil of an undisturbed tropical forest may suggest that the soil is very rich in plant nutrients. This is, however, seldom the case. Soils under tropical forest are in general nutrient-poor, because they are intensively weathered and because of the presence of a dense and deep root system which rapidly absorbs (recycles) nutrients from the moment they are released by mineralization. Certain plant nutrients are, as a result, stored in the above-ground biomass rather than in the soil. The latter is one of the reasons why many farmers in the tropics slash and burn: to release the nutrients which are stored in the biomass (see Chapter 6.2. for more explanation on burning).

Box 20. What are the mechanisms that make forests “soil-friendly” ecosystems?

· Forests cover the soil year round. The soil is thereby protected from an extreme impact of rain, runoff water and sunlight. Erosion and crusting (the formation of a hard “crust” on the topsoil during dry periods) is limited and the soil remains cool and moist. · Forested soils act like a sponge. They take up water during the rainy season and slowly release it afterwards. · Forests continuously add fresh organic matter to the soil. This organic matter gives yet more protection against erosion and contains nutrients for soil organisms and plants. · Natural forests are mixed plant communities. Mixed-species plant communities have several benefits compared to single-species plant communities (monocropping): 1) Different plants have different root lengths. A mixed plant stand, therefore, has an intense root network spanning a range of depths. This prevents excessive nutrient losses by leaching, or in other words, recycles plant nutrients. 2) Different plants have different needs. If plants are grown in a multi-species mixture they will extract different amounts of nutrients from different soil layers. Single plant stands, on the contrary, deplete specific nutrients from specific layers, which can lead to a rapid shortage of certain nutrients and/or nutrient imbalances. 3) Yet another advantage of mixed plant arrangements is that they are less likely to suffer from massive pest outbreaks.

41 The management of highland soils: an integrated vision

4.2 The forest as a model for soil-friendly farming.

Because of the above-mentioned favourable effects of forests on soil physical and soil biological properties, it seems logical and attractive to use a forest ecosystem as a model for a soil-friendly agricultural system. Agricultural practices which help to “imitate” a forest environment are:

Limited or no burning.

Minimum or no tillage.

Incorporating organic residues into the soil and/or covering the soil with organic residues (the latter practice is commonly known as mulching).

Cultivating perennial crops, i.e. crops which grow (and fruit) for more than one year (mainly shrubs and trees).

Mixed cropping and/or crop rotation, i.e. growing different crops together on the same piece of land or growing different crops after each other on the same piece of land.

This forest model should always be kept at the back of our mind and these soil- friendly cropping practices, or at least some of them, applied wherever possible. We should be realistic, however. Managing forest land or managing agricultural land are two different things. There are several practical problems related to the above-cited “model-practices”, problems that are obvious to farmers who are confronted with the reality of everyday-farming but that are often overlooked by people giving (well- meant) advice from behind an office desk.

4.3 Agroforestry, a compromise between forests and farming

Between the extremes of, on one hand undisturbed forests, and on the other hand tree-less agricultural fields, there is a range of so-called agroforestry systems, which combine trees with crops and/or animals (see Figure 18). Two major types can be distinguished, i.e. sequential systems where trees and annual crops are combined in time (trees after crops on the same piece of land) and simultaneous systems where trees and annual crops are combined in space (trees and crops together on the same piece of land). Some examples of agroforestry systems that can be found in the highlands of northern Thailand are given in Box 21.

Agroforestry systems - in particular the simultaneous ones - are both ecologically and aesthetically very attractive, and are therefore often proposed as a panacea for sustainable development of small scale tropical agriculture. We will, however, not present them as such, but rather as a valid option among the others. Just as with every

42 Chapter 4: Lessons from the forest other option, agroforestry too has its specific advantages and limitations, some of which will be addressed in the following chapters.

Box 21. Examples of agroforestry systems in the highlands of northern Thailand

· Secondary forest swidden cultivation. The traditional swidden cultivation system of the Karen and the Lua minorities is probably the oldest highland agroforestry system. Their farming practices aim at a fast and good regeneration of a secondary forest fallow after cultivation of the upland rice crop (see Box 25 for more details). · Miang systems. “Miang” is the local Thai name of fermented tea leaves. Chewing miang is a popular habit among ethnic northern Thai people. Miang “orchards” are natural forests where the lower-story forest vegetation is cleared around existing wild tea trees. · Home gardens. Home gardens can be found in many highland villages. They range from predominantly vegetable gardens with only a few scattered trees to real multi-species multi- story mini agroforests. Trees which are commonly grown are banana, papaya, mango, jackfruit, tamarind, coconut, “cha-ohm” (Acacia sp.), tea,... · Fruit tree based systems. Large scale planting of fruit trees (litchi, apricot,...) is becoming a popular practice in the highlands. In most cases the final aim is to establish uniform single-species orchards. In an initial stage, however, the young trees are planted among annual crops or in fallows - effectively a temporary agroforestry system. · Contour hedgerow systems. These are soil conservation systems that were introduced to highland farmers more than 20 years ago. Characteristic of these systems is the growing of annual field crops between contour rows of trees or shrubs (see also Chapter 7.7).

Figure 18. Between the extremes of undisturbed forests and tree-less agricultural fields are a range of agroforestry options - an attempt to reap the advantages of both.

43 Chapter 5: Fallow management

5.1 What is a fallow?

A fallow is a piece of land which is left uncultivated for a certain period, but which has been cultivated before and will be cultivated in the future. The practice of alternating periods of cultivation with periods of no cultivation is called fallowing, the period of no-cultivation is called the fallow period and agricultural systems which are based upon this practice are called fallow systems.

Figure 19. Fallowing is an integral part of most highland cropping systems.

5.2 What are the functions of a fallow?

In some cases land is left fallow for a short period just because of practical reasons such as lack of water (for example: the dry season fallow period between two rainy seasons) or a periodic lack of labour (for example: lack of labour in between 2 sequential crops during the same rainy season).

In general however fallowing is a deliberate practice, i.e. for most farmers fallow land has mainly an agricultural function towards the subsequent crop. A farmer who leaves a plot fallow expects to obtain a yield, the first year after a fallow, that is higher than the yield in the last cropping period before the fallow started. A fallow, therefore, is expected to perform 2 main tasks:

1) To “restore” the soil fertility, i.e. to raise the physical, biological and chemical soil conditions to levels that are more favourable than those at the end of the last cropping cycle. 2) To “clear” the land of a wide range of crop pests (weeds, soil-borne pests and above-ground pests).

45 The management of highland soils: an integrated vision

There are, however, other inherent ecological functions of a fallow. Fallow vegetation types will, obviously, never match the ecological richness and diversity of the original primary forest vegetation, but they might still harbour a wide range of plants and animals (this is in particular the case for the secondary forest fallows of the Lua and the Karen). Depending on the type of vegetation they might furthermore perform some of the same watershed functions as the original forest (this issue is still a point of discussion among scientists).

Finally, there are yet more benefits of a fallow to the farmer such as the availability of various fallow products (see Box 22) and the use of fallow plots as grazing lands for livestock.

Box 22. Some common fallow and forest products

The products mentioned below are used forhome consumption, bartered or sold.

· Food: bamboo shoots, a wide range of edible herbs, fruits, tubers, mushrooms, insects, honey, wildlife. · Medicines: a wide range of plant-derived products. · Poisons: various plant-derived poisons are used for fishing and hunting · Construction materials: bamboo, wood, Imperata grass. · Materials and utensils for domestic use: fuelwood, charcoal, broomgrass, rattan, bamboo, banana leaves.

5.3 Fallow degradation: the start of a crisis

Good fallows should be able to fulfil the previously mentioned agricultural, ecological and watershed functions. Fallow types that do not perform these functions well are called degraded fallows. Previous studies suggest that, in order to keep a fallow system sustainable under the conditions of northern Thailand, a fallow should last 8 years or more. Due to land pressure, however, there are few areas nowadays where farmers are still able to maintain such long fallow periods. In most areas the duration of fallow periods has been shortened to periods of 1 to 5 years.

Shortening of the fallow periods, together with other factors such as lengthening of the cropping periods (see Box 23), disappearance of the surrounding primary forest (the seed source - see Box 25) anduncontrolled fires (see Chapter 6.2.) has lead to a serious degradation of much of the fallow land.

This fallow degradation has triggered an agricultural crisis characterised by declining upland rice yields, soil degradation and an increase of pest problems. Due to the degradation of both vegetation cover and soils the highlands are also facing an environmental crisis.

46 Chapter 5: Fallow management

Box 23. Are shortening of the fallow periods and lengthening of the cropping periods one and the same?

Both are adaptations to a shortage of fallow land that, at first glance, might seem similar but are quite different. This can best be illustrated with a concrete example. Suppose that a farmer has 3 plots of land that can be used in a fallow rotation (in many villages this is still a realistic situation). If he cultivates only one plot at a time for a period of 2 years this implies that each plot is left to fallow for 4 years. Suppose that he has to give up one plot because of a reforestation project. In that case he keeps only 2 plots, which can be used according to different fallow rotation schemes. If he sticks to leaving each plot fallow for a period of 4 years, this automatically implies that he will have to lengthen the cropping periods to 4 years. If he sticks to his previous cultivation period of 2 years this implies that he has to reduce the fallow period to 2 years. Alternatively, he might also opt for a lengthening of the cropping period and a shortening of the fallow period according to a 3/3 rotation (3 years cultivation/3 years fallow) or reduce both the cropping and the fallow period according to a 1/1 rotation. There is little scientific data available that can tell us what the best option is (i.e. whether any one scheme can be more beneficial than another). Certainly this will depend on the management practices during both the cropping and fallow periods. The data that is available suggests though that under no-external-input management it is better to decrease the fallow periods instead of lengthening the cropping periods. In the case of our examplea 2/2 or 1/1 option would therefore be the best, and it seems that many farmers are indeed adopting such fallow rotations patterns.

5.4 Away with fallow-based farming systems?

Fallow-based farming systems have long been (and still are) heavily criticised by many scientists and environmentalists, due to the fact that they generally get associated with 1) the destruction of primary tropical forest; 2) subsequent biomass burning and 3) erosion (see Box 24 for more details on these issues). This leads us right away to a very fundamental discussion that is not only of concern to the highlands of northern Thailand but to all of the tropics: should farmers be encouraged (or even forced) to give up fallow-based farming and instead adopt permanent farming?

Some people think that fallow-based farming is only temporarily adopted by certain societies, in response to unfavourable biophysical, social, economic or political conditions (lack of flat land, lack of strong social organisation, warfare,...). They regard it as a transitional phenomenon bound to disappear. Others, however, regard fallowing as a very deliberate and valuable farming practice, highly adapted to certain biophysical environments. According to this latter group, fallow-based farming deserves an equal status among other permanent farming systems.

In order to answer the above raised question we should consider the various sub- issues that are raised in Box 24. A summary of the main advantages and limitations of fallow-based versus permanent farming is given further below.

47 The management of highland soils: an integrated vision

Box 24: Some issues related to the discussion of fallow-based vs. permanent farming

· To what extent is fallow-based farming responsible for deforestation? In (northern) Thailand swidden agriculture is often used as a scapegoat for the deforestation that has taken place. There is no doubt that swidden farming has made (and still makes) an important contribution to the disappearance of (primary) forest and the subsequent degradation of the highland vegetation. Besides that, however, one also has to mention the deforestation that has occurred due to large scale commercial logging practices in the past (by foreign and Thai timber companies) and due to illegal logging activities that are still taking place. · To what extent is deforestation in the highlands responsible for environmental problems in the lowlands? See Chapter 7.3. · To what extent should and can (primary) tropical forests be protected? There are many sound ecological, scientific and ethical arguments to support the call for a maximal protection of the primary forests that are still left in the tropics. The key-question is, however, to what extent are people - both in developing and industrialised countries - prepared to make economic sacrifices to protect those forests? The high-productive (and sustainable?) farming and forestry systems in Europe, for instance, were developed at the cost of almost all of the primary forests (real primary forest in Europe is only left in some remote areas in Poland and Tjechië). It can be argued that because of the extreme climatic conditions (heavy rainfall and intense sunshine) and the vulnerability of many tropical soils to soil degradation, the need for keeping a forest cover may be higher in tropical zones than in temperate zones. But even then we can raise the question to what extent those forests should be real primary forests versus other types of production forests, fallows or agroforests? · Is fallow-based farming always associated with biomass burning? In general, yes. There are, however, examples of fallow-based farming where fire is used only sparingly or not at all. Examples of such slash-and-mulch systems are briefly described in Appendix 2.4. · Is biomass burning a sound farming practice? See Chapter 6.2. · Is erosion typically associated with fallow-based farming systems? See Chapter 7.2. · Is permanent farming on tropical highland soils sustainable? In the case of permanent irrigated rice farming there are few doubts: all over Asia there are examples of irrigated rice terraces that have been producing high and stable rice yields for many generations, if not for centuries. In the case of rainfed farming the answer is less clear. Some people think that permanent rainfed farming on nutrient-poor (sloping) soils in a tropical environment is unsustainable. Arguments to support this opinion are based on the intrinsic characteristics of these soils and problems with weeds and soil-borne pests. Other people, however, think that with proper management (either low- or high-input) permanent farming is possible. For northern Thailand there is, at this moment, not enough scientific information available to elucidate this matter. Regardless of all scientific discussions, though, it seems that giving the soil some “rest” from time to time can’t be but beneficial. · Is the transition towards permanent farming socio-economically and practically feasible? See various discussions throughout this book.

48 Chapter 5: Fallow management

· Main advantages of fallow-based farming: + Fallowing is simple and requires no money. + Farmers have a lot of traditional knowledge about it. + If the system functions well, tillage and weeding requirements are low to moderate, fertilisers are not needed (or only in low amounts) and pests are not a big problem. + In fallow systems that are based on regeneration towards “healthy” secondary forest much of the area remains under forest cover and thereby retains (at least part of) its original ecological and watershed functions.

· Main limitations of fallow-based farming: - Requires much land. - Fallow clearing (slashing) demands (very) much labour input. In degraded fallow systems, tillage and weeding requirements will gradually increase. - The farmer has to “manage” large amounts of plant residues and very often his only option is to burn these residues (see Chapter 6.2.). - Under conditions of land pressure fallow-based systems will very often become unsustainable for the farmers and the environment.

· Main advantages of permanent farming: + Requires less land than fallow-based farming. + Is somewhat more “convenient” than always moving around. + Does not require frequent clearing (and burning) of large amounts of plant biomass.

· Main limitations of permanent farming: - Results in a permanent removal of the natural vegetation. - Highland farmers are traditionally not familiar with it. - Permanent farming on nutrient poor soils in the tropics has its specific technical “difficulties”. Compared to fallow-based farming it often requires either more labour, more chemicals, more water or more financial inputs.

Given the physical and socio-economic conditions in northern Thailand it seems likely that fallowing will remain an important feature of highland agriculture. There lacks any sound argument to radically oppose this farming method. We should be fully aware, however, that in most areas fallow periods will continue to be shortened, whereas cropping periods will continue to be lengthened. Looking at fallow-based farming in northern Thailand, then, we can foresee three possible scenarios (with reference to individual farming households, villages or entire regions):

1) fallowing is no longer possible; 2) fallowing is still possible, but will become impossible in the near future; 3) fallowing remains a farming option in the long-term.

In the case of fallowing no longer being possible it is evident that research and/or development efforts should be directed towards establishing sustainable permanent

49 The management of highland soils: an integrated vision farming systems. If fallowing remains a medium-term or long-term option there are two possible pathways to stabilise the farming systems, i.e. 1) looking for improvements during the fallow period and/or 2) looking for improvements during the cropping period.

In the remainder of this chapter we will focus on different ways of fallow management. Management practices during the cropping period will be covered in the following chapters.

5.5 Fallow management options

Unmanipulated natural fallows

Highland farmers that belong(ed) to the group of thepioneer swiddeners (see Box 1) seem ignorant about the fate of the land once it is abandoned and are particularly ignorant about fire (regarding this latter point, things are starting to change though - see Chapter 6.2.). No efforts are made to facilitate a good natural regeneration (regrowth) of the fallow vegetation. There are no strict fallow rotation patterns - fields are cultivated until the yields spectacularly drop and/or weeds are no longer manageable. In some cases this might implicate 3 to 4 successive years of cropping. What is left behind is an exhausted, eroded soil that is covered with weeds. There are few remaining trees or tree seedlings.

· Advantages of unmanipulated natural fallows: + Require no inputs whatsoever + Can provide some fallow-products that are not present in natural forests (grasses in particular - see Box 22).

· Limitations of unmanipulated natural fallows: - Often lead to land degradation in areas where land pressure is high.

Manipulated natural fallows

Highland farmers belonging to the group of the rotational swiddeners (see Box 1) are praised by researchers for their concern and efforts to keep fallow lands in a good condition (see Box 25). There are reports which mention communities that have been farming the same area for a period of more than 100 years, without creating major agricultural or ecological problems. It should be mentioned, though, that very often rotational swiddeners are not solely dependent on swidden cultivation, but derive varying proportions of their rice harvest from irrigated fields. Also, since they were among the first settlers they generally had the selection of the best lands. Last but not least it should be noted that these people are oftencontent with a subsistence lifestyle. Today, many rotational swiddeners still farm following the old ways, especially in the more remote areas. In other areas, however, their system is at the brink of collapse, due to land shortage and changes brought in from the outside world.

50 Chapter 5: Fallow management

· Advantages of manipulated natural fallows: + The fallows are mostly of good quality (i.e. fulfil all fallow functions). + Much of the land remains under secondary forest, some patches remain under primary forest.

· Limitations of manipulated natural fallows: - Require a lot of land (if fallow periods are long). - Require much labour for clearing secondary forest vegetation.

Box 25. Sustainable farming practices of rotational swiddeners (aiming at a good regeneration of the fallow vegetation but having other agricultural benefits as well).

· Very short cultivation periods (in general only one year). · Strict long fallow periods (7 years or more). · Big trees are not cut at their base, but instead only “trimmed” (i.e. the branches are removed and the top is cut back). In this way they can regrowwhen the field is left fallow. · Strict fire control (based on technical methods and villager-established rules, see Appendix 2.2.). · Conservation of patches of primary forest around the swiddens and close to water resources. These patches serve as a seed source for forest regrowth in the swiddens after cultivation. · No- or minimum tillage (see Chapter 7.7.). · Implementation of soil conservation structures (logs and frameworks - see Chapter 7.7.). · Retention/promotion of certain plants by selective weeding, i.e. plants (“weeds”) which are beneficial for soil fertility restoration during the fallow period are not removed during the cropping period.

Improved planted fallows

Researchers and farmers have been trying to manipulate fallow vegetation in order to let it fulfil its functions towards a subsequent crop better and/or in a shorter time. Such fallow improvement can be achieved by planting shrubs, trees, herbaceous plants, grasses or even crops that were selected because of their “ideal” characteristics as a fallow plant (those characteristics include, among others, a good ability to improve the soil and to keep out troublesome weeds - see Appendix 2.1. for more practical tips).

In northern Thailand this practice seems almost non-existent, the only type of improved fallow that has been reported is one that is based on the use of spineless mimosa. Intensification of fallow based systems is apparently mainly taking place through adaptations during the cropping period. Today, managing fallow vegetation seems for many farmers a more exotic concept than using agrochemicals. We believe however that it remains a useful option that should get more attention from researchers, extension workers and farmers.

51 The management of highland soils: an integrated vision

· Advantages of improved-planted fallows: + Require very little financial input. + Give the same or even better results as natural regrowth fallows while requiring less time and land.

· Limitations of improved-planted fallows: - Require some initial extra labour input. - Require strict fire control during the fallow period (see Chapter 6.2.). - Might lack immediate benefits for the farmer (depending on which plants are used).

Enriched-planted fallows

Enriched or more productive fallows aim at increasing the benefits derived from the land during the fallow period. This is achieved by growing plants which can yield a financial profit. Such a system can significantly contribute to the stability of the farming system as a whole.

Fallows enriched with fruit trees (mainly litchi) are becoming a common feature of mountain agriculture in many areas of northern Thailand (see Box 21 and Chapter 11.5). Other plants which have potential for use in enriched fallows are banana and paper mulberry (Broussonetia papyrifera). The latter one is an indigenous fast growing tree, the bark of which is used to produce expensive paper for the handicraft- industry.

· Advantages of enriched-planted fallows: + The farmer benefits from otherwise (temporarily) unproductive land.

· Limitations of enriched-planted fallows: - Require some extra labour inputs. - Require some extra financial inputs and/or planting material. - Require very strict fire-control.

Conclusion: Don’t neglect the fallow

Fallowing is an important component of highland farming and this will probably remain so for the foreseeable future. Traditional secondary fallow systems have proven to be sustainable in northern Thailand but their potential application area is limited, due to the increasing shortage of farming land. Other types of local fallow management have, unfortunately, lead to serious environmental and agricultural problems.

We are convinced, though, that despite some bad reputations, sound fallow management remains a valid option that can help to stabilise or improve swidden

52 Chapter 5: Fallow management farming systems under stress. It can also be an intermediate stage towards permanent farming.

Many farmers are already enriching their fallows, especially with fruit trees. This approach is relatively simple, does not require too many extra inputs and can significantly contribute to the stability of the farming system. The concept of improving fallows with certain beneficial plants is still unfamiliar to most farmers. It does not give short-term benefits and will therefore not be easily adopted. The long- term benefits are however worth the effort and therefore we would encourage farmers, extension workers and researchers to continue experimenting with it.

53 Chapter 6: The management of plant residues

6.1 General overview of residue management options

Farming activities yield, besides products which have a direct food, commercial or practical value, also considerable amounts of plant residues. Especially in the tropics, where the growth of fallow vegetation, crops and weeds is luxurious, farmers almost continuously have to decide ”what to do with those plant residues”.

Figure 20 gives a general overview of the different options a farmer has relative to the management of plant residues generated in his field. In this chapter we want to draw attention to the fact that plant residues are valuable resources which should be used in a well-considered way. At the same time we should be well aware, however, that managing (large amounts of) plant residues on steep slopes involves a lot of practical problems for farmers.

Materials for construction and handicrafts

Fuel PLANT RESIDUES Animal feed wood

Dung BURN NON-BURN

Mulch Gully Mulch Green Compost lines plugs manure

field boundary

Figure 20. Flow-chart of options for plant residue-management (for explanation of the different non-burning options see Glossary or Chapters 7 and 8).

55 The management of highland soils: an integrated vision

Which options a farmer prefers depends on 2 sets of factors:

1) The amount and the ”quality” (see Table 4 in Appendix 2.6.) of the plant residues.

2) The specific farming situation:

· the soil type and degree of slope of the field;

· the means available (knowledge, tools, labour, money);

· the farmers’ objectives and priorities

· the farmers’ personal preferences.

From Figure 20 it is clear that plant residues can be used in many different ways, inside as well as outside the boundary of the field from where they originated. The use of those residues as fuel wood, construction material or raw material for handicrafts is in general limited, as such materials can still be easily obtained from nearby forests or other fallows which are not yet going to be cleared. We will therefore only concentrate on those management options which have direct consequences for the soil and for crop production.

To start with we will elaborate extensively on the consequences of in-situ (on-the- spot, in-the-field) burning of plant residues, because this option is the one that is most commonly chosen by the farmers. We will also give a first general introduction to non-burning alternatives for residue management.

6.2 Management based on burning of plant residues

Burning: a hot and controversial topic

When a farmer in the tropics is confronted with plant biomass (fallow vegetation or crop/weed residues) on land that he wants to prepare for cultivation, he will very often decide to burn it. Because this practice is so wide-spread and because it evokes so much controversy and misconceptions, we will address it here quite in detail.

Figure 21. Is fire a valid and rational farming tool, among the various other tools?

56 Chapter 6: The management of plant residues

Many people associate burning with ”primitive” swidden agriculture in the tropics. They see the use of fire as a symptom of poverty, lack of ”modern” farming technologies or as straightforward backwardness. It should be stressed, though, that burning is or has been used in agriculture and forestry all over the world, on small- scale subsistence farms as well as on large commercial estates. In most cases burning is a deliberate strategy. In other cases, however, it appears to be a rather indifferent decision, almost a traditional or intuitive habit.

In Thailand burning is still extensively used, in highland as well as in lowland agriculture. Farmers generally praise burning (see Figure 22 and Box 26), non-farmers (researchers, extension workers, environmentalists and politicians) generally oppose it (see Box 26). We will try to look for a compromise, taking scientific as well as practical arguments into consideration.

In order to avoid any misunderstanding, we would like to stress that the point we want to discuss here is NOT whether or not the remaining tropical forests should be slashed-and-burned, but whether or not burning is a valid farming practice on land that is already being used for agriculture.

Figure 22. Most small-scale farmers consider fire as a multi-purpose, cheap, easy and labour-saving practice.

57 The management of highland soils: an integrated vision

Box 26. Some contrasting opinions about fire (in agriculture and/or forestry)

Against burning Buddhist monk: ”The earth is our mother, how can we burn our mother?”. Akha farmer: ”If a field (with alley cropping) is not burned, the soil will be softer”. Western organic farmer: ”Burning is a crime against nature”. Development worker: ”Burning is the worst kind of recycling of plant nutrients”. Scientist-environmentalist: ”Fire (in forests) is disastrous”. Agronomist: Slash-and-burn destroys the soil and is dangerous for the future of the land”. Moderate opinion Soil scientist: ”It is significant that traditional farming on acid soils in the tropics is not based on incorporating organic matter into the soil but on burning it”. Journalist-environmentalist: ”If the conditions are appropriate for a ground fire (in the forest), why go against nature?” Karen farmer: ”City people like to throw big money to solve small problems. They don’t understand nature. They think forest fires (in deciduous forests) are a serious problem and we don’t”. In favour of burning Akha-farmer: ”Burning is better. I saw the difference on the growth of cabbage”. Akha farmer: ”Burning is easy and gives fertiliser to the soil”. Lahu-farmer: ”Ashes are a good fertiliser”. Lahu farmer: ”Burning kills weeds and protects against diseases”. Northern Thai floriculturist: ”I spray used oil (from a nearby gasoline station) on weeds before burning them. It is cheaper and works better than herbicides.”

Uncontrolled burning is the big bad dragon

When considering the effects of fire it is important to make a clear distinction between controlled burning (prescribed burning) and uncontrolled burning (wildfires).

In the case of controlled burning the timing, intensity and area affected are managed by the people who lit the fire. In the case of uncontrolled burning, there is no effort made to contain the fire to a target area. Also, the area affected is in general not cultivated after the burn.

Uncontrolled fires sweep yearly through large areas of the northern Thai highlands and many other regions of the tropics. It is, in particular, these uncontrolled fires which give burning such a bad reputation and which provoke wide-spread negative feelings against swidden farmers, although it should be mentioned here that there are various other people as well who are responsible for the start of bushfires (see Box 27). It is not our intention to discuss in detail the effects of (wild)fire on forest ecology. It appears, however, that (yearly) uncontrolled burning of forest and fallow lands has major practical, ecological and agricultural disadvantages (see Box 28).

58 Chapter 6: The management of plant residues

Box 27. Who starts the fire?

· Northern Thailand. The yearly occurring wildfires in the highlands are (accidentally or intentionally) caused by hill tribe people as well as by lowland Thai people, who all use fire for various reasons: preparing fields, clearing roadsides, fire prevention (areas around houses and orchards are preventively burned as protection against wildfires) and to facilitate hunting and mushroom collection. · Indonesia. A notorious example of uncontrolled burning were the wildfires that raged through the forests of Indonesia in 1997. Those fires had dramatic effects, not only in the areas where the fires occurred, but also in big cities inside and outside Indonesia. Although small scale swidden farmers were initially blamed for these fires, it appeared later that most of the fires were started by big palmoil, rubber and forestry companies.

Figure 23. Uncontrolled burning is the big bad dragon that gives swidden farming an unfortunate reputation.

The biggest agricultural drawback of wildfires is that they undermine the beneficial effects of a (natural or improved) fallow. A fallow which is burned every year cannot regenerate towards a healthy secondary forest, cannot sufficiently restore the soil organic matter and cannot suppress the weeds. The Lua, cyclical swiddeners of northern Thailand renown for their sustainable agricultural practices (see Box 25), recognise indeed that ”a fire burning through the forest will reduce the productivity of a swidden cut there in future years”. Therefore they take elaborate precautions to prevent wildfires when burning their fields (see Appendix 2.2). Farmers that belong to the group of the (former) pioneer swiddeners are traditionally less careful with fire. In some areas, however, this mentality is changing (e.g. Mae Sa Long and Doi Sa Mun). Farmers are starting to organise community based fire-control, often assisted by government-initiated ”fire-brigades”. It can be expected (hoped) that due to land use intensification, orchard establishment in particular, the occurrence of wildfires will decrease in the future.

59 The management of highland soils: an integrated vision

Box 28. Disadvantages of (yearly) uncontrolled fires in forest and fallow areas

· Practical - Direct physical danger for people and animals in the immediate area. - Smog formation poses a health threat to city people and disturbs air navigation. - Damage to fields, orchards and property. - Loss of fuel wood (for home use) and construction material. · Ecological - Damage to the forest canopy, which leads to soil and watershed degradation. - Damage to young trees, which hampers natural forest regeneration. Ultimately this may lead to a fire-climax vegetation (a plant population dominated by a few plant species which are able to survive fire) and a consequent loss of biodiversity. - Air pollution (without any benefit of agricultural production). · Agricultural - Loss of plant organic matter, thus less soil organic matter build-up in the fallow plot. - Loss of fuel, thus less ash production when the fallow is slashed and burned. - Waste of plant nutrients: much of the ashes (rich in nutrients) which are produced during wildfires will get lost by erosion and run-off and will not benefit a crop. - Increase of weed problems due to 1) invasion and growth of weeds because of a more open fallow canopy and 2) establishment of a fire-tolerant weed community, which mainly exists of difficult-to-eradicate grasses and shrubs.

Controlled burning: advantages and limitations

Controlled burning for field preparation has advantages as well as limitations (see list below and Figure 24). The effects of burning on soil organic matter and on soil organisms, two particularly controversial issues, are discussed in Boxes 28 and 29.

· Advantages of controlled burning for field preparation: + Cheap and easy way to get rid of excess vegetation, which may hamper field preparation, planting activities and seedling emergence. + Improvement of soil chemical status through ash and heat effects: increase of pH; temporary increase of mineral N; important and long-lasting increase of available P; potential increase in K, Ca, Mg and several micro-nutrients. + Reduction of initial infestation levels of a wide range of crop pests (weed plants and seeds, rodents, insects, nematodes, fungi, etc.).

· Limitations of controlled burning for field preparation: - Loss of a protective cover of plant organic matter. - Potential loss of soil organic matter (on the long term).

- Release of particles and gasses (CO2, CH4, NOx, N2O, SO2) into the atmosphere, which implies nutrient losses from the system and air pollution. - Loss of fertile ashes through wind and erosion. - The increase in nutrient availability can lead to increased leaching losses. - Killing of above- and below-ground living beneficial organisms.

60 Chapter 6: The management of plant residues

Figure 24. Burning soil is like cooking food. Farmers burn their fields for reasons similar to those for eating cooked instead of raw food. Burning speeds up the release of plant nutrients (digestion), makes the soil less acid (less toxic) and kills weeds and other pests (sterilisation). A major drawback of burning is the loss of certain plant nutrients (vitamins).

Briefly summarising the complex debate, we can state that:

Burning … ☺ is the easiest and cheapest way to clear a field, L but is risky, requires strict control and adversely affects the agroecosystem if it happens in an uncontrolled manner.

☺ seldom leads to direct physical, biological or chemical soil degradation L but can indirectly (on the long term) harm the soil if it is carelessly used.

☺ can be a fast and effective tool to make plant nutrients available and to control a wide range of pests, L but causes direct and indirect nutrient losses which can lead to on-site soil fertility decline and off-site air pollution.

The overall effect of controlled burning cannot simply be judged as being ”good” or ”bad”. In some situations it may be advantageous to burn, whereas in other situations it may be disadvantageous.

61 The management of highland soils: an integrated vision

Box 29. Effects of burning on soil organic matter

· What is burned: plant or soil organic matter? It should be stressed that in many burning events only plant organic matter (organic matter present above the soil surface) is burned, not the soil itself nor the soil organic matter. Heat effects in the soil are generally shallow (1- 2 cm deep), of low intensity (seldom higher than 100 °C) and of short duration (a few minutes to half an hour) when low to moderate amounts of plant residues are burned. Only under ”extreme” burning conditions will heat generation be so high, so deep and so long lasting that soil organic matter is destroyed (at temperatures above 150 °C). This can happen when a primary forest or a well established secondary forest is burned, or when biomass is piled and burned on a small area (burning piles). · The ”relative” importance of soil organic matter. The importance of soil organic matter is generally acknowledged (see Box 14) but should not be exaggerated. Cultivation, even without burning, will generally lead to a soil organic matter decline (relative to the virgin forest soil). As long as the soil organic matter stays above a certain ”critical” level, there is no reason to worry. These critical levels are difficult to define (they are soil and climate specific), but as soil organic matter levels in the highlands are fairly high, soil organic matter decline does not seem an issue of capital concern. · What are the long-term effects of burning on soil organic matter? Long-term studies about the effects of burning are scarce, but it seems logical however that if plant residues are burned every year, soil organic matter might finally fall below its critical level.

Box 30. Effects of burning on living soil organisms (flora and fauna)

· Effects on above-ground living organisms. The effect of fire on plants is different from plant to plant: some are extremely sensitive to burning whereas others can ”tolerate” it (they are only slightly damaged or can easily regrow). The effect of fire on animals and insects is obvious: if they cannot escape they simply die. When harmful organisms (pests) are killed this can be seen as an advantage, because at least at planting time the field is free of these organisms. Useful organisms, however, are also killed and the existing natural equilibrium is disturbed. Because little information is available about the recolonisation dynamics of different organisms after the burn it is not possible to state whether, in this regard, the overall effect is positive or negative. · Effects on below-ground living organisms. Quantitative information about this issue is, again, rather scarce. In Box 29 we saw that during most burning events heat penetration is shallow. Therefore we can assume that, in general, the impact of fire is not that great. Two favourable effects of burning that have been reported are reduction of the number of viable weed seeds and reduction of the number of nematodes (microscopic worms; several species parasitise plant roots). Beneficial soil micro-organisms such as bacteria, fungi and actinomycetes are initially much affected by fire but recover rather quickly (within a few weeks to a few months). Their numbers and/or activity after the burn are often even higher than before the burn, which leads to a (temporary) increased nutrient mineralisation, in particular of nitrogen. For fast-growing crops this may be an advantage, for slow-growing crops a disadvantage as much of these nutrients may be lost through leaching.

62 Chapter 6: The management of plant residues

Should burning be totally banned?

Based on the information presented above it follows that burning can create problems at two levels:

1) Problems at the local level: relate to negative effects in the field that is burned (loss of plant nutrients and organic matter from the system, possible increase of erosion and killing of beneficial organisms) and to the effects burning may have on the entire village area (damage of property and fallow/watershed degradation). 2) Problems at the global level: relate, in addition to the problem of watershed degradation, mainly to the air pollution that is caused by burning. Of greatest concern are the emissions of climatically important trace gasses, i.e. gases which contribute to the so-called greenhouse-effect and to the depletion of the ozone layer.

Let’s turn now to the question we are trying to answer:what can or should be done to solve or at least alleviate the problems created by biomass burning in tropical farming systems? In order to answer this question we first of all need very solid data about the global ecological consequences of agricultural biomass burning. Besides that we also need detailed statistics which enable us to compare how much of the trace gas emissions are released through agricultural biomass burning and how much of these gases are released by various other sources of human-induced pollution (factories, cars and other transport means, heating systems, cooling systems, etc.). The latter data are needed if we want to propose solutions that are socially and economically fair towards resource-poor farmers.

If we take a look at the literature it appears that we still lack substantial information regarding biomass burning and global change issues in general. It has been ”estimated” that about 25% of global warming is attributable to the burning of tropical forests. That is a very large contribution, indeed, but it also suggests that most of the global warming (75%) is caused by various other human activities. If one day we would have all the essential information needed to justify concrete measures to restrict agricultural biomass burning, this would only be the beginning of a very complex and sensitive debate. Such a debate should be carried on at a broad regional or international forum. It should hear arguments for the urgent need of environmental protection, balanced by many social, economic and political considerations. Ultimately this will end up in very fundamental political and ideological discussions, similar to the ones that were previously raised in Box 5.

In conclusion, it seems - at present - that an absolute rejection of biomass burning in agriculture would be unnecessary, unrealistic and even unfair. If we are really concerned about trace gas emissions, we should first of all take drastic measures to reduce our own emissions. If we want farmers to reduce or stop burning this should not be done by blaming them or by forcefully implementing a burning-ban. Instead we should try to come up with concrete methods/measures that encourage/facilitate farmers to use alternatives to burning.

63 The management of highland soils: an integrated vision

Can burning practices be improved?

If we carefully reconsider the problems of burning at the local level, it seems that it is not so much the use, but rather the misuse of fire which causes problems. Many of these problems can be tackled by sound fire-management. Some guidelines to improve fire-management are formulated in Appendix 2.3. They aim at limiting the damage and maximising the benefits of fire. The basic ideas behind this are:

· Implementing strict fire control.

· Decreasing the burning frequency (i.e., the number of times a field is burned).

· Implementing soil conservation practices in the area which was burned.

· Maximally utilising the plant nutrients contained in the ashes, by preventing losses of ashes and/or concentrating the ashes on a smaller area.

6.3 Management based on non-burning of plant residues

Under which conditions should farmers be able to avoid burning?

We have extensively argued that in some situations burning may be advantageous whereas in other situations it may be disadvantageous. The factors which should be considered in order to make an appropriate decision are listed in Appendix 2.4., together with some concrete examples. Briefly summarising we can say that burning can be avoided if:

· It is feasible to plant crops in (thick) layers of mulch. This feasibility depends on the amount of residues present, the type of crop to be grown, the climate, the amount of labour available and the opportunities to use mechanical equipment.

· Decomposition rates of the plant residues are sufficiently fast (to provide the crop a timely availability of required nutrients.

· Soils are naturally rich in plant nutrients (e.g. limestone soils).

· Pest problems are manageable without a burn.

If these conditions are met, farmers can indeed cultivate crops without or with minimal use of fire (see example of indigenous slash-and-mulch systems in Appendix 2.3). The alternatives to burning, then, fall into to two basic categories:

1) low-input alternatives that rely mostly on the principles and practices of organic farming 2) high-input alternatives that rely mostly on agrochemicals and fuel-based mechanisation.

Organic farming will be introduced here, as it is actually the most direct alternative to fire-based agriculture. The use of agrochemicals, essentially as ”substitutes” for some of the direct beneficial effects of burning (fertilisation and pest control) will be addressed in Chapters 8, 9 and 10.

64 Chapter 6: The management of plant residues

Organic farming

As a reaction against the excesses of high-external-input agriculture, concepts such as organic farming and ecofarming are getting increasingly popular these days. Both are general and somewhat vague terms for a range of alternative eco-friendly agricultural systems (see Box 31), which may differ in what is and what is not ”allowed” but do generally encompass convergent philosophies. Their common goal is to achieve long-lasting productivity and environmental conservation by:

1) Relying (almost) exclusively on (local and/or external) ”organic” resources, i.e. plant residues, animal manure and several other types of natural (waste) products or home-made extracts. Most of these systems reject the use of external ”chemical” inputs. 2) Soft and well-considered manipulation of (agro)ecological processes, based on scientific and/or indigenous knowledge (see Box 31 for some of the specific practices this implies).

Without going into details, it should be mentioned that some of those systems comprise more than merely ecological ways of farming. Often they also call for radical changes in human society, changes which should lead to a more sustainable life-style closer to nature.

Box 31. Alternative eco-friendly agricultural systems (this is just a brief overview; specialised literature should be consulted for more information).

· Organic farming. An agricultural system in which plant nutrient management is based on nutrient recycling through a sound use of organic matter. Other practices are site-adapted crop selection, crop rotations, mixed cropping, fallow improvement, proper timing of cultivation practices, biological pest-control, the use of botanical pesticides and avoidance of synthetic agrochemicals. · Ecofarming. Farming practices that enhance or, at least, do not harm the environment. Burning or agrochemicals are not promoted but also not excluded. · Natural farming. A way of farming that seeks ”to follow nature”, according to the principles of M. Fukuoka (Japan). · Biodynamic farming. A holistic agricultural system that tries to connect nature with ”cosmic creative forces”, as devised by R. Steiner (Germany). · Integrated farming, mixed farming. Highly diversified farming systems which combine many different farming activities (annual and perennial cropping, livestock raising, fish raising) instead of relying on just one type of crop or farming activity. This principle is promoted in Thailand by His Majesty The King as ”The New Theory”. · Agroforestry. Integrated systems of trees with crops and/or livestock (see Chapter 4.3.). · Sloping Agricultural Land Technology (SALT). A contour hedgerow system (see Chapter 7.7.) that was designed by the Mindanao Baptist Rural Life Center (Philippines). · Permaculture. A well-designed, integrated system of perennial or self-perpetuating species of crops, trees and animals, as devised by Bill Mollison (Australia).

65 The management of highland soils: an integrated vision

Is organic farming a feasible option for the highlands?

Because of the increasing concern for the environment, organic farming systems are strongly promoted by many Thai and foreign development workers. The proponents of organic farming are very often radically against burning and against the use of agrochemicals.

We acknowledge that there are many sound organic farming practices/systems which deserve our maximum attention. At the same time, however, we think that it is not realistic to propose organic farming as the one and only alternative to traditional fire- based agriculture or to conventional high-input agriculture. Striving after highland agricultural systems that are ”100% organic” may lead to frustrations, among extension people as well as among farmers. Striving after farming systems that are ”as organic as possible” seems a much more workable objective. After all we should realise that :

· there is a substantial difference between the feasibility of organic gardening and the feasibility of organic farming (see Box 32);

· adopting an entire system is always more difficult than adopting individual practices (remember the blueprint vs. the basket approach, Chapter 2.2.);

· there are a range of factors that hinder adoption of organic farming in the highlands (see Box 33).

The immediate alternatives to burning that were displayed in Figure 20, i.e. contour mulch lines, gully plugs, mulching, green manuring and composting, are organic farming practices that can be used to protect and/or improve the soil. These five practices will be discussed more in detail throughout the following chapters, together with several of the other eco-friendly practices that were mentioned in Box 31. People who want yet more information about specific ways of organic farming should consult the resource persons and publications that are listed in Appendices 3 and 4.

Box 32. Organic gardening vs. organic farming

Adherents of organic farming are often themselves enthusiastic and successful organic gardeners. It should be stressed, though, that what is possible in your garden is not necessarily feasible and economically viable at a farm level. Between gardening and farming there are, indeed, important differences with regard to:

· the scale of the activities: small plots vs. large plots

· the aim of the activities: leisure activity and/or generation of extra food and income vs. main professional activity for subsistence and/or income generation

66 Chapter 6: The management of plant residues

Box 33. Factors that facilitate and factors that hamper adoption of organic farming

· Factors that facilitate adoption of organic farming (in general): + Soils with a high natural soil nutrient status. + Availability of medium or high quality organic fertilisers (see Appendix 2.6.) and transport facilities to bring them to the fields. + High labour availability. + High degree of mechanisation. + Thorough knowledge about the functioning of agroecosystems. + Few pest problems. + Marketing facilities to sell organic products and consumers willing to buy them. · Factors that hamper the adoption of organic farming in the highlands: - Highland soils have in general a medium to poor nutrient content (see Chapter 3). - Large amounts of medium or high quality organic fertilisers are not available, nor is the infrastructure for their transportation. - Mechanisation on steep slopes is difficult. - Where in the past labour was assumed to be ”abundant and free”, it is nowadays more scarce and expensive due to labour opportunities in the lowlands. - Our knowledge about the functioning of highland agroecosystems is still limited. - Organic farming technologies are often extended by development workers who have only a limited awareness of the true complexity of an organic system. - Rainfall and temperature favour prolific growth of weeds and fallow vegetation, resulting in problems of weed control and large amounts of difficult-to-handle plant residues. - A tropical environment is in general prone to a wide range of crop pests. - Producing eco-friendly vegetables is easier than getting rid of them, whether by own consumption or by selling the products (this is a farmers’ statement!). Although the demand for chemical-free food products is emerging, this alternative circuit is not yet well organised (labels, control, packing, publicity campaigns, etc.) .

Conclusion: Plant residues are resources that should be judiciously managed

In this chapter we gave a first introduction to the various ways plant residues can be used in agriculture. Thereby we paid major attention to the highly controversial burning-option, which is still preferred by the vast majority of highland farmers. We have tried to explain that burning can be advantageous as well as disadvantageous, depending on when and how the practice is used. We also made several suggestions to fine-tune the use of fire. In order to come up with straightforward recommendations, however, more research and political debate is needed. Based on the current state of knowledge, it appears to us that burning can be considered as a valid farming tool. Radically rejecting the practice seems unnecessary and unrealistic. Instead we should encourage and facilitate farmers to avoid burning whenever possible. Last but not least farmers should also show their goodwill in order to reach a

67 The management of highland soils: an integrated vision compromise that pleases everyone, i.e. they should make serious efforts to prevent wildfires and give up indifferent burning.

Several non-burning alternatives can be proposed to farmers, belonging either to the category of the conventional high-input farming systems (based on the use of agrochemicals) or to the category of the alternative eco-friendly farming systems (based on recycling organic residues to protect and/or improve the soil). Each of these categories has its specific potentials and limitations.

The alternative organic options are the ones that are most commonly promoted by advocates of sustainable highland agriculture. These options deserve our maximum attention but their promotion should happen in a realistic (thus compromising) manner. We should, indeed, be well aware that farming according to rigorous organic principles is not always possible. Practically speaking it seems that adopting individual organic practices will be easier than adopting entire organic systems, and that adopting such practices on a home-garden scale will be easier than adopting them on a field-scale.

68 Chapter 7: Soil erosion control

7.1 What is soil erosion?

Due to the impact of raindrops (among other factors), soil aggregates (clumps of soil) can gradually be broken down into smaller particles. If this happens on a slope, those soil particles can get detached and transported downwards by running water runoff( water) - a process which is called soil erosion. If soil is removed more or less uniformly from every part of the slope one speaks of sheet erosion, a type of erosion that is often difficult to observe (unless you have experience). Erosion becomes much more visible if the runoff water gets locally concentrated in small or larger channels, processes that are called rill and gully erosion respectively (see Figure 25a). In extreme situations entire soil profiles may get saturated with water and, because of the resulting tremendous weight, slide downslope, a phenomenon known as a land slide (see Figure 25b).

Soil erosion is a natural process which can occur under all types of vegetation. Under natural vegetation, erosion generally happens slowly and the amounts of soil removed are rather low. Part of the eroded soil will be deposited in valleys and it is this natural process of erosion and deposition that formed the fertile lowland basins where most agriculture today takes place. Due to human activities (logging, farming, road construction, etc.), however, erosion can occur beyond natural rates. This accelerated erosion can threaten both highland and lowland agriculture and their respective environments (see Box 34). The factors that influence (accelerated) soil erosion are briefly explained in Box 35.

Figure 25. Erosion symptoms: a) rills and gullies; b) land slides.

69 The management of highland soils: an integrated vision

Box 34. Negative effects of soil erosion.

· On-site effects: soil degradation and ”crop erosion” - The soil which is removed by erosion is the soil from the top layer, which contains most of the nutrients present in a soil profile (see Chapter 3). Erosion thus causes a direct loss of plant nutrients at the site that is being eroded. - Due to erosion the subsoil will gradually get exposed. This can affect crop production because the subsoil has in general poor - sometimes even toxic - soil characteristics. - On shallow soils, so much soil can be removed that only stones or bare rock are left. - Farmers often mention that their greatest concern related to erosion is the physical damage it causes to crop seedlings (upland rice in particular). During the early rainy season one can indeed observe on certain fields that seeds are washed away or that seedlings get uprooted.

· Off-site effects: changes in the amount and quality of water in rivers - Changes of the soil surface, caused by erosion, will lead to less infiltration of water into the soil during the rainy season. The consequences are two-fold: 1) more water in the rivers during the rainy season, which can lead to flooding in the lowlands; 2) less water in the rivers during the dry season, which can lead to water shortage (drought). - Excessive soil erosion will lead to high amounts of soil particles in rivers (”dirty or muddy” water). When these soil particles settle down, they can obstruct dams and rivers, thereby limiting their capacity to store water thus increasing the risk of floods. Muddy water can also have negative effects on fish populations.

Box 35. Factors that influence soil erosion

· Rainfall pattern. We put this factor on top of the list, as it is rain which is the ”activator” of the erosion process. The more rainfall and especially the higher the ”force” of the rain (called the intensity, i.e. the amount of rain which falls per minute), the more erosion can occur. · Slope angle and slope length. If rainwater can flow down a field uninterrupted by any barrier it will gain greater and greater speed, considerably increasing the water’s ability to erode the soil. Special attention is therefore needed when cultivating very steep or very long fields or when several fields are connected to each other in the direction of the slope. · Slope curvature. The topography of the slope determines whether the runoff water will be spread uniformly over the slope or whether it will be channelled in certain areas. A sheet of water is less erosive than water that is channelled. · Spatial organisation of the agroecosystem. The way in which various landscape elements (cultivated plots, fallow plots, secondary forest, roads and paths, rivers, irrigation channels, water ponds, habitation) are organised has an important effect on the spatial distribution of erosion features, in particular on the larger types of soil movements (gullies and landslides). · Soil type. Clayey soils generally show more resistance to erosion than sandy or loamy soils. A uniform layer of stones on the soil surface gives a protection against erosion. · Soil moisture content. The soil moisture content at the moment raining starts will be a factor in determining whether and when runoff will be generated. · Cropping practices. Cropping practices influence soil erosion through their effects on the soil surface state and the soil cover (see later in this chapter). · Erosion control structures. Well-established and well-maintained erosion control structures can reduce erosion (see further in this chapter). Poorly-established or poorly-maintained erosion control structures can increase erosion (see Box 44).

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7.2 Is soil erosion a problem typical only of subsistence farming in the tropics?

Soil erosion, just as deforestation and biomass burning, is often typically associated with subsistence farming in the tropics. It is, however, a problem of global concern. Rich as well as poor farmers, the world over, are cultivating sloping lands and thus are inevitably confronted with erosion. To illustrate that the way farmers deal with erosion is case-specific and thus generalisations cannot be made, two contrasting examples (one good and one bad) of slopeland farming in Western Europe are given here below.

Box 36. Examples of soil conservation and lack of it in Western Europe

· Chestnut- and mulberry-based agroforestry in the Cevennes, France. The ”Cevennes” is a harsh, economically marginal mountain area in the south of France. It is similar in altitude with the highlands of northern Thailand but characterised by shallow/rocky soils and a much drier climate. Centuries ago, a unique agroforestry system was developed by monks who settled down in this region. They promoted the planting of chestnut trees, which became the ”sustainer” of the mountain folks. Later on, people also started to grow mulberry trees, which became the basis of a profitable cottage-based silk industry (the silkworms were raised with mulberry leaves). Further contributing to the sustainability of the overall farming system were extensive stone-wall terraces (local people tell that, in the old days, farmers would never go to the field without a bag of stones or soil, to build or repair those terraces) and home gardens, often with ingenious small-scale irrigation systems. Nowadays the Cevennes is France’ only national park where agriculture is still allowed. · Erosion in the hills of central Belgium. The central part of Belgium has some of the best agricultural land of Western Europe. Farming is completely mechanised, the production is high and the farmers are rich. Despite the fact that most fields are located on hill slopes with loamy and thus erosion-sensitive soils, farmers make little efforts to control erosion, because the soils are deep and farmers can compensate the loss of topsoil with fertiliser application. Erosion is, obviously, severe and the effects are very visual: big erosion gullies in the field and regular occurrence of mudflows in low-lying residential zones. Lobbying against these (and other) unsustainable farming practices is nevertheless difficult, because the farmers have strong organisations that have much political influence.

7.3 Is soil erosion a problem in northern Thailand?

Soil erosion is an inherent problem of agriculture on sloping lands the world over (see Box 36), so the answer is undoubtedly ”yes”. More difficult to answer though ishow serious the problems are and where they are the most acute. In the public opinion and among many academics it is generally believed that soil erosion is very serious all over northern Thailand and that it is the major cause of declining soil fertility and declining yields in the highlands and flood and drought problems in the lowlands (see Box 34). In the same breath it is generally the hill tribe farmer that gets blamed for all the environmental calamities. It is dangerous however, for a number of reasons, to make such generalising statements.

71 The management of highland soils: an integrated vision

First of all it cannot be emphasised strongly enough that erosion is a very site-specific problem. In some areas/fields erosion may be of major concern, whereas in other areas/fields it may be of no concern at all. Unfortunately there are few studies available for northern Thailand that have rigorously assessed and explained the spatial variability of erosion, neither at the village level nor at the regional level. Secondly, it is seldom possible to find simple relations between erosion and soil fertility or yield decline. Soil fertility and yield are, on the contrary, generally determined by a complex set of interacting factors. Pursuing just soil erosion as the culprit in declining yields may, therefore, be of little value to the farmer, extension worker or policy maker. Last but not least it should be stressed that at present there are no studies available for northern Thailand that incontestably prove a link between flooding (or drought) in the lowlands and land use in the highlands. Obviously it is not easy to undertake sound scientific studies on a large watershed scale. Furthermore we should be well aware that besides land use in the highlands there are other, equally important factors that contribute to flood and/or drought problems in the lowlands (see Box 37).

In conclusion we can state that erosion is a concern in northern Thailand but that there is (yet) no evidence that the situation is of unconditional concern. This does not imply that we should not undertake any (preventive) action. It only tells us to berealistic and pragmatic in our efforts to promote soil conservation among highland farmers.

Box 37. Other factors that contribute to flooding (or drought) problems in the lowlands

· Erratic rainfall. Rainfall is probably the most crucial, the most unpredictable and the most uncontrollable factor that causes flooding problems, not only in Thailand but all over the world. It is very telling that in the Netherlands and various other countries where impressive measures are taken to prevent flooding, man is still not able to tame the forces of water in case of extreme rainfall. A similar reasoning applies to problems of drought. To which extent deforestation and land use in the highlands interfere with monsoon-governed rainfall patterns in northern Thailand is still an open question. · Urbanisation. Rapid urbanisation is leading to massive filling in of paddy fields/irrigation channels and extensive covering of the soil with concrete. This (partly) explains why, in case of exceptionally high rainfall, water levels in rivers can rise so fast: water is immediately drained to the rivers and no longer temporarily stored in ”buffer reservoirs” such as the soil or paddy fields. Another important aspect that should be mentioned here is that in the not-so distant past people could better cope with flooding problems than nowadays, or to put it another way - flooding was not seen as a problem beyond possible impacts on yield (houses were built on stilts and people had little boats). Now, however, there is an increasing number of urban residents, living in urban-style houses in a largely rural environment. The typically high-volume, muddy monsoon waters simply stand out more to these urban emigrants than to the local rural inhabitants. A similar reasoning applies to problems of drought: exceptionally low rainfall is not caused by urbanisation, but the increased water consumption (for swimming pools, golf-courses, car cleaning, factories, etc.) aggravates the water crisis during periods of drought. These and other conflicting urban-rural attitudes are a growing problem in Thailand .Very sensitive people will be needed to solve these issues…

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7.4 Is soil erosion a problem in the village where you are working?

Because soil erosion is, as previously mentioned, a very site-specific problem, it is essential to make a careful assessment before undertaking any action.

Discussing the problem with the farmers, by preference in the field, is always the first thing to do. Farmers are, indeed, often well-aware of the extent and causes of erosion in their fields. Further in this chapter we will see that some farmers do implement their own soil conservation measures. It should be mentioned, though, thatfarmers seldom perceive soil erosion as a top-priority problem. Weeds, various other pests and lack of money are in general of much greater concern.

Making your own soil erosion survey is another way to evaluate soil erosion problems. The best period to observe erosion symptoms in the field is the beginning of the rainy season, when most of the soil is still bare (from May to the beginning of July). The occurrence of rills and/or gullies is a serious and easy-to-recognise sign of soil erosion. In extreme situations you might even observe land slides (see Figure 25). Sometimes erosion is less clear (in case of sheet erosion), but can still be recognised by the occurrence of stones on small pillars or by accumulation of soil on obstructions in the field such as tree stems and stones.

Observing erosion symptoms is a first step but equally important is to find out why and how erosion is occurring, as this will help to find ways to control it. The least convenient but most efficient way to find this out is to observe erosion processesdirectly in the field during a heavy rainfall event.

7.5 When should erosion control measures be taken?

Several people think that the need to implement (certain) soil conservation measures or even the prohibiting of agriculture on sloping lands should be linked to the slope angle of the land under consideration. Putting forward ”critical” slope angles seems however somewhat arbitrary and unrealistic. Slope is indeed a very important factor with regard to soil erosion, but it is not the only one (see Box 35). Besides that, mountain farmers simply have few other options than cultivating sloping land.

Farmers should however, as a basic rule, always take measures to minimise erosion when cultivating sloping lands. In some situations soil conservation should be a top-priority issue that requires immediate and drastic action. In only a few exceptional cases low amounts of erosion can be ”tolerated”. Some examples are given in Box 38.

73 The management of highland soils: an integrated vision

Box 38. When does erosion requires drastic action and when can it be ”tolerated”?

· It requires drastic action if:

· fields are very steep (> 50%);

· the topsoil is only a few centimetres thick;

· the depth of the soil is less than a meter;

· stones/rocks are being exposed;

· large amounts of runoff water can accumulate on the slope (see Box 39). · It can be ”tolerated” if:

· Cultivation periods are short and fallow periods long. In this case the overall erosion, expressed on a year basis, will be low. Suppose, for example, that a farmer cultivates a field for one year and thereby looses 70 tonnes of soil per hectare (about 7 mm of soil). This is far above the ”acceptable” soil erosion rate for Northern Thailand, which is supposed to be somewhere around 10 ton/ha/year (or 1 mm/year). If after cultivation, however, the field is left fallow for 9 years, then the average erosion over the 1+9=10 year cycle becomes only 7 ton/ha/year, which stays below the acceptable level.

· Farmers make a deliberate benefit from the erosion and runoff. Soil sediments and runoff water from micro-watersheds are sometimes collected in channels and brought to paddy fields, fishponds or orchards.

7.6 Basic principles of soil erosion control

Due to the increasing awareness of the problems created by erosion, a wide range ofsoil- and-water conservation strategies and methods have been developed, by researchers as well as by farmers. These methods generally aim at (1) avoiding losses of soil at the field-level and (2) guaranteeing a stable supply of clean water at the watershed-level.

The best way to prevent erosion is by sound land use planning, i.e. avoiding to use land that is vulnerable to erosion. In reality, however, this is seldom possible in mountainous regions. If erosion prone land needs to be brought into cultivation thenerosion control measures have to be implemented, which should actualise one or more of the following:

· protect the soil surface from the forces of rainwater;

· increase water infiltration;

· decrease the velocity of the runoff water;

· and intercept eroded soil.

These measures should furthermore also fit into the local farming system. Measures which easily fit into the local farming system are measures which:

· require little labour input;

· are easy to implement, to maintain and to change;

· show minimal or no competition for area, light, nutrients and moisture between the soil conservation structure (see further) and the crop;

· provide short-term benefits.

74 Chapter 7: Soil erosion control

The requirements mentioned here are the ones that are generally met byindigenous soil conservation practices (see further in this chapter). If local soil conservation practices exist but do not effectively control erosion they might possibly be improved. If the latter isn’t possible or if no local conservation practices are available at all then soil conservation practices need to be introduced.

Before however introducing soil conservation practices we should have a wide-angle view of the problems related to soil conservation - by this we mean the agrotechnical, socioeconomic, political and personal reasons behind a farmer’s acceptance or rejection of soil conservation extension. Such a comprehensive view is needed in order to have theright attitude and realistic expectations before starting off with a soil conservation campaign.

The following key-issues deserve careful consideration:

4 It should be stressed that soil erosion control by itself is not a very complicated technical issue. Research and extension have been going on for decades (also in northern Thailand), so a wide range of techniques are currently available and extensively documented.

4 One ideal method for soil erosion control does not exist. Each single method has its specific advantages and limitations. Several methods might need to be combined in order to find a strategy that fits in the local conditions.

4 Erosion control is an absolute precondition for sustainable highland agriculture, but soil erosion control ALONE gives no guarantee for long-term soil productivity. It does not improve soil fertility nor prevents its decline, neither does it solve other agricultural problems (pests, too much or too little water, etc.). Soil conservation should focus on improved production practices as part of a greater, comprehensive agricultural development strategy.

4 It seems that in many soil conservation programs the land has been considered (studied) too much, whereas the land user (the farm household) considered too little. A very delicate but crucial issue in this respect is the fact that the majority of the highland people are still lacking any official form of land (use) rights. Farmers who have no single guarantee about the future of their land are poorly motivated to make major investments towards sustainable land use.

4 Researchers and development workers are increasingly realising that adoption (or non- adoption) of soil conservation is not only related to agrotechnical issues but to various social, economic and political factors as well. Soil erosion problems therefore need to be addressed with a holistic approach, i.e. an approach that takes ALL these factors into consideration.

75 The management of highland soils: an integrated vision

7.7 Erosion control strategies and methods

Sound land use planning

As previously mentioned, sound land use planning should always be the first strategy to prevent erosion. Careful field selection is a key-component of this strategy. Situations which should be avoided are:

· fields where large amounts of runoff water can accumulate on the slope (examples of such situations are described in Box 39);

· fields which are too erosion-sensitive because of their soil characteristics (e.g. sandy soils or shallow soils).

Areas which are absolutely unsuited for annual cropping are the immediate borders along streams (the riparian zone) - especially in steep and narrow valleys (see Box 39). Locations with few erosion risks are flat areas on ridges (plateaus) and flat lands in wide valleys. These types of land are therefore often intensively cultivated. Agriculture on flat ridge tops is however controversial. Environmentalists and also soil conservationists are generally against it, arguing that once hill-tops are deforested and eroded it is very difficult to rectify the damage.

Box 39. Situations where large amounts of runoff water can accumulate on the slope

· Fields connected to each other along the slope. · Fields with a long and concave slope. · Fields adjacent to paths or to the outlet of diversion ditches (see further in this chapter). · Fields located right at the edge of a river (suffer from incision by the forces of the river). · Fields at the lower part of a slope. Such fields are extremely prone to erosion (and in extreme cases even land slides) because it is there that all the runoff water accumulates. The situation is even worse if such fields are cultivated right up to the edge of a stream (theriparian zone) in a narrow valley. In such a situation there is no vegetative ”buffer” which can intercept the eroded soil, so it will be all carried away by the stream. Therefore it is strongly recommended not to use the lower parts of slopes for annual crop cultivation, especially in narrow valleys with a stream. Such areas can best be left under natural vegetation or only used to plant trees or other perennials (bamboo, banana, rattan,...). The only possible exception to this rule is paddy rice cultivation. Because of the scarcity of land that is suited to paddy rice cultivation it is often observed in the highlands that very narrow valley floors (of merely 5 to 10 meters wide) are converted into paddy terraces. Often these terraces do not only span the riparian zone but even the river streambed itself. If the terraces are well-constructed and if the bordering valley slopes remain under permanent vegetation cover, this practice seems sustainable. If the latter preconditions are not met it can lead to very severe erosion and complete losses of the crop in case offlash-floods caused by very heavy rainfall.

76 Chapter 7: Soil erosion control

Sound crop husbandry practices

The way crops are managed greatly affects the amount of soil loss. If the slopes are not too steep, soil erosion control can be achieved by adopting sound crop husbandry practices. Such practices can be used individually but it is always better to combine several methods whose benefits complement each other.

Fallow rotations

A first positive aspect of fallowing with regard to soil conservation is the fact that soil losses are ”budgeted” over longer periods (see Box 38). Another positive aspect is the beneficial effect fallowing has on the physical characteristics of the soil. Roots and organic matter which were supplied by the fallow vegetation strengthen soil aggregates (improve soil structure), which increases water infiltration and hence reduces runoff. This explains why in general recently opened fields suffer less from erosion than fields which have been cultivated for one or several years: after 1 or 2 years of cultivation the soil aggregates degrade, rendering the soil more susceptible to erosion.

· Advantages of fallow rotations: + Improve the physical, biological and chemical soil characteristics. + Provide weed and pest control (if the fallows are of ”good quality”).

· Limitations of fallow rotations: - Require much land. - Clearing fallow land is labour-intensive. - Have only temporary benefits for soil erosion control.

”Proper” tillage

Deep hoe-tillage on steep slopes is a common practice nowadays in the cultivation of annual crops, mainly as a response to increasing weed problems. It is a drastic but very effective method to get rid of several types of perennial grasses. Another major reason why farmers till is to obtain a particular soil surface state thought to be ideal (or even necessary) for a good rooting and growth of the young crop. The way in which farmers till their fields depends on the degree of weed infestation, the physical soil conditions and the type of crop which will be grown. The various tillage practices are described in Box 40. Why different crops receive different tillage treatments is explained in Box 41.

Deep tillage on sloping lands is almost as controversial as burning, because it is generally believed that tillage increases erosion. No- or minimum tillage have become, in consequence, ”standard recommendations” because these practices are thought to minimise erosion. The effects of various types of tillage can however not be generalised. Whether certain tillage practices increase or decrease erosion depends on the specific circumstances. More explanations are given in Box 40. The advantages and limitations of deep versus no- or minimum tillage are listed here below.

77 The management of highland soils: an integrated vision

· Advantages of deep tillage: + Improves (temporarily) the infiltration of water. + Slows down (temporarily) the speed of runoff water (in case of rough tillage). + Results in a favourable seedbed (eventually after harrowing). + Gives a good control of grasses and a moderate control of broadleaf weeds. + Conserves subsoil moisture. + Increases mineralisation, which can be a short-term benefit for certain crops. + If tillage is done immediately after burning it prevents the loss of ashes (see Appendix 2.3). + Can reduce the number of certain soil-borne pests (see Chapter 10).

· Limitations of deep tillage: - Requires much labour input. - Creates dry tillage erosion and increases the risk of (deep) gully formation. - Causes the topsoil to dry out quickly. - Increases mineralisation, which might be a disadvantage for soil and crops in the long run if the loss of soil organic matter is not compensated for. - Plant residues (if present) are worked into the soil and so can no longer function as a cover to protect the soil surface from rain and runoff-water.

· Advantages of no- or minimum tillage: + Require no or limited labour input. + Give less chance for gully formation. + Allow plant residues to remain as a protective cover on the soil surface.

· Limitations of no- or minimum tillage: - Give no or poor weed control. - Increase the velocity of runoff-water (if there is no mulch cover). - Provide inadequate seedbed preparation for certain crops, which results in lower yields.

Figure 26. Tillage on steep slopes is almost as controversial as burning

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Box 40. Methods of soil preparation and their effects on soil erosion

· No-tillage. In traditional swidden systems, long fallow periods result in favourable physical soil conditions and virtually weed-free seedbeds. Upland rice is planted without any previous tillage, with only a minimum disturbance caused by the use of a dibbling stick. · Minimum tillage. Consists of ”scraping” the soil with a hoe to remove weeds and part of their root system. Both zero and minimum tillage result in a smooth soil surface, thus runoff water is easily generated and can attain high velocities. This can lead to sheet erosion, or to the formation of rills. Because of the limited depth of disturbance (a few centimetres), however, deep gullies are unlikely to develop. · Deep tillage. The soil is ”turned” with a hoe to a depth of 10 cm or more. The farmer makes a deliberate attempt to expose roots of perennial weeds to the soil surface, where they are left to dry and are later eventually removed. Deep hoe tillage results in the formation of soil clods (aggregates) on the soil surface. If the clods are left undisturbed after the tillage operation, we speak of rough tillage, because the result is a rough soil surface (seedbed). If the clods are broken after tillage, which is done either by ”smashing” with the backside of the hoe or by using a rake, we speak of fine tillage. Deep cultivation improves (temporarily) water infiltration and slows down the speed of runoff water if a rough soil surface is generated. Both effects slow down erosion. How long the effects last depends on the size and stability of the soil aggregates which result from the tillage operation. Big and strong clods give a good and long-lasting erosion control. Small and weak clods have only temporary effects. Deep tillage on steep slopes has two major limitations. First of all considerable erosion takes place during the tillage operation itself - dry tillage erosion. Secondly, if runoff water is generated this can lead to deep gully-formation and thus very high erosion losses. · Ridge tillage. A deep tillage method which aims at giving the soil surface a certain desired micro- topography. Basically it leads to an alternation of strips where the original soil surface is raised (ridges, bunds, beds) and strips were the original soil surface is lowered (furrows). If these ridges follow the contour lines they can reduce runoff and erosion. If they are oriented at an angle oblique to the contour line (to drain water, as is the case in the cultivation of rainy season cabbage) they can increase runoff and erosion.

Box 41. Why different crops receive different tillage treatments

· Upland rice. In areas with short fallow durations upland rice is nowadays generally planted under conditions of deep and fine tillage. Weed control is the main reason, because young rice seedlings are very sensitive to weed competition. But even if weeds are controlled by other means it appears that rice yields are still better with deep tillage. Apparently rice (seedlings) places high requirements to the physical conditions of the soil. · Maize. Is often planted after minimum or deep but rough tillage. Maize seedlings are more ”robust” than rice seedlings, i.e. can better compete with weeds and are apparently less demanding with regard to the physical soil conditions. Another, more pragmatic reason for a less elaborate tillage is the fact that maize often is considered a less important crop than rice. · Ginger. Requires deep and fine tillage in order to get a product with a good shape (price). · Vegetables and flowers. Are often grown on (contour)ridges to drain-off water.

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In an attempt to briefly summarise the tillage debate we can state that:

Deep hoe-tillage ☺ has several important short-term advantages, L but continued on the long-term implies a serious threat to the soil.

No- or minimum hoe-tillage ☺ has long-term soil conservation benefits, L but has several short-term disadvantages.

Because of the various advantages and limitations of different tillage options, it is impossible to give standard recommendations regarding tillage. Whether or not or how tillage should be done depends on the situation. Deep hoe-tillage should, however, by preference only be used in situations where farmers have no other alternatives. Furthermore it should always be combined with a maximum set of soil conservation measures, including the establishment of erosion control structures.

If we want farmers to reduce deep tillage, we have to find alternative solutions to control (grassy) weeds, the main reason why farmers grab their hoe. These alternatives can be broadly grouped into two methods: (1) those based on the maintenance of a continuous soil cover and (2) those based on the use of herbicides. We will discuss these options in various parts in the remainder of this book. What we want to stress here, however, is that under the current highland farming situation farmers often have few other options than the use of a hoe.

Mulching

A layer of plant residues which covers the soil of an agricultural plot is called a mulch. Practically speaking, we can distinguish 2 ways of mulching:

· in-situ mulching: plant residues remain where they fell on the ground; examples: residues resulting from field clearing can be left on the soil surface and crops are directly planted in this mulch (slash-and-mulch systems, see examples in Appendix 2.4.); residues resulting from a weeding or a pruning operation, can be left on the soil surface under an already established crop canopy.

· cut-and-carry mulching: plant residues have to be moved before being used as a mulch; examples: rice straw is often collected after harvest to be applied as mulch on beds for garlic or onion cultivation; hedgerow prunings can be applied as mulch for the crop in between the hedgerows (see further in this chapter).

Mulching offers very good erosion control, even if the soil surface is not completely covered. That’s why mulching is a standard recommendation in almost any soil conservation manual. Highland farmers do practice mulching, but not for all their crops. To make sure that our mulching recommendations are realistic, it is useful to have a look at why certain crops are planted in a mulch and others not (see Box 42).

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Box 42. Why certain crops are mulched and others not

· Case 1: mulching has obvious direct benefits for the cultivated crop. Mulching is done for various cash crops for specific reasons. Onion and garlic are mulched to keep the soil moist and cool (these crops are usually grown during the dry season under irrigation) and to control weeds (early hand weeding would be very difficult without damaging the crop). Mulch is also commonly applied under flowers and strawberries, mainly to protect the fragile and valuable products against soil splash. · Case 2: mulching saves labour. Mulching is often seen in maize fields, before as well as after crop establishment. In Box 41 we already mentioned that maize can reasonably well compete with weeds. Some farmers therefore plant maize, without tillage, in a mulch of weeds which were killed with herbicides. This is obviously less labour demanding than performing a tillage operation. Because maize is planted with a large spacing and requires less rigorous weeding, weeding is often done by slashing. The residues are left on the ground because there is no obvious need (or desire) to remove them. · Case 3: mulching has several limitations. Mulching is never seen in upland rice, for various reasons. Upland rice requires deep tillage (see Box 41) so mulching, if done before planting, would have to happen in a cut-and-carry way after tilling, which is difficult and labour demanding. Planting rice in a (thick) mulch, with the traditional method of using a dibbling stick, is also very impractical. Mulching rice after its emergence is difficult because of the dense plant spacing. And finally, leaving weed residues behind as a mulch is also never done because certain weeds may regrow if the soil is moist (some farmers were even observed to bury the weed Ageratum conyzoides because of this). What is quite common, however, is to see weed residues being used to construct contour mulch lines in upland rice (see further in this chapter).

· Advantages of mulching: + Gives very good erosion control. + Suppresses (broadleaf) weed growth (if applied in a thick layer). + Recycles organic matter and plant nutrients. + Keeps the soil moist and cool. + Encourages the presence of beneficial organisms, i.e. serves as a habitat for beneficial soil organisms and natural enemies of crop pests.

· Limitations of mulching: - Is labour intensive and difficult if used in cut-and-carry systems, especially on steep slopes or if the mulch needs to be applied after crop emergence. - Seeding or planting crops in a (thick) mulch may be difficult, especially if no adapted planting equipment is available. - Some plants may have difficulties to germinate through a (thick) mulch. - Some weeds applied as mulch can regrow (if it rains or if the soil is moist). - Does not suppress the growth of perennial weeds (grasses, bamboo). - Mulches can harbour crop pests and dangerous animals (snakes, scorpions, ...). - Suitable mulching materials may be difficult to find. - Dry mulches can catch fire (see Appendix 2.4.).

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Erosion-preventive weed management

Weeds, dead or alive, contribute greatly to the soil cover. It is therefore evident that the timing of weeding, the weeding intensity (number of weedings and thoroughness of weeding), the weeding method and the management of weed residues are important issues with regard to soil erosion control:

· Timing. The first weeding often has to happen, unfortunately, during a period when the crop does not yet completely cover the soil and rainfall is intense. Delaying this first weeding will, in most cases, result in a serious yield decline. Adjusting the timing of weeding therefore offers limited or no perspectives for a better erosion control.

· Intensity. Given the importance of a good soil cover, weed control should not aim at completely eliminating the weed cover but at reducing its harmful effects on the crop to an acceptable level.

· Method. With regard to soil conservation, weed control practices can be grouped in two classes, i.e. methods which disturb the soil surface (tillage and manual weeding such as ”pulling” weeds or ”scraping” weeds with a small hoe) and methods which do not disturb the soil surface (slashing, mowing or use of herbicides). Under conditions where soil erosion is problematic, the last group should be adopted whenever feasible.

· Weed residue management. ”Traditional” ways in which farmers get rid of weed residues are throwing them away in adjacent fallows, piling them up on small heaps in the field, burying them or burning them. Alternative methods that can help to control erosion are using the residues as mulch, contour mulch lines or gully-plugs. The potential use of weed residues as mulch was already discussed above. Contour mulch lines and gully plugs will be discussed at the end of this chapter.

Selecting crops which provide a good soil cover

Whenever possible, crops which provide a limited soil cover (due to the nature of the canopy or because of slow growth) should be avoided on erosion-prone fields. Examples of such crops are upland rice, ginger (if not mulched), cabbage and carrots. Crops which provide a good soil cover, such as maize and soybean, should be planted instead. The ideal, of course, is to plant perennial crops because once well-established they can give a continuous soil cover. Perennials can therefore be planted even on steep slopes.

Crops which are grown for the primary purpose of covering the soil, as a companion crop or as a fallow crop, are called cover crops. Some cover crops that do well in the highlands are cowpea, ricebean, lablab bean, spineless mimosa and pigeon pea.

· Advantages of appropriate crop selection: + Requires no extra efforts/inputs. + Keeps the soil moist and cool. + Decreases weed problems.

· Limitations of appropriate crop selection:

- Farmers may have a limited range of crops to select from.

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Establishing a dense crop stand

A seemingly obvious and easy way to attain a good and fast soil cover is to establish a dense crop stand. To achieve this, line and contour planting are often recommended by extension people and researchers, as alternatives to the so-called ”wide”, ”haphazard” or ”top-down” planting methods of the locals.

The feasibility of those recommended practices is however much dependent on the type of crop grown, the planting techniques available, the slope angle, the soil conditions and the weeding practices and requirements. If there is one practice that farmers have been testing and improving since time immemorial, it is for sure the crop arrangement. Therefore, when local crop varieties are grown under local management practices, we can almost be certain that the planting arrangements are very close to the optimum density and that there is little or no ”room” left for any further improvement.

· Advantages of a dense crop stand:: + Suppresses weed growth. + Line planting facilitates weeding. + Keeps the soil moist and cool. + Gives high yields in case of favourable conditions.

· Limitations of a dense crop stand:

- Is difficult (and therefore labour-demanding) to realise on steep slopes.

- Very dense plant spacing renders access to the field (and therefore weeding) difficult.

- Can result in very poor yields if conditions are unfavourable (drought, lack of nutrients, pest outbreaks).

Mixing and rotating crops

Different crops can be arranged in space and time in such a way that all together they give a maximum canopy cover throughout the cropping season (see Box 43). It is an alternative to monocropping (growing only one crop on a piece of land in a given crop season) which is typical for conventional high-input cropping systems.

· Advantages of mixing crops: + Requires little extra effort/inputs. + Favours recycling and a balanced uptake of plant nutrients (see Box 20). + Makes maximum use of the available cropping area. + Allows the farmer to budget food/income supply, labour, and risk over time. + Decreases the risk of complete yield loss in case of pest outbreaks or unfavourable climatic conditions. + Provides a better/more diverse habitat for beneficial organisms (birds, insects).

· Limitations of mixing crops: - Can lead to competition between crops.

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Box 43. Ways to mix and rotate crops

· Mixed cropping. This is the growing of two or more crops simultaneously in the same field. In traditional mixed cropping the plant arrangement often seems ”haphazard” to an outsider. A closer look, however, reveals that farmers often adapt the arrangement suiting local variations in the soil or (micro)topography or according to simply practical considerations. It is very common to see other crops mixed in upland rice swiddens. They can be annuals (e.g. maize, sesame, sorghum, cucumber, squash, tobacco, chilli) as well as perennials (banana, papaya). It is also very common nowadays to see high-value fruit trees planted in rice swiddens (see Box 21). Although traditional mixed cropping in the way it is observed in northern Thailand is undoubtedly beneficial, it should not be over-idealised with regard to its potential benefits for soil erosion control. Mixed cropping is done mainly because of practical reasons and does not specifically aim at nor result in a complete soil cover. · Strip cropping (intercropping). A mixed cropping layout whereby different crops are grown in alternate strips (rows) in the same field (by preference along contour lines). · Double cropping (sequential cropping). Growing two crops, one after the other, on the same piece of land within the same year. · Relay cropping. A variant of double cropping, whereby the second crop is planted after the flowering but before the harvesting of the first crop. Relay cropping is quite common with maize as the first crop, followed by soybean, cowpea, lablab bean,...

Fertiliser application

Fertilisers are applied to increase crop yields, but can have useful side-effects on erosion control as well. If the crop reacts positively on the fertiliser, the bare soil will be covered more quickly. The use of fertilisers may also stimulate farmers to practice soil conservation, to prevent these costly inputs from simply being washed away!

Erosion control structures

The most effective and long-lasting way to prevent soil erosion is to establish soil erosion control structures - physical barriers which aim at reducing the speed of runoff-water and intercepting eroded soil in the runoff-water. Most of the methods that will be discussed in this chapter, i.e. contour mulch lines, weed strips, crop strips, gully plugs, diversion ditches, logs and frameworks and terraces appear to be indigenous to northern Thailand or at least indigenous to the Upper Mekhong region. The only method that was introduced by extension workers/researchers, some 20 years ago, are contour hedgerows of perennial grasses or nitrogen-fixing shrubs/trees.

Contour mulch lines

Contour mulch lines are buffer strips (barriers) made by piling up plant residues (from fallow vegetation, weeds and/or crops) along the contour lines (see Figure 27). They are most commonly seen in upland rice fields where they are established during the clearing and weeding operations performed just before planting.

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Figure 27. Contour mulch lines are the most easy-to-implement erosion control structures.

Contour mulch lines can effectively control erosion as long as there are enough plant residues to break the force of the runoff-water. Very often though mulch lines are broken a few weeks after establishment, due to heavy rain storms. In such cases they may increase erosion damage (see Box 43).

To avoid break-through, mulch lines can be reinforced by: (1) regularly adding extra plant residues; (2) constructing bamboo or wooden frameworks; (3) leaving the mulch lines unweeded and (4) interplanting the mulchlines with crops. Crops which farmers were seen to plant in mulch lines are upland rice, sweet potato, maize, chillies, pineapple, banana, fruit trees and tea, i.e. crops which do not compete too much with the main (rice) crop.

If contour mulch lines are well-maintained and left in place during several cropping cycles, they can evolve to permanent terraces and/or hedgerows if the farmer would desire this (see further vegetative contour strips). Alternatively, they can also be re-established every year in different areas of the field. This ”mobility” is, by several farmers, regarded as a major advantage of the method.

· Advantages of contour mulch lines: + Are easy to implement, to maintain and to change. + Require little labour input. + Give no or little competition (for area or other factors) with the main crop. + Organic matter and nutrients are recycled. + If crops are planted in the mulch line, the farmer derives a direct benefit from the conservation structure. + Provide a habitat for beneficial organisms. + If well-established they give rise to gradual terrace-formation. + If a mulch line would catch fire it will never destroy the whole field (this is an advantage compared to mulching - see Appendix 2.4.).

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· Limitations of contour mulch lines: - Considerable amounts of residues are needed to make the mulch lines efficacious, in particular on steep slopes. - If poorly established or maintained mulch lines may increase erosion damage. - Can harbour crop pests and dangerous animals. - If mulch lines are allowed to evolve towards permanent structures (terraces or hedgerows) fertility gradients may arise (see Figure 31).

Box 44. Badly established/maintained erosion control structures can increase erosion damage.

· Gully erosion. During periods of heavy rainfall, runoff water can accumulate behind erosion control barriers (mulch lines, diversion ditches, terrace bunds or hedgerows). If this water can break through the barrier, its force can be so high that gullies are formed. If this is the case, the erosion damage in the field will probably be higher than without any conservation structure (in which case erosion might have been limited to sheet or rill erosion). · Land slides. If terraces are established in unsuitable areas (very steep and shallow soils at the lower part of a slope) and/or if they are not properly drained (i.e. excess water not channelled off), then during heavy rainfall they can get seriously damaged by landslides.

Gully plugs

When severe erosion gullies are already present in the field, farmers will often use weed residues to fill up these gullies. This is done simply because it is a convenient way to get rid of the residues, but at the same time it is an act that may help to prevent further incision and expansion of the gullies.

Diversion ditches

Diversion ditches are ditches which run diagonal to the slope, aiming at intercepting and draining runoff-water and soil sediments (see Figure 28). They can be very effective in runoff control, thereby limiting on-site erosion.

Diversion ditches need to be maintained very well. If a ditch gets obstructed, the risk of gully formation is very high (see Box 44). They further also may need to be reinforced, inside (with stones) and outside the ditch area (with mulch lines or vegetative strips).

Another concern related to the implementation of declining ditches is increased off-site erosion. Declining ditches drain large amounts of water out of the field, but what happens with this water once it is beyond the field boundary? If it is just left to go its own way it can lead to severe erosion problems in adjacent fields. This can be prevented though by leading the water into fallow land, rivers or irrigation channels, by means of special drop structures constructed to slow down the water flow. The collected water can then be used in paddy fields, orchards, home gardens and fish ponds (in the latter case you may first want the soil sediments to settle out in sediment ponds).

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· Advantages of declining ditches: + Can control on-site erosion very well. + Are easy to construct and to change. + Require little area and do not compete with the crop. + The water and sediments collected can be used in several beneficial ways.

· Limitations of declining ditches: - The method requires good maintenance and water-engineering skills, otherwise it can seriously increase erosion problems. - Given this need for maintenance and engineering work, the method is quite labour intensive.

Figure 28. Declining ditches are used to drain rain water from sloping fields.

Logs and frameworks

Two practices which are sometimes observed among rotational swidden farmers is to position unburned logs perpendicular to the slope and/or to construct wooden frameworks in some very erosion-prone spots in the field. Sometimes farmers also plant less ”erosion- sensitive” crops in these areas, such as cucumbers and squash.

· Advantages of logs and frameworks: + Can prevent gully-erosion.

· Limitations of logs and frameworks: - Do not prevent sheet and rill erosion. - Require much labour to be put in place.

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Terraces

Terracing, i.e. reshaping a sloping field into several horizontal fields (see Figure 29), is the most drastic and labour intensive method to control soil erosion. If it is well done, however, it is also the most efficient and long-lasting one.

Terracing is seldom done for rainfed farming of subsistence crops, because the high labour investment is generally not worth the output. A characteristic problem of (no-input) agriculture on rainfed terraces is that yields are generally low in the first years, which is due to the exposure of infertile subsoil during terrace construction. This problem can, however, be counterbalanced by fertilisers and/or flooding (see Box 49). Terracing is therefore a common practice in intensive vegetable and flower production (cash cropping). The area of irrigated rice terraces is also steadily increasing.

· Advantages of terraces: + Provide good and long-lasting erosion control if well-constructed and maintained. + Many crop husbandry practices are easier to carry out on flat terraces. + Flooded terraces (paddy fields) offer a range of specific nutrient management and cropping advantages (see Box 49 and Chapter 11).

· Limitations of terraces: - Require deep soils. - Require much labour for construction and maintenance. - Require solid regulations (guarantees) for land (use) rights and/or economic incentives (because of the high labour investment). - Risk of land slides if the terraces are badly constructed/managed (see Box 44).

Figure 29. Terraces are an excellent means of erosion control but can highland farmers afford such an investment?

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Vegetative contour strips

We have already given a cursory introduction of the concept of vegetative contour strips when we addressed reinforced or planted mulch lines and weed strips (see above). Vegetative contour strips are simply rows of plants, planted along the contour at more or less regular intervals (there is an ”optimum” interval based on the angle of the slope). While there exist many variations on this theme, they all have the same purpose of slowing down the speed of runoff-water and intercepting (part of) the eroded soil.

Vegetative contour strips can be composed of any type of plants (see Box 45), but most widely promoted are contour strips with (introduced) fast-growing perennial grasses and nitrogen-fixing shrubs. These types of vegetative strips are referred to under a range of names such as grass strips, contour hedgerows, alley-cropping and SALT, terms which actually refer to particular researcher-designed packages that comprise, besides vegetative contour strips, a range of ”recommended” cultural practices such as no-burning, no- or minimum tillage, mulching and permanent farming with crop rotation.

Despite two decades of intensive research and extension work on hedgerow systems, farmers’ adoption has been very disappointing in northern Thailand. After all this should not surprise us because farmers look at those systems from a very different perspective than we do (see Box 46). Other causes that explain the failure of adoption are summarised in Box 47. The lack of farmers’ interest in hedgerow systems may, however, not lead us to conclude that hedgerows should no longer be regarded as a valid soil conservation option. What we should learn from this experience is to have realistic expectations of what various types of vegetative strips can and what they can’t contribute to sustainable highland agriculture. Finding the ”ideal” plant for these strips (i.e. one that can produce a crop, can produce beneficial residues and presents little competition with the main crop) is difficult, if not impossible. What we can do, however, is increase the choice of plants so that farmers can choose from a wide range of ”compensations” in return for losses or inconvenience due to the presence of vegetative strips in their fields. We should also be more open to the idea of temporary strip systems as opposed to the generally recommended permanent strip systems. Other possible improvements are suggested in Appendix 2.5.

Box 45. Plants that can be used to establish vegetative contour strips

· Weeds. · Fast-growing perennial grasses. Vetiver grass (Vetivaria zizanoides), Setaria anceps, Brachiaria ruziziensis, Paspalum notatum, lemon grass (Cymbopogon citratus). · Fast-growing nitrogen-fixing shrubs/trees. Leucaena leucocephala, Cajanus cajan, Tephrosia candida, Flemingia congesta, Gliricidia sepium. · Annual crops. Maize, sweet potatoes, chillies, sesame, sorghum, pineapple, taro, cassava. · Perennial crops. Banana, papaya, coffee, tea, paper mulberry (Broussonetia papyrifera), fruit trees.

89 The management of highland soils: an integrated vision

Figure 30. Contour hedgerows are a valid soil conservation technique, but we should have realistic expectations of what hedgerows can and what they can’t contribute to sustainable highland agriculture

· Advantages of vegetative contour strips: + Give a good erosion control if well-established/maintained. + Lead to gradual terrace formation (see Figure 31). + Depending on the type of plant used to establish the strips they can produce an extra crop and/or multi-purpose plant residues (for soil improvement, livestock fodder, fuelwood). + Can provide shade for plants that require shade. + Provide a habitat for various beneficial organisms. + Hedgerows of nitrogen-fixing crops can help to speed up and improve the fallow regeneration process (in case the field would still be fallowed). + Weed strips are easy to establish and remove. + Crop strips may need no or only minimal maintenance labour.

· Limitations of vegetative contour strips: - Compete with the main crop for area (10-20%), light, water and plant nutrients. - Require extra labour input and knowledge (use of an A-frame) for their establishment. - Require in general much maintenance labour (for cutting the strips and eventually using of the cuttings as mulch or livestock-fodder). - Provide no short-term benefits (unless the strips are composed of crops). - Eventual soil improvement happens slowly and is very limited (see Box 47). - Can lead to fertility gradients under long-term use (see Box 47 and Figure 31). - Can increase erosion damage if they are badly established/maintained. - Can harbour crop pests and dangerous animals. - Hedges of perennial plants are very difficult to remove once they are established. - Weeds strips can invade/infest the rest of the field (or even adjacent fields) if they are not regularly cut back.

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Box 46. Hedgerow systems, seen from a researcher’s and a farmer’s perspective. (the persons and the scenario are fictitious, but the statements of ”Khun Doi” are a compilation of statements made by several farmers)

PART 1

R : Hello Khun Doi. [R=researcher] F : Hello Khun Mo Din. [F=farmer] R : I see that you are preparing your field already? F : Indeed, the rains will soon arrive and I would like to plant my rice in time. R : A steep slope you are hoeing there, isn’t it? F : Yes, indeed, but all the flatter areas are already occupied. R : Why don’t you plant your rice without hoeing the field? F : Because there are many grasses coming up and the soil is hard. R : Don’t you think that a lot of soil will come down on such a steep slope? F : Maybe, that will depend on the rain. R : Do you mind if the soil comes down? F : Yes, because together with the soil seeds and young rice plants will come down. R : You could prevent the soil from coming down by growing rows of other plants in your field, like on this picture. [R shows a poster of hedgerow systems] F : Hmm? What are the plants in these rows? R : Kratin [Leucaena leucocephala]. Look, I brought seeds with me. F : I don’t know that plant. Can you eat it? R : No, but it can make your soil better. F : How can these plants make my soil better? R : You should cut them regularly, and put the cuttings as fertiliser between your rice plants. You can also feed the leaves to your cows and use the wood of the stems and branches. F : Wood?! Is it a tree?! I think the rice will not be good if it is planted close to trees! R : I understand your concern. That’s why you have to cut the rows regularly. R : Hmm? How wide are these rows, and how many rows do I have to plant? R : They should be half a meter wide, and you need one row every 6 meters. F : Oh, but then I will loose a lot of planting space for rice! [10-20% of the cropping area] R : Indeed, but in return you will get the benefits I just mentioned: better soil, cattle feed and wood. Furthermore you won’t have to move your fields any more. The longer you use the fields with kratin rows, the better your soil will become! F : Will I get a good rice yield every year? R : Yes, if you would follow a few more pieces of advice. First of all you should never burn nor till the soil. Furthermore, instead of only growing rice between thekratin rows, you should also grow maize and beans in the way that is shown on these pictures. [R shows a series of flip-charts that explain the concept of crop rotation] F : I cannot follow your last suggestion, because if I don’t plant the whole field with rice my family won’t have enough to eat this year. But I want to try and see whether thesekratin rows can make the soil better.

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Box 46 (continued)

PART 2 (3 years later, in the same village...)

R : Hello Khun Doi. F : Hello Khun Mo Din. R : I see that you are slashing a new field?! F : Indeed, I badly need a good rice harvest this year. R : Oh?! What happened with the field where you planted the kratin hedgerows? F : I will leave it fallow this year. R : Oh?! Aren’t the hedgerows growing well and don’t they keep the soil in the field? F : That’s not the problem. The hedgerows look very good and the soil remains in the field. But the rice is not good any more. R : What’s the problem with the rice? F : The rice grows well in the area just above the hedgerows, but grows very bad in the area just below the hedgerows [fertility gradients, see Box 47 and Figure 31]. Each year the yields went down. And there are also too many weeds and wumaphu [white grub, a beetle larvae that feeds on rice roots] in the soil. Besides, my wife is sick and I cannot cut all the hedgerows alone. R : Did you put the cuttings in between the rice plants as I suggested? F : No, I didn’t. I always put them in the hedgerows and the third year I burned them in the areas between the hedgerows, before planting rice. R : Why didn’t you do it the way I advised? F : I tried in one strip to plant the rice in the cuttings, but that was very difficult and the rice didn’t come out well. I never tried to put the cuttings in between the standing rice plants because that seemed too much work. The third year I burned all the kratin branches to give some fertiliser to the soil and to kill weeds and wumaphu. R : I have seen that some of the villagers are still using fields with kratin hedgerows. F : Yes, indeed. Some people plant maize in between the rows and that works better than with rice. My neighbour doesn’t like the hedgerows though, but he continues to plant them because he hopes that pha mai [the officers of the Forestry Department] will not take away his fields if he plants kratin rows. R : Are you going to do something on this new field to prevent that the soil comes down? F : Yes, I think that next year I will make rows with dead weeds and rice straw. And I will plant maize and sweet potato in these rows. R : That’s a good idea, but I know something that is even better! You can plantja feik [vetiver grass] in the rows. F : What is ja feik? Is it something that you can eat? R : No, it is a grass. It has very deep roots that can hold the soil. And you can use it to make baskets and many beautiful things. F : There are already many plants around which I can use to make baskets and beautiful things. F : The roots can be used to make perfume! R : Will your wife buy my ja feik perfume? R : Euh...could we try to plant ja feik in your old field with kratin hedges? F : Sure, if you have a few weeks to help me with digging out the hedges!

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Box 47. Why is farmers’ adoption of hedgerow systems not very successful?

· Because of the way they were promoted.

· Only a few types of hedgerow plants were promoted.

· The hedgerow plants that were promoted were mainly plants without immediate benefit to the farmer. The possibility to establish hedgerows with plants which have a direct use did not receive enough attention.

· Hedgerows were mainly promoted in combination with annual crops, although they might be easier to combine with perennial crops (less severe competition effects).

· The recommended management practices (no-burning, no-tillage, mulching, using residues as livestock fodder) are not very attractive to farmers.

· Hedgerow systems were promoted for permanent land use and with emphasis on soil conservation. Other problems related to permanent land use were thereby neglected. The possibility of temporary hedgerows systems received no attention. · Because of agrotechnical constraints

· Competition between hedges and crops is high, even if the hedges are regularly pruned. This applies in particular to root competition. Due to frequent pruning the hedges are under stress and might develop a very shallow rather than a deep root system.

· Improvement of soil fertility in the area between the hedges is limited and happens slowly, due to various reasons. First of all one can doubt whether the ”nutrient pump theory” is a reality or a myth: are the roots really going deep and, if yes, are they really absorbing much nutrients from the poor subsoils, which can then be transferred to the topsoil as trimmings? A second question is whether hedges with nitrogen fixing plants really contribute much nitrogen to the main crop. Results from on-station experiments in northern Thailand, where all the recommended practices were followed (mulching, etc.), are not very convincing.

· Another specific problem is that fertility-gradients may arise after several years of continuous cropping. Hedgerows control erosion at the overall field level, but erosion between the hedgerows keeps going on (partly due to the impact of rain but predominantly due to the impact of tillage). This leads to terrace formation which, depending on your perspective, can be seen as beneficial, but it also leads to a redistribution of soil fertility that is less beneficial. In the long run we might end up with nutrient-rich and prolific growing hedgerows vs. nutrient-poor inter-hedgerow zones which yield a poor crop. In the case of upland rice we can observe, after only a few years already, that the crop reacts to these fertility gradients (see Figure 31). Due to this phenomenon, the overall crop yield is not better or might be even lower than in fields without hedgerows. · Because of farming systems constraints.

· Due to the lack of land rights and the fact that hedgerow systems give no or only limited short-term benefits, farmers are reluctant or simply cannot risk to invest area and time in these structures.

93 The management of highland soils: an integrated vision

Figure 31. Erosion between vegetative strips causes accumulation of topsoil at the lower part of the terrace and concomitant uncovering of the subsoil at the upper part of the terrace. This results in a nutrient gradient which manifests itself as a yield gradient.

Conclusion: Soil conservation should be an integral part of a comprehensive strategy

In this key-chapter we addressed the fundamental issue of soil erosion, an issue which is inevitably linked to any type of farming in a hilly or mountainous region. We acknowledged the urgent need for wide-spread adoption of soil conservation measures in the hills of northern Thailand, but stressed at the same time also the need for a pragmatic, holistic and creative approach to this complex problem. Thereby it is the responsibility of the scientist/extension worker to understand the variety of the causes of erosion, and the responsibility of the administrator/politician to create a climate that favours sustainable use of the land.

Erosion control then can take many forms. It can be the implementation or the cessation of one or more cropping practices or strategies. It can also be the implementation of structures having the dedicated purpose of erosion reduction. It cannot be stressed too much that probably the best approach in soil conservation (and indeed in sustainable agriculture in general) is to mix and match pieces of the various options available. We should aim for a strategy of ”complementary mixes”, i.e. combining options to collectively reduce or eliminate the limitations that those options present individually.

94 Chapter 8: Soil nutrient management

Many of the management options addressed in the previous chapters talk to the ends of maintaining, restoring or improving soil fertility one way or another (or, indeed, several ways or several others). Since soil fertility includes nutrient availability considerations, those options then also address nutrient management, i.e. the balancing of those soil and/or crop factors that enhance and hinder plant nutrient availability.

The scientific theories behind plant nutrition and plant nutrient management are complex, and to be honest, still not completely understood by researchers. This chapter will therefore only give a very general overview of nutrient management, hoping that the reader keeps in mind thevarious nutrient management issues that were addressed in the previous chapters. As we recognise that fertilisers play a direct and very important role in nutrient management, we will talk in this chapter specifically about fertiliser application. We will also try to clarify some misconceptions that are linked to the use of “chemical” fertilisers.

Box 48. Processes that affect the amount/availability of plant nutrients in the soil (+ denotes gains; - denotes losses; ± denotes both gains and losses)

+ Weathering. Most plant nutrients present in the soil were released from rock through complex processes of weathering (see Chapter 3). + Mineralisation. (see Chapter 3). + Sediment deposition. Depending on their position in the landscape, certain soils may receive nutrient-rich soil deposits. + Atmospheric deposition. Small amounts of nutrients deposited through rain and dust.

+ Nitrogen fixation. The biological conversion of elemental atmospheric nitrogen (N2) into organic compounds. This important soil process is carried out by bacteria that can “catch” nitrogen from the air (where it is present abundantly as a gas) and turn it into plant available nitrogen forms. Some bacteria can do this on their own, but the most important ones require a close association with the roots of certain plants. - Nutrient removal by physical processes. Plant nutrients can get lost through erosion, runoff, leaching and volatilisation (losses in the form of gasses). - Chemical fixation. Some nutrients can “stick” so strongly to soil particles that plants cannot readily absorb them (e.g. phosphorus or potassium). - Micro-biological nutrient immobilisation. Soil micro-organisms also need nutrients for their own growth. If a soil is low in nutrients they’ll have to compete with crops for what little nutrients the soil does have, which, ultimately, can jeopardise crop production. This phenomenon applies in particular to nitrogen (nitrogen-immobilisation). - Crop harvesting. Important amounts of nutrients are removed from the field through the harvesting of crops. The higher the yields or the more often a field is cultivated, the higher these losses. ± Burning. see Chapter 6.2. ± Flooding. See Box 49.

95 The management of highland soils: an integrated vision

8.1 Why do we need to manage plant nutrients?

To answer this question, it is very tempting again to make a comparison with people (see Figure 16, Chapter 3). As long as we have a normal health and lifestyle, we don’t have to pay much attention to our diet. People who are ill, pregnant mothers ortop athletes, however, may require special food or special amounts of food because of the exceptional “performances” that are asked from their bodies. For soils and the plants they “feed” the situation is very similar.

In natural ecosystems, nutrient gains and nutrient losses (see Box 48) are generally in balance. When we convert natural systems into agricultural systems, however, this balance gets disturbed. This may lead to a net loss of nutrients from the system, especially if we put high demands on the soil regarding the quantity and quality of agricultural products we want it to produce. In order to control/compensate those nutrient losses and to achieve (high) anticipated crop yields, soil nutrients should be carefully managed.

8.2 How can we diagnose plant nutrient problems?

By observing plants

The most direct way to learn whether or not plants are suffering nutrient problems, is by carefully inspecting the plants, as lack of nutrients or nutrient imbalances may cause characteristic nutrient deficiency symptoms. When we suspect a soil of being low in plant nutrients, we should be careful however and first check a range of other factors which can cause a plant to show similar symptoms, even though there may be adequate nutrient levels in the soil. Are the soil physical characteristics all right? Do the plants receive enough water or, on the contrary, do they suffer from too much water? Is the temperature optimum? Is the plant suffering competition from other crops or weeds? Is the plant attacked by any above-ground or below-ground pests? Concerning the latter it is important to have a good look at the roots, because soil- borne pests may cause symptoms which are very similar to symptoms of nutrient deficiency. If none of the previous factors is playing a role, then there is a big chance that a lack of one or more soil nutrients is causing trouble. Conducting simple pot experiments may help to elucidate the matter (see Appendix 1.7.)

By taking soil and/or plant samples and bringing them to a lab for analysis

If observation of plants does not give clear information, one can take soil or plant samples and bring them to a lab for analysis. In the case of plant sampling it is best to first ask the lab technician or another specialist for advice, as different crops might require different sampling procedures. Lab analyses are always expensive. It is therefore advisable to have them done only when they are really needed/justified (see further Appendix 1.6).

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8.3 Nutrient management strategies and methods

If we exclude a few high-tech methods of plant nutrient management that are not (yet) practically or economically feasible in the highlands, then we can distinguish four major nutrient management strategies:

Erosion control and enhancement of nutrient recycling

As was already pointed out in Chapter 7, the implementation of erosion control measures (structures) is an absolute precondition for sound nutrient management on sloping lands. Most practices that were presented under the denominator “erosion control” (e.g. fallow and crop rotation, mixed cropping, mulching and mulch lines, vegetative contour strips, etc.) are practices that conserveat once soil material and soil nutrients (the latter by preventing erosion-induced losses, leaching losses and atmospheric losses).

Controlled burning

Burning is the traditional tool for managing nutrients in the highlands. In essence it is a process that represents a vast redistribution of nutrients between the soil-, plant- and atmosphere compartments of an agroecosystem. The general result is an increase of the amounts and availability of nutrients in the soil, at the cost of a net loss of nutrients from the soil-plant system to the atmosphere. It has been argued previously (see Chapter 6.2.) that burning can be considered a valid (nutrient) management tool, if it is used in a judicious manner.

Flooding

Flooding (or submergence) is, just like burning, a traditional and rather drastic way to alter soil conditions in order to favour crop cultivation. Rice is the only major food crop capable of growing in flooded soils. The advantages and limitations of flooding are addressed in general in Chapter 11. Here below (Box 49) we explain in brief the main effects of flooding on the soils’ chemical properties.

Box 49. Chemical changes in flooded soils

The most immediate effect of flooding is that it brings the soil from an oxidised condition into a reduced condition, i.e. a condition where there is little or no oxygen supply to the soil. This brings about a series of physical, biological and chemical changes that provide a completely different set of soil-plant relationships from those observed in crops grown under dryland conditions. Major beneficial chemical changes, among others that have no consequences and still others that might be detrimental, are: · Increase of the pH of acid soils. · Increased phosphorus availability. · Reduced soil organic matter decomposition.

97 The management of highland soils: an integrated vision

Fertiliser application

The three strategies discussed so far are essentially strategies to manage the internal nutrient resources of a cultivated field. On nutrient-rich soils that are not too intensively cultivated they may be adequate to provide crops with enough nutrients and to keep the soil nutrient content in balance. Those strategies have their limitations though when soils are nutrient-poor, when soils are permanently and intensively cultivated or when (very) high yields are anticipated. Under the latter conditions nutrients must be imported from resources external to the system (from outside the field or outside the farm). Such resources are called fertilisers, i.e. materials that are added to the soil in order to raise the soil’s plant nutrient content. They can be divided into two main classes:

· Organic fertilisers: organic soil amendments of plant, animal or human origin (see Box 50).

· Inorganic fertilisers: inorganic soil amendments that were industrially prepared (see Box 51)

Box 50. Types of organic fertilisers

· Green manure. Green manure is a collective term for all possible types of fresh (“green”) plant materials that can be incorporated into the soil as fertiliser: residues of (improved) fallow vegetation, weeds and crops (e.g. rice straw and husks, corn stems and cobs, soybean stover and pods, etc.); (nitrogen fixing) cover crops; prunings from vegetative strips (see Chapter 7.7); others, such as algae, waterplants, etc. · Animal manure. Excrements of animals (or humans). · Compost. A collective term for organic materials (of plant and/or animal origin) which have been piled (according to various kinds of methods) to undergo an accelerated decomposition process before application in the field. · Agro-industrial organic wastes. Bagasse (residues of sugar cane), distillery waste (from factories that produce alcoholic drinks), coconut fibres, etc.

Box 51. Types of inorganic fertilisers

· Purified products mined from natural mineral deposits (e.g. K-fertilisers). · Chemically altered geologic materials (e.g. P-fertilisers). · Products chemically synthetised in fertiliser factories (e.g. N-fertilisers).

Since ancient times till present, the use of organic fertilisers, animal manure in particular, has been synonymous with productive and stable agriculture. Not only do organic fertilisers feed and protect the soil, their well-considered use also allows the integration (linking) of production and consumption chains and thus recycling of nutrients and energy, at the farm level or even beyond.

98 Chapter 8: Soil nutrient management

The extensive use of inorganic fertilisers (also called chemical, mineral, synthetic or artificial fertilisers) is a rather recent phenomenon in the history of agricultural development. It lays, together with the use of high-yielding varieties and crop protection chemicals, at the origin of the so-called green revolution. This green revolution has, particularly in Asia, resulted in a spectacular increase of agricultural production, an increase that was needed - let us not forget - to feed the rapidly growing populations. Nowadays, however, the initial euphoria about the spectacular effects of the green revolution has somewhat subsided and people are becoming increasingly critical about the use of chemical fertilisers and other external inputs (see Chapter 2.1.).

The current aversion towards chemical fertilisers is due to the now obvious negative effects which can result from their indiscriminate use, as well as to the increasing popularity of alternative ecological ways of farming, which reject the use of chemical fertilisers as a matter of principle. Further contributing to this are several misconceptions about the nature and use of chemical fertilisers, some of which we have tried to clarify in Box 52. A general overview of the advantages and limitations of organic and inorganic fertilisers is given below.

· Advantages of organic fertilisers: + Have long term fertilising effects (the nutrients are relatively slowly released, depending on the type of organic fertiliser). + Contain organic matter, which can protect and/or improve the soil (depending on the way of application - mulching vs. incorporation). + Contain, besides the basic NPK, several other plant (micro-)nutrients. + Stimulate the activity of soil organisms. + Many organic fertilisers are free and locally available.

· Limitations of organic fertilisers: - Their fertilising effects are rather slow. - Nutrient concentrations are in general low (compared to chemical fertilisers), so large amounts are needed to significantly improve the soil. - Are heavy and/or bulky and therefore difficult to store and transport. - Their application, especially on a large scale and on sloping land, may pose practical difficulties and requires much labour input or mechanisation. - Animal manures, if applied in too high amounts, can have a negative impact on crop yields and pollute the soil and water resources. - Organic fertilisers can contain considerable amounts of viable weed seeds (especially if the residues are not composted). They can also be a vector for the introduction of various other crop pests.

· Advantages of inorganic fertilisers: + Give fast and spectacular effects (because they contain high concentrations of readily available plant nutrients). + Are easy to store, transport and apply because of their low weight and volume. + Facilitate precise timing and dosage of nutrient supply.

99 The management of highland soils: an integrated vision

· Limitations of inorganic fertilisers: - Have in most cases (except rock phosphate) only short term effects. - Indiscriminate use (i.e. over-dosage, continuous use of only inorganic fertilisers or of only one type of inorganic fertiliser) can have negative impacts on soil (soil organic matter decline, structure degradation, acidification, micro-nutrient depletion), water (eutrophication and pollution) and crop production (lodging and/or increased susceptibility to various pests). - Always imply a financial risk (poor or no effects in case factors other than the soil nutrient status seriously limit crop production). - Are difficult to obtain in remote areas; make farmers dependent on outside suppliers (who may cheat the farmers).

From the list presented above it is clear that organic and inorganic fertilisers both have their specific benefits and limitations. A maximum use of organic fertilisers should be encouraged, but complementary application of chemical fertilisers is often necessary. It cannot be denied that chemical fertilisers are playing an important role in agriculture and that this will remain so for the foreseeable future. Advocating farming methods solely based on organic ways of nutrient cycling appears naive in the context of certain tropical soils that are so poor that there are hardly any nutrients that can be recycled. Chemical fertilisers, used in a judicious way (see Appendix 2.6. for some practical recommendations), are in many cases a necessary input to “boost” the development of more sustainable cropping systems. Their use may allow many nutrient-poor soils to become productive while at the same time enabling farmers to withdraw lands of low quality (marginal lands) from cultivation.

Figure 32. A balanced use of both organic and chemical fertilisers may often give the best guarantee for sustainable soil and crop management.

100 Chapter 8: Soil nutrient management

Box 52. Common misconceptions about inorganic fertilisers.

· Are inorganic fertilisers “unnatural”? Scientific research has since long established that plants do not take up “humus” (soil organic matter), but instead inorganic compounds which result from weathering of rocks and mineralisation of organic residues. It is exactly these types of compounds which, in a purified and concentrated form, are applied through inorganic fertilisers. Inorganic fertilisers, then, are not exactly “unnatural”. What can be considered as unnatural though is the fact that, by applying chemical fertilisers, natural processes are “boosted” which, in case of poorly managed use, may eventually disturb soil life and nutrient balance (acidification and micro-nutrient depletion). · Are inorganic fertilisers toxic? Unlike many pesticides, inorganic fertilisers are not toxic to people nor to the environment (unless used in extremely high amounts). · Do inorganic fertilisers make the soil “hard”? The idea that the (long-term) use of inorganic fertilisers inevitably leads to soil degradation seems to be widespread, among development workers as well as among some farmers (whether the latter base this statement on own experiences or on what other people say is not always clear…). It is thought that inorganic fertilisers cause a decrease of the soil organic matter content which, in turn, would cause a detrimental effect on the soil structure. Consultation of scientific literature regarding this issue yields, at first glance, conflicting information. A closer look at the literature tells us however that the reported soil degradation is not the effect of the fertilisers per se, but rather the effect of a poor overall magement (over-dosage of fertilisers, removal of plant residues, use of heavy machinery, too frequent tillage, lack of erosion control, etc.). Long-term experiments have shown that a sound use of only inorganic fertilisers can keep soil organic matter at levels that are higher compared to treatments with now fertiliser at all. This remarkable observation is explained by an increased production of root-biomass in well-fertilised crops: the roots that remain in the soil after harvest decompose and contribute thereby significantly to the soil organic matter pool. Experiments have further established that, to maintain organic matter at a favourable level, the ideal is to combine inorganic fertilisation with a maximum return of crop residues to the field and/or the use of animal manure. · Is the use of inorganic fertilisers in the highlands a threat for the lowlands? The probability of severe downstream fertiliser pollution seems small, given the fact that natural concentrations of soil nutrients in the highlands are low (thus fertiliser nutrients will be readily immobilised by the soil and the plants) and the total area receiving fertilisers limited. Research supports this hypothesis: runoff water from upland rice fields which received inorganic fertilisers could still meet standards for drinking water. While in some of the more intensively cultivated areas of the highlands downstream fertiliser pollution is a possibility, the effects are arguably minimal when compared to what is already being contributed by lowland fertiliser application. The situation in the highlands of northern Thailand is very different from the situation in some West European countries (e.g. Belgium), where decades of very intensive fertiliser application (animal manure as well as inorganic fertilisers) have caused an oversaturation of the soil with certain nutrients, which has led to eutrophication and pollution (even to levels approaching or exceeding toxicity for animals and humans) of groundwater and rivers.

101 The management of highland soils: an integrated vision

Conclusion: Nutrient cycling and balanced fertilisation are the key-components of sound nutrient management

It has been pointed out in this chapter that sound nutrient management involves the following key-components: (1) the combination of a wide range ofsoil and/or crop husbandry practices that aim at conserving and recycling the nutrients that are already present in the field or on the farm and (2) balanced fertilisation, i.e. the complementary use of both organic and inorganic soil amendments. Other nutrient management options that can be valid under specific circumstances are controlled biomass burning and flooding.

The common bias that apparently exists against the use of inorganic fertilisers is, in our point of view, unjustified. This bias is partly due to several misconceptions we have tried to clarify by scientific arguments. There is a growing consensus these days that a balanced use of organic and inorganic fertilisers gives the best guarantee for sustainable soil and crop management. Organic fertilisers should be favoured as the primary source of nutrients for soil fertility maintenance, while inorganic fertilisers should be regarded as an extra tool a farmer can reach for when necessary.

102 Chapter 9: Weed management

9.1 The burden of weeding

A weed is any plant which grows in a place where it is not wanted by humans. Farmers do not want weeds in their fields because they compete with the cultivated crops for light, water and plant nutrients.

If highland farmers in northern Thailand are asked what their main agricultural problems are, very often weeds rank first or second place. It is, indeed, widely known that weeds are a major constraint in tropical agriculture. This is in particular the case for rainfed upland farming (see Box 53), not only in Thailand but all over Southeast Asia. It seldom happens, though, that crops are completely lost to weeds. Farmers know the importance of weeding very well and will therefore devote much of their labour to this practice (30% - 60% of the total labour input in upland rice cultivation). As such weeds are not that much a constraint at the field level but rather at the overall farming system level, i.e. the labour that is allocated to weeding cannot be allocated to other activities.

Box 53. What kind of weed problems do highland farmers face?

· During the cropping period.

· Broadleaf herbs: Rapid invasion during the early cropping stage, characterised by a quick soil cover but a relatively slow vertical growth.

· Grasses and sedges: Gradual invasion of grasses occurs in fields with minimum tillage and/or poor weeding. Most grasses have extensive, shallow root systems and show a vigorous vertical growth and biomass production. Some grasses can even form large clumps which develop from a single plant.

· Vines: Can locally “strangle” fieldcrops but do generally not reach high densities and are easy to remove if this is done in time. · During the fallow period or in orchards.

· Rapid invasion of grasses if no weeding activities are performed. Grasses give problems during field preparation and are prone to yearly burning (which retards fallow regeneration and can destroy orchards).

9.2 What is the purpose of weed control?

· To keep weeds at an acceptable level during the critical (early) stage of crop development. There is no need to keep fields absolutely weed-free, because this is a waste of labour and increases nutrient losses by erosion and leaching. It is difficult though to define what is an “acceptable” level, as this depends on the type and value of the crop, the type of weeds and the period of weed infestation. In general farmers know very well when they have to weed. If they do not weed in

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time it is often because of labour constraints or because they foresee that other factors (insects, poor soil fertility, drought) are going to be more limiting. · To prevent the build-up of a weed seed bank. Farmers should always try to avoid massive flowering of weeds, especially when the same field is being used for several years. Many types of weeds can indeed produce huge amounts of seeds, which can accumulate and survive in the soil as a so-called weed seed bank. · To prevent fire damage in fallows or orchards. An accumulation of dry weed biomass, especially of grasses, is prone to fire during the dry season. · To avoid providing hosts or cover for crop pests. Certain weed types are alternative hosts for several plant pests (soil-borne pests in particular). According to farmers, a weedy field is also more frequented by rats.

9.3 Weed control and soil conservation: irreconcilable objectives?

Interactions between weed control and soil management are important and complex. The way the soil is managed can be either beneficial or problematic with regard to weed control, whereas the way weeds are managed can be either beneficial or problematic or with regard to the soil. Some examples:

· Soil conservation measures such as permanent cultivation, no-burning and no- tillage may aggravate weed problems and therefore be rejected by the farmers.

· Weed residues used as a mulch or used to establish contour mulch lines (see Chapter 7) are an important asset to soil conservation.

· Clear weeding, deep tillage and injudicious use of herbicides are weed control practices which can cause much damage to the soil.

These examples show that weed control and soil conservation are two of the many inextricably linked challenges in the pursuit of soil and farmer friendly agriculture, or in other words, that weed control should be an integral part of a comprehensive soil conservation strategy.

9.4 How to diagnose weed problems

By talking with the farmers

Farmers know better than anyone else what the problem weeds are. Just by asking them to collect the weeds or to bring you to the fields, you will get a good first introduction to the situation.

By regular field visits

When you want to assist farmers in weed control you need to make your own detailed observations. Therefore you have to visit the fields regularly, especially during the

104 Chapter 9: Weed management early rainy season (early crop stage) and if possible also during the dry season (when many weeds flower). If you are not (yet) familiar with weeds, you will need a book with botanical descriptions or you can ask advice from a botanist.

9.5 Weed control strategies and methods

Several weed control methods have already been addressed in the previous chapters. We will here only highlight those methods or simply refer to the previous chapters. Methods that so far were not yet addressed will be given due consideration.

Preventive weed control

Judicious fallow management

A good fallow can help to get rid of many weeds, can prevent the build-up of a weed seed bank and can also prevent seed dispersion into adjacent fields (see Chapter 5).

Post-harvest weed control

It is often observed that, after harvest at the end of the rainy season, farmers leave their fields idle until far into the subsequent dry season. This dry season fallow period can last several months and allows many weeds to grow and flower, without the competition of a crop. If those weeds can shed their seeds before the next field preparation, they will contribute substantially to the build-up of a weed seedbank.

If, however, weed control is carried outas soon as possible after harvest (by slashing, burning, tillage, planting cover crops or spraying herbicides), massive production of weed seeds can be prevented and less weeds will germinate during the subsequent cultivation period.

· Advantages of post-harvest weed control: + Can substantially reduce weeding labour during the next cropping period. + Post-harvest weed control with cover crops can protect and improve the soil.

· Limitations of post-harvest weed control: - Requires labour input during a period the farmer may have other activities to do (transporting and processing the harvest, off-farm labour, hunting).

Stale seedbed method

In the stale seedbed method, sowing of the crop is postponed while weeds are allowed to germinate after soil preparation and the first rains. When a significant number of weeds has germinated they are destroyed by tillage or by the use of chemicals, after which the crop is planted.

105 The management of highland soils: an integrated vision

· Advantages of the stale seedbed method: + Prevents weed competition by removing weeds before the crop is established. + Access to the field is easy because there is no crop yet on the field. + Can reduce the weed seed bank considerably if done several years in a row.

· Limitations of the stale seedbed method: - The practice is somewhat risky because its success depends on the rainfall. If the crop is planted too late this might result in a serious yield reduction. - If planting is postponed, the soil will be bare for a longer period, which may increase soil erosion losses unless extra erosion control measures are taken. Mechanical weed control

Burning (see Chapter 6.2.)

Fire can destroy part of the weed seed bank, destroy most of the standing weed vegetation and retard the growth ofcoppicing weeds (grasses, bamboo, vines).

Hand weeding

Hand weeding, which is in general a combination of pulling and hoeing operations, remains by far the most effective weed control method, if properly timed and carefully performed. The biggest constraint is the great amount of labour it requires.

· Advantages of hand-weeding: + Very effective. + Very selective.

· Limitations of hand-weeding: - Very labour intensive. - The soil gets loosened (thereby increasing erosion risk after weeding).

Slashing or mowing

Slashing weeds by hand remains one of the most common methods of weed control. It is mainly done as a preparation to burning but it is often also done in between a standing crop (e.g. maize or fruit trees). The most widely used tool for manual slashing is a big knife or machete (see Figure 19). Better-off farmers (in particular those with orchards) are using hand-operated mechanical mowers nowadays.

· Advantages of slashing: + Slashing is less labour intensive than hand-weeding. + The soil does not get loosened (thus no increased erosion after weeding).

· Limitations of slashing: - Weeds are not killed, their growth is only retarded.

Tillage (see Chapter 7)

106 Chapter 9: Weed management

Mulching (see Chapter 7)

Flooding (see Chapters 8 and 11)

Few weeds can germinate or survive in submerged soils. Flooding is therefore one of the most efficient weed control practices. Cultural weed control

Canopy cover management

Cultivating weed competitive crops/varieties, dense crop spacing, mixed cropping and crop rotation (see also Chapter 7) are methods that aim at rapidly establishing a complete and long-lasting ground cover, in order to shade the weeds in the understorey. Particularly useful for this purpose are so-called cover crops.

Fertiliser application

Chemical fertilisers, applied close to the roots of a crop (by preference on individual plants or hills), will improve crop growth without increasing weed growth. Chemical weed control

A broad spectrum of herbicides (chemicals for weed control) are available nowadays and their use is wide-spread in commercial highland horticulture. Herbicides of the old generation are often non-selective and very toxic to people and to the environment, whereas modern herbicides are more selective and less toxic. Unfortunately, the latter are also more expensive and therefore often beyond the reach of highland farmers.

In upland rice cultivation the use of commercial herbicides is (still) limited. Popular though is the use of a home-made herbicide, consisting of common salt NaCl)( mixed with washing detergent. More details about this odd and at the first sight noxious indigenous practice can be found in Box 54.

· Advantages of herbicides: + Require far less labour input than handweeding. + Are an easy alternative to fallow-, fire- and tillage-based weed control. + Spraying herbicides induces less erosion then burning, weed pulling or hoeing: the soil surface is not loosened and the dead plant residues/roots can remain in place to protect the soil against the force of rain and runoff-water.

· Limitations of herbicides: - Need to be purchased. - The herbicides generally available to highland farmers are very toxic to people and to the environment. - Require a lot of knowledge; if they are indifferently used they may be ineffective, damage the crop or lead to herbicide resistant weed populations.

107 The management of highland soils: an integrated vision

Box 54. Salt (NaCl) as a herbicide: a brilliant or noxious indigenous practice?

· Procedure. About 2 to 6 kg of kitchen salt (NaCl) is dissolved in 1 tang (=20 l) of water, which gives concentrations ranging between 100 and 300 g NaCl/l. Very often also a small amount of washing powder is added, which probably acts as a sticking agent. The solution is directly sprayed on the weeds (by means of a knapsack sprayer), thereby avoiding the rice plants as much as possible. Spraying is done by preference on a sunny day, 30-70 days after planting of the rice. The total amounts of NaCl applied vary from about 100 to 500 kg/ha, with about 300 kg/ha on average. · Indigenous practice. It is not known who introduced/invented the practice, but it appears to be widespread. In Mae Haeng village the practice was only recently introduced while in other areas it seems to have been around for at least 20 years. · Effects on weeds. The method is mainly used to control the problem weed Ageratum conyzoides L. (goatweed) and it is extremely effective for that purpose. In less than 15 minutes after spraying the leaves show permanent wilting symptoms and after one or two days the plants have completely dried out. The salt also affects various other broadleaf weeds, with varying degrees of control. Grasses and sedges are apparently not affected. · Effects on crops. The method is mainly used in upland rice which does not seem to suffer from the salt. The practice is also reported in the cultivation of carrots. · Effects on the soil. The practice inevitably raises anxious questions about possible negative effects on the soil. When considering the problem theoretically (taking into consideration the soil types, amounts applied, climate, topography and relative tolerance of salt by rice) there seem to be no reasons to worry. Experiments have meanwhile shown that the salt is very rapidly leached out of the soil and that low to moderate amounts of salt (150 - 300 kg/ha) do not adversely affect soil properties. · Downstream effects. This issue is quite sensitive in Thailand because in the northeastern part of the country there are serious problems with salt-affected soils. The situation in that region is however quite different from the situation in the northern region: different soils, a different (drier) climate and a different topography. The salt problems in the northeast are due to geological salt deposits which are already present in the deeper soil layers. Eventual downstream effects due to the use of salt in the north have not yet been studied. Based on theoretical considerations, it seems that there are no serious dangers. Probably the salt is simply washed back to where it comes from: the sea.

· Alternative “solutions”. Experiments have shown that fertilisers such as KCl, (NH4)2SO4 and urea, dissolved in water, have similar weed-killing effects as NaCl (some farmers actually use urea in stead of NaCl). The weed-killing effect is probably due to dehydration (osmosis). · Conclusion. Based on our current state of knowledge it seems that salt is a cheap, non- toxic, easy-to-use, selective and efficient “alternative” herbicide. If used in moderate amounts it seems pretty harmless to the soil and the environment, especially when compared to other conventional and more toxic herbicides. Just as with any other agrochemical, though, it should be used only after careful consideration of other options available. People who are reluctant to the idea of spraying salt as herbicide, but who already apply chemical fertilisers, can try to derive maximum benefit from these fertilisers by testing their potential side-effects as herbicides.

108 Chapter 9: Weed management

Conclusion: Weeds are a huge challenge to the development of sustainable highland farming

Not one single practice can guarantee at once labour-efficient and environment- friendly weed control in rainfed farming conditions. In order to reach these goals we should combine a wide range of methods in an integrated weed management strategy. Preventive measures should be maximised and the input of labour and use of herbicides minimised. Weed control should happen during all stages of the crop-fallow cycle and should be an integral part of a comprehensive soil conservation strategy.

A better timing of weed control appears to be a crucial issue towards improving current weed management practices. Post-harvest weeding and the stale seed-bed method are promising options which are worth exploring. Sound fallow and crop canopy management are complementary methods that can further reduce weed problems. For rice cultivation, establishing flooded terraces is the most effective way to (permanently) solve weed problems.

Chemical weed control should, in any case, only be considered a last-choice option. In areas where cultivation periods are drastically lengthening or where land is being farmed on a permanent basis, the use of chemical methods seems to be unavoidable though. This is a reality we should face rather than deny and therefore the proper and safe use of these products should be explained to those farmers who choose to use them.

109 Chapter 10: The management of soil-borne pests

10.1 What are soil-borne pests?

To explain what soil-borne pests are, we should first define the general term pests. Pests are any kind of living organisms (weeds, insects, fungi, nematodes, animals, bacteria or viruses) which people want to control or eliminate because they can cause harm to crops. Soil-borne pests are pests which complete at least part of their life cycle in the soil. They damage plants by directly affecting plant roots.

Soil-borne pests are a little difficult to study because they live under the ground, are not - or barely - visible with the eye and cause plant stress symptoms which are often very similar to the symptoms of nutrient deficiency problems. Our knowledge about their presence and the possible damage they cause on highland crops is therefore limited.

For upland rice we know that soil-borne pests are a serious problem in northern Thailand. This is not surprising, given the fact that upland rice is generally grown in single stands for successive growing seasons. Soil-borne pests which are reported are rice root aphids, white grub, termites, ants and nematodes. There might be several others which we still don’t know. For crops other than upland rice we have little information, but it would not be surprising if there they are causing serious troubles too.

10.2 How to diagnose soil-borne pests

By talking with the farmers

If farmers tell you that the soil is “tired”, this may be due to a lack of nutrients, the presence of soil-borne pests or even to a combination of both. Experienced farmers will in general know the most common soil-borne pests which are visible with the eye. The very small ones (such as rice root aphids) are not known by all farmers and the microscopically small ones (such as nematodes) are not known at all.

By detailed field observations and sampling

If a plant is growing poorly and if there are no immediate indications of limiting factors, you should always be suspicious of the presence of soil-borne pests. Pull out some plants and have a look at the roots. If there are no roots at all, if the roots are damaged, have a “strange” shape or if you can see a large number of organisms attached to the roots, it is quite likely that soil-borne pests are damaging the plant. If you can’t identify the organisms in the field, you should collect some specimens and

111 The management of highland soils: an integrated vision ask a specialist for identification. Nematodes can be identified in soil samples or, even better, in root samples.

10.3 Methods to control soil-borne pests

Pest control is always a difficult issue, and this is particularly true for soil-born e pests. Firstly because they are difficult to diagnose, secondly because they are protected by their environment (a thick “mantle” of soil). The following is only a brief summary of some possible management options. For more information specialised books should be consulted.

Fallowing (see Chapter 5)

Fallowing can be an effective method to reduce the numbers of soil-borne pests, if the fallow is of a “good quality”. Weedy fallows may increase pest problems if they contain plant species that can function as alternative hosts for the pests.

Burning (see Chapter 6.2.)

Tillage (see Chapter 7)

Tillage can reduce problems of soil-borne pests by exposing them to a “hostile” environment (heat of the direct sunlight, drought and natural enemies).

Crop rotation

Crop rotation is the single most effective and easiest method to control soil-borne pests. The main advantage of crop rotation is that it interrupts the life cycle of pests, i.e. prevents them from multiplying.

The method requires profound knowledge about the interactions between crops and their physical (soil and climate) and biological (pests and other living organisms) environment. A key-issue in crop rotation for pest control is to know which crops are sensitive to certain pests and which are not. In some more advanced methods certain plants can be used as trap or decoy crops. Trap crops are crops which attract the pests, after which the plants can be harvested and destroyed. Decoy crops are crops which attract the pests but prevent their multiplication. Either of such crops can be used in rotations or, alternatively, can be planted as intercrop.

· Advantages of crop selection/rotation for (soil-borne) pest control: + Are low-input methods with multiple advantages.

· Limitations of crop selection/rotation for (soil-borne) pest control: - These methods require detailed agroecological knowledge and a large range of crops to select from.

112 Chapter 10: The management of soil-borne pests

Pesticides

The use of pesticides should only be an ultimate tool if crop rotation does not work or, for one or another reason, is not feasible. To be effective against soil-borne pests high doses are required, so its practical use is limited to very intensive cash-cropping systems.

· Advantages of pesticides to control soil-borne pests: + Might in some extreme situations be the only solution available.

· Limitations of pesticides to control soil-borne pests: - Pesticides against soil-born pests (e.g. furadan) are very toxic and therefore dangerous to people, animals and the (soil) environment. - Have to be purchased. - Require (very) high doses to be effective. - Detrimentally affect beneficial soil organisms.

Conclusion: Rotate and mix to avoid problems with soil borne pests

If plants are rotated and mixed, problems with soil-borne pests are unlikely to become serious. Our knowledge about such rotations and/or plant combinations is however still limited. More study and experimental work by both scientists and farmers will be needed to keep soil-borne pests under better control.

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