Agroecology: Simplified and Explained [1st ed.] 978-3-319-93208-8;978-3-319-93209-5

Table of contents :
Front Matter ....Pages i-xviii
Introduction (Paul Wojtkowski)....Pages 1-14
Agroecosystem Design (Paul Wojtkowski)....Pages 15-31
The Agroecological Matrix (Paul Wojtkowski)....Pages 33-56
Agrotechnologies (Paul Wojtkowski)....Pages 57-74
Productive Intercropping (Paul Wojtkowski)....Pages 75-87
Feed Systems and Facilitative Intercrops (Paul Wojtkowski)....Pages 89-104
Complex Agroecosystems (Paul Wojtkowski)....Pages 105-115
Risk (Paul Wojtkowski)....Pages 117-133
Landscape Agroecology (Paul Wojtkowski)....Pages 135-154
Advanced Economics (Paul Wojtkowski)....Pages 155-171
Macro-Challenges (Paul Wojtkowski)....Pages 173-189
Summary (Paul Wojtkowski)....Pages 191-204
Back Matter ....Pages 205-437

Citation preview

Paul Wojtkowski

Agroecology Simplified and Explained

Agroecology

Paul Wojtkowski

Agroecology Simplified and Explained

Paul Wojtkowski Universidad de Concepción Pittsfield, MA, USA

ISBN 978-3-319-93208-8    ISBN 978-3-319-93209-5 (eBook) https://doi.org/10.1007/978-3-319-93209-5 Library of Congress Control Number: 2018949050 © Springer International Publishing AG, part of Springer Nature 2019 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

Preface

As agroecology has advanced, it has become less a consensus and more a strewing of ideas. The situation is analogous to the story of five blind men describing an elephant. The first, touching the trunk, thinks the elephant is like a large snake. The second, tusk in hand, finds it like a spear. The third, feeling the ear, is reminded of a large leaf. The fourth finds the leg like a tree trunk, and the fifth assumes the side is similar to a wall. Of course, all are correct in their interpretation. This goes to the central dilemma. What does the beast actually look like? The monoculture has become the face of what is termed modern agriculture. In this text, the preferred phrase is conventional agriculture. Further along this same road is the green revolution model. This is monocultural where yields are boosted by high, plot-external inputs and by high-yielding crop varieties. This model is often supported by GMO varieties and the liberal use of agrochemicals. Agroecologists reject this narrow view, instead putting forth the notion that agriculture, by way of agroecology, is based around biodiversity and the use of nature-­ supplied, goal-furthering bio-interactions. These insure crop yields. Beyond this, the situation gets messy. This comes about because agroecology is plagued by complexity. The initial view is of a labyrinth of concepts, ideas, principles, practices, theories, and approaches. All front various manifestations of biodiversity. The shortfall lies in the fact that there are few simplifying perspectives on how to navigate the maze. In practice, the complexity is handed by subdividing agroecology into different schools of thought. Each can have a philosophical and/or a political bent and be represented by one or a series of practical applications. Through subdivision, the complexity of the whole is circumvented. Permaculture and organic agriculture are the most prominent of these schools. This point is brought home by reading the books and articles on agroecology, organic agriculture, permaculture, and related topics. These texts have a consistent destination and many topical commonalities, but, at times, each seems to be looking at a different beast. The goal of this book is to offer one view, one perspective. v

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Aggregating It may seem strange to begin the process of sorting by aggregating. The various schools of thought are clearly part of agroecology. If shorn of their political and philosophical undertones, the underlying ecology comes to the fore. In explaining agroecology, there is a need to aggregate the land use sciences, i.e., agriculture, forestry, and agroforestry. This is not a broadening of agroecology. The logic behind this is watertight. The theories that govern agronomic agroecology apply, in equal strength, to both forestry and agroforestry.

Universality Going forward, agroecology must apply to all: to the rice farmers in Asia, to those trying to eke a living from poor soils and erratic rainfall of sub-Saharan Africa, and to the backyard gardeners of the developed world. One must not forget the very large commercial farms found in all parts of the world. Although those that accept conventional agriculture may eschew agroecology, they may be eventually forced into the fold by (a) changing societal values, (b) by climate change, (c) by consumers seeking something better, (d) by better economic prospects, and/or (e) through a need for sustainability. The hope is that, for all, the forces for change become irresistible and the land users seek and find more eco-accommodating agroecosystems. In presenting the paths and options, the avenues for change are discussed in this text.

Agroecology Explained The main idea is to restate agroecology. The scattered studies in the literature give little inclination that there is a skeletal core. This also applies to the needed economics. At the risk of spoiling any textual surprise, the core of agroecology is the plot or parcel of land. This contains a single agroecosystem. These are planned and managed systems as opposed to the unplanned ecosystems of natural ecology. The single agroecosystem, of indeterminate size, has defining characteristics. These are common to all agrosystems. The main characteristic is the bio-­composition. This can be a single plant species or two or more interacting species. Timing and spacing complete this core. Counters to the various threats are added to the core design, e.g., herbivore insects, weeds, drying winds. The individual counters, when nature supplied, are also termed eco-services.

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Whatever the form, they should be present, and in sufficient quantity, such that all of the immediate threats are sufficiently thwarted. This analysis goes to the essence of agroecology. From this, it is more than possible to formulate an agroecosystem, one that incorporates the desired crops and attains the desired objectives. This step is shortcutted by employing, as a starting point, a standard design. Most often, this is a field-­ proven agrosystem. It is through these standard designs, referred to as agrotechnologies, that the field experiences of the many are incorporated into the whole. There is reason for this pre-summary. This, and the brief recap the beginning of each chapter, is offered so the reader does not lose sight of the macro-whole among the many micro-pieces. For further emphasis, the last chapter is a comprehensive overview of the same.

Economic Goals Agroecology may be an offshoot of ecology and some take this as the unifying motif. Although true, this is not as strong an influence as one might think. A portion, but not all, of the content carries over. The differences may be far greater than the commonalities. The strongest divergence comes by way of the economic goals. Natural ecology is governed by nature, but nature is not directed by economic need. Much of agroecology is directly or indirectly profit driven. The remainder is yield-driven, cost-controlled, subsistence agriculture. In short, agroecology is fully secured by economics. In keeping, this text pairs the development of the central theme with the accompanying economics.

Agroecology Expanded Agroecology goes well beyond the core and the subsequent progression. There is far more to agroecology than a simple intercrop. Complex agroecosystems epitomize biodiversity and constitute a discrete agroecological category. For this, they deserve a separate chapter. There are also agroecosystems that are not species complex and cannot be classified under an intercrop heading. These too deserve a freestanding explanation. Objectives go beyond yields, revenues, and costs. As an objective, risk aversion is critical to many. However, some may wish to skip over risk and the risk counters, while others see this as a vital topic. For these reasons, risk is a separate chapter. As stated, agroecology is a labyrinth of ideas, concepts, etc. In keeping the text streamlined, the main flow of the book, in 12 chapters, centers on those topics that are at the core of agroecology.

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Not included in the core are the options, alternatives, and nuances along with elaborations on the chapter-presented themes. Some of these are interesting asides, some have targeted or specialized appeal, and others achieve importance given the right circumstances. Rather than chance these nuances being overlooked, they are included as a part of an extensive Glossary. This Glossary is large compared with the chapter text (by word count, the Glossary is about 60% of the book). This reflects the amount of information contained within the previously mentioned labyrinth of concepts, ideas, principles, practices, theories, and approaches. The elaborations contained in the Glossary are cited, where topically congruous, within the chapter text. The purpose is to allow the reader to delve deeper into specific discussions without disrupting the flow across the core of agroecology.

Theory Throughout this text, a number of theorems are presented. Some were put forth by this author, but most are the work of others. Some are well established, and others reside closer to the frontier of science. Some come from the published literature, and some are the product of on-farm observation. Some have empirical support, and some are based on unassailable logic (for more, see, as a Glossary topic, Decision Theory, page 250). A few are speculative and open to challenge. Included are the rules of intercropping, the theory behind domestic fowl and insect control, the reason for spatial disarray, risk reduction, complex agrosystems, and a host of other topics. The notion that agroecology has an explanatory core is, in and of itself, a theorem. It is the form that this takes that is open to challenge; its existence is not in question. For those who are educated or experienced in conventional agriculture, traveling from empirically based agriculture to theory-based agroecology can be an alien experience. This should be less the case for those who have studied economics or ecology. For those embracing agroecology, theory can be an essential step. Theory imparts an ability to sort through the bio-complexity, assign relationships, and, when questions arise, foretell a likely solution or outcome. This is especially true when, for agro-complex agrosystems, direct empirical results fall short or are missing. This is especially true for those bio-complex systems where empirical data is in short supply. It should be noted that theories are not laws. Biology is laden with exceptions. This applies to agroecology. This does not mean that the theory should be heavily discounted. Quite the contrary, being the only game in town, it is the pillar which supports the entire structure, exceptions included. Clearly, the viability of agroecology has been amply demonstrated. The theories explain but, more importantly, they serve to guide future directions and future research. With theory in place, agroecology can proceed at a much quicker pace than otherwise possible.

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Vocabulary As any discipline advances, it pushes against the limits of the existing vocabulary. This is true for agroecology. The choice is to layer more meaning on existing words or to embrace more pristine, less laden, newer expressions. The agroecological matrix is a new concept that can be central to ecological thought. As a result, it merits a discrete expression. Other concepts are time tested and are gaining in importance. Ecological dynamics, threat counters, and eco-services are more or less synonymous. Most utilized in this text is the word eco-services. Although less prominent in the literature, it offers greater exactitude. To describe variations on the agrosystem, some prefer the expression farm practices. Being heavily layered with meaning, this is supplanted in this text by the less-­ used word agrotechnologies. It should be noted that, as part of this expansion, the words intercropping and agroforestry are not distinct agrotechnologies. These are headers that classify like, but slightly different, agroecosystems.

Rules/Guidelines Throughout this text, various rules/guidelines are put forth. Some have a narrow focus and/or are of less importance. An example are the rules of intercropping. These aid in selecting species for co-planting. Some are critical for success. An example are the rules for complex agroecosystems. These are critical, as management would not be possible without the understanding provided. With many other examples, these rules/guidelines should be looked at as a starting point or check in the design/formulation process. There are always exceptions. Notwithstanding, if what is being contemplated violates a rule, a rethink is in order.

Scope Agroecology is worldwide. Through examples and photos, this book takes this global perspective. These examples and photos come from various countries and continents. This should not be viewed as a dilution of agroecology. There is only one agroecology. Enrichment comes when farms employ different versions. This is most manifest when the solutions found in one part of the world transfer to a similar problem in another part of the world. More often, the solutions are not universally known.

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This also occurs with the practices, options, and methods. As an example, most assume the best way to plant trees is to use seedlings. Unbeknownst to many, there are five tree planting methods (as a Glossary topic, see Planting Methods (shrubs and trees)). Choosing a less than suitable method represents a correctable inefficiency. The same happens on a larger scale when selecting cropping systems. Understanding the full scope of agroecology requires exposure to how others utilize the potential and the ability to relate this to the whole. Pittsfield, MA, USA

Paul Wojtkowski

Live in each season as it passes breathe the air drink the drink taste the fruit and resign yourself to the influence of the earth Henry David Thoreau Walden 1854

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Contents

1 Introduction����������������������������������������������������������������������������������������������    1 Definitions��������������������������������������������������������������������������������������������������    2 Comparisons����������������������������������������������������������������������������������������������    2 Agriculture and Agroecology����������������������������������������������������������������    3 Ecology and Agroecology����������������������������������������������������������������������    4 Early Agroecology ������������������������������������������������������������������������������������    5 The Old (Reigning) Paradigm��������������������������������������������������������������������    5 Mono-Cropping������������������������������������������������������������������������������������������    6 Advantages��������������������������������������������������������������������������������������������    7 Disadvantages����������������������������������������������������������������������������������������    7 Economic Forces������������������������������������������������������������������������������������   11 Logical Progression ������������������������������������������������������������������������������   11 The New Paradigm������������������������������������������������������������������������������������   13 References��������������������������������������������������������������������������������������������������   14 2 Agroecosystem Design ����������������������������������������������������������������������������   15 Topic Prerequisites������������������������������������������������������������������������������������   16 The Agroecosystem Defined������������������������������������������������������������������   16 Simple Agroecosystems ������������������������������������������������������������������������   17 Essential Resources��������������������������������������������������������������������������������   17 Base Analysis ����������������������������������������������������������������������������������������   17 Sigmoidal Functions������������������������������������������������������������������������������   18 The Core Elements������������������������������������������������������������������������������������   18 Species ��������������������������������������������������������������������������������������������������   19 Spacings ������������������������������������������������������������������������������������������������   21 Spatial Patterns��������������������������������������������������������������������������������������   24 Timing����������������������������������������������������������������������������������������������������   26 Sequencing (Rotations)��������������������������������������������������������������������������   27 Evaluation��������������������������������������������������������������������������������������������������   27 Economic Measures ������������������������������������������������������������������������������   28 Economic Orientation����������������������������������������������������������������������������   29 xiii

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Profitability��������������������������������������������������������������������������������������������   31 Other Objectives������������������������������������������������������������������������������������   31 References��������������������������������������������������������������������������������������������������   31 3 The Agroecological Matrix����������������������������������������������������������������������   33 Agroecology Redefined ����������������������������������������������������������������������������   34 Cropping Threats���������������������������������������������������������������������������������������   34 Soil Fertility ������������������������������������������������������������������������������������������   35 Rainfall (Too High or Too Low)������������������������������������������������������������   35 Insects����������������������������������������������������������������������������������������������������   35 Weeds ����������������������������������������������������������������������������������������������������   37 Pathogens ����������������������������������������������������������������������������������������������   37 Pollination����������������������������������������������������������������������������������������������   37 Temperature (Again, the Extremes) ������������������������������������������������������   37 Wind������������������������������������������������������������������������������������������������������   37 Small Animals (Birds, Mice, etc.)����������������������������������������������������������   38 Large Animals (Deer, Elephants, etc.) ��������������������������������������������������   39 Threat Counters (Eco-Services)����������������������������������������������������������������   39 Single-Purpose Counters������������������������������������������������������������������������   39 Multipurpose Counters��������������������������������������������������������������������������   40 The Counters Listed������������������������������������������������������������������������������   42 The Counters Described������������������������������������������������������������������������   43 Permanent and Introduced Counters������������������������������������������������������   47 The Agroecological Matrix������������������������������������������������������������������������   47 Matrix Manifestations����������������������������������������������������������������������������   47 Expansion����������������������������������������������������������������������������������������������   48 Matrix-Based Analysis��������������������������������������������������������������������������   49 Matrix (Cell) Elements��������������������������������������������������������������������������   50 As an Analytical Tool����������������������������������������������������������������������������   52 An Applied Example������������������������������������������������������������������������������   52 Agroecological Intensity����������������������������������������������������������������������������   55 Economic Implications������������������������������������������������������������������������������   55 References��������������������������������������������������������������������������������������������������   55 4 Agrotechnologies��������������������������������������������������������������������������������������   57 Agroecology Redefined ����������������������������������������������������������������������������   58 Agrotechnologies ��������������������������������������������������������������������������������������   58 Classification������������������������������������������������������������������������������������������   59 Simple and Complex Agroecosystems��������������������������������������������������   63 Agrotechnological Components������������������������������������������������������������   63 Economic Underpinnings����������������������������������������������������������������������   63 The Non-Harvest Option������������������������������������������������������������������������   64 The Complete Package��������������������������������������������������������������������������   64 Other Parameters������������������������������������������������������������������������������������   68 Improvement (Facilitative) Agrotechnologies ������������������������������������������   68 Bio-Structures����������������������������������������������������������������������������������������   69

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Land Modifications��������������������������������������������������������������������������������   69 Purpose Reclassified������������������������������������������������������������������������������   69 Monocultures ��������������������������������������������������������������������������������������������   72 Multi-Varietal����������������������������������������������������������������������������������������   72 Uneven Aged������������������������������������������������������������������������������������������   74 References��������������������������������������������������������������������������������������������������   74 5 Productive Intercropping������������������������������������������������������������������������   75 Rules/Guidelines for Productive Intercropping ����������������������������������������   76 General Rules����������������������������������������������������������������������������������������   76 Belowground Rules��������������������������������������������������������������������������������   77 Rules for Shade Systems������������������������������������������������������������������������   78 Provisos��������������������������������������������������������������������������������������������������   78 Associated Agrotechnologies��������������������������������������������������������������������   79 Productive (Seasonal) Intercropping����������������������������������������������������������   79 Simple Mixes ����������������������������������������������������������������������������������������   80 Strip Cropping����������������������������������������������������������������������������������������   82 Boundary/Barrier ����������������������������������������������������������������������������������   82 Productive Agroforestry����������������������������������������������������������������������������   83 Alley Cropping (Tree Row) ������������������������������������������������������������������   83 Agroforestry Intercropping (or Orchards with Understory)������������������   83 Shade Systems (Light) ��������������������������������������������������������������������������   84 Tree-Over-Crop Systems ����������������������������������������������������������������������   84 Taungyas������������������������������������������������������������������������������������������������   85 Multi-Species Forest Plantations ��������������������������������������������������������������   86 Supplementary Additions��������������������������������������������������������������������������   86 References��������������������������������������������������������������������������������������������������   87 6 Feed Systems and Facilitative Intercrops����������������������������������������������   89 Facilitative Gains ��������������������������������������������������������������������������������������   89 Types of Facilitation����������������������������������������������������������������������������������   90 Rules/Guidelines (Facilitative)������������������������������������������������������������������   90 Desirable Plant Characteristics������������������������������������������������������������������   91 Mixed-Role Agroecosystems ��������������������������������������������������������������������   92 Economic Underpinnings��������������������������������������������������������������������������   93 Facilitative Agrotechnologies��������������������������������������������������������������������   94 Facilitative Intercropping ����������������������������������������������������������������������   94 Facilitative Agroforestry������������������������������������������������������������������������   96 Feed Systems ��������������������������������������������������������������������������������������������  101 Productive Intercropping������������������������������������������������������������������������  101 Forage Trees������������������������������������������������������������������������������������������  102 Forest Feed Systems������������������������������������������������������������������������������  103 Aqua-Agroecology��������������������������������������������������������������������������������  104 References��������������������������������������������������������������������������������������������������  104

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7 Complex Agroecosystems������������������������������������������������������������������������  105 Described ��������������������������������������������������������������������������������������������������  106 Agroecology����������������������������������������������������������������������������������������������  107 Natural Ecology ������������������������������������������������������������������������������������  108 Patterns��������������������������������������������������������������������������������������������������  108 The Non-Harvest Option������������������������������������������������������������������������  108 Rules/Guidelines������������������������������������������������������������������������������������  109 Economics��������������������������������������������������������������������������������������������������  110 Variations ��������������������������������������������������������������������������������������������������  110 Pastures (Natural/Mixed Species)����������������������������������������������������������  111 Homegardens ����������������������������������������������������������������������������������������  111 Shrub Gardens����������������������������������������������������������������������������������������  111 Agroforests��������������������������������������������������������������������������������������������  113 Forest Gardens ��������������������������������������������������������������������������������������  113 Shade Systems (Natural Canopy)����������������������������������������������������������  113 Managed Forests������������������������������������������������������������������������������������  114 Interest In ��������������������������������������������������������������������������������������������������  114 References��������������������������������������������������������������������������������������������������  115 8 Risk������������������������������������������������������������������������������������������������������������  117 Agro-Threats����������������������������������������������������������������������������������������������  117 Trends��������������������������������������������������������������������������������������������������������  118 Water Harvesting����������������������������������������������������������������������������������������  118 Types of Risk ��������������������������������������������������������������������������������������������  119 Economic Risk ��������������������������������������������������������������������������������������  120 Climatic Risk ����������������������������������������������������������������������������������������  121 Anti-Risk Agrotechnologies����������������������������������������������������������������������  121 Agroecological Solutions��������������������������������������������������������������������������  122 Plot Based����������������������������������������������������������������������������������������������  123 Landscape Based������������������������������������������������������������������������������������  125 Other Defenses������������������������������������������������������������������������������������������  130 Other Solutions������������������������������������������������������������������������������������������  131 References��������������������������������������������������������������������������������������������������  133 9 Landscape Agroecology ��������������������������������������������������������������������������  135 Gains����������������������������������������������������������������������������������������������������������  136 Landscape Models ������������������������������������������������������������������������������������  137 Inherent Agroecology��������������������������������������������������������������������������������  138 Farm-Wide Economic Orientation������������������������������������������������������������  140 Associated Agrotechnologies����������������������������������������������������������������  141 Landscape Objectives��������������������������������������������������������������������������������  142 Economics����������������������������������������������������������������������������������������������  143 Risk Reduction��������������������������������������������������������������������������������������  144 Environmental Outcome������������������������������������������������������������������������  145

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Landscape Deciders ����������������������������������������������������������������������������������  147 Factors of Likeness��������������������������������������������������������������������������������  147 Impediments to Change ������������������������������������������������������������������������  148 Major Site Influences ����������������������������������������������������������������������������  148 Types or Categories of Agroecology����������������������������������������������������������  149 Do-Less-Harm����������������������������������������������������������������������������������������  150 Matrix����������������������������������������������������������������������������������������������������  151 Bio-Complex������������������������������������������������������������������������������������������  152 The Larger Picture ������������������������������������������������������������������������������������  153 References��������������������������������������������������������������������������������������������������  154 10 Advanced Economics ������������������������������������������������������������������������������  155 Agroecological Intensity����������������������������������������������������������������������������  156 Surplus Ecology ����������������������������������������������������������������������������������������  157 Opportunity Costs��������������������������������������������������������������������������������������  157 Eco-Services������������������������������������������������������������������������������������������  157 Trade-Offs����������������������������������������������������������������������������������������������  158 Orientation Restated����������������������������������������������������������������������������������  159 The Upper Bound����������������������������������������������������������������������������������  160 The Lower Bound����������������������������������������������������������������������������������  161 The Practical Range ������������������������������������������������������������������������������  161 Optimization������������������������������������������������������������������������������������������  162 Deviations from the Norm ��������������������������������������������������������������������  162 Trade-Offs����������������������������������������������������������������������������������������������  164 Design and the Agrotechologies����������������������������������������������������������������  166 Returns Within the Landscape ������������������������������������������������������������������  167 Commercial Farms��������������������������������������������������������������������������������  167 Subsistence Farms����������������������������������������������������������������������������������  168 Eco-Service Universality ��������������������������������������������������������������������������  168 Eco-Service Realism����������������������������������������������������������������������������������  168 Hybrid Farms ����������������������������������������������������������������������������������������  169 Conventional Agriculture with Agroecological Overtones��������������������  170 References��������������������������������������������������������������������������������������������������  171 11 Macro-Challenges������������������������������������������������������������������������������������  173 Malthus, etc.����������������������������������������������������������������������������������������������  174 Population����������������������������������������������������������������������������������������������  176 Urbanization/Land Loss������������������������������������������������������������������������  176 Water������������������������������������������������������������������������������������������������������  177 Energy����������������������������������������������������������������������������������������������������  177 Diet��������������������������������������������������������������������������������������������������������  178 War ��������������������������������������������������������������������������������������������������������  178 Freedom from Want ����������������������������������������������������������������������������������  178 Sovereignty��������������������������������������������������������������������������������������������  178 Trade������������������������������������������������������������������������������������������������������  180

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Genetic Resources��������������������������������������������������������������������������������������  180 Properties ����������������������������������������������������������������������������������������������  181 Heirloom Varieties ��������������������������������������������������������������������������������  181 New and Useful Species������������������������������������������������������������������������  182 Research Challenges����������������������������������������������������������������������������������  183 Theory����������������������������������������������������������������������������������������������������  183 Quantitative Agroecology����������������������������������������������������������������������  184 Qualitative Agroecology������������������������������������������������������������������������  185 Decision/Game Theory��������������������������������������������������������������������������  187 Acceptance Challenges������������������������������������������������������������������������������  187 Guidelines����������������������������������������������������������������������������������������������  187 Pitfalls����������������������������������������������������������������������������������������������������  188 References��������������������������������������������������������������������������������������������������  189 12 Summary��������������������������������������������������������������������������������������������������  191 Ecology and Agroecology��������������������������������������������������������������������������  191 Theories��������������������������������������������������������������������������������������������������  192 Goals������������������������������������������������������������������������������������������������������  192 Overview����������������������������������������������������������������������������������������������������  192 The Core Elements��������������������������������������������������������������������������������  192 Matrix Analysis��������������������������������������������������������������������������������������  193 Agrotechnologies ��������������������������������������������������������������������������������������  195 Agroecosystem Categories������������������������������������������������������������������������  195 Simple Agroecosystems ������������������������������������������������������������������������  195 Complex Agroecosystems����������������������������������������������������������������������  197 Major Influences����������������������������������������������������������������������������������������  199 Types of Agroecology��������������������������������������������������������������������������������  199 Do-Less-Harm����������������������������������������������������������������������������������������  200 Matrix����������������������������������������������������������������������������������������������������  201 Bio-Complexity��������������������������������������������������������������������������������������  201 Outcome������������������������������������������������������������������������������������������������  201 Agroecology Defined ��������������������������������������������������������������������������������  202 The Central Theme������������������������������������������������������������������������������������  203 Conclusion ������������������������������������������������������������������������������������������������  203 References��������������������������������������������������������������������������������������������������  204 Glossary������������������������������������������������������������������������������������������������������������  205 References ��������������������������������������������������������������������������������������������������������  421 Index������������������������������������������������������������������������������������������������������������������  433

Chapter 1

Introduction

Contents Definitions Comparisons Agriculture and Agroecology Ecology and Agroecology Early Agroecology The Old (Reigning) Paradigm Mono-Cropping Advantages Disadvantages Economic Forces Logical Progression The New Paradigm References

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In many ways, agroecology is a science in flux. There are questions, not to validity and need, in regard to the scope, contents, methods, and applications. These arise from the myriad of concepts, ideas, principles, practices, theories, and approaches that constitute agroecological thought. This has led to a range of interpretations. This book presents yet another view. At the heart of agroecology are the (agro) ecological dynamics that sustain crop growth, yields, and a wished-for economic outcome. The active and supporting ecology (as eco-services) mostly stem from well-­ directed and well-applied uses of biodiversity. The better outcomes originate from biodiversity-derived ecological dynamics that are plentiful, potent, and reinforcing. It is these dynamics that are the very definition of agroecology.

© Springer International Publishing AG, part of Springer Nature 2019 P. Wojtkowski, Agroecology, https://doi.org/10.1007/978-3-319-93209-5_1

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Definitions The existing definitions present varying pictures and emphasize different aspects of this broad and developing science. Until things gel, practitioners must be content with various definitional renderings. In total, these help in framing the science. These begin with: Agroecology as “the study of the ecological processes that operate in agricultural production systems” (Wikipedia, Agroecology, 2016). Agroecology as “the science of ecology applied to the design, development, and management of agriculture” (Dictionary.com, Agroecology, 2016). Agroecology as the “… ecology of food systems” (Francis et al. 2003). Given the belief that agriculture, forestry, and agroforestry are subsets of agroecology, there are some more encompassing definitions. These are: Agroecology is, by way of ecology, the scientific basis for agriculture, forestry, and agroforestry. Agroecology is the scientific basis for the cultivation of food, fuel, fiber, and other land-raised products with deference to and/or in cooperation with nature and natural processes. The latter definitions are more inclusive. There is no reason that forestry and agroforestry, and the agroecosystems and practices contained, should be excluded. Forestry and agroforestry are ecologically comparative to an equivalent bio-­ complex agricultural ecosystem. Also in support of this inclusion, trees can be as much of an on-farm ecological contributor, and a tool toward achieving agroecological objectives, as any other plant. The definitions do not always fully reflect a diversity of views. Clearly, agroecology is a science. It is also a series of practices and, in some hands, a political movement. Although mostly discounted in this text, the latter view still holds value (For additional discussion, see, as a Glossary topic, Agroecology).

Comparisons As a science, agroecology stands alone. Comparison can, and should, be made between conventional agriculture and the still-emerging agroecology. Although close cousins, there is the ongoing detachment of ecology from agroecology. Nevertheless, there are still opportunities for cross-fertilizations.

Comparisons

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Photo 1.1  Farmers harvesting rice. Taken in Bangladesh, this photo examples how agriculture is commonly practiced and the reliance placed upon a single staple crop. (Being worldwide, this picture could be of any of millions of farmers)

Agriculture and Agroecology What might be termed conventional agriculture centers around the monoculture. This continues with the notion that outside inputs, often in agrochemical form, allow crops to thrive in an otherwise yield-unfriendly environment. In part, this is a self-imposed penalty. A single crop and the lack of biodiversity can create such an horticulturally hostile situation. The green revolution model doubles down on this. The view is that yield-denying forces can be thwarted by improved varieties. Here genetically modified crops (GM crops) loom large in providing an answer. Academically, there is only a modicum of theory in conventional agriculture. Simplicity allows for a science built on empirical underpinnings. Agronomists do venture into other agro-expressions, but the monoculture is the starting point. The switch from what might be termed conventional, monoculturally based agriculture, or from the chemically dependent green revolution model, to agroecology can be quite profound. The various definitions do not reflect this. Simply stated, the change is from one-crop systems to numerous expressions of bio-complexity (often as manifestations of biodiversity). To handle this, theory must override the empiricism that underpins monoculturally based agriculture.

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There are other equally profound differences that similarly relate (as an expanded Glossary topic, see Precepts). In embracing agroecology, the monoculture is no longer the central theme. It is theory, mostly lacking in conventional agriculture, that allows the synergies and interactions to be understood and utilized. Understanding is an important aspect, but there remains a large leap from theory to the applied. The overall problem is to navigate through the biodiversity and the added in-field options to reach and manage terrestrial agrosystems. Much of this is for the food, fuel, and fiber that sustain human health and happiness. Over time and in this age of ecology, one expects that agroecology will be co-­ opted into, and be part of, conventional agricultural (Holt-Giménez and Altieri 2013). Although this is for the good, there are caveats. As a science, the essence of agroecology is the reliance on theory, biodiversity, and a healthy respect for the environment. This means that, at the very least, toxic chemical use is reduced or eliminated. In full-on mode, there is a need to design plots and farms such that natural processes prevail and interspecies synergies are utilized to their highest degree. All these goals require a systematic and coherent approach, one that allows progress to be made and the potential to be realized. This starts with a full understanding.

Ecology and Agroecology In the previous definitions, there is a need to stress ecology, natural processes, and interspecies synergies. With these, agroecology is clearly an offshoot of and a branch of ecology. The other main subdivision of ecology is natural ecology. Although there is some overlap between natural ecology and agroecology, e.g., through population ecology, there are major differences. Success in natural ecology lies in maintaining a wholesome mix of native species (both flora and fauna) and the accompanying functionality of the between-species dynamics. In contrast, agroecology is often based on exotic/foreign species, i.e., common crop species. The needed dynamics are achieved through planning, planting, and subsequent management. In agroecology, success lies in meeting productive and/or economic goals. There is a clear dividing line. Natural ecology is not a land-use science (with the possible exception of invasive and noninvasive tourism). If a natural ecosystem is modified for productive purpose, i.e., the harvesting of flora and/or fauna, it enters the realm of, and becomes, an agroecology application.

The Old (Reigning) Paradigm

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Early Agroecology Early people began the transition from hunting/gathering to agriculture roughly 4000–5000  BCE.  This occurred independently on various locations across the globe. These early efforts, and what occurred into relativity modern times, were not an all-out battle against nature. Virgil, Pliny, and, much later, Chaucer describe agricultural landscapes rich in biodiversity. Yields were, by modern standards, generally quite good (Reynolds 1980). This is factually supported by the existence of advanced societies. Found in Asia, Middle East, the Americas, Africa, and Europe, these could only rise if they acquired a mastery beyond true subsistence agriculture. This indicates good, if not stellar, crop yields. A strong presupposition is that early farmers understood how crops could be raised by harnessing or co-opting natural processes. These efforts could easily be characterized as agroecology. Even with this understanding, farms of the period were not risk-free Gardens of Eden. Effort was required, the knowledge of the time could not always guarantee sustainable yields, also the risk of crop failure would have been high.

The Old (Reigning) Paradigm From about the latter 1800s, western society was moving toward a form of agriculture characterized by the phrase “... endless fields of ripening grain.” This denotes a land of plenty where mankind, through agriculture, gained authority over nature. This transposed agriculture into a system where agricultural products come by way of high inputs and high energy use. From an ecological perspective, nature has been fully marginalized. This is characterized by the complete lack of biodiversity and the notion that mankind can handle the adversities of nature. The transition away from the nature-dominated farm came about through technical advances. Tractors and harvesting machinery replaced draft animals and hand labor. Other developments have been along the chemical front. Fertilizers replaced manures and compost, and herbicides replaced hand weeding. Other chemicals helped protect the large-scale, insect and disease-prone monocultures. Genetic engineering has boosted yields all while providing a uniform, less variable output. Termed the green revolution, this reduced food shortages in many parts of the world. Many avoided starvation as the new crop varieties and the change in farming methods became widespread. Countries that suffered from chronic food shortages were brought back from the edge. The breeding of high-yielding staple crops was one step in bringing the green revolution to its current state. The underlying model rests upon monocultures and the goal of optimizing yields.

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Optimal yields require optimal growing conditions. Mandated in this quest are a range of agrochemicals (including fertilizers, insecticides, herbicides, and fungicides) and, where possible and necessary, the use of irrigation. The notion of cheap food for the masses has been a factor in the rise of this form of agriculture. This has been aided, unnoticed, by a period of relative consistency in weather patterns. The changing of the climate may not be enough to alter this simple, entrenched, and well understood agricultural model. However, the reigning paradigm has exposed a host of troubles. Among these are environment side effects and, where climate change intercedes, the reigning paradigm might be at its worst. This is ongoing.

Mono-Cropping The overriding advantage of this paradigm lies with its simplicity. Nothing could be easier than a single crop grown on a single plot where, when problems occur, the solutions are to spray and forget. The ability to operate within these simple parameters can favor large-scale, single-crop operations.

Photo 1.2  A large plot monoculture most associated with conventional agriculture

Mono-Cropping

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Conventional, monoculture-based agriculture is often viewed, through the spray-­ and-­forget mentality, as discrete problems, each with individual solutions. This is true, but there are also larger, interrelated issues. There is a purpose in offering a lengthy discourse on the advantages and the disadvantages associated with the large-scale monoculture. It is the latter, the extent of the disadvantages, that highlight what could be if other, more nature-­ accommodating forms of agriculture are adopted.

Advantages Farming is not an easy occupation. To be successful, the knowledge required is extensive. In addition to a familiarly with the crops, farmers are managing a business. There is the accounting, the worries over future crop prices, the repairing of the farm equipment, the maintaining the farm infrastructure, the hiring, allocating, and managing of labor, and a host of other concerns. Farmers often do not have the time, and the inclination, to seriously consider more complex agrosystems. Having adopted the simplest, that of chemically dependent monoculture, it can be very difficult to change to the complexity of biodiversity-­ based agriculture.

Disadvantages In the long run, expectations have not been fully met. The yield gains have stalled and, in many countries, no longer keep up with population growth. In addition, corollary effects have started to influence public opinion. Although the toxicity of the chemicals utilized has been reduced, these remain a problem and ultimately a concern. The continued expansion of super-large, single-­ crop farm fields has also taken a toll on the environment and on public perception. Weather As a high-input, high-output form of agriculture, crops must be protected, and, to do this, farmers must purchase wide array of inputs. These include seeds along with the accompanying agrochemicals. These purchases open farmers to increased risk. This occurs along two fronts. These are: 1 . The risk of total yield failure. 2. The risk of low, crop-selling prices.

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Because of this, high-yielding monocultures may be the most risk prone form of agriculture. Often, there is nothing, except inputs, to keep the threats at bay. High in the list are changes in normal weather patterns. In this case, there is little, except for irrigation, to counter unfavorable climatic events. When crops fail, farmers have little to sell. In of itself, this is serious enough. Crop failures also mean that farmers do not recoup the cost of seeds, fertilizers, herbicides, and other costly inputs. There are other dangers. These arise from those high-yielding species bred to expect optimal growing conditions. Per-unit costs of production are low only because the per-area yields are high. The high cost of the many inputs means that, as yields decline, the per-unit cost of production rises dramatically. If crop prices are low or inputs more costly than expected, the anticipated profits can quickly become an undesirable monetary loss. With so much weather and price risk, farmers would rightly shun this model, instead using cropping systems less prone to failure and/or with less monetary loss when failure does occur. In the developed world, governments have removed a lot of this uncertainty. Farmers can obtain crop failure insurance and price supports. This often makes the continued reliance upon green revolution model possible. Water In the absence of consistent and ample rainfall, high yields can come through the use of irrigation. This is becoming less possible. People, cities, industry, and even decorative landscaping can have a higher priority on water than agriculture. This is especially true when major rivers cross from one country to another. In this case, local officials are less concerned with the people and economy of the downriver country. Water will not always be distributed wisely. Rivers and catchments are not the only source; groundwater often figures heavily in agriculture. Here again, there are problems. The green revolution model can drain slowly to replenish sources. Published examples of groundwater overused are common (e.g., Brown 2005). None seems as problematic as the case of Northern India where huge declines in groundwater have negative effects (Kerr 2009). This is not the only consequence. Contamination from chemical runoff is a pollutant and an environmental issue. Environmental Issues The green revolution model achieves very high, per-area yields; it does little or nothing to address accompanying environmental issues. Most of the criticisms are along the environmental front.

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As mentioned, the agrochemicals initially sold were quite toxic. Over time, some of the more dangerous agrochemicals have been replaced by those with less apparent toxicity. Since many agrochemicals are designed to kill, there is debate on whether these are truly harmless or the peril is just less evident. The mere fact that, in some regions, a high tonnages of dubious chemicals are applied is cause for concern (for more, see Insecticides). There is also the issue of truant resources, those that escape from where they have been applied and cause environmental havoc elsewhere. Fertilizers and agrochemicals do not often stay put. Runoff is the source of water contamination and for dead zones in lakes and oceans. Most notable is the situation in the Baltic, Lake Eire, and in the Gulf of Mexico at the mouth on the Mississippi River (Wikipedia, Dead Zones (Ecology), 2016). These chemicals are not good for agriculturally beneficial flora and fauna. The often cited example is the honeybee. These suffer from the onslaught of various insecticides. In turn, herbicide use has destroyed field margins and the habitat for natural pollinators (Bretagnolle and Gaba 2015). This can reduce yields for many crops.

Photo 1.3  An example of all-to-common, unsafe insecticide use. This situation is encountered in small farms in poor regions. (This photo shows, while spraying, the lack of protective clothing and the presence of nearby children)

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There are also issues of improper use. This can be especially troublesome in poorer countries (as in Photo 1.3). Problems include no protective equipment, not reading warning labels, and not properly disposing of empty containers (Stadlier 2016). In addition to the unsafe use of chemicals by untrained farmers, there is the easy availability of internationally banned agrochemicals in developing regions. To accomplish this, companies hide the active ingredients under obscure synonyms (this authors work in Africa and Asia). Deception is not limited to poor farmers in poor countries. In developed regions, some agrochemical companies pay scientists to subvert or bury studies that prove their insecticides as unsafe (Hakim 2017). Genetic Modification Within the context of the green revolution model, genetic improvement would seem a real plus. Informally, it has been going on since the beginnings of agriculture. Some view the genetically modified organism (GMO) is just an extension of this. Often high yields come by applying plant nutrients in more than sufficient quantities. The green revolution has become the gene revolution. This is an attempt to squeeze yields and mitigate some of the many problems and drawbacks, through even more elaborate, more invasive in-plant genetic engineering. The tendency is to achieve high yields based on an abundance of inputs. This becomes a disadvantage when farmers plant genetically modified (GM) crops, but cannot afford the added plant nutrients. It is also a disadvantage when rainfall is less and irrigation is not possible. In these cases, local varieties often yield better. The ability to tolerate resource shortfalls allows crops to tolerate competition from weeds. This inability to tolerate even small populations of weed species necessities a greater weed reduction effort. This includes the use of herbicides and herbicide-­resistant varieties. Nature has a counter. Weeds eventually acquire herbicide resistance. To counter to the now-resistant weeds, farmers often apply additional or a mix of herbicides. Centering so much effort on a few common-crop varieties represents a serious reduction in the gene pool. For each of the major crops, e.g., rice, potatoes, maize, wheat, etc., there are hundreds of varieties. These offer anything from a different color to how they interact with neighboring plants and the local climate. Losing this to a few, highly marketed GM varieties can only be termed tragic. This is compounded knowing that the promised high yields of the GM varieties can be matched with existing, local types. Some advocate genetic modification to add dietary vitamins to the crop output, e.g., vitamin A-enriched rice. This is another seemingly good selling point, but it is more of a ploy. It is far better to add dietary vitamins in the form of on-farm crop biodiversity and, commensurately, offer consumers more culinary choice.

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Despite industry promotion, and the claim that GMOs are essential in feeding ever-growing populations, the research is not supportive. In rebuttal, the overall yields from GMO crops, as compared with conventional varieties, produce “small” gains. This includes those GMO crops that counter insects and well the herbicide-resistant varieties (National Academies of Science, Engineering, and Medicine 2016; Hakim 2016). Consumptive The availability of one or a few cheap food sources may be considered a societal disadvantage. Economic and environmental issues aside, the argument is dietary. Consumers and/or food producers will have greater reliance upon the cheapest foodstuffs, this being the case in the USA. Maize, readily available and low in cost, is utilized in a wide variety of products. This lack of dietary variability contributes to human health problems, and high on the list is obesity. The counter is greater use and consumption of different crops. There is another side, that of quality, of the food being produced. The most sought-after varietal characteristics are not taste and nutrition, but superior handling and storage properties. This means consumers must look to local farmer’s markets to find the varietal diversity and better taste.

Economic Forces There are vested interests that want conventional agriculture to continue as the dominate agriculture model. In the quest for high yields, farmers purchase expensive farm equipment and large amounts of costly inputs. This allows agro-industries to thrive, boosting the economy and providing the opportunities for taxation. In contrast, more frugal agroecology would use less inputs and offer governments potentially less in tax revenue.

Logical Progression This chapter looks at the issues associated with the chemically dependent green revolution model. There are resulting trends. The green revolution approach is a progression with two distinct, but not inevitable, end results. The first is the super-plant ideal where, through genetic modification, plants resist all the natural forces acting against them. The second is the factory farm where the high-input, high-output monoculture is on full display and encompasses vast areas.

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Super Plants For the super plant, it is theoretically possible to breed a desert variety of normally water-demanding rice. It would also be possible to breed, into this same rice plant, resistant to all herbivore insects and all plant diseases. Also nice would be to make rice perennial so as to avoid the cost of planting, only seasonal harvest would be required. Futuristic as this might seem, nature has other ideas. Large areas of super rice would be an inviting target to those organisms that can overcome the built-in resistance and consume the crop. Nature may initially fail, but it will keep on trying. If there is resistance to all, a super rice would, in essence, become a super weed. In being indestructible, it could easily invade ecosystems and dominate other plants, crops included. There are reports of herbicide-resistant crops sprouting in fields devoted to another crop. Since these invaders are unwanted and herbicide-resistant, the best eradication method might involve old-fashion hand weeding rather than, as mentioned, the use of more and more potent herbicides. Factory Farming With green revolution model, there are economies of scale. Seeds and agrochemicals are cheaper purchased in very large quantities. Application can be quicker per area and often more cost-effective with very large machinery. If risk is low or a government or a corporate entity bears both the price and weather risk, very large farms become economically viable. In addition, the simplicity of the chemically dependent monoculture allows management by directive or proxy. This is not an abstraction. As stated, in the midwest of North America, parts of Africa, in south-central Brazil, and other regions, farms of gigantic size have evolved. This is not an environmental plus, the area becomes inhospitable for most local flora and fauna. Also, the potential for chemical runoff is magnified. In some countries, individuals and corporations, seeking land for ultra-large farms, have been accused of displacing people and taking the land and water under dubious legalities, e.g., for large-scale rice cultivation in Ethiopia (Burgis 2016). As an offshoot and clear expression as to what is happening, farm animals have been overly concentrated. The conditions under which some are raised are not always what society has come to expect. The marketing of meat and eggs from free-range animals is an indication of the discontent. Another concern of society is the disposal of the quantities of manure that concentrated feed operations produce.

The New Paradigm

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Photo 1.4  Intercropping, marigolds beneath olive trees. The better growth of the flowers under the trees can be attributed to shade and improved water use. (This photo is from Morocco)

The New Paradigm This chapter has detailed the many self-imposed issues that accompany, and disadvantage, the green revolution model. Depending on one’s point of view, agroecology has the potential to eliminate or mitigate many, most, or all of these problems. One might think that the potential alone would result in a high degree of enthusiasm. This is not a given. Before the conventional model is usurped, there are a wide array of countervailing forces that must be overcome. High on the list are those entities that profit from the existing paradigm. Going from the spray-and-forget mind-set of mono-cropping to bio-complexity is another wide, possibly the widest, barrier to adaption. A lot of this involves understanding the parameters and practicalities of use. Here, knowledge is the key. In essence, knowledge trumps all. If farmers, gardeners, and other land users don’t know of it, it will not find use. True in agroecology, the purpose of this text is to expand knowledge by laying a path through the bio-labyrinth of ideas, views, concepts, etc. This text puts an emphasis on those versions of agroecology that are driven by ecological dynamics. This is where targeted ecology is used to mitigate the various threats and/or impediments to achieving good or superior crop yields. To insure the

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best outcome, the eco-dynamics (or eco-services) should be redundant, potent, and fully evoked. Statement in one thing, transition another. For the ordinary farmer, success lies in knowing the bio-tools that are available and how they are best used. With this knowledge in hand, it should be possible to (a) construct new or adopt existing agroecosystems to fully employ eco-dynamics, (b) add eco-services where needed, and (c) deconstruct existing agroecosystems to fully understand the eco-­ services supplied by the component parts. In addition, any study of the eco-components requires robust economics. This can be traditional profit-loss or, better yet, economics specifically tailored to needs of agroecology. It is along this front that the potential of agroecology is decided.

References Bretagnolle, V., & Gaba, S. (2015). Weeds for bees? a review. Agronomy for Sustainable Development, 35(3), 391–409. Brown, L. R. (2005). Outgrowing the earth: The food security challenge in the age of falling water tables and raising temperatures. New York: W.W. Norton and Company. Burgis, T. (2016). The Billionaire’s farm. Financial Times 39, 101(March 2):7. Francis, C., Lieblein, G., Gliessman, S., et al. (2003). Agroecology: The ecology of food systems. Journal of Sustainable Agriculture, 22(3), 99–118. Hakim, D. (2016). Doubts about a Promised Bounty. The New  York Times CLVXVI(57,401-30-Oct.):1. Hakim, D. (2017). Scientists loved and loathed by an agrochemical colossus. The New York Times CLXVI (57,465–2 Jan.):1. Holt-Giménez, E., & Altieri, M. A. (2013). Agriculture, food sovereignty, and the new green revolution. Agroecology and Sustainable Food Systems, 37(1), 90–102. Kerr, R. A. (2009). Northern India’s groundwater is going, going, going. Science, 5942(325–14 August), 789. National Academies of Science, Engineering, and Medicine. (2016). Genetically engineered crops, experience and prospects. Washington, DC: The National Academies Press, 420p. Reynolds, P.  J. (1980). The working agroscape of the iron age. Landscape History (Vol. 2, pp. 1–20), Journal of the Society for Landscape History, Rampart Press. Stadlier, M. (2016). CropLife Nigeria assesses contract sprayers in Borno State. N2Africa (­ http:// www.n2africa.org/print/4288).

Chapter 2

Agroecosystem Design

Contents Topic Prerequisites  16 The Agroecosystem Defined  16 Simple Agroecosystems  17 Essential Resources  17 Base Analysis  17 Sigmoidal Functions  18 The Core Elements  18 Species  19 Spacings  21 Spatial Patterns  24 Timing  26 Sequencing (Rotations)  27 Evaluation  27 Economic Measures  28 Economic Orientation  29 Profitability  31 Other Objectives  31 References���������������������������������������������������������������������������������������������������������������������������������� 31

Fundamental to agroecology is the internal ecology of a plot-defined agroecosystem. Despite its prevalence, the monoculture is at the fringe of agroecology. Often, agroecology is fronted by the interaction two or more species. The internal agro-­ design determines how they interact and the outcome of these associations. This is the first of the three design steps: (1) the core, (2) the threat counters, and (3) the resulting agrotechnology. Interaction is gauged by user objectives. Often these involve economic criteria, e.g., monetary profit or loss. For subsistence farmers, risk, output in the face of uncertainty, can be a critical objective. Whether the goal is monetary or subsistence, the internal design should comply.

© Springer International Publishing AG, part of Springer Nature 2019 P. Wojtkowski, Agroecology, https://doi.org/10.1007/978-3-319-93209-5_2

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Topic Prerequisites At the core of agroecology is the interaction of two or more plant species. Before being explained, these should be defined.

The Agroecosystem Defined In this book, a loosely defined agroecosystem (or agrosystem) is the central constituent of applied agroecology. This is a managed land area containing plant species (one or more) that, through their interactions, exhibit set ecology with the hope of reaching prestated yield, risk, and/or other, often economically expressed, objectives. The agrosystem is plot-demarcated. The plot is an economic unit best defined by the phrase “per-area yield(s).” The areas on a farm for which yields are measured or estimated would be, in the eye of a landowner and/or land user, the plots. A single agrosystem occupies one plot. Take the case of strips of differing crops. If the strips are one or a few plants wide, and this results in a single measure, either land equivalent ratio or profit/loss. The crop rows (strips), collectively, are considered a single, one-agrosystem plot. Wide strips may be evaluated individually. If this is the case, each strip is a separate agroecosystem and a separate plot. An agroecosystem starts when some or all of the productive species are first planted. This ends when the primary species (one or more) have been harvested. Subsequently, the site is agronomically reset. A new agroecosystem follows, often from bare ground. In the majority of cases, these criteria are unambiguous. Most likely, well over 90% of the agrosystems would fall within these definitional parameters. As an example, intercropped carrot and onion are planted and subsequently harvested. What follows is a new agrosystem. There are less clear situations. Carrots may be planted among an already existing perennial cover crop. The planting and the harvest of the carrots, as the primary crop, defined the temporal limits of the carrot/cover crop system. More confusing are some of the planting variations for some tree crops (e.g., rubber, possibly fruit and nut trees). Saplings can be introduced a few years before the old trees are harvested. When the older are finally cut, so are the now taller saplings. This facilitates the removal of the older trees. The saplings, with their now developed root systems, resprout quickly. This strategy cuts the period between the last harvest of the old plantation and first harvest of the new trees. For all intents, these would be separate plantings and separate agrosystems. The overlap is discounted.

Topic Prerequisites

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Simple Agroecosystems It should be stressed that, based on the number of species present in an agroecosystem, agroecology subdivides. There are the simple agroecosystems; those of seven or fewer species. There are also complex agroecosystems; those with seven or more species. Complex agrosystems are explained in Chap. 7. In this, and the next few chapters, the focus is on simple agrosystems.

Essential Resources Essential resources are at the heart of all agrosystems. Basically, there is complex battle between interacting plant species. The fight is to acquire the necessities of growth. Needed are light, water, CO2, as well as the key soil nutrients, nitrogen, phosphorus, and potassium (NPK). Also on the list are the trace elements, e.g., calcium, iron, zinc, etc.

Base Analysis The difference between natural and agricultural ecology is the need to evaluate yields. This starts with base measures. If more is needed, output values are assigned. This is can be done with raw yields or by converting the numbers into ratios. Foremost among the ratios is the land equivalent ratio (LER). This evaluates the outcome where different crops are interplanted, e.g., apples and oranges. Comparing the interplanted mix with monocultural yields, the better outcomes have LER greater than one. Basically, the higher the number, the better the outcome. The basic equation has

LER = (Yab / Ya ) + (Yba / Yb )



where Ya and Yb are the monocultural yields of species a and b, Yab being yield output of species a grown in close association with species b. Correspondingly, Yba is the productivity of species b when in combination with species a. Simply explained, an LER value of 1.50 is interpreted as yields equivalent to 150% of what the site will yield if only apples or oranges are grown, i.e., at 100% (1.0). If less successful, the mix will have an LER of less than one.

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Sigmoidal Functions In mathematical terms, agroecology is seldom based around linearity. The vast majority of the underlying functions, e.g., the effects of one input on yield, are sigmoidal. This is exampled in Fig. 2.1. The importance lies when a small increase in, for example, an essential resource translates into a large increase in yield (or the reverse can occur). This relationship applies not just to an essential resource but to any number of changes. Exploiting this property is an important aspect of agroecology. The majority of the explanations rely upon the sigmoidal form. As such, Fig.  2.1 is referenced throughout this is text.

The Core Elements There are certain elements of agro-design that are shared, without exception, in all terrestrial plots/agroecosystems. These are the: Species content (with one through seven intended and interacting species) Spacings/planting densities (uniform or variable) Spatial pattern Timing (the entry and exit of one or more species relative to others) Beginning with these core design elements, there are other design variables or inputs that, when added, shift the internal ecology and/or the economics. Keeping things simple, this chapter discusses the four core elements of design.

Yield

Essential Resource Fig. 2.1  A sigmoidal production function and the large yield gain from adding small amount of a resource (shown by the arrows). That depicted here is a representative function. This and the other sigmoidal functions illustrated in subsequent chapters are shown because they underwrite many of the key relationships in theoretical agroecology

The Core Elements

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Species When biodiversity prevails, questions arise on which species (two or more) to pair and the planting densities of each. Farmers often have a preferred crop. This would be the primary species (for more, see Primary Species, also Biodiversity). Most often, it is the secondary species that must be decided. The classic example is maize (corn) interplanted with beans. Maize generally intercrops well, i.e., has good interspecies complementarity. When paired with beans, maize yields are anticipated to be 100% (1.0), and bean yields are reduced to 50% (0.5). The resulting LER is often a favorable 1.5. With complementarity, there are different mechanisms at work, some understood and others less so. Certainly, interspecies complementarity can be a basis for beneficial agroecology. At the other side of this spectrum, competitive relationships (with LER values less that one) are not as exploitable but do find use. The classic example is to design agrosystems, through species and spacings, to discourage weed growth. There is yet another category, that of facilitation. This is where a second species provided benefit to the primary crop.

Photo 2.1  The classic maize with bean intercrop

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Complementarity The between-species interactions lie along a spectrum. These range from highly complementary to highly competitive. As expected, most intercropping possibilities are in the middle range. There are a number of reasons for affirmative complementary. Overall, LER-based complementarity is more common on well-watered, welldrained soils (for more, see Competitive Partitioning). When this occurs, one species may require more phosphorus, less nitrogen. The second paired species may need more nitrogen and less phosphorus. With this, the potential is good for strong, interspecies complementarity. Other mechanisms can be at work. Separate sources are where two species get a key nutrients from different origins. A deep-rooted species, one drawing nutrients from lower soil strata, interplanted with a shallow-rooted species, can result in an LER-affirmative pairing. There is yet another mechanism at work, one that could possibly be paramount in the success of seasonal intercrops. On well-watered, well-drained, fertile sites, the yields of each of two species, when intercropped, may be slightly reduced. This is expected. If the yield reductions for each species are less than 50%, the LER will exceed 1.0. If the yield reductions are slight, the LER could be quite high (for more explanation on this abstract, but entirely workable concept, see Marginal Gains under Competitive Partitioning, especially Fig. C4, page 235). Despite the many mechanisms of complementarity, these are cumulative only to a point, two different interplanted species, through complementarity alone and without any facilitative effects, would face an LER upper limit of 2.0. Competition At the competitive side of the complementarity-competitive spectrum are those mechanisms that discourage coexistence. Some long-term perennials actively discourage other plant species. Pines and eucalyptus fall in this category for different reasons. Pines change the soils acidic while eucalyptus is thought to be water competitive. Not all trees are as competitive; poplar can result in a high LER when young and paired with many crops. At the cropping level, big leaf plants, such as squash, can discourage weeds. These plants can be combined with other crops; a common example is squash beneath maize. Because of the low squash yields, the mix finds favor because the two species control weeds. This reduces weeding costs. The maize, bean, and squash mix examples another competitive mechanism, that of niche crowding. Provided the planted species have niche ascendency (i.e., they occupy the various niches before the unwanted weeds arrive), there are fewer resources left untapped. Most pronounced, shading would have a large role in the success of this combination (for more, see Competitive Exclusion).

The Core Elements

21

Facilitation With biodiversity, there exists the possibility that one species aids another. The common example is where a nitrogen-fixing plant is planted simultaneously with, or before, the primary crop species. When in-soil nitrogen is not in abundance and limits yields, the result can be substantial increase in the site LER. Two-species LERs of around 2.5 are quite possible, e.g., 2.6 (Seran and Brintha 2010). One of the highest recorded LERs, above 3.6 (Ong 1994), came through facilitation. This was not a passive intercrop where close proximity alone allowed for the interspecies conveyance of nitrogen. This involved hedgerow alley cropping where belowground nitrogen is released through plow-caused root pruning and the above­ ground biomass is cut and carried to the nitrogen-demanding maize (for more on this example, see Alley Cropping). Facilitation is not always with nitrogen. Other plant nutrients may be part of the interspecies relationship. Another common case is an improvement in the in-soil moisture due to the presence of a second species, e.g., less soil drying. Figure 2.1 shows the reason for these high values. The arrows show the added essential resource and the corresponding upward gains in yield. The steep section of the sigmoidal curve means that a small amount of an essential resource can translate into a comparatively large productivity (yield) gain.

Spacings In league with complementarity competition, there is the question of planting densities for the component species. Crop species that have high complementarity can be interplanted, on an agriculturally favorable site, such that the planting densities of both are at the recommended monocultural densities. Where species exhibit less interspecies complementarity, the highest LER values might be where densities of one or both species are slightly reduced. There are other aspects to this. Another involves planting ratios, where a facilitative mix may involve a lesser number of the secondary plants. In the case of a cover crop, there can be far more cover plants than the primary crop. This is the planting ratio and it varies as to the species paired (for more, see Planting Ratios). Concisely put, there are two variables under spacing. The first is the planting density of each species; the second is the planting ratio. In finding the best combination for crops (two or more), the effect of climate, site, climate, etc., are questions that are best answered through in-field trials. The obtained data points should allow for the subsequent derivation of density-based possibilities curves.

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Density As with yield and LER, densities comparisons are made against monocultural figures. The maximum density for a single species within an intercrop is the same as the recommended density for that selfsame crop in monocultural setting. The overall bicultural density, i.e., the density index (DI), is DI = ( Dab / Da ) + ( Dba / Db )

Fig. 2.2  Plant densities for species a and b in relation to LER. The solid ridge line links those points along this surface that maximize the LER

LER

where Dab is the density of species a when interplanted with species b and Dba has b interplanted with species a, Da and Db being the recommended monocultural densities. Figure 2.2 shows the possible LER outcomes given a good site, two productive species, uniform interspecies spacing, and no facilitation. The 2.0 DI value, in the upper right corner, has the two species crowded together. The surface shows that, in this case, maximum density does not give the highest LER. At times, more space between plants can be the best option. A lessor spacing generally allocates more of the essential resources to each plant. This can move each plant higher in the resource curve. Although there are slightly fewer plants per area, if this results in a large jump in per-plant yield (as in Fig. 2.1), the net effect is to increase plot-wide yields, i.e., LER (for more on this, see Marginal Gains under Competitive Partitioning, page 235). This spacing/density, in regard to essential resources, is best expressed as a biculture density-response surface, e.g., as in Fig. 2.3. The densities that maximize overall yield are illustrated by the dotted ridge line. For the assumed level of essential resources, the LER often peaks at a less crowded spacing.

The Core Elements Fig. 2.3  An overview of Fig. 2.2 with added ratio lines

23 50%-50%

Planting Ratios There can be various planting ratios for two intercropped species. Figure  2.3 is Fig.  2.2 in overview. Both show the ridge line. This overview also includes the planting ratios in the form of ratio lines. These radiate outward from the 0,0 point (lower left). In addition to the axes, the three radian lines represent for species a and b, respectively, 25–75%, 50–50%, and 75–25%. The point where each ratio line crosses the

Fig. 2.4  This illustrates, top to bottom, some of the possible, and more common, spatial patterns. The top is individual or grouped. The middle are peripheral and the bottom are row and strip. Those on the right are fine patterned. Those on the left are course patterned

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Photo 2.2  A two-species intercrop. This shows a block pattern, onion with radish

ridge line represents the best possible LER for that planting density (for more, see Planting Ratios). For Fig. 2.3, the highest LER is where 50–50% ratio intercepts with the ridge line. There are situations where, even with this surface, one might want a different ratio. There are cases where more of one species, less of another, gives the highest LER. An example may be maize with a shorter crop. With fewer maize plants, more light is available in the understory with higher yields from the shorter species. This can be less a yield and more an economic decision. If one species is much higher in value than the second, a farmer might plant more of the higher valued and fewer of the less valued. There are also situations where a different planting pattern may, for other reasons, prove advantageous. Each pattern can require a singular density function (Fig. 2.4 and Photo 2.2).

Spatial Patterns The previous analysis, as presented in Figs. 2.2 and 2.3, has assumed a set planting pattern. The default is often a fine checkerboard pattern where, in a biculture, each plant species is bordered on all sides by a second species. This maximizes the

The Core Elements

25

amount of interspecies interface, and where the potential interspecies complementarity is high, so would be the resulting LER. As mentioned, equal populations for each intercropped species may not be best. For uneven populations, three-dimensional possibilities curves are the preferred means of evaluation as in Figs. 2.2 and 2.3, Rather than just uneven planting densities, there can be variations in the spatial pattern. Some of this may relate to the division of resources, e.g., light apportionment and LER gains. For other patterns, the reason may relate less to the net LER and involve, e.g., planting and/or harvest efficiencies. There are some general rules that govern patterns. These depend upon interspecies complementarity. With a lesser degree of complementarity, courser patterns may be better than lessening the planting density for one or both species. It may be better to forgo a single species checkerboard pattern and, instead, interplant like species in small blocks. These would closely bordered by similarly formulated blocks of a different species (this design is shown in Photo 2.2). A block of plants can be awkward to manage. Rows can be the preferred means to incorporate lesser amounts of interplant interface without reducing the intraspecies planting densities. Figure 2.5 shows some a few of the possible row arrangements. These are shown in cross section. There is also a general rule that, lacking any overriding concerns, rows be north-­ south oriented. The idea is improved light dynamics. This may be especially important where there is a meaningful height difference between the component species. The overriding concerns can be topography, wind direction, and harvest needs. This applies to row systems such as alley cropping (for more on the tradeoffs involving row direction, see Row Orientation).

Fig. 2.5 Various cross-sectional row arrangements. This figure is labeled as to species placement, a and b, where, as shown, alternating rows are ...abababa..., ... abbabba..., and ... aabbaabbaa..

...abababa...

...abbabba...

...aabbaabbaa...

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Timing As a core element of design, timing refers to the temporal dynamics of an agroecosystem. This can be, for a single crop, when to plant. For intercrops, planting can simultaneous or the planting can be staggered, each component species at a slightly or widely different time. Timing can apply to activities within a single season or species changes that occur within a single, long-duration agrosystem. The latter exists across multiple seasons or across many years. In this regard, timing effects the ecology and the economics. This can be a means for an LER above 1.0. One crop might need more light and water early in the growing season. This crop can pair well with a second one that needs these inputs later in the season. A slight stagger in the sowing times could bring these temporal dynamics more to the fore. An example is lettuce with tomato. The lettuce grows fast, taking more light and water before the tomato achieves peak growth and peak needs. There are examples where simultaneous planting may result in a resource unbalanced agrosystem. Most common is when a crop species, one with faster growth, outpaces a second species. Unfavorable shading on the second, and shorter, species could result.

Photo 2.3  A maize and bean sequence. In this example, the maize stalks, post-harvest, remain as a climbing support for the beans. Sequencing may be done when rainfall is too low for intercrop needs. This follows the general rule where species that intercrop well also sequence well

Evaluation

27

This can be rectified by planting the slower growing species first, followed by the faster growing second species. Here again, the goal is often LER related. Timing also applies to long-duration systems. When the trees are small and widely spaced, an orchard or similarly, a wood-producing, forest-tree plantation, can be co-planted with crops. With these taungya systems, the LER is a multi-­ seasonal sum.

Sequencing (Rotations) As stated, there is a clear relationship between interspecies complementarity and intercropping success. There are occasions where, due to a shortfall in one essential resource, interspecies success is not always assured. For example, water can be the limiting resource that negates an otherwise successful species pairings. The highly productive bean with maize (with a projected LER of ≈ 1.5) does not yield well if the seasonal rainfall is below 400 mm (Rao 1986). Although rotations often involve a series of discrete agrosystems, it is worth mentioning that complementarity can be the basis for the sequencing, i.e., the relative timing, of rotations. As a general rule, crops that intercrop well, generally sequence well. There are questions on the actual succession. In this mode, there are fewer constraints regarding a possible limiting resource (for more on this topic, see Rotations).

Evaluation The above core elements form the base agroecosystem. Although all the inputs and influences are not yet in place, the core or base does foretell the socioeconomic character of a proposed agrosystem. Most often, the user objectives are monetary and this can include a requirement to turn a profit. This can be done by increasing revenue and/or decreasing costs. Conventionally, revenue increases are accomplished through harvest gains in the one, plot-occupying crop. Through biodiversity, revenue increases can be expected with multiple species and multiple harvests from the single plot, i.e., with LER values greater than one. Cost-wise, nature offers many eco-services that are free or nearly free. If used effectively, these are prime opportunities to lower costs. As above, agroecology offers possibilities for yields and profits. These alone understate agroecology. The overall outlook can include an improved environmental outcome. A reduction in toxic chemicals is part of this. Better outcomes also come when well-formulated agroecosystem meets monetary as well as non-monetary social-economic goals. Such systems can be expected

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to be superior along the environmental front, e.g., not only in chemical reductions but in, for example, allowing local flora and fauna to thrive. These latter gains are intangible and judgmentally challenging to quantify. Although for the good, the starting point lies with a profitable financial outcome. With this in mind, the following sections bring revenue and cost into the picture.

Economic Measures Needed are means to gauge economic outcome both in absolute terms and relative to competing agroecosystems. In absolute terms, standard accounting is utilized where profit is the costs subtracted from the revenues. Other accounting techniques, e.g., net present value, can be applied as needed. Relative Value Total One advantage of the LER is that monetary values are not employed. There are times when the relative value of the different yields is important in designing the best agrosystem. Adding these, the result is the relative value total (RVT). For this, RVT = ( paYab + pbYba ) / paYa The variables are the same except the addition prices. Species a has a selling price of pa and species b has a selling price of pb, the divisor being the more valuable of the two outputs (for more, see Relative Value Total). For some uses, RVT directly substitutes for LER. This substitution can be made with density functions/surfaces (as in Figs. 2.2 and 2.3). Often, the net effect is to change the planting ratio in favor of the species that contributed the most to overall agrosystem revenue. Cost Equivalent Ratio With the normal profit calculation, revenue subtracted from costs equals profit. With ratios, this is no different. The cost equivalent ratio (CER) is determined through the equation CER = ca / cab where ca are the plot-based costs for monocultural production of the primary species, i.e., species a. For comparison, cab are the costs for species a and species b when closely intercropped. The above equation is more suitable where one, nonproductive species facilitates a crop species. For classic, multiple-output systems, another equation is favored. This is the intercropping-based CER where

Evaluation

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CER i = ( ca + cb ) / cab





For two monocultural plots, the costs for each (ca and cb) include site preparation and weed removal. With one intercropped plot, these costs are, in essence, halved. The above equation includes these savings. There are variations of these measures (for more on these variations, see Cost Equivalent Ratio). There are examples where the CER is not a secondary measure. An often cited study of the in-use CER is found with shade-grown coffee. From Perfecto et  al. (1996), the costs for an in-full-sunlight coffee monoculture are $1740, whereas the costs of an equivalent area of coffee with a shade-tree overstory are $269. The resulting CER is

= CER $= 1740 / $269 6.47

The basic CER shows that, for a given area, the shade agrosystem, in term of added inputs, increases efficiency by 6.5. This brings on the notion of two opposing economic options. One involves a greater level of inputs, increased revenue, and a greater profit. The other entails less inputs brought about by more reliance on natural dynamics and, through this, a greater profit.

Economic Orientation The importance of CER lies with more advanced analysis. This starts when the RVT minus the CER (i.e., RVT – CER) roughly approximates economic orientation. This starts a line of development often ignored in conventional analysis. Within the range of possible agroecosystems, some systems are revenue oriented, some cost oriented. Positive values indicate revenue orientation. Negative values result when an agrosystem is cost oriented. In brief, with revenue orientation, costs are increased. This is done in the hope of boosting yields and, if all goes well, overall profitability. As mentioned, green revolution monocultures employ this strategy. The opposite is cost orientation where inputs are substituted or lesser amounts used. Expecting modest yields and/or some loss in revenue, the hope is that this will be the most profitable strategy (for more, see Economic Orientation). Revenue Orientation Going beyond the subtracting of the CER from the RVT, there is a more sophisticated rendering of the revenue-cost relationship. The explanation starts with the sigmoidally stated, standard production function (as pictured in Fig. 2.1). This can be shown through the relationship between yield and a nutrient input, e.g., nitrogen.

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Simply expressed, with revenue orientation, the goal is to reach a high level on the production function. In doing so, the nutrient is applied until the cost of adding an additional unit exceeds the value of the yield increase attained. When this happens, no more is added. Based on one nutrient alone, this would determine the yield level. It goes without saying, there is more than a single nutrient involved. In a multi-input environment, the notion of reaching the upper level on the curve holds as long as the other plant needs are in sufficient quantity. Cost Orientation There is a marked difference in philosophy with cost orientation. With a cost-­ featured agrosystem, the idea is to substitute natural dynamics for outside inputs. The notion being that eco-dynamics can be put in place at no or at a low cost. Within an agrosystem, eco-services can take space or be slightly competitive with the crop. This can result in a yield and revenue reduction. With implementation, the hope is that the cost savings will greatly exceed the yield/revenue loss and that this will maximize profits. In multi-resource situations, both revenues and cost strategies may be initiated. Further development of economic orientation, including a mathematically based explanation, is deferred to Chap. 10. Overview Based only on the core elements and the resulting base agroecosystem, there are additional insights to be had. A single-species/variety monoculture, optimally spaced, optimally timed, and with a base level of inputs, can be considered as having a neutral orientation. Farmers have the option of adding eco-services or adding external inputs. Adding inputs to boost mono-yields is generally revenue orientation. Stronger yields, obtained through eco-dynamics, would be cost orientation. In this preliminary design phase, intercrops begin to exhibit an orientation. Facilitative systems tend to be cost orientated while productive intercrops are more inclined to be revenue orientated. Clearly, the best outcome where high yields couple with reduced costs. These agrosystems, although infrequent, do exist. The common example may be maize with bean. In addition to the productive potential of dual outputs, costs are reduced through favorable nutrient dynamics and improved weed control.

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Profitability The common assumption is that, because more cash is being spent, revenue orientation will be more profitable. This may not be true. Strong cost orientation can be more profitable than pricey, input-supported agrosystems. This is the foundation of low-input agriculture and, through eco-services, a central facet of agroecology.

Other Objectives This chapter puts the focus on yield and economic outcome. Without these, there may be no incentive to plant crops. For many, risk, i.e., certainty in yields, is of paramount importance. For others, environmental goals, in all their manifestations, can be a significant concern and a strong motive for an agroecological approach. Keeping within the core of agroecology, discussion on risk and the environment are deferred to later chapters.

References Ong, C. (1994). Alley cropping ecological pie in the sky? Agroforestry Today., 6(3), 8–10. Perfecto, I., Rice, R. A., Greenberg, R., & Van der Voort, M. E. (1996). Shade coffee: A disappearing refuge for biodiversity. Bioscience, 46(8), 598–608. Rao, M. R. (1986). Cereals in multiple cropping. In C. A. Francis (Ed.), Multiple cropping systems (pp. 96–132). New York: Macmillian Publishing, 383p. Seran, T. H., & Brintha, I. (2010). Review of maize based intercropping. Journal of Agronomy, 9, 136–145.

Chapter 3

The Agroecological Matrix

Contents Agroecology Redefined Cropping Threats Soil Fertility Rainfall (Too High or Too Low) Insects Weeds Pathogens Pollination Temperature (Again, the Extremes) Wind Small Animals (Birds, Mice, etc.) Large Animals (Deer, Elephants, etc.) Threat Counters (Eco-Services) Single-Purpose Counters Multipurpose Counters The Counters Listed The Counters Described Permanent and Introduced Counters The Agroecological Matrix Matrix Manifestations Expansion Matrix-Based Analysis Matrix (Cell) Elements As an Analytical Tool An Applied Example Agroecological Intensity Economic Implications References

 34  34  35  35  35  37  37  37  37  37  38  39  39  39  40  42  43  47  47  47  48  49  50  52  52  55  55  55

In the proceeding chapter, the core elements of intercropping design, i.e., species (two or more), spacings, pattern, and timing, are presented. If well exploited, these core elements, taken together, can be the basis for positive plant-on-plant complementarity and/or for corresponding facilitation. Likewise, these go a long way in determining the internal ecology of any one agrosystem. Assuming a stable climate and a site devoid of threats, they alone will determine the base LER. © Springer International Publishing AG, part of Springer Nature 2019 P. Wojtkowski, Agroecology, https://doi.org/10.1007/978-3-319-93209-5_3

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Within an agrosystem, there are numerous forces at work. In practice, site and weather-related stability are seldom assured. In addition, the yield-reducing cropping threats are many and active, i.e., insects, diseases, etc. The core elements help with some, but are seldom effective against all.

Agroecology Redefined How and when these specific counters, and the associated ecology, enter the picture is fundamental to agroecology. So much so that some of the definitions feature this perspective. With this view in mind, it holds that agroecology is a science that “… seeks to enhance agricultural systems by mimicking natural process, thus creating beneficial biological interactions and synergies among components of the agroecosystem” (Kerschen 2013). In this definition, agroecology is fronted by the beneficial ecology of the interacting parts. This perspective may capture more of the essence of agroecology, but, in some aspects, it is less than complete. It can be argued that monocultures, lacking in biodiversity, do not have synergies and are therefore outside formal agroecology. Even with the high-input green revolution model, there are nonchemical additions that, when applied, offer a modicum of active ecology. Whether it be a one-species monoculture or a species-rich agro-polyculture, the notion is to ecologically fortify an agroecosystem against natural threats. This can be through enhanced plot-internal ecology and/or through the ecology that surrounds the targeted plot. With all the different factors in play, there is a need to systematically present the threats, the corresponding counters, and to show how these associate, and achieve, system objectives within an agrosystem context. This is best understood, and presented, by way of the agroecological matrix.

Cropping Threats Briefly summed, the cropping threats are: Soil fertility (reduced) Rainfall (the extremes; too high or too low) Insects (herbivore) Weeds Pathogens Pollination (lack thereof) Temperature (again, the extremes) Wind (constant and in microbursts) Small animals (birds, mice, etc.) Large animals (deer, bison, etc.)

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Soil Fertility Soil fertility often starts with the NPK components. To these, a host of trace elemental needs are added. Nitrogen-fixing species, cut-and-carry nitrogen-rich leaves, or some other N-input often spells the difference between success and failure. Not to be dismissed, and of equal importance, are the other nutrients and their sources. Under this heading comes the structure of the soil. Low bulk density, high in-soil carbon, and other factors contribute to a good outcome.

Rainfall (Too High or Too Low) The key aspect of high rainfall is to prevent erosion. Here the enemy is water flow along the surface. When surface water flows, it loosens and carries away soil particulates. It is far better if water infiltrates into the ground. Below ground, it does not erode the soil, travels far slower, and is available to plants for a prolonged period. There are two overlapping categories of counters: (1) barriers and (2) soil cover. Both categories promote infiltration. The first of these contours the land. These can be as terraces, mounds, ditches, and/or rows of vegetation. These can be large structures, located every few meters, or smaller features located decimeters apart. The size and distance depends on the rainfall, steepness of the land, and looseness of the soil structure. They can strictly follow an elevation gradient or use the gradient as rough guide. The other category, that of soil cover, also presents a range of options. This can be dead vegetation, either imported, the residue of a previous planting, and/or leaf fall from an existing crop. Living plants, as a cover crop, also serve. These can be living and purposely planted (either productive or facilitative) or a harmless or a less harmless weed. Whatever the source, there must be enough, in extent and depth, to provide the needed protection (for more, see Infiltration, Erosion, and/or Barriers). These same measures are implemented for low rainfall. Although erosion may not be the immediate danger, water infiltration and retention, for what little rain that does fall, make it readily available (for more, see Infiltration).

Insects As a threat, herbivore insects exhibit two states. The first is nonthreatening where no or some damaging insects inhabit a plot. Yield losses are minimal and acceptable, and controls seek to maintain this status quo.

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The second occurs when the status quo breaks down. This can be an insect outbreak which requires immediate, enhanced control. Status Maintenance Of the control options, the best may be insect-on-insect predator-prey where good insects eat the bad. For this, zero crop losses are not expected. Some herbivore insects must be present to maintain a threshold population of good insects. Economically, it may be better to endure minor crop loss (usually less than 5%) than to undertake costly spraying. The main disadvantage is that predator-prey is easily disrupted by direct insecticide application or from spray drift from nearby insecticide use. The potential for insect-on-insect predator-prey is easily gauged. If insecticides are not area present and there is sufficient biodiversity, below, above, and/or adjacent the crop, this is a good indication of latent effectiveness. Next on the list of control options is the use of repellent plants. In the best case, designated facilitative plants would drive the bad insects into the field margins. These boundary areas are best if stocked with attractant plants and heavily populated with predator insects (for the full listing of counters, see Insect Control). Noteworthy is an anti-insect technique mostly lost to history. Chickens and other domestic fowl eat insects. In the distant past, their use was commonplace. In league with natural avian predators, e.g., barn swallows, they again could become a potent control (for more, see Attracting under Birds). Outbreaks Populations of herbivore insects can, if triggered by some event, e.g., a weather anomaly, reach crop-threatening levels. This is when, through population dynamics, the number of bad insects approaches or reaches the upper plateau on the sigmoidal population curve (as exampled in Fig. 2.1). Given time, an outbreak will naturally abate. Unfortunately, waiting is not always an option. Outbreaks require additional measures, often including a switch in controls. Repellent plants, cut and carried, to a site are a viable counter. Another is to purchase and release a predator species. As a last ditch action, crop-saving insecticides may be required. As oft stated, of the many options with regard to insect control, insecticides with exception (as above) are to be avoided. For insect maintenance, insecticides can destroy predator-prey controls. These can be difficult to quickly reestablish (for more, see Insecticides).

Cropping Threats

37

Weeds The bane of the farmers, unwanted plants, can take light, water, and/or essential nutrients from productive species. Physical removal is one control. Increased biodiversity, long fallows, the timing of the plowing or sowing, crop rotations, planting density, and a preplanting burn can all be part of integrated weed management (for more, see Weed Control).

Pathogens Another bane of high yields are plant diseases. The broad counters are increased biodiversity, healthier and/or more resistant plants, and/or plot and field layouts that do not favor spread.

Pollination The lack of pollinating insects can be an unnoticed cause for poor crop yields. For crops that need pollination, this is the number one reason. As counters, those same conditions that favor strong predator/prey can also support natural pollinators. The alternative is the honeybee (for more, see Pollination).

Temperature (Again, the Extremes) Temperatures have direct and indirect effects. Indirectly, they increase evaporation leading to a water shortfall and water stress. Windbreaks can help retard transpiration. Directly, low-soil temperatures can forestall seed germination. At the opposite end of the spectrum, high temperatures can halt pollination, e.g., the commonly cited example is with maize. Large, open fields of a single crop are more temperature exposed. Biodiverse ecosystems offer a small degree of internal moderation, more so if trees are present.

Wind Winds come in varying forms. In some regions, there is a constant breeze. This can have serious dying effect, magnified if the humidity is low and/or the winds are channeled, or wind tunneled, through a gap or alley. A gap or alley can be formed when spaced trees are internal or nearby.

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Intermittent, stronger winds, in addition to drying, can cause sandblasting. This is when soil particles strike and damage stems and leaves. Although each strike is minor, the cumulative effect can be a significant force in reducing area yields. Further along this strength scale, there are stronger wind bursts that can break branches, dislodge fruit, or lodge some crops. These strong bursts can be associated with thunderstorms. Inclusive are microbursts, downward winds that can flatten areas of taller, seasonal crops.

Small Animals (Birds, Mice, etc.) There are measures to keep small fauna away from crops. Biocontrols often are the least effective. Classically, the scarecrow has serve this purpose with crop-eating birds. This can have mixed results (for slightly more on this topic, see Scarecrows). The ultimate crow repellent may be dead crow, easily visible. Bird management may require a delicate balance. Crop-eating birds can feast off bugs when there are young to be fed. At the end of the cropping season, these same bird species turn to grains. A late season scarecrow might help. There are direct measures. Grains with long spikes (awns) can keep birds from perching. Most of the counters are, as with scarecrows, indirect. Predator birds (e.g., eagles, hawks), if encouraged, can keep the others away (for more, see Repelling under Birds).

Photo 3.1  A scarecrow used to frighten away unwanted birds

Threat Counters (Eco-Services)

39

For mice, rats, and other rodents, there are a few vegetative counters, e.g., mice do not like mint. The best controls may be ex-plot. Again, attracting predator birds (hawks, owls, etc.) is a possibility. A less popular control is the presence of snakes. Nonvenomous types are suggested.

Large Animals (Deer, Elephants, etc.) For the larger fauna, there are two basic controls, fencing and hunting. Both are ex-­ plot. Fencing is good, but not always fully effective against large, more powerful animals, e.g., deer, bison, and elephants. For the latter, locals state that honeybees and chili spray can be effective.

Threat Counters (Eco-Services) For each of the above threats, there are eco-services that mitigate or eliminate each. This can be single purpose (one threat, one counter) or multipurpose (one threat, more than one counter). This categorization is a key concept toward understanding agroecology.

Single-Purpose Counters A key aspect of conventional agriculture is the use of outside, ex-plot inputs. Much of this is accomplished through agrochemicals, there being a different chemical for each threat category. These are one-on-one solutions. Although there are options among the counters, the pairings can be concisely summed where: Low-soil fertility = fertilizers Herbivore insects = insecticides Plant pathogens = fungicides Weeds = herbicides Low rainfall = irrigation There are a number of contrary aspects to using single-purpose, one-threat, one-­ counter solutions. First, when compared against natural controls, they are inherently inefficient and represent a cost. A second aspect is the implicit environmental toll in field-applying huge volumes of artificial compounds. In fairness, it should be noted that not all spray-based, single-purpose solutions are inherently evil. Against insects, a mix of soap and water (using common soap) or organically accepted chemicals are safer and less environmentally troublesome

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Photo 3.2  Close-spaced trees with wire form a living fence, one that is sturdy enough to deter both cattle and elephants. (This photo was taken in northern Kenya where roaming cattle and elephants are cropping threats)

(for more, see Insecticides). The same holds true for milk solutions that counter fungal attacks. The single-purpose counter goes beyond sprays and applies when a threat has one, dedicated (with no other purpose) response. For example, insect traps have only one target, one purpose.

Multipurpose Counters There are three guiding precepts or principles that differentiate agroecology from the one-on-one mind-set of conventional agriculture. These are: 1 . To counter threats through natural means 2. To use a single counter against diverse threats (i.e., more than one) 3. To layer the different counters so they mutually reinforce and, in unison, are more than enough to overwhelm or eliminate any one threat

Threat Counters (Eco-Services)

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The first two principles, (1) and (2) above, can be illustrated through the possible gains from biodiversity. Agroecosystems consisting of more than one species can, if the species are well selected, address various threats. Examples are numerous. These extend far beyond the marigold/tomato intercrop shown in Photo 3.3. In adding a cover crop below a primary crop, the eco-services provided could include: Increased fertility (by way of a nitrogen-fixing species) Reduced soil loss (through a soil-covering, dense planting) Controlling weeds (through niche-occupying bio-density) Retaining rainfall (better capture through increased water filtration) Controlling insects (through predator-prey dynamics or with a repellent plant) Hosting pollinating insects A well-selected cover crop might offer all or most of these services. If there are specific threats that need addressing (e.g., the nematode situation in Photo 3.3), a specific-purpose cover crop might be the better option. One documented example has the facilitative species desmodium co-planted with maize. The main purpose is to repel insects. In this case, effectiveness extends to hard-to-kill stem borers.

Photo 3.3  This chapter is formulated around agrosystems where one agro-feature offers an array of eco-services. This is evident in this photo where the marigolds, planted between the tomatoes, benefit in six ways: (1) controlling nematodes, (2) stabilizing the soil, (3) reducing weeds, (4) slowing the spread of diseases, (5) attracting pollinating insects, and (6) attracting predator insects

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A desmodium preplanting can have a second purpose; it can eliminate or reduce the population of the parasitic African weed striga. It does by acting as a false host. Planted before maize, it triggers germination of the striga seeds without supporting subsequent growth of this weed. This clears the soil for an upcoming maize crop. Going beyond the cover crop, there are other counters that seem single purpose but can be multipurpose. Animal manures supply plant nutrients. It has a less-than-­ intuitive secondary effect; manures can also help control some insect species, e.g., aphids (Morales et al. 2001). The third principle, (3) above, is mutual reinforcement, i.e., having enough ecological superfluity such that each threat is easily overcome. A biodiverse agrosystem can support predator-prey dynamics, but this might not be ecologically assertive enough to control all the unwanted insects. A second counter, close-at-hand field margins, could be a source of predator insects. This could favorably tip the insect balance (for more on the related theory, see Eco-Services).

The Counters Listed A full listing of the sources of eco-services is quite long. Sans toxic or environmentally dubious sprays, these include: Productive/facilitative biodiversity Species (two or more) Spacing Spatial pattern Timing Genetic/varietal Rotations Fallows Fire Landscape (plot surroundings) Location Land modifications Absorption zones/micro-catchments Gabons Infiltration barriers Mounds/beds Cajetes Catchments Riparian buffers

Threat Counters (Eco-Services)

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Stone clusters Terraces Tree-based Earthen Stone Water storage/transport Paddies Ponds Water channels Water-breaks Bio-structures Windbreaks/shelterbelts Anti-insect barriers Corridors/habitats Riparian buffers Firebreaks Living fences Ex-plot inputs (organically recommended) Fertilizers (e.g., compost, manures, green biomass) Insecticides (e.g., soap solutions, dichotomous earth) Microbes Environmental settings Tillage method Mowing method (plot and/or fringe) Pruning

The Counters Described Carrying forth from the three guiding principles, it is possible to describe, in eco-­ service terms, the threats countered. As mentioned, a bio-diverse, base agrosystem can provide a range of eco-services. Being ever present, this is always the starting point. Since multiple threats are addressed with a single counter and multiple counters address a single threat, there is considerable task overlap. As a consequence, the following descriptions can come across as being repetitive. To avoid this, the eco-­ tasks associated with each counter are only briefly touched upon.

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Productive/Facilitative Biodiversity As the number of species in the base agroecosystem increases, so does the favorable ecology. A companion non-facilitative or a facilitative species can be selected to increase in-soil nutrients (particularly nitrogen), protect against erosion, control weeds, and/or accomplish other eco-tasks. Density and spacing reinforce the eco-services that the species, singularly or together, carry out. The planting pattern reinforces or introduces other controls. For example, a strip or alternating row pattern can slow the spread of plant diseases and harmful insects. Continuing this example, crop strips that contour a hillside can be a barrier against erosion. Timing is mostly employed to maximize the LER. There can be gains in weed suppression. Genetic/Varietal As a counter, it is possible to substitute of one crop variety for another. This might be replacing a drought-prone variety for one that survives low rainfall. These exist for many crop species. Rotations There are many gains to be had by changing the sequence of crop species. If well formulated, the gains can be improved in-soil nutrients and/or improved in-soil moisture. Rotations can also negatively impact harmful insects and resource-­ robbing weeds (for more, see Rotations). Fallows Allowing the land a rest period is a site reset with positive gains. The nutrient and moisture content are increased. A reset can reduce or eliminate weeds and be part of an insect control strategy. A fallow can last one season or many decades (for more, see Fallows). Fire Uncontrolled, fire can destroy agroecosystems. Fire, as a preplanting counter, can be a positive. For the upcoming crop, a burn releases the nutrients contained in existing biomass. Fire can also destroy hidden insects, burn weed seeds, and ease the preparation needed for an upcoming planting (for more, including the disadvantages, see Fire, also Slash and Burn).

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45

Photo 3.4  An example of post-fallow, preplanting burn. This burn was of moderate to low intensity, most likely with only a minor effect on upcoming weed populations. The primary purpose would be to reduce the cost of brush clearing

Landscape The impact of surrounding plots, and those more distant, can broadly impact a targeted plot. The gains come through better wind, water, disease, and insect management. Some come through direct protection, e.g., from winds and surface water flow. Other protections are indirect where, e.g., insect-eating insect breed in the surroundings and venture forth to seek prey in among the crops. The size and shape of the plot(s) can be a key factor. Plots, long and narrow, can aid the spread of abovementioned, boundary-inhabiting, good insects. This would include natural pollinators. Plots, long and narrow, when contouring a hillside, is one of many erosion control measures (for more, see Landscape Agroecology). Location The basic idea is to plant crops where they are subject to fewer, or the least damaging, threats. For example, a crop that is killed when the roots are waterlogged should not be placed where standing water is a regular event.

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Land Modifications There are earthen structures of various designs that offer better water management, protection from rainfall extremes (high and low), and erosion control. As stated, the basic idea is that water should not flow across the surface. It is far better if water infiltrates into the soil. Once underground, it is available to crops for a longer period. This brings additional gains, mostly from reduced erosion and in water purity (for more, see Infiltration, also Micro-Catchments, Gabons, Mounds, Cajetes, Stone Clusters, Ponds, and Terraces). Farm Practice This is a catch-all category involving the many aspect of management. This includes when to mow, plow, prune, weed, etc. Also, how and where this is best done. Bio-Structures There are rows, strips, or blocks of vegetation that cross the farm landscape thereby providing various ecological services to nearly crop plots. The vegetation can be naturally occurring, be purposely planted, or be an ecologically rich agrosystem. The eco-services offered include the blocking of drying winds and providing a habitat and a travel corridor for predator and pollinating insects. The affects extend belowground where, from this reserve of micro-organisms, active plots can restocked (D’Acunto et al. 2016). These structures also allow for water infiltration, control soil loss, stop the spread of wildfires, and contain roaming animals (for more, see Windbreaks/Shelterbelts, Barriers (general use), Corridors, Riparian Buffers, Firebreaks, Field Margins, and/or Fencing). Ex-Plot Inputs This category can include worrisome chemicals. These are also some that are recommended. For fertilizers, the multipurpose application of manures has been mentioned. Along these same lines, and possibly with the same properties, are compost and green biomass (for more, see Mulch). The latter can be multipurpose, e.g., also suppressing weeds. An ancient technique that has come to the fore is in-soil charcoal (for more, see Tierra Prieta). Charcoal does not add nutrients, but helps retain those present. It also improves soil permeability and soil moisture. Against insects, there are the less eco-disturbing soap solutions, dichotomous earth, and wood ash. The latter also provides nutrients. Also, against insects are

The Agroecological Matrix

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introduced predators, e.g., wasps are brought in to control leaf-eating caterpillars (for more, see Insect Control). Environmental Setting This category describes some seemingly minor, and quite diverse, agronomic practices. Despite appearing minor, these can contribute to the ecology, threat reduction, and the agro-outcome. They include the options for plowing (or lack thereof), mowing, tree pruning, tree planting, and weeding (for more, see Weeding Methods, Pruning, and Planting Methods). Also benefiting agriculture are specific microbes. These single-cell organisms can be detrimental, others not so. Microbes can make nutrient available, counter plant diseases, and can even help conserve water by reducing plant transpiration (for more, see Microbes).

Permanent and Introduced Counters As stated, the above counters have been divided into two categories, (1) single and (2) multipurpose. Another division is useful. For this new category, there are also two classes, (1) those that are always in place, always working, and (2) those that are ex-plot and are applied or introduced when needed. The former category would be infiltration ditches and windbreaks, whereas the latter, those introduced, would be insect-repellent biomass, cut-andcarried mulch, and/or burning.

The Agroecological Matrix A matrix presentation can, from a user perspective, save the reader from unavoidably long, untidy, and tedious explanations. Instead, these are reduced to a manageable and a concise form. The agroecological matrix lists the previously discussed threats as rows and the above-presented threat counters as columns. The cells or elements denote the effectiveness relationship between one threat and one counter. Each line represents and itemizes the options for countering a threat.

Matrix Manifestations In this layout, the matrix element values can be qualitatively stated (as in Table 3.1). In an advanced and more intuitive form, they can be quantitatively expressed (as in Table 3.2).

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Table 3.1 shows what might be a general-purpose/generic matrix. Taking a single line out of Table 3.1, weeds (line 3) can be combated through a combination of the base agrosystem, crop rotations, variations in farm practice, a preplanting burn, the surrounding landscape, and hand removal. Under the right circumstances, all can be contributory. Clearly, some are more potent than others. The purpose of a qualified matrix is to provide insight and a brief overview. This does not, nor is it the purpose to, fully explain the details, occurrences, and nuances of each threat/counter relationship.

Expansion If a site is challenging and more active agroecology needed, a farmer would take additional measures. The adding of more eco-services to counter more threats would be reflected in an expanded matrix. This would translate into additional lines and/or columns. In Table 3.1, soil fertility is a single line. This line could focus on overall soil fertility or on the nutrient most limiting. If there are, as often the case, co-limiting essential resources, these would be represented by two or more lines. The same could apply to insects. Instead of one insect row, more rows, one for each specific insect pest, could be included. In Table 3.1, the left side are the mostly permanent counters, and the right has those that are optional to the plot and agrosystem. Often the best economic outcome comes by first relying on the permanent, often the lower cost counters. Table 3.1  A qualified, non-numeric, agroecological matrix Counters → Threats ↓ Insects

Base agrosystem Good

Rotations/ fallows Good

Farm practice Fair

Soil fertility

Fair

Good

Good

Weeds Wind Diseases Temperature Erosion Infiltration Low rainfall

Good Good Good Fair Good Good Poor

Fair – Good – – – –

Good Poor Good Fair Good Fair Good

Fire Landscape Fertilizers Insecticides Good Good – Fully effective Good – Fully – effective Good Fair – – – Good – – Good Good – – – Good – – – Good – – – Good – – – Good – –

If these are not up to the task, optional or transitory inputs would further fortify an agrosystem. These are added as needed, e.g., compost to boost soil fertility.

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Table 3.2  A quantified matrix. This is the same matrix as in Table 3.1 but restated in numerical values. Instead of nonexistent to excellent, the ranking are 0–1 Counters → Threats ↓ Insects Soil fertility Weeds Wind Diseases Temperature Erosion Infiltration Low rainfall

Base agrosystem 0.75 0.50 0.75 0.75 0.75 0.50 0.75 0.75 0.25r

Rotations/ fallows 0.75 0.75 0.50 – 0.75 – – – –

Farm practice 0.50 0.75 0.75 0.25 0.75 0.50 0.75 0.50 0.75

Fire 0.75 0.75 0.75 – 0.75 – – – –

Landscape 0.75 – 0.50 0.75 0.75 0.75 0.75 0.75 0.75

Fertilizers – 1.0 – – – – – – –

Insecticides 1.0 – – – – – – – –

Matrix-Based Analysis Restarting, the three guiding precepts/principles that underlie matrix-based agroecology, i.e.: 1 . Use natural means 2. Thwart multiple threats with a single counter 3. Use multiple counters to attack a single threat. The focus now shifts to the quantitative matrix. For this, numbers replace qualitative estimates. Using a common denominator, the counters (matrix elements) are ranked 0–1 where zero represents no effect and one is highly effective. The equivalency is a 0–100% scale. Again, the across-the-row elements can be mutually reinforcing with regard to a single threat. In the simplest and possibly the most common of the intercell manifestations, the cells in each row constitute a summed effect. From Table 3.2, row 4, the wind counters are shown. These are the base agrosystem (0.75) and the surrounding landscape (0.75). As presented, the summed effect is good. The values sum to over 100% For most rows, the row functions are a nonlinear, sigmoid form where the counters (cells) are additive within the equation. The matrix elements along a single matrix line are shown, along the lower axis in Fig. 3.1, as summed arrows. Reaching the lower plateau of the inverse sigmoid function is generally enough to mitigate a threat. With a single matrix line and more study, it is plausible that some of the individual effects, i.e., the cells, are more than additive. This would be a mutual reinforcement where the sum of both is greater than the total of each. An example would be where attractant plants (within or at the fringe of an agrosystem) concentrate herbivore insects such that predator/prey is more effective. Also possible is to use repellent plants (within the agrosystem) to direct unwanted insects into predator-rich surroundings (the landscape element).

50 Fig. 3.1  An inverse sigmoidal function showing how, in small steps (as illustrated by the four arrows), each threat counter sums and reduces the danger. The analysis could also apply, with fewer, longer arrows, to Fig. 3.2

3  The Agroecological Matrix

100%

Threat Level

Matrix Elements (cells)

If there is both a species-specific lure and species-specific repellent, this is known as a push-pull (for more in this topic, see Push-Pull). This relationship might prove even more than additive. As previously stated, the best approach may be to start with the in-place, permanent counters. If these are not up to the task, i.e., a summed value near 100%, then introduced or optional eco-services are added. Turning to an applied example, the two wind counters illustrated in Fig.  3.2 would be represented in Fig. 3.1 by three arrows. The first would be the resilience of the agrosystem itself to whatever type of wind damage is being countered, i.e., drying, sandblasting, etc. A change in, e.g., species composition or planting density might suffice where the winds are minor. This later situation is shown with the reduced treat function (dotted line, Fig. 3.1). Here two counters (arrows) can handle this reduced threat. In more trying situations, a tall windbreak surrounding a small plot would be a more effective counter. In Fig. 3.1, this would be represented by an extended arrow. For larger, wind-prone plots, internally planted tree would provide protection. This is the third arrow. It should be noted that an actualized total (Fig.  3.1 and the right column of Table 3.2) could sum to over 1.0 (100%). Although this represents an overkill, it helps insure that the right amount of ecology is present and active. This is for the good. If the level of protection reaches the lower threat plateau (as in Fig. 3.1), this might, in many cases, prove sufficient.

Matrix (Cell) Elements For each matrix element, there are two entries. The first is the inherent and purported effectiveness of any one counter. When used in full strength, i.e., as recommended, an insecticide can be theoretically 100% effective in killing insects. The effectiveness value is therefore 100% or one when a zero to one scale is employed. For other counters, the effectiveness values range more.

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Fig. 3.2  Two methods to counter damaging winds. Top left shows windbreaks, the top right has scattered trees. These can be combined (bottom) and qualitatively or quantitatively stated within one matrix line

Due to various shortcomings, not all counters live up to their full effectiveness. A case in point, an insecticide, if poorly applied, could be less potent than advertised. This is the second entry, what actually happens or how much is applied or realized. This would also scale in the zero to one range. The actualized value multiples the theoretical effectiveness by the field situation, i.e., the true application. This can be demonstrated, as below, using plausible values as related to predator/prey insect control. Effectiveness (a) The base agroecosystem 80% (0.8) × (b) Fallow 25% (0.25) × (c) Farm practice 25% (0.25) × (d) Fire (with fallow) 50% (0.5) × (e) The surrounding landscape 100% (1.0) ×

Application 50% (0.5) 100% (1.0) 25% (0.25) 0% (0) 75% (0.75)

= Actualized = (0.4) = (0.25) = (0.0625) = (0) = (0.75)

In the first line, the core or base agroecosystem (as in Chap. 2) can be 80% (0.8) effective while at full strength. This assumes a mature ecosystem. During the early in growth phase when the plants are small and host fewer predator insects, the system might have an application value of 50% (0.5). The actualized effect would be 40% or 0.4.

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As an Analytical Tool The previous section has looked at the details in quantifying individual matrix lines. Taken together, the lines, as sigmoid functions, constitute a series of equations where, as threat counters, each line must be above (greater than) a stated threshold value. In this form, the full matrix represents a nonlinear, mathematical programming problem where the line with the lowest value sets the upper limit on site productivity (for a justification of this approach, see Matrix Equations). The goal or objective is profit maximization. Starting with an estimate of the revenue (yield-based) and with appropriate costs assigned to each column, matrix analysis returns those column values that optimize profit. Since the example presented here looks at an intercrop, LER measures productivity. Along with selling prices, this provides an approximation of revenue.

An Applied Example From the Sahel of West Africa, this example is of a four-phase cropping system. Following (1) a long, multi-year fallow, farmers plant (2) a sorghum/cassava/yam intercrop (as in Photo 3.5). This is seasonally followed by (3) maize and then (4) soybean. The following is from a published case study (Wojtkowski 2016). The single plot modeled here is rectangular, small ( bean Maize --> bean --> potato Tomato --> onion --> squash Oats --> clover --> ryegrass Soybean --> groundpea (peanut) --> sunflower Wheat --> clover --> alfalfa --> ryegrass Clover --> alfalfa --> ryegrass The General Rule As stated at the end of Chap. 2, species that intercrop well, i.e., possess interspecies complementarity, tend to sequence well. From the above list, maize intercrops well with bean; tomato can be occasionally seen with onion. The reverse is not always true and there are questions on the planting order. This general rule forms a fairly strong guide that is helpful in determining which species should be in rotation. On the flip side, established rotational sequences would be a starting point when looking at possible intercrop combinations. Another general rule is that more crops in rotation are better than having fewer. In one study, Anderson (2017a) found yield increases of 52% when the rotation was expanded from two to five crops. Other Gains There are a host of secondary reasons for rotations. These include ridding the land of certain crop-specific, in-soil herbivore insects and crop-specific, disease organisms. Also possible are rotations as a strategy to reduce the populations and impact of weeds. When applied as a disease control measure, longer seems better. A period of 6 years eliminates nematodes and rhizoctonia in potato and prevents carrot leaf spot and wheat head blight. Some crops, e.g., carrots, seem best with even longer rotations (Reinders 2007).

Row Orientation In Chap. 2, the topic of row orientation is briefly mentioned. This may not rise to the level of a core agrosystem design element, but in some situations, it comes close.

Glossary

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Yield and/or economic gains accrue when rows are properly oriented. Often there are yield and economic trade-offs that temper the situation. For this, there are four primary considerations; these are: 1. 2. 3. 4.

Direction Topography Harvest Wind

Direction For a monocrop where all plants are of like height, row orientation is of less importance. This comes to the fore where the component species (two or more) are of unequal height. The flatland default direction is always north-south except when the crops dictate otherwise. The reason is maximization of light interception for all the component species. The exception is where the between-row, understory species seeks early morning light and/or afternoon shade. Also theoretically possible, but less likely, is the case where an understory species does best with late day light and morning shade. These scenarios would suggest a slight directional modification. Topography In overriding the north-south direction, topography is a major factor. Specifically, this involves soil erosion. Simply put, rows on hillsides generally follow the contours. This general rule holds except when the soils are not erosion prone or when sufficient counters, e.g., cover crops, contour barriers, etc., are in place. Harvest The idea here is that workers are more task efficient when they traverse along and do not cross rows. Also, workers should move loads, e.g., bundles of prunings or containers of harvested produce, along a level path or in a downhill direction. Wind In looking at the trade-offs, one must not forget destructive winds. Air flow, channeled along rows, can be a drying and a yield-reducing force. Where important, this means rows orientated perpendicular to the prevailing winds. This can also mean well-positioned, well-designed windbreaks that allow other directional considerations to prevail.

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Glossary

Salt Most regard salt, when added to or present in crop plots, as yield reducing or yield destroying. This is not always the case. Salt can be a negative or a positive. Benefits A reported positive effect occurs when salt is applied to fields in minuscule amounts. Accounts hold that a small salt addition destroys weeds and some in-soil pests and makes grasses more palatable to cattle. This time-tested technique is mentioned by Virgil (29 BCE), much later by Johnson (1844), and by Rham (1853). Research provides partial support. Sodium chloride (salt) will control harmful green slugs, e.g., Ester et al. (2003). Not so good, salt can upset the nematode balance, killing beneficial nematodes, leaving the plant-parasitic types. Another gain is the speeding of leaf-litter decomposition (Kaspari et al. 2014). Dangers The accumulation of salt, if in more than minor amounts, is a yield-reducing, land-­ use problem. If in more than minuscule quantities, the land can be rendered useless for agriculture and for most forestry uses. Salt naturally arrives in soil in three different ways: (1) through groundwater, (2) through irrigation water, and (3) windborne. There are agroecological solutions that counter these detrimental transfers. If in the water table, farmers must keep the groundwater from reaching the roots of crops. Deep-rooted, water-thirsty trees are the favored solution. They keep the water table low. Trees, such as eucalyptus, are used for this task. When the irrigation water has a slight salt content, this can accumulate in the soil over time. The normal counter is to flush the salt away through inundation and good drainage. This is done periodically. There are only a few vegetative solutions. The placing of crops or cover species that provide large amount of in-soil biomass can dilute the salt concentration. This may not eliminate the problem, periodic flushing may still be necessary, but the interval between flushing can be increased. The other vegetative solution is a salt-tolerant primary crop. Here again, the problem is not eliminated. The period between flushes is increased. When salt arrives through the wind, it must come from a nearby salt flat. A good system of shelterbelts and windbreaks can slow or prevent the problem. This is a landscape measure that may require regional inter-farm cooperation.

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Other Counters In directly addressing the sources, the previously listed counters are the most prevalent. There is some evidence that bio-remediation can be effective (Ammari et al. 2013). This is when growing plants uptake salt. This is taken from the site where the plant is removed. If viable, this would be a slow process. Another option is to dilute the soil. Adding mulch or compost would be one means. Some have gone as far as to remove and replace saturated soils. Drip irrigation may represent a reprieve. This flushes the salt from around and immediately below root zones (e.g., Burt and Isabel 2005; Thompson et al. 2010).

Scarecrows As a push or part of push-pull strategy, the scarecrow is a time-tested means to repel some bird species. The standard design is a dressed dummy propped up in a small plot. Other low-tech versions are possible. Photo 3.1, page 38, shows a stuffed animal, the more ferocious looking the better, in a cherry tree. This is reported effective when combined with a decoy crop. In the case, nearby mulberry trees provided this service. As anti-bird technique, there is room for improvement in scarecrow design. As a nondestructive means of dealing with seed-eating birds, mechanical versions are possible. This would be the push alone or be combined with the pull, e.g., the abovementioned mulberry trees.

Semi-Husbandry Cattle, goats, sheep, hogs, and horses, as well as domestic fowl, can be confined and fed. This is a fairly intensive, revenue-oriented process with environmental problems and, in a few cases, animal cruelty issues. At the other end of this spectrum, free-ranging livestock and domestic birds are thought to be healthier and better for human consumption. Taken to the extreme, it is possible to raise bird and animals in an entirely natural setting. The only activity is the harvest. Large cattle ranches allow for unfettered grazing. This is a form of semi-husbandry. The same can be undertaken with goats, sheep, and hogs. All tend to be cost oriented. Turkeys and chickens, in their pre-domesticated form, run free in forests, roosting nightly in trees (Photo S1). If eggs are not the end product, these birds can be raised in an environment close to what they originally sought in nature. Semi-husbandry has broader applications, especially with animals that are not domesticated. Deer, bison, llamas, and types of rodents can be encouraged and harvested. This would mean an encouraging environment. To make the landscape more conducive, feed might be provided in off-seasons and/or crops planted for these animals to directly feed.

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Glossary

Photo S1  Tree-roosting chickens

Semi-husbandry is far from universally applicable. The region and the site must be suitable. Also, there must be little or no opportunity to destroy crops or to seek refuge where not wanted. As a topic, semi-husbandry bears a close resemblance to mimicry (for comparison, see Mimicry).

Shade Systems There are situations where an understory species is shaded by a taller growing companion species. The defining attribute is that the overstory canopies are touching or are in close proximity. The overstory and understory components can be spatially ordered or disarrayed. As a growth strategy, there are a lot of variations off this theme. In seasonal intercropping, a taller species will overtop and take light from other plants. Where the smaller species is shade tolerant, this is not a problem; both can yield well. The rules of productive intercropping (Chap. 5) take this into account. There are tree-with-crop designs where shade is integral to the agroecological dynamics. On economic bases, the seasonal and the perennial tree systems are categorized into two distinct systems: (1) light and (2) heavy shade. In theory and practice, both light and heavy shade systems can be seasonal. For example, maize grown over highly shade-resistant beets could qualify. These examples are also inclusive in seasonal intercropping.

Glossary

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Photo S2  Coffee grown beneath a mixed-species, light shade system. (This photo is from the Dominican Republic)

Commonly, light and heavy shade systems are perennial. Similarly, wood-­ producing shade systems and the associated tree management options are part of silviculture and, as such, are so discussed (see Silviculture). Light Shade With light systems, the overstory species is most often a woody perennial. These trees are widely scattered or with an open, light-penetrating canopy. This insures that ample sunlight reaches the understory plants. For most of these designs, both the understory and overstory species provide an economically contributing output. The purpose is to achieve the highest LER and/or per-area profit. Costs are contained through shared tasks, e.g., a weeding that benefits both species. Light shade systems can also be facilitative with a nonproductive overstory. The primary gain from the overstory would be to block winds (as in Photo S2). There are two categories of light shade systems: (1) uniform overstory and (2) mixed species.

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Uniform Overstory With a uniform canopy, light shade systems require a productive species that allows, by way of less dense canopy, considerable light to reach ground level. The number of such species is limited. Most common are palms of various types. Coconut and oil palms are often encountered. The understory can be some crop type or, far more common, grasses and grazing. Coconut with ginger is an example of an in-use crop combination. Dual-output, light shade systems tend to be revenue oriented. Mixed Overstory Rather than a one species overstory, multiple species can be employed. This can be open-canopied species. The other option is to use trees with dense canopies. For these, the key to success lies in the positioning of the overstory species mix. The gaps that form should permit ample light to reach lower levels allowing for ground-level growth opportunities. This eliminates from use trees with excessive canopy spread. Heavy Shade In contrast to the high LER, high-revenue, light shade agrosystems, heavy shade systems are almost universally cost oriented. This is, in part, due to their low input needs, and hence, their high, labor-based return when compared to an equivalent monoculture (Armengot et  al. 2016). These tend to be single output with one ground-level, yielding species. With the possible exception of an infrequent wood harvest, the overstory trees generally have little or no productive role. With a dense, overstory, understory yields are reduced. The reliance is upon a very low-cost upper story to achieve a profit. Normally, the understory species is highly shade resistant. The most common example is shaded coffee. The nonproductive overstory provides a number of facilitative services. In cycling nutrients, these should eliminate the need for fertilizers. Since productivity from the shaded understory can be lower, lesser amounts of nutrients are withdrawn upon harvest. This makes these systems self-sustaining. The heavy canopy and in-­place root structure keep soils and essential nutrients from being eroded or washed away. Another benefit of the canopy is in water capture and retention. Helpful in this is the water-holding ability of the soil humus layer. Shade systems should equate with forest plantations or natural forests in this regard. With two canopies, there is usually not enough light to support more than the planned plant species. This means weeding costs are very low. With plenty of predator-­prey relationships, insect losses should be minimal. There are three canopy versions: (1) natural forest, (2) a purposeful shade species, and (3) wood-producing plantation.

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Natural Forest Overstory In order to further reduce costs and get the system up and running quickly, farmers have the option of utilizing the trees on hand. This can mean directly replacing the understory of the natural forest with the crop species. In tropical regions, coffee or coca are common crops. In temperate forests, ginseng planted under a forest canopy is occasionally encountered. Environmentally, this is the better of the heavy shade options. The natural canopy will support a range of natural flora and fauna. Because light and belowground are not uniform, productivity will vary between individual plants. These generally find use where there are large areas of natural forest. The land user plants throughout the natural forest. As the crop grows and marketing opportunities emerge, the understory planting density may be increased. Purposeful Shade Species It is more than possible to find a single shade species with the best desirable characteristics. The idea is to maximize yields without sacrificing any of the cost advantages. This means keeping light dynamics constant while ensuring light is the only limiting resource. All other essential resource needs of the productive plant are met through the facilitative association with the tree. The yield and costs associated with this strategy are a balancing act. High crop prices can mean more light to the crop; with lower crop prices, less light should reach the crop. With higher prices, pruning becomes an economically beneficial option. The common technique is to leave the main stem and main branches and cut a portion of the secondary branches (branch pruning). If crop prices drop, the canopy is allowed to fill out and the base amount of shade restored (for more on this, see Pruning). As a shift toward revenue orientation, pruning may be economically prohibited where labor is in short supply and/or expensive. Wood-Producing Species While the notion of a single, well-chosen, overstory species is enticing, some feel that the wood produced is an exploitable resource. This means selecting a tree species first for the retail value of the tree stems, second for characteristics as a shade species. If the primary species is the understory crop, this is best classified as a heavy shade system. If the overstory tree and the resulting wood are the primary output, this would be classified as a forest-tree plantation. This division is not solely categorical. As a heavy shade system, a greater emphasis would be placed on desirable plant characteristics (DPCs), i.e., the trees with crop complementarity and with some

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desirable facilitative effects. The wood extracted is not the primary concern. Still, given the large choice of tree species from which to select, the combination of good DPCs and high wood value is more than possible. A forest-tree plantation with productive understory would be managed as tree plantation, i.e., the management options are silvicultural. Inclusive are even- or uneven-aged designs. In this case, the most common understory is a forage crop and grazing (for expanded discussion, see Desirable Plant Characteristics and/or Silviculture).

Shelterbelts The advantages of protecting crops from wind are well established. Worldwide, the number of wind-protected farm plots is testament to this. The most common barrier-type system is the windbreak. Less common, but equally effective, are shelterbelts. The latter are generally wider, more substantial in design, and less closely spaced within a farm landscape. For these reasons, these are mostly encountered on larger farms and across rural landscapes located in drier, wind-prone, agricultural plains. Agroecology Windbreaks and shelterbelts prevent the drying of the land, moderate temperature, and lessen direct wind damage (e.g., lodging and sandblasting). The end goal is better yields on nearby crops (for more on ecological benefits and joint utilization of shelterbelts and windbreaks, see Windbreaks). Variations Shelterbelts offer many of the same ecological and economic benefits as windbreaks, except that their larger footprint on the land offers productive opportunities. With income potential, they are less of a cost and more likely to be accepted. This brings about design questions. There are two variations. One would emphasize forestry (wood) outputs; the other is more for fruit production. For the forestry design, the outer trees are only guide species; the inner would be harvested for wood. The fruit design has the opposite cross section. The outer trees are fruit or nut bearing; the inner are of greater height and reinforce the primary design purpose, that of a wind shelter. It must be remembered that orientation is dictated by the primary use. For the fruitor nut-producing designs, the fruiting trees would be placed on the side with the most light. Where a north-south orientation is possible, the trees can be on both flanks.

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Sigmoidal Equations There are a number of mathematical equations that offer a classic sigmoidal form. This form is the basis for the yield functions referred to throughout this text. Five commonly utilized are: Bertalanffy

(

Y = a (1 − e − bx ) = a (1 − exp ( −bx ) ) 3 3



∧

)

Chapman-Richards Y = a (1 − e − bx ) = a (1 − exp ( −bx ) ) c ∧

c





Gompertz

Y = ae − be

= a exp ( −b exp ( −cx ) )

− cx



Korf

(

Y = ae − bx = a exp −b ( x ∧ − c ) −c



)

Hossfeld Y=

xc  x  b +  a   c

( (( x c ) / a ))

= ( x∧c ) / b +

∧



These are shown in standard mathematical form and as spreadsheet equations. In either form, Y is the yield, x the input being considered. The equation parameters are a through c. All, except the last, are logarithmic.

Silviculture (Forest Management) Forest ecosystems, if managed for useful output, are part of agroecology. This can involve multiple goals. Wood, from one or many tree species, is the primary output. Clean water runoff from a fauna-welcoming natural ecosystem is the secondary goal.

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Within the farm landscape, these can be smallish plots. The latter are usually planted with one or two tree species. These are considered plantations, not forests (for more, see Plantations). Qualifying To be considered under a silviculture or forest management heading, the first requirement is that these be complex agroecosystems formulated around density, diversity, disarray, and duration. If naturally sprouting, nature most always insures that these criteria are met. There exists the option of enriching natural forests. If enriched with more than one or two fruit or nut trees, these can be considered agroforests and are so managed (see Agroforests). In addition to wood output and bio-complexity, silviculture applies only to larger blocks or stands. At the lower end of the range, there are stands of a few hectares. At the high end, managed forests can span hundreds of hectares. Whether a stand qualifies can be roughly ranked as a percent of the forest area that lacks an edge effect. Edge effect occurs when a forest borders open, non-forested land. At the forest edge, horizontal light reaches the ground and disrupts what would be the prevailing ecology, i.e., the species composition, the branching characteristics, and often the species density. If more than 20–40% of the area is edge effect, these are best managed using the rules for complex agroecosystems (page 109). If the edge effect is slight, the silvicultural prescriptions (described in this section) apply. The last requirement is management. If left unmanaged, these forest stands are viewed from an ecological perspective. If planned and managed, these qualify as an agroecological activity. Agroecology As with all complex agroecosystems, there are shared goals. These can include water infiltration and the subsequent runoff of clean, potable water. Natural ecosystems are reservoir of beneficial insects and can offer windbreak or erosion protection to neighboring plots. The latter tasks depend upon the positioning within the larger farm landscape. Economics Stands of infrequently harvested forest trees can be economic gain. Harvests of valuable wood can be a windfall used to pay a large bill. In some regions where banking systems are weak, standing trees are a form of saving. The advantage is that, over time, tree growth increases the stand value. The

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trees may be harvested to meet a large, long-anticipated expense, e.g., the cost of wedding or purchase of farm equipment. The market may be for firewood. In this case, the management would be different than if the best return comes by way of large, high-value logs. The economics may be contingent upon the topography. Income-earning forest blocks are often best located on marginal land. These are areas of poor soil and/or steep slopes where annual, higher-valued crops would not yield well. This makes these locations ideal for perennial agrosystems that are not disturbed for long periods of time. Along these same lines, the labor requirements for forest stands are time-flexible. Work can be scheduled when manpower is available, not during busy periods in the calendar. It goes without saying that forest stands are generally highly cost oriented. Management Prescriptions If the area is large enough, there are a number of silvicultural instructions that achieve the above-stated goals. These are: 1 . Sparse and infrequent harvests 2. Damage-salvage cuttings 3. Species-oriented sequences 4. Senility cuttings 5. Selective-shelterwood thinnings (a) Light crown (the French method) (b) Heavy crown (the Danish method) (c) From below (the German method) 6. Liberation cuttings (a) Advancing (b) Reverting 7. Enrichment These are often chosen less for their labor requirements, more for the type of wood sought. This can range from large, knot-free, high-value logs to low-valued firewood. Anything in between is also possible. Sparse and Infrequent Harvests Under this management system, only a few trees are harvested, and each of the harvests may be decades apart. In order for this to be done profitably, only the largest and most valuable trees are taken. None of the smaller trees are extracted. This finds use where the wood market, usually the export of logs, demands only large sizes. This might also happen when there is a plywood factory which draws from large areas of remote forest.

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The advantage of this system is that the full ecological character of the forest is maintained. The disadvantages make this system highly improbable. Because such a small volume of wood, when compared against the total, is harvested, this prescription requires large forest areas in order to maintain a wood industry. As a result, there will be considerable pressure from commercial interests for greater wood extraction. This method would only find use in agricultural landscapes when most of the wood taken is for firewood or construction poles. A few trees are left standing, allowed to grow to large size and, because of this, infrequently harvested. Damage-Salvage Cuttings Under this prescription, the only wood harvested is from trees that have been damaged, i.e., wind toppled, killed by disease, and/or have been fire damaged. If these events are infrequent, this management system will not provide enough wood to maintain a viable industry. This system finds use when there are local plantations and/or regularly harvested forests that provide the bulk of the logs. In this case, damage-salvage cuttings are employed in nearby protected, and normally not logged, forests. The advantage is, with caveats, a minimal impact on forest ecology (Royo et al. 2016). The disadvantage is that commercial interests, often wood-seeking individuals, have motive to set fires. Species-Oriented Sequences With a species-oriented method, each cutting or harvest cycle removes a different tree species. The cuttings can be at a 10 year or greater interval. With less species diverse forests, e.g., those in Europe, there would be limits on the size diameter; otherwise the impact, in terms of the number of trees removed, is very severe. In highly species-diverse tropical forests, the impact on the forest would be far less (Rice et al. 1997). Designed to lessen the impact on forests, this system requires a rotation. This is where one species is harvested in one area while, at the same time, another species is extracted from another part of the forest. Due to the complexity, this method seldom finds use. Senility Cuttings Some feel that the best way to lessen the impact on forest ecosystem is to only cut overmature trees, those that would die naturally in the next few years (Seydack 1995; Seydack et  al. 1995). A variation of this theme is to harvest mature trees, those that no longer experience high growth rates.

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This system provides larger logs, but these must be limited. If not, the forests will lack dead and dying trees, an ecological niche that provides food and shelter for many bird and animal species. Selective-Shelterwood Thinnings Among the commonly employed management systems are shelterwood thinnings. There are three variations, (1) light crown (also called the French method), (2) heavy crown (the Danish method), (3) and from below (the German method). The purpose may be to provide more logs of certain species and/or diameter classes. Such uniformity can be more serviceable for a local wood industry. These prescriptions are generally for use in less, species-rich forests, e.g., those in temperate regions, less applicable in highly species-diverse, humid tropical forests. The light canopy prescription first cuts the larger, less value tree species with the goals of increasing the growth of the valuable species. Subsequent harvests still remove the smaller, less valuable trees but also take a few of the now larger, valuable species. The heavy crown system harvests only the largest size, dominant trees. There is no limit on which species are cut. This opens the forest canopy for the faster understory growth, mostly in light-demanding species. The goal is to maintain continued harvests of the largest trees. The from-below method first cuts a large percentage of the lower suppressed trees; the next harvest is also of the suppressed tree species. After a few decades, what should be left are large diameter trees. As these larger trees are cut, the system repeats, again starting with the suppressed understory. Liberation Cuttings This management method may be more suited to species-rich forest ecosystems. One requirement is that the forest should have distinct successional phases, each with their own mix of species. This system has two variations, (1) advancing and (2) reverting. When more of the valuable trees occur in the climax or ending stage of forest succession, it is economically beneficial to rush through the less valuable intermediate succession. The idea is that, once the climax trees are in place as the understory, a harvest is undertaken. The purpose is to accelerate the growth of the more valuable climax species. Since the climax species are generally more shade tolerant, this is normally a light, overstory harvest, e.g., Mesquita (2000). If the reverse occurs and the most valuable trees are in an intermediate forest successional phase, it is advantageous to remove a fair percentage of the canopy. This should favor the growth of more light-demanding, early-stage, successional species and result in a more valuable mix of forest-tree species. This has found use in Malaysia, e.g., Matthews (1989) and Whitmore (1975).

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Photo S3  A strip cleared in a natural forest. This would be the location for an enrichment planting (Photo courtesy of the World Agroforestry Center (ICRAF))

Enrichment Rather than the strategic removal of trees as means to change the harvest mix and improve the economics, there exists the option of planting young trees of desirable species. Under the hope that these will thrive, the notion is to have these for a future harvest. This can be scattered plantings or in narrow strips specifically cleared for this purpose (as in Photo S3).

Silvopastoral Agroecosystems Traditional pastures have grazing animals feeding off perennial grasses or other herbaceous forage. This need not be the case. Animals, e.g., horses, cattle, goats, sheep, lamas, and the like, can eat the leaves from woody plants.

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Agroecology There are advantages to the agroforestry-based, silvopastoral technology. The main one is that woody plants, once established, tend to resist arid climates and droughts much better than grasses and other non-woody forage. There are other advantages in that the taller trees grow out of reach of most grazers. This brings about an on-site cut and carry, i.e., the leaves and branches are cut and dropped to the animals waiting below (for additional discussion, see Pastures). Variations As expected, there are some minor deviations of the animal-eating-trees theme. Most of these involve the role of tree forage with regard to ground-level pasturage. Trees Within Pastures Where there is a wet season followed by a dry season, the pasture grasses can run out or dry out before the end of the dry period. In this case, trees make up the difference, providing grazing and animal feed until the start of seasonal rains. This is done in one of two ways. For the first, the danger is that the animals will eat the tree forage before the grasses. This can leave them with nothing to eat at the end of the dry season. To avoid this, the trees can be a less sought-after forage source, only consumed after the more desirable ground forage is gone. This design is animal specific, more useful for cattle and less with all-consuming goats. The second variation has tall trees and their leaves out of browsing harm. Out of necessity, the grasses and other ground level forage are eaten first. After which the tree branches are hand cut and supplied to the animals. There is yet another variation of the silvopastoral theme. This is where forests are thinned to promote grass growth and grazing. This technique was documented in the Northeastern United States (Orefice et  al. 2017). This is a form of taungya (see Taungyas). Trees Without Pasture In tree-over-crop designs, e.g., parkland systems, the ground level can be devoted to the crop; the tree canopy serves as a pasture of sorts. At the end of the dry season, when forage is in short supply, the tree branches are cut and fed to animals. This allows the trees to serve as a pasture, and the trees, with fewer branches, are less competitive with the subsequent crop.

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Glossary

The animals present for only a short period do, through their droppings, help fertilize the site. This takes the place of slow- to-decay, on-site leaves that would normally recycle and boost soil fertility prior to crop establishment.

Slash and Burn For many millenniums, across many continents, slash and burn has found use. This is where farmers cut down sections of forest or scrubland, allow the cut vegetation to dry, burn the site, and hand plant crops. This technique is popular as the fire ash and forest soils contain high levels of nutrients. These produce high crop yields. In addition, intense burns kill in-soil weed seeds. This means less maintenance/labor inputs. Slash and burn is faulted for being environmentally destructive. This occurs when large areas of natural forest are destroyed. The unprotected soils in large areas of cleared ground are subject to erosion. Also, large-area clearings tend to be permanent, meaning forests, along with the flora and fauna contained, are lost. This is the negative side of slash and burn agriculture. There are positive uses. As is traditional, small groups, inhabiting large areas of forest, practice slash and burn. Their plots, scattered across large areas, tend to be small in size. In many aspects, these duplicate gaps that occur naturally in forests. The trees that establish tend to be from an earlier stage in the forest cycle than these climax trees that are in place before the slash. Since these gaps are often filled through seeds deposited by birds, the resulting regrowth is often friendly to these bird species. In general, end-of-farming tree growth promotes a more biodiverse forest. There is another benign use of slash and burn. This is in regions where the forest is long gone. The slash and burn process occurs as part of a long fallow cycle. After a 5- to 10-year period, the shrub vegetation is cut and burned; crops are then planted. If well done, i.e., without erosion or other damaging results, this can be an acceptable, low-intensity farming method (for peripheral topics, see also Duration under Fallows, also Slash and Char, and Slash and Mulch).

Slash and Char In the preparation of long fallowed or virgin forest for agricultural use, the woody vegetation is cut and allowed to dry. Instead of surface burning as in a slash and burn approach, the wood is burnt in covered pits; the intent is to produce large volumes of charcoal. This is mixed into the soil with animal manure, fertilizer, or some other high-­ nutrient material. Although the exact process is not fully understood, the purpose is to produce nutrient holding tierra prieta soil (for more on this topic, see Tierra Prieta).

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Slash and Mulch In contrast to slash and burn, there is the less destructive slash and mulch. Both slash and mulch and slash and burn deal with the same situation, that of converting forest or scrub-covered land to post-fallow agricultural use. The difference is that, instead of burning, the leaves from the dry vegetation are allowed to drop and decay in place. As the woody branches are very low in essential elements and are slow to decay, they may be removed and utilized for other purposes. This is done after the leaves naturally dropped off. The common use for the branches is as firewood. The advantages of slash and mulch lie with the full complement of nutrients remaining on-site. Also, due to the ground cover, there is a very large reduction in the erosion danger. On the negative side, the slow-decaying leaves do not always release the contained nutrient in accordance with agricultural requirements. Without the added check of a burn, weeds may flourish in the available sunlight and essential resources. This technique is generally not suitable when, e.g., broadcast grains are the upcoming crop.

Solution Theory (Landscape) In formally modeling complex farm landscapes, it is entirely possible, and quite probable, that multiple optimal or multiple near-optimal solutions exist. It is also conceivable that these solutions will vary greatly in the range and application, i.e., the design of one farm solution could vary greatly from the next even through these farms are of similar size, layout, objectives, and physical presence (e.g., soil type). Solution theory pushes this line of development along a logical path. There is the why, i.e., why farms are much alike even though other, more diverse, options and alternatives may fit one land user better than another. Distillation The likenesses between farms are the result of concordance of traditions, societal values, economic influences, and user knowledge. These likenesses, as compared with the possible, distill out these semblance-producing influences. The lack of individuality between factory farms can result from different forces or influences. Restating the list presented in Chap. 9, these can be: ( 1) Economic (a thriving trade in one commodity) (2) Governmental (extension agents pushing one crop or form of agriculture) (3) Societal (the community accepts and exerts subtle influence that results in everyone doing the same thing)

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(4) Commercial (merchants marketing specialized products designed for one and only one form of production) (5) Banks and lending (for agreed-upon farm equipment, farm structures, land modifications, etc.) (6) Crop needs (dictates similarities in field layout, irrigation, etc.) (7) User knowledge (where there is limited cognition as to the agronomic possibilities which causes all to raise only one or a few crops) (8) The site (the soils, topography, and climate that may favor one agrotechnology) Logical Outcome Individual farms differ in terms of their site, surroundings, soils, crops, weather patterns, and yields. As an economically optimized series of agrosystems, each could and should differ in the types of agroecology employed. This results in farms, even neighboring holdings, that would be visually different in their layout and composition. The degree in which this holds true is another aspect of solution theory. It also holds that, in order to achieve the optimum result, the best expressions of agroecology are farms that are quite different. This would be more apparent when the topography is extremely variable. The inverse of this theorem, as their reliance upon agroecology lessens and the topography becomes less variable, is the plots and the farms begin to resemble each other. Underlying solution theory is the notion that biodiversity is not only expressed in the number and populations of the plant species present. Biodiversity is also manifested in the types, i.e., designs, of agroecosystems. The more the better, the more diverse the better. It is possible to take this concept to its logical endpoint. The more each farm varies from others in their crops, soil types, and plot layouts, the greater the inter-farm differences should be. This would appear in the range of agrotechnologies employed.

Streuobst A German/middle European form of agroforestry, the streuobst consists of a mixed-­ species orchard, of apples, pears, cherries, plums, etc. Another feature, animals are allowed to consume the fallen, non-harvested fruit. As orchards, these are ordered, not disarrayed systems. In their traditional use, they were not extensive in area and and they had a distinct placement. These were normally located near barns and homes, outside the vegetable gardens, but interior to fields where the staple crops are grown.

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Strip Cropping As an agrotechnology, strip cropping can alternate strips of annual crops or perennial species. The strip contents can be woody or non-woody. Also possible are facilitative strips. These might have a nutrient-beneficial, inter-strip rotational pattern where one strip is planted while the neighboring strips are fallowed. In normal usage, the width of each strip is set by different factors. One of these would be the width of farm equipment. Width would be constant across the entirety of the agrosystem in question. Agroecology The primary reasons for strip systems lie along two fronts. The first is the contour placement and the anti-erosion, water-infiltration benefits of this layout. The second and lesser reason lies with insect control where this layout can discourage those insects that feed on specific crops. Other than the above, gains come by way of special-purpose designs. These designs focus on the nutrient possibilities and, again, to a lesser extent on controlling unwanted insects. Standard Design The normal layout would be strips that contour shallow hillsides. These systems would be for annual crops. On the steeper sites, 3 meter width is suggested; for flatter areas, a greater width is possible. Where hand cultivation is utilized, there is more flexibility in strip width. Sans farm machinery, erosion control would be the main width determinate. As mentioned, farm equipment commonly sets the strip width. Another key factor, there should be different crops on abutting strips. Any number of crop types could be employed; two would be the minimum. This would both improve erosion and insect control. If the strips are in direct, close contact, adjoining strips should have a high degree of interspecies compatibility. Variations Beyond the standard design, variations are more than possible. One small change is a buffer species located between adjoining strips. These species are short and deep rooted so as not to interfere with crops. The non-woody perennial vetiver is common in frost-free applications. If the buffer species is a seasonally pruned woody perennial, this system can easily transform in to a hedgerow alley agrotechnology (as in Photo 4.2, page 66).

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Facilitative Designs It may be in a farmer’s best interest to plant only alternate strips. The unplanted strips are facilitative additions, harboring predator insects that spillover into the crops. It is also possible that the facilitative strip can be a source of nutrient-rich biomass that is cut and carried to the crop, e.g., Kwesiga and Coe (1994). The biomass can be planted for this purpose, used both for crops and for forage. This strip could also be a productive fallow, e.g. off-season grazing. There are different combinations of these themes. A pairing of the crop with the correct, nutrient content biomass is possible. For a two-crop, alternative-row, strip design, every other row would contain the best biomass type. These facilitative systems can be part of a crop rotation. Alternating strips, those in fallow, would provide insect and other forms of support to an active crop strip. To avoid a weed bloom, the fallow strip might be planted with some superior nutrient-­ supplying, weed-excluding, facilitative cover crop. The facilitative strip design can help in the harvest. The facilitative strip can serve as a short-duration road, allowing ease of removal for a high-volume, high-­ weight crop, e.g., melons or pumpkins. Most often the facilitative strip would contain perennial, non-woody vegetation. It is also possible that the facilitative swath contains a wood shrub or short tree. Bamboo has been used in nutrient-supporting design, i.e., where the bamboo is cut and burned to supply directly planted crops or cut and burned on an adjacent crop strip (e.g., Christanty et al. 1997). If the facilitative strip is replaced by single or double tree rows, this is a variation of alley cropping. Productive Tree Strips In a variation of the tree-row system, a strip can contain a productive shrub or tree. The intent is to have alternate strips for the woody perennial; the other, alternating and non-adjoining strips are open for a variety of crops. As with the tree-row system, the woody plants cannot over hang the crop strip. Examples can include tea or dwarf fruit trees. If the tree strip is taller than the crop, there is a requirement for strip orientation. The norm is for a north-south placement. As with facilitative system, this design can be of aid with the harvest. The proviso is that the crop be harvested before the woody strip. The now unused strip can be a temporary roadway during the brief harvest period. To aid in the harvest of the perennial strip, the rows within the strip are oriented perpendicular to the strips themselves. This is to ease the movement of workers carrying the harvest.

Glossary

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Forest Strips There are cases where crops are planted between strips of yielding trees. Instead of one or two tree crops, the tree strips can comprise a shrub garden or a low-height agroforest. As these ecologically resemble a natural forest, there are positive spillovers. High on the list are beneficial insects, e.g., predator and/or pollinating. Also possible are crop strips between strips of natural forest. Again, positive spillover is expected and this can be the rational for the design. An example is tea with forest strips (Wang 1994). With either the agroforest or the natural forest strip, the design is limited by the inter-strip/intercrop height differential. It holds that, where there is little overtopping of the crop strip by the tree canopies, a north-south orientation is needed (for more on the intricacies of a tall tree row, see Alley Cropping, specifically tree-row alley cropping). Where overtopping occurs, the only alternative is a shade-resistant crop. At this stage, transformation to a pure shade design might prove best (for more, see Shade Systems). Beyond the permanent crop alternating with forests strips are some pure forestry applications. These variations, strips of young trees within a forest setting, are intended as an enrichment mechanism. These fall outside the strip cropping into the sphere of the enriched forest.

Stones (Clusters, Walls, etc.) In agroecology, stones can contribute in a major or a minor way to output gains and to system ecology. These can be as stone fencing, stone terraces, as a ground cover in agricultural plots, or when placed around individual plants. Agroecology Stones provide a number of useful functions. Foremost may be their heat-holding ability. Rocks absorb heat during the day, releasing this heat during the night. This shields a young, sensitive crop from night cold and can mitigate some of the daytime heat. Other uses lie in the erosion protection. A large number of on-the-surface rocks, those that blanket the ground, protect soils from the impact of raindrops and help keep soils from being washed away. Well-positioned stone fences serve as anti-­ erosion and as infiltration barriers. Similarly, stones may also help hold essential nutrients on-site. In addition, rock clusters may also function to keep weeds in check, by covering much of the ground,

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Photo S4  Small, rock-bordered enclosures. Here, the owner is growing grapes atop the stone fences. The shade from the trees and grapes may be indicative of a system designed to protect from midday, midsummer heat, rather than nighttime cold. (This photo is from the mountains of Lebanon)

reduce the number of unwanted plants. The physical or chemical breakdown of stones may be too slow to be a major source of mineral nutrients. Variations Stone clusters can consist of a few rocks placed around individual plants. If rocks are readily available, clusters can be small enclosures, e.g., 2–6 square meters in area. The latter usually contain annual or small perennial crops within more substantive rock borders (as in Photo S4). The protections offered are the same as with smaller clusters. These larger-area designs offer a bit more cropping flexibility. Both are generally revenue oriented (for more, see Fencing and/or Barriers). Again, if small rocks are plentiful and handy, the entire ground may be covered. This can serve with specific perennial crops, e.g., grapes can benefit from this application. The rocks should be small enough so as not to trip workers and impede machinery. In yet another variation, plots can be blanketed with very small stones. These should be small enough to allow plowing and planting. These small stones, the size of everyday coins, have very little role in collecting and releasing heat. They do serve to protect against erosion.

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Support (Physical) The core notion behind physical support is to have living plants replace trellises. An example that goes back to ancient Roman times had grape vines growing, not on trellises, but on living trees. Early writers, e.g., Chaucer (1382), observed that elm was the preferred tree to support grapes. For these early agriculturists, the preferred canopy shape, to avoid the need for revenue-oriented pruning, would be umbrella-shaped. An elm species with this canopy shape is Ulmus glabra. Grapes-on-trees systems have fallen from use. They seem to be relegated to remote part of the world, e.g., FAO (1994), but remain a less explored option that might yield some benefit, especially for organic wine production. Vine support can also aid other crops. These could be black pepper, vanilla, kiwi fruit, hops (Photo S5), and guaraná. A vine atop a dwarf or pruned tree is not the only option. Two more exist. More shade-tolerant vines can be (1) grown within the canopy or (2) below the canopy and against the trunk of the supporting tree. An example of the latter is pepper (as in Photo 6.6, page 100). Photo S5  A vine crop, in this case hops, supported by poles. The alternative is to have the vine grown atop a woody perennial. Photo 6.6, page 100, shows a living support system

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These systems are bicultures and, because of their unique dynamics, rank as separate agrotechnologies. There are other forms that may, or may not, rise to this level. There are belowground variations. These prevent over-laden fruit trees from toppling. Interlocking roots keep this from happening. This is done by anchoring the roots to nearby shrubs that are planted for this purpose. Both the above- and belowground effects are versions of facilitation.

Taungyas The notion of directing excess resources, during one or more temporal phases, to companion species is not new. This has been the norm across time and cultures. The term taungya originated in Burma during the early 1800s. It is applied to teak plantings with farmer participation and a crop-aided establishment phase. The taungya is a temporal agrotechnology. This has application whenever wood, fruit, or other productive trees are planted. For management purpose, the tree is always the primary species. Agroecology Conceptually, taungyas, as one temporal agrotechnology, can also be looked upon as an across-time series of nontemporal agroecotechnologies. That is, as the trees grow, the internal resource dynamics change. This produces, at the different stages, situations that duplicate or are similar to other nontemporal agrotechnologies. Economics Taungyas exist because they confer economic advantage. Because a second crop is planted and harvested, revenue is increased. Costs are also reduced as weeds, those that would normally hinder tree growth, are controlled. In addition, intense farming among the trees allows for problems to be seen and corrected quicker than if the trees are less frequently observed. Variations There are four taungya variations: (1) (2) (3) (4)

Simple Extended Multistage End stage

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The first two involve the beginning phase; the latter occurs in the final phase. It is possible that a plantation can open with a simple taungya and close with an end-­ stage taungya. Simple Taungya When trees are planted, they are generally small and draw few essential resources. Weeds and/or erosion can be a problem. The simple taungya is a way around this. Instead of fighting these forces, crops are planted between the young trees. All can be done by one farmer (e.g., when planting orchards) or the system can be a multi-participational endeavor (e.g., when one group plants the trees, another plants and tends the crops). The latter is the classic case. There are drawbacks. For the multi-participant version, success requires a high degree of cooperation between the groups (for more see Multi-Participant Agroecosystems). The economic gains are clear. Rather than paying for weeding and other land maintenance, these costs are a crop-related expense. In some situations, farmers are willing to assume other costs, e.g., land preparation, in exchange for the right to farm between the trees. There are other gains. Fertilizer, applied to the crops, will aid tree growth. The now worked and loose soils may promote water infiltration. There is also, as mentioned, a greater monitoring of the trees as the land is intensively managed. The taungya phase ends when tree growth and shading make farming uneconomic. Since the growth characteristics of the tree have some bearing on the success of the system, caveats exist as to which crops best pair with the tree (King 1968). This includes the main danger, insuring that crops do not overtop and steal light from the trees. There are also concerns with root crops that, upon harvest, might damage the tree roots. For this, the solution might be a small, crop-free buffer zone around each tree. Nontemporally, these early years can also be classified as a simple, tree-with-­ crop mix. Thus, the rules of intercropping (page 77) would apply. Photo 5.4 (page 85) shows a simple taungya.

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Extended Rather than limit the taungya to the early establishment phase, it is possible to continue this across the life of the plantation. This differs from a long-term, tree-based intercrop in that the understory continually changes with the different tree growth phases. They can be anywhere from two to six cropping changes. The first crop, planted when then the trees are small, is the most light demanding. There can be series of crops during this initial phase. As shade increases, this may be followed by longer-term, more shade-tolerant crop. The latter phase is often grazing with a shade-resistant forage crop. After some years, the trees could be thinned, and understory conditions might again favor lightdemanding short-­duration crops. Latter stage thinning is found with some foresttree plantations. The economic gains come from the crops and the trees. The shared costs, e.g., plowing, weeding, should be lower than if raising the trees and crop separately. The stages of the extended are definable in their nontemporal form. At first these are mixed-species systems; they then transfigure into alley cropping or a light shade system. In final form, these are a heavy shade design. There are some conditions that underlie a successful extended taungya. Because of the management complexity, these are usually undertaken by one individual or group. Multi-participant systems are possible, but these are more difficult to manage. Another limitation lies with the overstory tree species. These must be highly crop compatible. One example comes from southern Chile. In the first few seasons, the poplar trees are initially underplanted with maize (Photo P4), oats (Photo T1), or sugar beets. The second phase has shade-resistant currants. The final, decade or longer, end stage features shade-resistant grasses and grazing. The full rotation takes 20–25 years (author observed). Multistage Rather than having a single overstory primary species, it is possible to change the overstory. This system starts with an orchard or tree plantation. As this nears overmaturity, a second tree species is planted as the understory. Over time, the taller trees are cut. The second planting replaces the first and becomes the primary species. The system can start with a forest-tree or tree-crop plantation. When it is time to change the initial species, the transition period is, in nontemporal form, a light or heavy shade system. Because of the overlap, the second-phase species must have the ability to initially survive as a shade-resistant understory species. Not all multistage taungyas start with a tree species. It is more than possible that the initial phase can include species such as banana or papaya. Any fruiting or wood-producing species can follow. As the canopies of the first phase crop intercept less light, there is wider choice of second-phase species. For this second species, planting under an established crop can be a disadvantage when shading retards growth or an advantage when being protected from drying in the hot sun.

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Photo T1  The third year of stem-planted plantation showing oats grown under poplar trees. (This photo was taken in southern Chile)

End Stage When trees are first planted, there are excess resources available. These same conditions hold true after a major thinning. The advantages are much the same as those from the simple taungya. These late-stage systems are, in nontemporal form, also light shade systems. The default design has grasses and grazing under the trees. Suitable grasses will grow even under competitive tree species, e.g., eucalyptus and pines. When the tree species is more crop compatible, the list of understory cropping possibilities expands greatly.

Terraces For agriculture on steep hillsides, the terrace is a common and often a necessary structure. These are normally found in steep, mountainous landscapes. This is because of the associated productive and economic gains.

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Photo T2  Farming on a steep hillside. The lack of erosion permits farming where normally terraces or other countermeasures would be necessary. (This photo was taken in the Dominican Republic)

Agroecology The importance of terraces on steep hillsides goes without question. Their role in erosion control is the principle reason for use. In some regions, those where the soil are less erosion prone, it is possible to farm hillsides without investing in terraces. This situation is found in, but not exclusive to, the mountain regions of New Guinea and, as in Photo T2, parts of the Dominican Republic. In these exceptions, slash and burn, not permanent on-site agriculture, is the dominant force. In addition to preventing erosion, terraces increase the efficiency of farm work. It is easier to operate on flatland rather than trying to labor while clinging to a steep hillside. There are a few other advantages. Cold air flows downward and terraces actively shed frosts. Stone wall construction helps counter frosts. The heat absorbed during the day is released at night. This can keep more favorable temperature during the cooler nighttime. There are some other gains. Flat terraces are good infiltration structures and help keep the soil moist between periods of rainfall.

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Economics For farmers, terraces can be an expensive investment. Stone terraces are more expensive to construct than tree-faced designs. In light of the gains, many see this as sensible investment. These can be a mainstay where population densities are high, erosion is ever present, and flat, fertile, and well-drained land is not available nor found in sufficient quantity. Standard net present value analysis does not always suffice in expressing the gains versus the benefits. Many cultures have forgone this form of analysis and found expensive terracing to be in their best interest. The Incas constructed finely hewn, long-lasting structures. Their descendants still install terraces, but lacking societal organization and regime support, their efforts are far less impressive. Design Factors There are three design aspects to any terrace; these are (1) the outward projection, (2) contour positioning, and (3) the facing. The first two involve the shape with regard to the hillside. Since each, in turn, has two variants, there are a total of four topographic terrace options. The third aspect is the facing, e.g., stone or grass. This defines the terrace as a land modification agrotechnology. Outward Projection How a terrace projects outward from the hillside is a key aspect. A terrace can have a flat projection. The classic examples are hillside rice paddies where the need to hold water dictates the projection. The other type is slope reducing. This is where the terrace surface is not level but only reduces the degree of slope or steepness of the original, unmodified hillside. Contour Positioning In addition to outward projection, terraces conform to the hillside in another aspect. They can follow a level contour. The abovementioned hillside rice paddy has a flat projection and is contour level. The second type is the ramp type (as in Photo T4). These do not follow a level contour line, but contour upward or downward. The comparison is to a road zigzagging up a hillside.

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Photo T3  A very old terrace system from the mountains of Lebanon

Variations As discussed above, there are four possibilities based upon the above two design aspects. Terrace can be (1) flat and follow the contour. Terraces can also be (2) flat and ramped, (3) slope reducing and follow the contour, and (4) slope reducing and ramped. The terrace in Photo T3 follows the contour but has a slight downward projection. Photo T4 is of a ramp design. Despite these variations, terraces, as land modification agrotechnologies, are normally classified according to the facing type. Three types are in common usage: stone, grass, or tree-faced. Stone A stonewall can be the retaining face or front for the rise portion of a terrace (as in Photo 8.6, page 130, also T3 and T4). This type construction is durable and longlasting, confers heat-holding capacity, and is the most expensive. Possible, and equally expensive, are terrace retaining walls made of concrete or some other hard and durable material, e.g., a treated or a decay-resistant wood. A less costly alternative is an earthen bank covered with large stones. These offer erosion protection with some of the heat-maintaining advantages of rocks.

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Photo T4  A ramp-type terrace

Grass Steep, soil-retaining slopes can be covered with grass. This provides the erosion protection needed. Grass, as a form of strip arrangement, offers a habitat for predator-­prey insects. There is a cost in keeping the grass mowed or lightly grazed. Tree Trees are a vegetative alternative to the grass-faced retaining slope. For ease of maintenance, these are normally small shrubs planted after earthen terraces are constructed. There are variations on this design. Progressive terrace is formed by first planting a close-spaced row of trees along the line where the terrace will be. After a few years, the pruned branches and available stones are piled against the upward side of the trees. This barrier traps loose and eroding soil. Over time, a tree-supported terrace will form. Accounts say that, in forming a 35 mm high, 80 mm wide terrace on a fairly steep slope, this takes about 6 years (Banda et al. 1994). In another variation, the progressive terrace is constructed using tree or hedgerow. Branches are piled and dirt is shoveled against the upward side of the hedge. In aggressively adding soil, the hedge may be buried. This helps support the structure,

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while the hedge regrowth out of the terrace face allows the process to be continued for greater height growth.

Threat Counters (See Eco-Services)

Tierra Prieta A lost and rediscovered technique, tierra prieta or biochar is a method for keeping tropical soils fertile. Rather than having nutrients leach away, this involves mixing or infusing the soil with charcoal. Effectiveness comes because the charcoal captures and lightly holds nutrients and moisture. These are still available to plants. The technique is persistent; charcoal does not decay, and nutrients are retained and not leached away. Reportedly, the resulting tierra prieta (meaning good earth) has more available phosphorus, calcium, sulfur, nitrogen, greater organic content, more micronutrients, and an improved ability to hold nutrients and moisture, There is a growing body of research on these various gains from biochar, e.g., Atkinson et al. (2010), Zhenga et al. (2017), Gao et al. (2016), and Yang et al. (2016). With all these positive effects, increases in yields are expected. The amount depends much on the starting soils. Increases of 60% have been reported, e.g., Genesio et al. (2015). Because the charcoal persists, high yields should last for centuries (Mann 2002). This technique was noticed in eastern Brazil. This dates from pre-Columbian times. The overall effect was to permit greater agricultural output and larger population than possible with consistently poor tropical soils. This has prompted interest, and scattered examples have been noted outside South America, e.g., Japan. This has modern application in revenue-oriented systems. Tierra prieta would be classed as a land modification agrotechnology.

Till/No-Till How land is prepared prior to planting is a subject of debate both within agroecology and within conventional agriculture. This debate looks at the advantages as well as the disadvantages and how no-till is best put into practice, e.g., Carr et al. (2012a, b) and Luna et al. (2012). For conventional agriculture and agroecology, relative cost is a key point. For agroecologists, the debate extends to the eco-services provided.

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Tilling Seasonal plowing was once the standard. Although comparatively expensive, there are some advantages. Standing vegetation is incorporated into the soil increasing the amount of in-soil carbon and organic matter. The major gain may come through weed control. Early plowing can disrupt weed germination. Later plowing, after weed emergence, is another alternative that will bury the first generation of weedy plants. One disadvantage, the newly exposed soils are at threat from both wind and water. No-Till The comparative gains from not plowing lie in lower costs and better in-soil nutrients. The lower costs stem from not expending the time and energy turning the soil. As part of no-till, the area may be crimped prior to planting, i.e., where a heavy roller flattens existing vegetation. Compared with plowing, the nutrient dynamics of no-till are far superior. In one study, the nitrogen requirement for corn was 25% lower in no-till compared with a tillage-based rotation. Also, phosphorus needs were 30% lower and yields higher after 20 years of no-till (Anderson 2016). Whereas tilling can reduce weed populations, no-till systems are fully exposed. This has led to the combination of no-till, herbicides, and herbicide-resistant crops. Without herbicides, there might be some initial reprieve as weeds adapt to the new growing environment, but this will not last. Eventually, weed populations will eventually reach crop-crippling levels (Halde et al. 2015). For no-till systems, the weed problem will be addressed with traditional counters. These would include weed-resistant or weed-tolerating crop varieties, dense planting, intercropping, cover crops, and rotations. In one study, weed populations fell more than 90% when alfalfa followed soybean and slightly less when alfalfa followed corn (Anderson 2017) (for more on this line of development, see Weed Control).

Trap Crops The underlying notion behind a trap crop is to lure harmful insects away from a valuable species onto a less valuable plant. This can be associated with field margins that are rich in predator insects. Trap crops can be part of a push-pull where a repellent plant, interplanted with the crop, keeps the unwanted insects from returning. There are also versions where trap or decoy plants, once heavily populated with herbivore insects, are sprayed with insecticides. The idea is to reduce the volume of insecticide used.

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Either use is best if the plot is so designed. Trap crops are often found in field margins. The most effective design forgoes large plots, using instead margin-­ bordered strips (for more, see Field Margins). The spray approach would have a trap crop planted every few rows. Parker et al. (2016) found that diverse trap crops are more effective. Also, they function well without insecticides. Another strategy might employ a cover crop that lures insects. This would work only if the plots are well stocked with predator insects. If not, there is the danger that this approach would allow the herbivore types to breed and their numbers to grow. As an added note, trap crops have been effectively employed against belowground nematodes (Navarrete et  al. 2016). In this case, populations declined by 80–90%. The trap crop was a variety of pepper (Capsicum spp.). Successes of this magnitude may be narrowly tailored, i.e., limited to a few pepper varieties (Laxa et al. 2016).

Traps An often overlooked aspect of insect management is the use of killing, capturing, or ensnaring devices. In addition to insects, these are also employed to snare rodents and fruit- or grain-eating birds. In their most promising form, they reduce the populations of plant-consuming insects. These come in different forms, (a) Lure and kill (b) Lure and contain The lure, for rodent and birds, is some form of food source. For insects, attracting pheromones are growing in popularity. The list of insects that can be so attracted is also expanding. As an outbreak defense, these are effective against, e.g., apple maggots, bag worms, corn earworms, European corn borers, fruit flies, and peach tree borers. As more of a monitoring tool and less a control measure, traps have a role in integrated pest management. The number and location of insects caught will decide if an outbreak defense, including possibly more traps, will be situated. Lure and Kill When traps are mentioned, most think of poisoned bait. Rodents and harmful birds can fall victim to this form of trap. This strategy can also be utilized again insects and other pests. The danger is that, unless well designed, harmless fauna can fall victim.

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For a trap of simple design, saucers are filled with beer. These are placed at ground level to trap and drown slugs. With this design, only the targeted slugs are at risk. More technically astute designs lure through attractant chemicals. Inside the trap is a poison. This is the kill mechanism. There are dangers; poison in the environment goes against the precepts of agroecology. Despite this prohibition, there are toxins that are species specific or that are chemically unstable and do not linger in environment. These can overcome the poison-in-the-environment objection. These tend to be used against rats and mice, less against birds and insects. Lure and Contain The other version attracts and imprisons the pest. These can later be removed and disposed of. In a simple example, a trap for destructive ants consists of a coconut with a single hole. Buried in the earth, ants are drawn in the trap, and the trap is removed and emptied of ants. It can later be repositioned (Brown and Marten 1986). For most used, the pest, rather than a user preference, dictates whether the trap is lure and kill or lure and contain. Part of the decision process depends if the trapped organism has value, for example, when captured insects are added to chicken feed.

Traumatic Release Repellent plants can be integral in an insect control strategy. These are plants that naturally release aromatic compounds that drive away unwanted insects. Repellent plants are a maintenance strategy and an in-place control. The intent is to keep insect populations low and at sustainable levels. Sustainability refers to amount of damage inflected on the crop and that any ensuing losses are economically acceptable. The everyday release of repellent compounds is also generalist strategy, not designed for any one specific insect species, but to repel all types. The more intense form is traumatic release. This is still a part of a generalist strategy but used as a counter for the rise in the populations (one or more) of herbivore insects. In traumatic release, some of the leaves of repellent plants are scathed or shredded. This allows for a greater release of the insect-repelling aromatic chemicals. Cutting may work; however more may be released shredding or crushing the leaves. This starts near where an insect outbreak is happening or anticipated. Monitored closely for effectiveness, the process may ultimately involve a larger area. This requires that the repellent plant be grown along the small plots. For larger plants, the plants must be intercropped or row planted with the plot. If this is not possible, cut-and-carrying repellent vegetation to a potential insect outbreak would be part of traumatic release.

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Photo T5  Limes, in the background, being grown with banana and cassava

Tropical Homegardens (See Agroforests)

Tree-Over-Crop Agroecosystems There are productive agrotechnologies that have trees over seasonal crop, a non-­ woody perennial or a woody perennial. There are two distinguishing characteristics: (1) all the species are productive and (2) the upper story is well-spaced where, even over a crop row, the canopies do not touch. These systems would be inclusive in agroforestry. They are a seldom encountered agrotechnology. As a perennial version of the simple intercrop. They can be found with a perennial or a season understory. In all, these systems are very flexible, especially when it comes to seasonal crops. A wide range of seasonal species can be included in a tree-crop or orchard environment. The only real limitation may be with root crops, e.g., potatoes and cassava, where the tree roots can be problematic during harvest. This is a lesser limitation as root crops have been found, e.g., rubber trees with cassava. There are also harvest considerations when workers must move about without impediment.

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Agroecology As with most tree-based systems, there are ecological gains. Being perennial systems, one can expect these to be more ecologically active than with seasonal bicultures. Expected are favorable insect dynamics, less diseases, and no erosion. As with a shaded understory, these follow the general rules for shade systems (page 78). Economics The economics is simple, to maximize plot yield and revenue. The LER is often the acceptance criteria. As a result, the majority of these are revenue orientated. Examples In addition to trees with annual crops, there are trees with woody and non-woody perennials. A sample list includes: Breadfruit and jackfruit Cloves and banana Coconut and cacao Coconut and pineapple Grape and almond

Macadamia nut and papaya Olive and grape Olives and opuntia Rubber and cacao Rubber and coffee

Truant Resources Within agriculture, there are mineral resources, especially applied chemical fertilizers and animal manures, that are not taken up by plants and escape a site. These resources, when they cause mischief, are truant from the system. Often they pollute standing or flowing water. On the macroscale, dead zones in the world’s oceans are a direct result of fertilizer runoff. These are found at the mouth of the Mississippi River, in Lake Erie, and in the Baltic. When the damage is economically valued, this should be considered as cost in a cost-benefit assessment. The problem is that this damage, indirect and, at times, distant from a plot, can be very difficult to assess and monetarize. The economics are more pronounced if viewed from the perspective of nutrients paid for, but not used. The solution is to wisely apply fertilizers and other external nutrients. This is more easily said than done. Tierra prieta (biochar), used to keep these on-site, is an expensive counter.

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Photo W1  A less-than-common method to harvest subsurface water. As an alternative to the borehole or well, hillside tunnels are seldom encountered and often date to antiquity. This example is from Lebanon

The tried-and-true method is the use of riparian buffers. These can stop most of the runoff and can even channel otherwise lost nutrients for productive use (for more, see Riparian Buffers).

Vines (See Support (Physical))

Water Channels Among the land modification agrotechnologies are small canals or channels used to convey water across farm landscapes. These can be a supporting feature for productive agrotechnologies, but within their own right, these can be an ecological and an economic feature within the farm landscape. Those being discussed here are small, usually not more than a meter wide. These can be dry some of the year or flow year round. Even though these channels are small, there are minor opportunities for productive or protective inclusions (for more, see Riparian Buffers).

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Agroecology As single-purpose systems, water channels would seem to be of little ecological interest. In many farm landscapes, this would be the case. Where channel water is for human consumption, clear, cool water results were the water course is overtopped and, through nutrient uptake, cleaned by vegetation. Where the water is only utilized for irrigation, there is less of a requirement for clean water. In many cases, nutrient-laden water may ultimately be better for crop growth. There is still the requirement that these channels not silt up nor the banks collapse. With this in mind, channels, being a rich water source, can expand cropping opportunities. This would be secondary perennial plants that can grow along and support the channel banks. Design There are some general guidelines for vegetation along channels. Normally, trees are grown only on the uphill side. On the downhill side are grasses, cover crops, or other small protective plants. There is a good reason for this. When cleaning, there is room to shovel the channel silt and deposit it to build up the lower bank. The other design option is much the same; only a few, widely spaced trees are placed along the lower bank. This still leaves space for cleaning, but with greater support and additional shading of the water. The water channel pictured in Photo 8.1, page 119, is lined and therefore less an ecological, more of an economic feature.

Water-Breaks As part of a series of anti-flood defenses, strips of trees or shrubs can be placed across flood-prone lands. These cross plots such that the flowing water is slowed, erosion is prevented, and waterborne silt is deposited. These bio-structures are employed when flooding is an irregular occurrence, but when it does happen, valuable soils are washed away. These structures can have multiple eco-purposes, i.e., they can double as travel corridors, windbreaks, and/or animal fencing. Examples of the in-use possibilities are found in Wallace (1997) and Nabham and Sheridan (1977).

Water Harvesting This text discusses the use of infiltration barriers and like structures to slow water and allow it to infiltrate into the soil. The purpose is to limit how much of the rainfall is lost to a site and to maximize how much is available to present and future crops.

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Water flowing underground is less likely to be lost (as happens with uncontrolled surface flows). Once underground, the hope is that it will linger and, over a growing season, crops will directly uptake this water. If not directly uptaken through roots, the moisture can surface, nearby or far away, through springs and wells, or eventually flow, underground, directly into streams and rivers. As a subsurface source, the water should be clean and long-lasting. The effectiveness of crop-supporting infiltration would depend on a cooperating soil structure and area geography. Infiltration can be done through active vegetation, either purposely planted or though left-in-place natural plants (for more, see also Catchments, Cover crops, and/ or Mulch). Other non-vegetative mechanisms of infiltration may also be utilized (for more on this aspect, see Infiltration, Cajetes, Mounds, Terraces, and/or Barriers). Water harvesting also applies when surface flows are used at a nearby or a distant site. In many cases, long-term use requires storage ponds (see Ponds). There are some inherent disadvantages. With surface flows, there are evaporative losses. There are also heavy-rain overflow losses.

Weed Control Weeds may be the greatest threat to cropping and one of the most difficult to overcome. From one source (Gharde et al. 2018), crop yield losses, plot-wise, range to a high of about 75%. On the macroscale, the overall losses are put at about 25%. These numbers are for the major crops of India. When one thinks of weeding method, what comes to mind are hand, mechanical, and chemical weeding. There are options which, in addition to physical removal, lessen the weed populations. Questions arise on how this is best done. In general, integrated weed management is an unsettled topic. The fault lies with the widespread use of herbicides. This has delayed progress on the nonchemical alternatives (Liebman et al. 2016). There are quite a few control options. As with most threat-countering methods, only a few are stand-alone. For most, effectiveness can be increased by simultaneously employing more than one. Listed the counters are: Hand weeding Plowing (tillage) Timing Fire Varietal resistance Crowding Intercropping Cover crops

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Rotations Mechanical Fallows Mulch Ducks/geese Chemical (herbicides) Miscellaneous Hand Weeding Hand removal is often the best course of action. The variations are: (1) Total removal (2) Selective weeding (3) Near the plant (4) Away from the plant Total removal is where all the weeds are removed or killed. This is the most common anti-weed strategy. Second on the list is selective weeding. Farmers know from experience which weeds are bad (have the most negative effect on the crop) and which are good (coexist, are complementary, or are slightly crop facilitative, e.g., help control erosion). The good weeds remain; the bad are removed. Photo 6.1 (page 93) is a close-up of selective weeding that has resulted in the edible weed purslane being employed as a cover crop beneath a pumpkin crop. This species was brought to the fore by the removal of the other weed species. To prevent the purslane from becoming troublesome, some advise mowing, but not weeding. The third option is to weed only near the plant. The assumption is that those weeds outside a crop-weed buffer do-less-harm. There is also the possibility that these weeds, in harboring predator insects, may do more good than harm. The forth option is away-from-the-plant weeding. The assumption here is that the crop can dominate and suppress nearby weeds. The greater threat comes mainly from those unwanted plants out of the reach of crop. Fast-growing crops with dense canopies are more likely to be weed dominant. Tillage The tilth can set back weed growth. The key lies in the type and timing, e.g., Brandsæter et al. (2017). The mechanisms are clear. One option, a seasonally late, deep plowing before planting, but after weed emergence, allows crops a period to gain ascendency over the weeds. As a related option, an early, deep plowing can bury weed seeds. Many would be too deep to sprout.

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Conventional agriculture has embraced no-till because it saves on plowing costs. To eliminate weeds, herbicides have been the go-to counter. The combination, herbicides and no-till, is effective against weeds, e.g., Anderson (2017). This may be proceeded, to effect, by crimping where the existing vegetation is rolled flat, e.g., Ciaccia et al. (2015). This is only seasonal. The initial weed reduction will not last (Halde et al. 2015). This is an unsettled topic with many, as of yet, unresolved counter combinations. If plowing is not used, weed control may be best if based on other countermeasures. For example, it has been shown that tillage is less important than rotations (TerAvest et al. 2015). Timing Since weeding is not a daily activity, the decision is to weed early when these plants are small or to wait. Timing also applies to tillage (above). Fire Post-fallow, pre-planting fires, especially a hot, fuel-rich burn, can destroy in-soil seeds and permit the crop some weeks of weed-free growth. This can be part of post-fallow strategy where the burn adds to the fallow effect. Varietal Resistance Some crops and/or some varieties are better able to tolerate weeds more than others. These varieties exist for many crop species. The mechanisms vary. These can include the ability to tolerate weeds or to actively suppress, through allelopathic properties, weed competition. It has been shown that taller maize with a larger leaf area yielded better than shorter, less leafy varieties (Boydston and Williams 2016a and b). Crowding Suppressing weeds by crowding them out is an obvious counter. It carries the proviso that the crops have initial ascendency over aspiring weed species. This is done through dense monocropping. Increased per-area density can be coupled with a weed-resistant crop, e.g., Bajwa et al. (2017) and Mhlang et al. (2016). Density carries an additional cost (more seeds) and may entail an additional risk. The crops may be less able to tolerate lower-than-normal rainfall.

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Intercropping The alternative to planting the primary crop in high density is to plant a second species. The mechanism relies less on physically crowding out weeds, more occupying all the essential resource niches. Intercropping can have a similar effect. The classic example remains the weed-­ controlling, maize, bean, vine-squash combination. Cover Crops A purposefully planted understory species can play a number of facilitative roles. Weed control would be high on this list. Cover crops are clearly effective when used as an understory during the cropping season. The mechanisms are the same as with intercropping. The affects are well documented, e.g., Masilionyte et al. (2017). Cover crops are also effective as an off-season counter. For example, Buchanan et al. (2016) found a 50% reduction in seeds and better crop yields when a winter cover was utilized. Rotations Rotations are a mainstay against most common weed species, e.g., Koocheki et al. (2009) and Eshel et al. (2015). To date, this is another unsettled topic with considerable potential, e.g., Boydston and Williams (2016a and b) and Shahzad et al. (2016). In one study, weed populations fell more than 90% when alfalfa followed soybean and slightly less when alfalfa followed corn (Anderson 2017) (for more on this line of development, see Rotations). There may be a need to target one weed species. Rotations make it possible to disrupt the life cycle of the weed being targeted. A notable example is the weed striga which is parasitic on maize. This weed is disrupted by a false host planted in the proceeding planting cycle. Mechanical This form of weeding utilizes a tractor or hand-pushed implement, one that rakes the between-row soil. This is an away-from-the-plant method that, if used alone, relies on the crop having weed resistance. Mechanical weeding can be coupled with hand weeding. For this, where the first pass is mechanical, the second go-around is a close-to-the-plant, hand weeding.

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Fallows This is also a time-tested, weed elimination method. The main requirement is there being enough time such that the potential weed species are replaced by an ecosystem succession. Weed species are normally considered as eliminated when the broadleaf, woody vegetation begins to emerge. This generally takes about 5  years (for more, see Fallows). Mulch The covering of the soil with dead vegetation is good against erosion, less so against weeds. This can be cut and carried; more often this is the residual biomass from the previous season’s crop. The usual outcome may be a delay in weed competition. Effectiveness is increased if the mulch has allelopathic properties. A mulch layer may also help by promoting the decay of weed seeds. A less than natural variation is the use of plastic sheeting. As a soil cover, this finds application with higher-valued vegetable crops. Clearly effective, weeds can still emerge next to desired plants. There are questions on cost as well as the disposal of the used plastic. Ducks/Geese These birds will eat weeds if fenced and provided they do not consume the crop, e.g., geese have proven effective in cotton, strawberries, and in taller, more mature maize. Chemical The development of herbicide-resistant, GMO crops has allowed for the widespread use of herbicides. Widespread, these poise a threat and are not advocated. On occasion, farmers spray with weed-suppressing solutions. These home remedies usually have a high or a low pH and kill leaves on contact. These solutions do not kill roots, but do allow time for crops to gain ascendency. Being indiscriminate, they must not come into contract with the crop. Miscellaneous There is interest in microbes in the form of plant diseases that attack and kill targeted weeds. The use of bio-herbicides has gained some traction (Cordeau et al. 2016) There is evidence that specific insects can play of role. One study has ground beetles eating 73% of the weed seeds (Petit et al. 2017).

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Goals In controlling herbivore insects and other threats, the goal is to have a diverse array of mutually supporting eco-services. If one fails or is weak, others complete the protection. Ideally, the theory should be strong, i.e., knowing whether a matrix line is additive or some other function. More important, in-field effectiveness should be assured. For weed containment, the natural counters, individually, have yet to live up to their full potential. There is also far less understanding on how, in combination, the weed counters, e.g., rotations, tillage, timing, etc., mutually reinforce.

Windbreaks A standard feature of many flat, open, windy, agricultural landscapes is the use of wind-blocking tree barriers. These can be as windbreaks or, within large farms or across regions, a mix of smaller windbreaks and larger, more substantial shelterbelts. Agroecology Windbreaks, in addition to their main role of blocking the wind, accomplish a number of ecological tasks. A reduction in wind speed diminish plant transpiration and soil drying. These can have a substantial effect upon yields. Windbreaks also eliminate sandblasting, where wind-borne sand particles strike and injure plant leaves and stems. The healing needed slows growth and lessens yields. The positive effects of a wind-sheltered environment transfer to domestic animals. Being protected from hot or cold winds allows for faster and greater weight gain. Protection also reduces the mortality for the more susceptible young animals. As a side benefit, windbreaks can serve as live fencing. In the off-season, when crops are not in place, a reduction in winds prevents soil erosion. It should be noted that windbreaks do more than just block winds. These structures can be a habitat for both pollinating and predator insects. They can increase the effectiveness of the latter. One reason is that slower winds make predator insects more effective. This is not minor. Numerically stated, these insects can be 66% more effective at their assigned task (Barton 2014). Given the totality of potential eco-services, the notion of using a single counter against diverse threats is very much alive. Windbreaks/shelterbelts merit a matrix column and, correspondingly, field consideration. With all the eco-service possibilities, one should not be distracted. Any secondary purposes should add, not take away, from their primary function (Sudmeyer and Speijers 2007).

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Design The effectiveness (or wind-blocking ability) is generally a function of height and density. In the design, the height extends the effective distance. This distance can be further lengthened if the wind structure is wind permeable. Permeability means close-spaced trees with open, less dense canopies or slightly wider spacing with many small, inter-tree gaps. A few large gaps can cause wind tunnel effect, i.e., localized areas where the force of the wind is forceful and often damaging (for more on this, see Wind Tunnel Effect). In practice, shelterbelts are usually placed 50–60 heights apart, and windbreaks are spaced 30 heights apart. The height measurement refers to the vertical altitude of the wind structure. Figure 3.2, page 51 shows the placement of a shelterbelt/windbreak system. If the plots are large, usually some measure is taken for internal protection. Figure 3.2 shows a parkland system augmenting the windbreak. Another large-plot option is small, sub-windbreaks. The plot and crop can be internally protected by short, multi-seasonal, non-woody windbreaks, e.g., sugarcane (Photo 6.2, page 96) or Jerusalem artichoke. Less effective are seasonal windbreaks. Photo W2 has a row of maize wind protecting a cabbage/hot pepper intercrop. Photo W2  A short-­ statured, seasonal, windbreak. This has maize protecting a cabbage/hot pepper intercrop. To the left is a carrot monocrop

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As to effectiveness, Zhang Fend (1996) found, with a combination of shelterbelts and windbreaks on a windy Mongolian plain, wind velocity decreased by 32–38%. This brought about increase in soil moisture by 3–6%, a decrease in summer temperatures by 0.1–0.7 °C, and an increase in winter temperatures by 0.5–1.6 °C. Seemingly small, this increased maize yields by 64% and millet yields by 70%. Variations In contrast to the wider shelterbelt (for more on these designs, see Shelterbelts), windbreaks range from one to three species wide. Height depends upon use and location. The key design features are dense, wind-restricting base, a slightly less dense canopy above the height of the crop, with much less density higher up. The purpose of less density higher up is to reduce the side pressure on the trees, i.e., to keep them from toppling. The latter is more important with single tree-row windbreaks. This is less an issue with mutually supporting multi-species designs.

Wind Tunnel Effect The design of farm landscape and of individual plots, if poorly thought out, can lead to a wind tunnel effect. This is where prevailing winds, when passing through an agroecosystem, are channeled and their velocity accelerated. These effects can be negative. This can cause plant drying and sandblasting from the wind-borne soil particles. Wind tunnels come in different forms. The first is where breezes are concentrated when flowing under plants. This can happen when winds are channeled under a row of dense-canopied trees. A second form has winds converging between and along rows between tall plants. The third effect is the side swirl where winds intensify when rounding the corner of a tall, tree-based ecosystem. The counter to the tunnel and swirl lies either in the orientation of the rows or the orientation of an entire agroecosystem. These can also be countered through changes in internal design and/or by establishing a protective and surrounding wind barrier. Although a minor, often overlooked effect, wind channeling is a consideration.

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Yield Functions (See Sigmoidal Equations)

Yield Gap Analysis Yield comparisons can be made on any level and for any purpose. Normally, the comparison is what can or should be against what is. A yield gap can result. For example, per-area output can be used to compare yields in good seasons with those where the weather is not favorable. In agroecology, this can measure the resilience of an agrosystem to climatic adversity. This type of analysis manifests in many forms and for many purposes. The yield gap was once used to present conventional agriculture, agrochemicals, and GMO crops included, in a highly favorable light. This argument was exampled in Chap. 10 (with Fig. 10.1, page 158, showing the equational location of the gap). The gist of the argument is that the high yields obtainable cannot not be surpassed and that, without these, populations could not be fed. This argument has been debunked (National Academies of Science, Engineering, and Medicine 2016; Hakim 2016). In agroecology, these upper limit yields have value as they anchor the sigmoidal curves (as in Fig. 10.1). Beyond this, the concept falters as meaningful measure. There are two main reasons for this. The first is that intercrops can exceed, in total, per-area useful output, anything that is possible with monocropping. Although, the possible uppermost LER values are, at this stage, not fully known, multi-output intercropping destroys the gap concept (for more, see Upper Limit under Competitive Partitioning). The second reason is that a yield gap assumes revenue orientation. For cost-­ orientated farms, the yield gap has little worth. The yield gap argument is a macroeconomic view of agroecology. The notion is that extreme revenue orientation requires large quantities of many inputs. This encourages economic activity in the ag-supporting community. For government this is good as there is greater employment and more opportunities for tax revenue. Policies to encourage revenue orientation include price supports, crop loss insurance, cheap inputs, and extension advice on how to use these inputs. This may not be in the best interest of farmers. Conventional and agroecological, revenue-oriented farming is better economically served without the yield gap. This can be more the case with a crop-balanced, lower-cost, eco-service, dependent farm.

References

Abraham, L., & Joseph, P. (2016). A new weed management approach to improve soil health in a tropical plantation crop, rubber (Hevea brasiliensis). Experimental Agriculture, 52(1), 36–50. Akinifesi, F. K. (2010). Fertilizer trees for sustainable food security in the maize-based production systems of Eastern and Southern African region: A review. Agronomy for Sustainable Development, 30(31), 615–629. Alomar, O., Goula, M., & Albajes, R. (2002). Colonization of tomato fields by predatory mirid bugs (Hemiptera: Heteroptera) in northern Spain. Agriculture Ecosystems and Environment, 89, 105–115. Altieri, M.  A., & Trujillo, J.  (1987). The agroecology of corn production in Tlaxcala, Mexico. Human Ecology, 15(2), 189–220. Altieri, M. A., & Nicholls, C. I. (2004). Biodiversity and pest management in agrecosystems (2nd ed., 236p). New York: Food Products Press. Altieri, M.  A., Nicholls, C.  I., Henao, A., & Lana, M.  A. (2015). Agroecology and the design of climate change-resilient farming systems. Agronomy for Sustainable Development, 35(3), 869–890. Aman, R. (1998) Rare and wild fruits of Peninsular Malaysia and their potential uses. In M. N. B Nair, M. H. Sahri, & Z. Asharri (Eds.), Sustainable Management of Non-Wood Forest Products (pp.  204–211). Proceedings of an International Workshop Universiti Putra Malaysia, 14–17 October 1997, Serdang: Universiti Putra Malaysia Press, 327p. Ammari, T. G., Ta’any, R. A., Abu-Baka, S., & Hasan, M. (2013). Bioremediation of extremely salt-affected calcareous soils. Journal of Food, Agriculture, and Environment, 11(2), 1. Anderson, R. (2016). Increasing corn yield with no-till cropping systems: A case study in South Dakota. Renewable Agriculture and Food Systems, 31(6), 568–573. Anderson, R.  L. (2017). Improving resource-use-efficiency with no-till and crop diversity. Renewable Agriculture and Food Systems, 32(2), 105–108. Armengot, L., Barbieri, P., Andres, C., et al. (2016). Cacao agroforestry systems have higher return on labor compared to full-sun monocultures. Agronomy for Sustainable Development, 36, 70. Assandri, G., Bogliani, G., Pedrini, P., & Brambilla, M. (2018). Beautiful agricultural landscapes promote cultural ecosystem services and biodiversity conservation. Agriculture, Ecosystems and Environment, 256, 200–210. Atkinson, C.  J., Fitzgerald, J.  D., & Hippe, W.  A. (2010). Potential mechanisms for achieving agricultural benefits from biochar applications to temperate soils: A review. Plant and Soil, 337, 1–18. Bäckman, J.-P.  C., & Tianen, J.  (2002). Habitat quality of field margins in a Finnish farmland area for bumblebees (Hymenoptera: Bombus and Psithyrus). Agriculture Ecosystems and Environment, 89, 53–68.

© Springer International Publishing AG, part of Springer Nature 2019 P. Wojtkowski, Agroecology, https://doi.org/10.1007/978-3-319-93209-5

421

422

References

Badgley, C., Moghtader, J., Quintero, E., et al. (2007). Organic agriculture and the global food supply. Renewable Agriculture and Food Systems, 22(2), 86–108. Bailey, L. H. (1907). The fertility of the land. London: The MacMillian Company, 421p. Bajwa, A., Walsh, M., & Singh Chauhan, B. (2017). Weed management using crop competition in Australia. Crop Protection, 95, 8–13. Banda, A. Z., Meghembe, J. A., Ngugi, D. N., & Chome, V. A. (1994). Effect of intercropping maize and closely spaced Leucaena hedgerows on soil conservation and maize yield on a steep slope at Ntcheu, Malawi. Agroforestry Systems, 27, 12–22. Banful, B., Dzietror, A., Ofori, I., & Hemeng, O. B. (2000). Yield of plantain alley cropping with Leucaena leucocephala and Flemingia macrophylla in Kumasi, Ghana. Agroforestry Systems, 49, 189–199. Bardner, R., & Fletcher, K. E. (1971). Insect infestations and their effect on the growth and yield of field crops: A review. Bulletin of Entomological Research, 64(1), 141–160. Barton, B. T. (2014). Reduced wind strengthens top-down control of an insect herbivore. Ecology, 95(9), 2375–2381. Baskin, Y. (1994). Ecologists dare to ask: How much does diversity matter? Science, 264(8 April – 5156), 202–203. Beale, G., & Boswell, M. R. (1991). The earth shall blossom. Woodstock, VT: The Countryman Press, 263p. Beer, J. (1987). Advantages, disadvantages and desirable characteristics of shade trees for coffee, cacao and tea. Agroforestry Systems, 5, 3–13. Bell, S. (1999). Landscape patterns, perceptions and process. New York: Routledge, 344p. Belsky, A. J. (1992). Effects of trees on nutrient quality of understory gramineous forage in tropical savannas. Tropical Grassland, 26, 12–20. Belsky, A. J., & Canham, C. D. (1994). Forest gaps and isolated savanna trees. Bioscience, 44(2), 77–84. Bianchi, F. J. J. A., Ives, A. R., & Schellhorn, N. A. (2013). Interactions between conventional and organic farming for biocontrol services across the landscape. Ecological Applications, 23(7), 1531–1543. Blitzer, E. J., Gibbs, J., Park, M. G., & Danforth, B. N. (2016). Pollination services for apple are dependent on diverse wild bee communities. Agriculture, Ecosystems and Environment, 221, 1–7. Botelho, M. I. V., Cardosa, I. M., & Otsuki, K. (2016). “I made a pack with God, with nature, and with myself”: Explaining deep agroecology. Agriculture and Sustainable Food Systems, 40(2), 116–124. Boydston, R., & Williams, M. (2016a). Sweet corn hybrid tolerance to weed competition under three weed management levels. Renewable Agriculture and Food Systems, 31(4), 281–287. Boydston, R., & Williams, M. (2016b). No-till snap bean performance and weed response following rye and vetch cover crops. Renewable Agriculture and Food Systems, https://doi. org/10.1017/S1742170516000405. Brainard, D. C., Bryant, A., Noyes, D. C., et al. (2016). Evaluating pest regulating services under conservation agriculture: A case study in snap beans. Agriculture, Ecology, and Environment, 235, 142–154. Brandsæter, L.  O., Mangerud, K., Helgheim, M., & Berge, T.  W. (2017). Control of perennial weeds in spring cereals through stubble cultivation and mouldboard ploughing during autumn or spring. Crop Protection, 98, 16–23. Bretagnolle, V., & Gaba, S. (2015). Weeds for bees? a review. Agronomy for Sustainable Development, 35(3), 391–409. Brown, L. R. (2005). Outgrowing the earth: The food security challenge in the age of falling water tables and raising temperatures. New York: W.W. Norton and Company. Brown, B. J., & Marten, G. G. (1986). The ecology of traditional pest management in Southeast Asia. In G. G. Marten (Ed.), Traditional agriculture in Southeast Asia: A human ecology perspective (pp. 241–272). Boulder, CO: Westview Press, 358p.

References

423

Buchanan, A. L., Kolb, L. N., & Hooks, C. R. R. (2016). Can winter cover crops influence weed density and diversity in a reduced tillage vegetable system? Crop Protection, 90, 9–16. Burgis, T. (2016). The Billionaire’s farm. Financial Times 39, 101(March 2):7. Burnett, K., & Murphy, S. (2014). What place for international trade in food sovereignty. The Journal of Peasant Studies, 41(5), 1064–1084. Burt, C.  M., & Isabel, B. (2005). Leaching of accumulated soil salinity under drip irrigation. Transactions of the American Society of Agricultural Engineers, 48(6), 2115–2121. Carr, P., Anderson, R., Lawley, Y., Miller, P., & Zwinger, S. (2012a). Organic zero-till in the northern US Great Plains region: Opportunities and obstacles. Renewable Agriculture and Food Systems, 27(1), 12–20. Carr, P., Mäder, P., Creamer, N., & Beeby, J.  (2012b). Editorial: Overview and comparison of conservation tillage practices and organic farming in Europe and North America. Renewable Agriculture and Food Systems, 27(1), 2–6. Carson, R. (1962). Silent spring. Boston: Houghton Mifflin, 368p. Carter, J. (1996). Alley farming: Have resource poor farmers benefited. Agroforestry Today, 8(2), 5–7. Charles, D. (1997). Can bison replace engines of war? New Scientist, 154(10 may – 2081), 10. Chaucer, G. (1382). Parliament of Foules. Christanty, L., Kimmins, J. P., & Mailly, D. (1997). ‘Without bamboo, the land dies’: A conceptual model of the biogeochemical role of bamboo in an Indonesian agroforestry system. Forest Ecology and Management, 91, 83–91. Ciaccia, C., Canali, S., Campanelli, G., et al. (2015). Effect of roller-crimper technology on weed management in organic zucchini production in a Mediterranean climate zone. Renewable Agriculture and Food Systems, 31(2), 111–121. Clark, J. S., Merkt, J., & Muller, H. (1989). Post-glacial fire, vegetation and human history on the northern alpine foreland, south-western, Germany. Journal of Ecology, 77(4), 897–925. Coffey, K. (2002). Quantitative methods for the analysis of agrobiodiversity. In H.  Brookfield, C. Padoch, H. Parsons, & M. Stocking (Eds.), Cultivating biodiversity: Understanding, analyzing, and using agricultural biodiversity (pp. 78–95). London: ITDG Publishing, 292p. Cohen, A. S., VanWey, L. K., Spera, S. A., & Mustard, J. F. (2016). Cropping frequency and area response to climate variability can exceed yield response. Nature Climate Change. Published online 7 March. Cohn, J. P. (2005). A new breed of ranchers. The Americas, 57, 6–13. Colbach, N., Licas, P., Cavelier, N., & Cavelier, A. (1997). Influence of cropping system on short eyespot in winter wheat. Crop Protection, 16(5), 415–422. Cooper, P.  J. M., Leakey, R.  R. B., Rao, M.  R., & Reynolds, L. (1996). Agroforestry and the mitigation of land degradation in the humid and sub-humid tropics of Africa. Experimental Agriculture, 32, 235–290. Cordeau, S., Trioleta, M., Wayman, S., et al. (2016). Bioherbicides: Dead in the water? A review of the existing products for integrated weed management. Crop Protection, 87, 44–49. Cressman, R., & Garay, J. (2011). The effects of opportunistic and intentional predators on the herding behavior of prey. Ecology, 92(2), 432–440. D’Acunto, L., Semmartin, M., & Ghersa, C. M. (2016). Uncultivated margins are source of soil microbial diversity in an agricultural landscape. Agriculture, Ecosystems and Environment, 220, 1–7. Das, A. J., Stephenson, N. L., & Davis, R. P. (2016). Why trees die? Characterizing the driver of background tree mortality. Ecology, 97(10), 2616–2622. Day, S. (2001). Fight the blight. New Scientist, 171(1 September – 2306), 36–39. de Bon, H., Huat, J., Parrot, L., et al. (2014). Pesticide risks from fruit and vegetable pest management by small farmers in sub-Saharan Africa. A review. Agronomy for Sustainable Development, 34(4), 723–736. de Foresta, F., Basri, A., & Wiyono, A. (1994). A very intimate agroforestry association cassava and improved homegardens: The Mukibat technique. Agroforestry Today, 6(1), 12–14.

424

References

den Biggelaar, C. (1996). Farmer experimentation and innovation: A case study of knowledge generation process in agroforestry systems in Rwanda, Community Forestry Case Study Series 12. Rome: FAO, 123p. Eeraerts, M., Meeus, I., Van Den Berge, S., & Smagghe, G. (2017). Landscapes with high intensive fruit cultivation reduce wild pollinator services to sweet cherry. Agriculture, Ecosystems and Environment, 239, 342–348. Ehui, S. K., Kang, B. T., & Spencer, D. S. C. (1992). Economic analysis of soil erosion; effects in alley cropping, no-till, and bush fallow system of southwestern Nigeria. In J. L. Moock & R. E. Rhoades (Eds.), Diversity, Farmer Knowledge and Sustainability (pp. 225–243). Ithaca, NY: Cornell University Press, 278p. Eshel, G., Egozi, R., Goldwasser, Y., et al. (2015). Benefits of growing potatoes under cover crops in a Mediterranean climate. Agriculture, Ecosystems and Environment, 211, 1–9. Ester, A., van Rozen, F., & Molendijk, L.  P. G. (2003). Field experiments using the rhabditid nematode Phasmarhdbditis hermaphodita or salt as control measure against slugs in green asparagus. Crop Protection, 22(5), 689–895. Faizool, S., & Ramjohn, R. K. (1995). Agroforestry in the Caribbean. Oficina regional de la FAO Para American Latina y El Caribe, Santiago, 35p. FAO (1994). Prácticas Agroforestales en el Departmento de Potosí Bolivia: Documemto de Trabajo No 1. FAO/HOLANDA/CDF, Proyecto “Desarrollo Forestal Comunal el Altiplano Boliviano”, Potosí, 134p. Feintrenie, L., Ollivier, J., & Enjalric, F. (2010). How to take advantage of a new crop? The experience of Melanesian smallholders. Agroforestry Systems, 79(2), 145–155. Ferguson, R. S., & Lovell, R. S. (2014). Permaculture for agroecology: Design, movement, practice, and worldview. A review. Agronomy for Sustainable Development, 34(2), 251–274. Fleming, W. E., & Baker, F. E. (1934). Testing contact insecticides on Japanese beetles and results with some sodium and potassium soaps. Journal of Agricultural Research, 49(1), 29–38. Francis, C., Lieblein, G., Gliessman, S., et al. (2003). Agroecology: The ecology of food systems. Journal of Sustainable Agriculture, 22(3), 99–118. Franzel, S., Hitimana, L., & Akyeampong, E. (1995). Farmer participation in on-station tree species selection for agroforestry: A case study from Burundi. Experimental Agriculture, 31, 27–38. Gable, J. T., Crowder, D. W., Northfield, T. D., Steffan, S. A., & Snyder, W. E. (2012). Niche engineering reveals complementary resource use. Ecology, 93(9), 1994–2000. Gao, S., Hoffman-Krull, K., Bidwell, A. L., & DeLuca, T. H. (2016). Locally produced wood biochar increases nutrient retention and availability in agricultural soils of the San Juan Islands, USA. Agriculture, Ecosystems and Environment, 233, 43–54. Garrett, H. E., & Jones, J. C. (2016). Companion crop recommendations for planting with black walnut. www.fs.fed.us/pub/misc/walnut/p102-106.pdf Genesio, L., Miglietta, F., Baronti, S., & Vaccari, F. P. (2015). Biochar increases vineyard productivity without affecting grape quality: Results from a four years field experiment in Tuscany. Agriculture, Ecosystems and Environment, 201, 20–15. Ghanbari, A., Dahmardeh, M., Siahsar, B.  A., & Ramroudi, M. (2010). Effect of maize (Zea mays L.) - cowpea (Vigna unguiculata L.) intercropping on light distribution, soil temperature and soil moisture in arid environment. Journal of Food, Agriculture and Environment, 8(1), 102–108. Gharde, Y., Singh, P. K., Dubey, R. P., & Gupta, P. K. (2018). Assessment of yield and economic losses in agriculture due to weeds in India. Crop Protection, 107, 12–18. Ghosh, S., Jung, C., & Meyer-Rochow, V. B. (2017) What governs selection and acceptance of editable insect species. p. 331–350. In: Halloran, A., Flore, R., Vantomme, P., and Roos, N. (eds.) Editable Insects in Sustainable Food Systems. Springer, Switzerland 478p. Gliessman, S.  R. (1998). Agroecology: Ecological processes in sustainable agriculture. Ann Arbor: Ann Arbor Press, 357p. Gliessman, S.  R., & Engles, E. (2014). Agroecology: The ecology of sustainable food systems. New York: CRC Press.

References

425

Glover, J. (1957). The relationship between total seasonal rainfall and yield of maize in the Kenya highlands. Journal of Agricultural Science, 49, 285–290. Godoy, R., & Bennett, C.  P. A. (1991). The economics of monocropping and intercropping by small holders: The case of coconuts in Indonesia. Human Ecology, 19(1), 83–98. Gupta, G. N., Mutha, S., & Limba, N. K. (2000). Growth of Albizia lebbeck on micro-catchments in the Indian arid zone. International Tree Crops Journal, 10, 193–202. Hakim, D. (2016). Doubts about a Promised Bounty. The New York Times CLVXVI(57,401-30-Oct.):1. Hakim, D. (2017). Scientists loved and loathed by an agrochemical colossus. The New York Times CLXVI (57,465–2 Jan.):1. Halde, C., Bamford, K. C., & Entz, M. H. (2015). Crop agronomic performance under a six-year continuous organic no-till system and other tilled and conventionally-managed systems in the northern Great Plains of Canada. Agriculture, Ecosystems and Environment, 213, 121–130. Halloran, A., & Flore, R. (2017) Ingredients: Aspiring chef’s opinions on insects in gastronomy. p. 129–137. In: Halloran, A., Flore, R., Vantomme, P., and Roos, N. (eds.) Editable Insects in Sustainable Food Systems. Springer, Switzerland 478p. Halty, V., Valdés, M., Tejera, M., et al. (2017). Modeling plant interspecific interactions from experiments with perennial crop mixtures to predict optimal combinations. Ecological Applications, 27(8), 227–2289. Harper, C., & Kurtz, W. (2016). Economics of Eastern black walnut systems. www.fs.fewd.us/pub/ misc/walnut/p32-36.pdf Harris, J. (2016). Outsmarting climate change. Discover May: 30–37. Harris, F. M. A., & Mohammed, S. (2003). Relying on nature: Wild foods in Northern Nigeria. Ambio, 32(1), 24–29. Herzog, F., & Oetmann, A. (2001). Communities of interest and agroecosystem restoration: Streuobst in Europe. In C. Flora (Ed.), Interactions between agroecosystems and rural communities (pp. 85–102). Boca Raton, FL: CRC Press, 273p. Hevia, V., Bosch, J., Azcárate, F.  M., et  al. (2016). Bee diversity and abundance in a livestock drove road and its impact on pollination and seed set in adjacent sunflower fields. Agriculture, Ecosystems and Environment, 233, 336–344. Hilgard, E.  W. (1893). Soap as an insecticide. Scientific American Supplement, 38(924), 14769–14770. Holmgren, D. (2002). Permaculture: Principles and pathways beyond sustainability. Hepburn: Holmgren Design Services, 320p. Holt-Giménez, E., & Altieri, M. A. (2013). Agriculture, food sovereignty, and the new green revolution. Agroecology and Sustainable Food Systems, 37(1), 90–102. Husain, A.  A. (2000). Scent in the Islamic garden: A study of Deceani Urdu literary sources. Oxford, UK: Oxford University Press, 284p. Jacobsen, S.-E., Sørensen, M., Pedersen, S.  M., & Weiner, J.  (2015). Using our agrobiodiversity: Plant-based solutions to feed the world. Agronomy for Sustainable Development, 35(4), 1217–1235. Jamieson, P. D., Porter, J. R., Goudriaan, J., et al. (1998). CERES-Wheat, Sirius, SUCROS2 and SWHEAT with measurements from wheat grown under drought. Field Crops Research, 55(1– 2), 23–44. Jashemski, W. F. (1979). The gardens of Pompeii. New Rochelle, NY: Caratzas Brothers, 272p. Jashemski, W. F. (1987). Recently excavated gardens and cultivated land of the villas at Boscoreale and Oplontis. In E. B. MacDougall (Ed.), Ancient Roman villa gardens (pp. 33–75). Washington, DC: Dumbarton Oaks Research Library, 260p. Jensen, M. (1993). Soil conditions, vegetation structure and biomass of a Javanese homegarden. Agroforestry Systems, 24, 171–186. Johns, N. D. (1999). Conservation in Brazil’s chocolate forests: The unlikely persistence of traditional cocoa agroecosystems. Environmental Management, 23(1), 32–47. Johnson, C. W. (1844). The Farmer’s encyclopedia and dictionary of rural affairs. Philadelphia: Carey and Hart, 1165p.

426

References

Kang, B. T. (1997). Alley cropping – Soil productivity and nutrient recycling. Forest Ecology and Management, 91, 75–82. Kareiva, P. (1994). Diversity begets productivity. Nature, 368(21 April), 686–687. Karim, M. R., Ishikawa, M., Ikeda, M., & Islam, M. T. (2012). Climate change model predicts 33% rice yield decrease in 2100 in Bangladesh. Agronomy for Sustainable Development, 32(4), 821–830. Karp, D. S., & Daily, G. C. (2014). Cascading effects of insectivorous birds and bats in tropical coffee plantations. Ecology, 95(4), 1065–1074. Karp, D. S., Moses, R., Gennet, S., Jones, M. S., Joseph, S., M’Gonigle, L. K., Ponisio, L. C., Snyder, W. E., & Kremen, C. (2016). Agricultural practices for food safety threaten pest control services for fresh produce. Journal of Applied Ecology, 53, 1402–1412. Kaspari, M., Clay, N. A., Donoso, D. A., & Yanoviak, S. P. (2014). Sodium fertilization increases termites and enhances decomposition in an Amazonian forest. Ecology, 95(4), 795–800. Kass, D.  C. L., & Somarriba, E. (1999). Traditional fallows in Latin America. Agroforestry Systems, 47, 13–36. Keenan, J. (2015). The blood cries out. Population Connection, 47(3 – October), 18–36. Kerr, R. A. (2009). Northern India’s groundwater is going, going, going. Science, 5942(325–14 August), 789. Kerschen, D. L. (2013). Agriculture’s future: Sustainable intensive agriculture and agroecology. Creighton Law Review, 46(4), 591–618. Khatiwada, J. R., Ghimire, S., Khatiwada, S. P., et al. (2016). Frogs as potential biological control agents in the rice fields of Chitwan, Nepal. Agriculture, Ecosystems and Environment, 230, 307–314. Kiebacher, T., Scheidegger, C., & Bergamini, A. (2017). Solitary trees increase the diversity of vascular plants and bryophytes in pastures. Agriculture, Ecosystems and Environment, 239, 293–303. Kihara, K., Nziguheba, G., Zingore, S., et al. (2016). Understanding variability in crop response to fertilizer and amendments in sub-Saharan Africa. Agriculture, Ecosystems and Environment, 229, 1–12. Kilgore, B. M., & Taylor, D. (1979). Fire history of a sequoia-mixed conifer forest. Ecology, 60(1), 129–142. King, K. F. S. (1968). Agro-Silviculture (The Taungya system). Dept. of Forestry, University of Ibadan, 107p. Koehler, C.  S., Barkley, L.  W., & Kretchum, T.  M. (1983). Soap as an insecticide. California Agriculture, 37(9/10), 11–12. Köhl, L., Oehl, F., & van der Heijden, M.  G. A. (2014). Agricultural practices indirectly influence plant productivity and ecosystem services through effects on soil biota. Ecological Applications, 24(7), 1842–1853. Koocheki, A., Nassiri, M., Alimoradi, L., & Ghorbani, R. (2009). Effect of cropping systems and crop rotations on weeds. Agronomy for Sustainable Development, 29(2), 401–408. Kremen, C., Iles, A., & Bacon, C. (2012). Diversified farming systems: An agroecological, systems-­based alternative to modern industrial agriculture. Ecology and Society, 17(4), 44. Kumar, S., Sah, U., & Singh, P. H. (2007). Traditional ecological management of late blight in potatoes. Leisa, 23(4), 12–13. Kwesiga, F., & Coe, R. (1994). The effect of short rotation Sesbania sesban planted as fallows on maize. Forest Ecology and Management, 64, 199–209. Lagerlöf, J., Goffre, B., & Vincent, C. (2002). The importance of field boundaries for earthworm (Lumbricidae) in the Swedish agricultural landscape. Agriculture, Ecosystems and Environment, 89, 91–103. Langenberger, G., Cadisch, G., Martin, K., et al. (2017). Rubber intercropping: A viable concept for the 21st century? Agroforestry Systems, 91, 577–596. Laxa, P., Climaco Rondan Dueñasb, J., & Ramosc, D. (2016). Host suitability of peppers to the false root-knot nematode Nacobbus aberrans. Crop Protection, 79, 15–19. Leibold, M. A. (1995). Mechanistic models and community context. Ecology, 76(5), 1371–1382.

References

427

Lelle, M. A., & Gold, M. A. (1994). Agroforestry systems for temperate climates: Lessons from roman Italy. Forest and Conservation History, 38, 118–126. Liebman, M., Baraibar, B., Buckley, Y., et al. (2016). Ecologically sustainable weed management: How do we get from proof-of-concept to adoption? Ecological Applications, 26(5), 1352–1369. Liping, Z. (1991). Biological control of insect pests and plant diseases in agroforestry systems. In M. E. Avery, M. G. R. Cannell, & C. K. Ong (Eds.), Biological research for Asian agroforestry (pp. 73–87). New Delhi: Winrock International, AK and Oxford and IBH Publishing, 285p. Litton, R. B., Tetlow, R. J., Sorensen, J., & Beatty, R. A. (1974). Water and landscape: An aesthetic overview of the role of water in the landscape. New York: Water Information Center, 314p. Lojka, B., Lojkova, J., Banout, J., Polesny, Z., & Preininger, D. (2008). Performance of an improved fallow system in the Peruvian Amazon—Modelling approach. Agroforestry Systems, 72(1), 27–39. Long, C. (2001). Bring on the bugs. Organic Gardening, 48(4), 10. Loudon, J. C. (1826). Encyclopedia of agriculture. London: Longman, Hurst, Rees, Orme, Brown, and Green, 1226p. Luna, J., Mitchell, J., & Shrestha, A. (2012). Conservation tillage for organic agriculture: Evolution toward hybrid systems in the western USA. Renewable Agriculture and Food Systems, 27(1), 21–30. MacDonald, J. (1994). The ornamental kitchen garden. Devon: David and Charles, 144p. Malézieux, E. (2012). Designing cropping systems from nature. Agronomy for Sustainable Development, 32(1), 15–29. Malézieux, E., Crozat, Y., Dupraz, C., et  al. (2009). Mixing plant species in cropping systems: Concepts, tools and models. A review. Agronomy for Sustainable Development, 29(1), 43–62. Mann, C. C. (2002). The real dirt in rainfall fertility. Science, 297(9 August-5583), 920–923. Marshall, E. J. P., Brown, V. K., Boatman, N. D., et al. (2003). The role of weeds in supporting biological diversity within crop fields. Weed Research, 43, 77–89. Masilionyte, L., MaikCsteniene, S., Kriauciuniene, Z., et al. (2017). Effect of cover crops in smothering weeds and volunteer plants in alternative farming systems. Crop Protection, 91, 74–81. Matlack, G. R. (1994). Plant species migration in mixed-history forest landscapes in eastern North America. Ecology, 75(5), 1491–1502. Matthews, J. D. (1989). Silvicultural systems. Oxford: Claredon Press, 284p. Mbabaliye, T., & Wojtkowski, P. A. (1994). Problems and perspectives on the use of a simulation model in an African research station. Experimental Agriculture, 30, 441–446. McLean, T. (1980). Medieval English garden. New York: The Viking Press, 298p. McNeely, J.  A. (1993). Economic incentives for conserving biodiversity: Lesson from Africa. Ambio, 22(2–3), 144–150. Mead, R., & Willey, J. (1980). The concept of ‘Land equivalent Ratio’ and the yield advantages from intercropping. Experimental Agriculture, 16, 217–228. Mertz, O. (1998). Wild vegetables as potential new crops in farming systems of Serwak, Malaysia. In M. N. B. Nair, M. H. Sahri, & Z. Asharri (Eds.), Sustainable management of non-wood forest products. Proceedings of an International Workshop Universiti Putra Malaysia, 14–17 October 1997, (pp. 70–83). Universiti Putra Malaysia Press, Serdang, 327p. Mesquita, R.  C. G. (2000). Management of advanced regeneration in secondary forests of the Brasilian Amazon. Forest Ecology and Management, 130, 131–140. Mhlang, B., Singh Chauhan, B., & Thierfelder, C. (2016). Weed management in maize using crop competition: A review. Crop Protection, 88, 28–36. Milius, S. (2003). Sweet lurkers. Science News, 164(13 December - 24), 374. Mitchell, M. G. E., Bennett, E. M., & Gonzalez, A. (2014). Forest fragments modulate the provision of multiple ecosystem services. Journal of Applied Ecology, 51, 909–918. Mmbaga, M. T., Mrema, F. A., Mackasmiel, L., & Rotich, E. (2016). Effect of bacteria isolates in powdery mildew control in flowering dogwoods (Cornus florida L.). Crop Protection, 89, 51–57. Mnifa, I., & Ghribia, D. (2015). Potential of bacterial derived biopesticides in pest management. Crop Protection, 77, 52–64.

428

References

Montenegro, M. www.ensia.com/voices/agroecology-can-help-fix-our-broken-food-systemheres-how Morales, H., Perfecto, I., & Ferguson, B. (2001). Traditional fertilization and its effect on corn insect populations in the Guatemalan highlands. Agriculture, Ecosystems and Environment, 84, 145–155. Mosttafiz, S., Rahman, M., & Rahman, M. (2012). Biotechnology: Role of microbes in sustainable agriculture and environmental health. The Internet Journal of Microbiology, 10(1), 1. Moynihan, E. B. (1979). Paradise as a garden in Persia and Mughad India. New York: George Braziller, 168p. Musau, D. M., & Perry, W. H. (1988). Comparison of potential of orgenophorus insecticide and soap in conifer aphid protection. Crop Protection, 7(4), 267–372. Nabham, G. P., & Sheridan, T. E. (1977). Living fencerows of the Rio San Miguel, Sonora, Mexico: Traditional technology for floodplain management. Human Ecology, 5(2), 97–111. Nair, P. K. R., Buresh, R. J., Mugendi, D. N., & Latt, C. R. (1999). Nutrient cycling in tropical agroforestry systems: Myths and science. In L. E. Buck, J. P. Lassoie, & E. C. M. Fernandes (Eds.), Agroforestry in sustainable agricultural systems (pp.  1–11). New  York: CRC Press, 416p. Nair, C. M., Salin, K. R., Joseph, J., et al. (2014). Organic rice–prawn farming yields 20% higher revenues. Agronomy for Sustainable Development, 34(3), 569–581. National Academies of Science, Engineering, and Medicine. (2016). Genetically engineered crops, experience and prospects. Washington, DC: The National Academies Press, 420p. Navarrete, M., Djian-Caporalino, C., Mateille, T., et al. (2016). A resistant pepper used as a trap cover crop in vegetable production strongly decreases root-knot nematode infestation in soil. Agronomy for Sustainable Development, 36(4), 68. Nchanji, Y.  K., Nkongho, R.  N., Mala, W.  A., & Levang, P. (2016). Efficacy of oil palm intercropping by smallholders. Case study in South-West Cameroon. Agroforestry Systems, 90(3), 509–520. NRC (1996). Lost crops of Africa: Vol. 1, Grains. Washington, DC: Board on Science and Technology for International Development, Natural Resource Council, National Academy Press, 383p. O’Conner, R. J., & Shrubb, M. (1986). Farming and birds. Cambridge, UK: Cambridge University Press, 290p. Olasantan, F. O. (1988). The effects on soil temperature and moisture content and crop growth and yield of intercropping maize with melon (Colocynthis vulgaris). Experimental Agriculture, 24(1), 67–74. Ong, C. (1994). Alley cropping ecological pie in the sky? Agroforestry Today., 6(3), 8–10. Orefice, J., Carroll, J., Conroy, D., & Ketner, L. (2017). Silvopasture practices and perspectives in the Northeastern United States. Agroforestry Systems, 91(1), 149–160. Otanes, F. Q. (1924). Soap as an effective killer for Philippine migratory locust. Crop protection, ixiii(2), 84–88. Ould-Sidi, M.-M., & Lescourret, F. (2011). Model-based design of integrated production systems: A review. Agronomy for Sustainable Development, 31, 571. Paris, Q. (1992). The von Liebig hypothesis. American Journal of Agricultural Economics, 74, 1019–1028. Parker, J.  E., Crowder, D.  W., Eigenbrode, S.  D., & Snyder, W.  E. (2016). Trap crop diversity enhances crop yield. Agriculture, Ecosystems and Environment, 233, 254–262. Perfecto, I., Rice, R. A., Greenberg, R., & Van der Voort, M. E. (1996). Shade coffee: A disappearing refuge for biodiversity. Bioscience, 46(8), 598–608. Peterken, G. F. (1993). Long-term floristic development of woodland on former agricultural lands in Lincolnshire, England. In C. Watkins (Ed.), Ecological effects of afforestation: Studies in the history and ecology of afforestation in Western Europe (pp. 31–43). New York: CABI, 224p. Petit, S., Trichard, A., Biju-Duval, L., & at. (2017). Interactions between conservation agricultural practice and landscape composition promote weed seed predation by invertebrates. Agriculture, Ecosystems and Environment, 240, 45–53.

References

429

Porteous, J. D. (1996). Environmental aesthetics: Ideas, politics and planning. London: Routledge, 290p. Pulido-Santacruz, P., & Renjifo, L. M. (2011). Live fences as tools for biodiversity conservation: A study case with birds and plants. Agroforestry Systems, 81(1), 15–30. Qureshi, M. A., Ahmad, Z. A., Akhtar, N., et al. (2012). Role of phosphate solubilizing bacteria (psb) in enhancing p availability and promoting cotton growth. Journal of Animal and Plant Sciences, 22, 1. Rachie, M. D. (1983). Intercropping tree legumes with annual crops. In P. A. Huxley (Ed.), Plant research in agroforestry (pp. 103–116). Nairobi: ICRAF, 595p. Racine, M., Boursier-Mougenot, E.  J.-P., & Binet, F. (1987). The gardens of Provence and the French Riviera. Cambridge, MA: MIT Press, 315p. Raintree, J.  B. (1983). Guidelines for agroforestry diagnosis and design: Draft for comment. Working Paper No. 6, ICRAF. Nairobi, Kenya, 35p. Raintree, J.  B. (1990). Theory and practice of agroforestry diagnosis and design. In K.  G. MacDicken & N. T. Vergara (Eds.), Agroforestry, classification and management (pp. 58–97). New York: John Wiley and Sons, 382p. Rao, M. R. (1986). Cereals in multiple cropping. In C. A. Francis (Ed.), Multiple cropping systems (pp. 96–132). New York: Macmillian Publishing, 383p. Reinders, H. P. (2007). Multiple strategies on an organic farm in the Netherlands. Leisa, 23(4), 32–34. Reynolds, P.  J. (1980). The working agroscape of the iron age. Landscape History (Vol. 2, pp. 1–20), Journal of the Society for Landscape History, Rampart Press. Reynolds, L. (1991). Livestock in agroforestry: A farming systems approach. In M.  E. Avery, M. G. R. Cannell, & C. K. Ong (Eds.), Biological research for Asian agroforestry (pp. 233– 256). New Delhi: Winrock International, AK and Oxford and IBH Publishing, 285p. Rezaul Haq, A. H. M., Ghosal, T. K., & Ghosh, P. (2004). Cultivating wetlands in Bangladesh. Leisa, 20(4), 18–20. Rham, W. L. (1853). The dictionary of the farm. London: George Routledge and Company, 498p. Rice, R. E., Gullison, R. E., & Reid, J. W. (1997). Can sustainable management save tropical forests? Scientific American, 276(4), 44–49. Royo, A. A., Peterson, C. J., Stanvick, J. S., & Carson, W. P. (2016). Evaluating the ecological impacts of salvage logging: Can natural and anthropogenic disturbance promote coexistence. Ecology, 97(6), 1566–1582. Ruc, J. (1990). Compounds from plants that regulate or participate in disease resistance. In D. J. Chadwick & J.  March (Eds.), Bioactive compounds from plants (pp.  213–224). New  York: John Wiley and Sons, 242p. Sanchez, P. A. (1995). Science in agroforestry. Agroforestry Systems, 30, 5–55. Schenck, C. A. (1904). Forest utilization, mensuration and silviculture. Biltmore, NC, 3parts. Schlich, W. (1910). Schlich’s manual of forestry (Vol. II, 4th ed.). London: Bradbusy, Agnew, 424p. Seran, T. H., & Brintha, I. (2010). Review of maize based intercropping. Journal of Agronomy, 9, 136–145. Seydack, A.  H. W. (1995). An unconventional approach to timber yield regulation for multi-­ aged, multispecies forest I. Fundamental consideration. Forest Ecology and Management, 77, 139–153. Seydack, A. H. W., Vermeulen, W. J., Heyns, H. E., et al. (1995). An unconventional approach to timber yield regulation for multi-aged, multispecies forest II. Application to a South African forest. Forest Ecology and Management, 77, 155–168. Shahzad, M., Farooq, M., Jabrand, K., & Hussain, M. (2016). Impact of different crop rotations and tillage systems on weed infestation and productivity of bread wheat. Crop Protection, 89, 161–169. Shamanskaya, L.  D., & Zhukovskii, A.  U. (2002). Use of insecticide soap in plant protection. Agrokhimiya, 10, 48–51.

430

References

Shepard, K. D., Ndufa, J. K., Ohlssong, E., Sjögren, H., & Swinkels, R. (1997). Adoption potential of hedgerow alley cropping in maize-based cropping systems in the highlands of western Kenya. 1. Background and agronomic evaluation. Experimental Agriculture, 33, 197–209. Singh, A. K., Gohain, I., & Datta, M. (2016). Upscaling of agroforestry homestead gardens for economic and livelihood security in mid–tropical plain zone of India. Agroforestry Systems, 90(6), 1103–1112. Singha, B., Singha, R., & Choudhury, D. (2007). Ecological pest management for emerging pest problems. Leisa, 23(4), 11–13. Snyder, W. E., & Ives, A. R. (2001). Generalist predators disrupt biological control by a specialist parasitoid. Ecology, 82(3), 750–756. Solomon, B., Ghezehei, S. B., Annandale, J., & Everson, C. (2016). Optimizing resource distribution and crop productivity in hedgerow intercropping by manipulating tree arrangement. Agroforestry Systems, 90(5), 861–873. Soluri, J.  (2001). Altered landscapes and transformed livelihoods: Banana companies, Panama disease and rural communities on the north coast of Honduras, 1880-1950. In C. Flora (Ed.), Interactions between agroecosystems and rural communities (pp.  15–30). New  York: CRC Press, 273p. Sorribas, J., González, S., Domingues-Gento, A., & Vercher, R. (2016). Abundance, movement and biodiversity of flying predator insects in crop and non-crop agroecosystems. Agronomy for Sustainable Development, 36(2), 34. Srivastava, R. J., Kumar, A., & Prasad, K. (2003). Studies on soil moisture variations with eucalyptus plantations. www.fao.org/docrep/article/wfc/XII/0500-b2.htm Stadlier, M. (2016). CropLife Nigeria assesses contract sprayers in Borno State. N2Africa (http:// www.n2africa.org/print/4288). Stringer, W. C., & Alverson, D. R. (1994). Use of fire as a management tool in alfalfa production ecosystems. p.  492–493. In K.  L. Cambell, W.  D. Graham, & A.  B. Bottcher (Eds.) Environmentally Sound Agriculture. Proceedings of the Second Conference, 22 April, Orlando FL. American Society of Agricultural Engineers, 578p. Styger, E., Kakotoarimanana, J. E. M., Rabevohitra, R., & Fernandes, E. C. M. (1999). Indigenous fruits of Madagascar: Potential components of agroforestry systems in improving human nutrition and restore biological diversity. Agroforestry Systems, 46, 289–310. Sudmeyer, R. A., & Speijers, J. (2007). Influence of windbreak orientation, shade and rainfall interception on wheat and lupin growth in the absence of below-ground competition. Agroforestry Systems, 71(3), 201–214. Talukder, B., Saifuzzaman, M., & VanLoon, G. (2016). Sustainability of agricultural systems in the coastal zone of Bangladesh. Renewable Agriculture and Food Systems, 31(2), 148–165. Tansey, J. A., Jones, M. M., & Vanaclocha, P. (2015). Costs and benefits of frequent low-volume applications of horticultural mineral oil for management of Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae). Crop Protection, 76, 59–67. Taverne, D. (2007, November) The real GM food scandal. Prospect (pp. 24–27). TerAvest, D., Carpenter-Boggs, L., Thierfelder, C., & Reganold, J. P. (2015). Crop production and soil water management in conservation agriculture, no-till, and conventional tillage systems in Malawi. Agriculture, Ecosystems and Environment, 212, 285–296. Thompson, T. L., Roberts, T., & Lazarovitch, N. (2010). Managing soil surface salinity with subsurface drip irrigation. 19th World Congress of Soil Science, Soil Solutions for a Changing World, 1–6 August, Brisbane, Australia, on-line. Tilman, D., Knops, J., Wedin, D., Reich, P., Ritchie, M., & Siemann, E. (1997). The influence of functional diversity and composition on ecosystem processes. Science, 277(29 August – 5330), 1300–1306. Tohiran, K. A., Nobilly, F., Zulkifli, R., et al. (2017). Targeted cattle grazing as an alternative to herbicides for controlling weeds in bird-friendly oil palm plantations. Agronomy for Sustainable Development, 37, 62–70. Tremblay, A., Mineau, P., & Stewart, R. K. (2001). Effect of bird predition on some pest insect populations in corn. Agriculture, Ecosystems and Environment, 83, 143–152.

References

431

Tscharntke, T., Steffan-Dewenter, I., Kruess, A., & Thies, C. (2002). Contribution of small habitat fragments to conservation of insect communities of grassland-cropland landscapes. Ecological Applications, 12(2), 354–363. Tschumi, M., Albrecht, M., Collatz, J., Dubsky, V., Entling, M. H., Najar-Rodriguez, A. J., & Jacot, K. (2016). Tailored flower strips promote natural enemy biodiversity and pest control in potato crops. Journal of Applied Ecology, 53, 1169–1176. van der Heijden, M. G. A. (2010). Mycorrhizal fungi reduce nutrient loss from model grassland ecosystems. Ecology, 91(4), 1163–1171. van der Heijden, M. G. A., Bardgett, R. D., & van Straalen, N. M. (2008). The unseen majority: Soil microbes as drivers of plant diversity and productivity in terrestrial ecosystems. Ecology Letters, 11(3), 296–310. van der Valk, H. C., Niassy, A., & Bèye, A. B. (1999). Does grasshopper control create grasshopper problem? Monitoring side-effects of fenitrothion applications in the western Sahel. Crop Protection, 18(2), 139–149. van Gils, S., van der Putten, W. H., & Kleijn, D. (2016). Can above-ground ecosystem services compensate for reduced fertilizer input and soil organic matter in annual crops? Journal of Applied Ecology, 53, 1186–1194. van Rijn, P. C. J., & Wäckers, F. L. (2016). Nectar accessibility determines fitness, flower choice and abundance of hoverflies that provide natural pest control. Journal of Applied Ecology, 53, 925–933. Vandermeer, J.  (1989). The ecology of intercropping. Cambridge, UK: Cambridge University Press, 237p. Veblen, K. E., Porensky, L. M., Riginos, C., & Young, T. P. (2016). Are cattle surrogate to wildlife? Savanna plant community composition explained by total herbivory more than herbivore type. Ecological Applications, 26(6), 1510–1623. Venturini, E. M., Drummond, F. A., Hoshide, A. K., et al. (2017). Pollination reservoirs for wild bee habitat enhancement in cropping systems: A review. Agroecology and Sustainable Food Systems, 41(2), 101–142. Vera, F. W. M. (2000). Grazing ecology and forest history. The Netherlands: CABI Publishing, 506p. Versteeg, M.  N., Amadji, F., Eteka, A., Gogan, A., & Koudokpon, V. (1998). Farmers’ adoptability of Mucuna fallowing and agroforestry technologies in the coastal savanna of Benin. Agricultural Systems, 56, 269–287. Vickery, J., Carter, N., & Fuller, R. J. (2002). The potential value of managed field margins as forging habitats for farmland birds in the UK. Agriculture, Ecosystems and Environment, 89, 41–52. Virgil (29 B.C.E.). Georgics III. Wallace, D. (1997). Give the foodplain a break a waterbreak. Inside Agroforestry (Fall):1. Wang, H. (1994). Tea and trees: A good blend from China. Agroforestry Today, 6(1), 6–8. Wezel, A., Bellon, S., Doré, T., et al. (2009). Agroecology as a science, a movement and a practice. A review. Agronomy for Sustainable Development, 29(4), 503–515. Whitcomb, W. H. (1970). Woodpeckers in the ecology of southern Hardwood borers. In Proceedings of the Tall Timbers Conference on Ecological Animal Control by Habitat Management. Vol. 2, 26–28 Feb 1970 (p. 309–315). Tallahassee, FL: Tall Timbers Research Station, 286p. Whitmore, T. C. (1975). Tropical rainforests of the Far East. Oxford: Clarendon Press, 282p. Williams-Guillėn, K., Perfecto, I., & Vandermeer, J.  (2008). Bats limit insects in a neotropical agroforestry system. Science, 320(5872), 70. Wilson, J. (1994). Landscaping with Herbs. Houghton Mifflin Company, NY, 220p. Wilson, T. D., Brook, R. M., & Tomlinson, H. F. (1998). Interactions between néré (Parkia biglobosa) and under-planted sorghum in a parkland system in Burkina Faso. Experimental Agriculture, 34, 85–98. Wojtkowski, P.  A. (1993). Toward an understanding of tropical home gardens. Agroforestry Systems, 24, 215–222.

432

References

Wojtkowski, P. A. (2002). Agroecological perspectives in agronomy, forestry, and agroforestry. Enfield, NH: Science Publishers, 356p. Wojtkowski, P.  A. (2006). Introduction to agroecology: Principles and practices. Binghamton, NY: Haworth Press, 404p. Wojtkowski, P. A. (2016). Agroecology: The universal equations. New York: CRC Press, 257p. Wood, D. (2000). In defense of monocultures. Leisa, 16(4), 14–15. Wood, S. L. R., Rhemtulla, J. M., & Coomes, O. T. (2013). Cropping history trump fallow duration in long-term soil and vegetation dynamics of shifting cultivation. Ecological Applications, 27(2), 519–531. Woodcock, B.  A., Bullock, J.  M., McCracken, M., et  al. (2016). Spill-over of pest control and pollination services into arable crops. Agriculture, Ecosystems and Environment, 231, 15–23. Yang, D., Liu, Y., Liu, S., et al. (2016). Biochar to improve soil fertility. A review. Agronomy for Sustainable Development, 36(2), 36. Yoon, C. K. (2000). Simple method found to increase crop yield vastly. The New York Times (22 August):D1–D2. Yoshida, T., & Kamitani, T. (1997). The stand dynamics of a mixed coppice forest of shade tolerant and intermediate species. Forest Ecology and Management, 95, 35–43. Young, A. (1989a). Agroforestry for soil conservation. Wallingford, Oxon: CAB International, 275p. Young, A. (1989b). The environmental basis of agroforestry. In W. E. Reifsnyder & T. O. Darnhofer (Eds.), Meteorology and agroforestry (pp. 29–48). Nairobi: ICRAF, 546p. Yue, S., Brodie, J. F., Zipkin, E. E., & Bernard, H. (2015). Oil palm plantations fail to support mammal diversity. Ecological Applications, 25(9), 2285–2292. Zhang Fend. (1996). Influences of shelterbelts in Chifeng, Inner Mongolia. Unasylva, 47(185): 11–15. Zhenga, J., Hana, J., Liua, Z., et al. (2017). Biochar compound fertilizer increases nitrogen productivity and economic benefits but decreases carbon emission of maize production. Agriculture, Ecosystems and Environment, 241, 70–78. Zimmer, C. (2016). Immunity underfoot. The New York Times CLXV(37,270–28 June):D4.

Index

The page numbers in bold type reference Glossary entries. These provide a more detailed look at a specific topic. A Adjusted CER, 244 Adjusted LER, 245 Aesthetics, 146, 208 Agroecological matrix, ix, 33–55, 57, 135, 156, 194, 197, 201 Agroecology (defined), 2, 34, 58, 202 Agroecology (types/intensity of), 55, 149, 156, 199 Agro(eco)system (defined), 16 Agroforestry, 210–212 Agroforestry (defined), 210 Agroforests, 211–212 Agrotechnologies, 211–212 Agrotechnologies (defined), 58–59 Alley cropping, 212–215 Animal control, 42, 46, 215 Animal husbandry, see Grazing and pastures See also Semi-husbandry Aqua-agriculture/forestry, 104, 217 B Barn swallows, 36, 221 Barriers (general use), 46, 218 Bats, 107, 147, 215, 219, 263, 300, 308, 314, 318, 361, 362 Bees, 361–362 Biochar, see Tierra prieta Biodensity, see Density Biodisarray, see Disarray Bioduration, see Duration Birds, 219–221 Bison, 34, 39, 101, 147, 289, 294, 331, 350, 351, 375

Branches, 4, 38, 97, 102, 191 Buffer species, 42, 43, 46, 69, 71, 73, 224, 249, 371, 391 C Cajetes, 224–225 Camellones, 69, 71, 122, 141, 225, 339 Canopy patterns, 100, 102, 110, 113, 226 Canopy strategies, 78, 227 Catchments, 228–229 Cattle, 40, 89, 97, 101, 102, 111, 132, 140, 159, 200 Chickens, 36, 103, 216, 220, 240, 308, 318, 375, 376, 407 See also Domestic fowl Classification, 55, 59, 230, 231, 281, 282 Climate change, vi, 6, 117, 118, 121, 175, 177, 247 Commercial farming, 167–169, 242, 317 Competitive exclusion, 20, 231 Competitive partitioning, 231–235 Complementarity, see Competitive partitioning Complex agroecosystems, 239 See also Rules Composting, 5, 43, 46, 239–242 Conservation agriculture, 47, 209, 242 Core elements, 18–20, 26, 27, 30, 33, 34, 57, 79, 159, 192–193, 195, 197, 202 Corporate farming, 140, 161, 167 Corridors, habitat, 43, 46, 69, 122 Cost equivalent ratio (CER), 28, 29, 162, 193, 243–245, 263–264, 275, 325 Cost orientation, see Economic orientation Cover crops, 245–247

© Springer International Publishing AG, part of Springer Nature 2019 P. Wojtkowski, Agroecology, https://doi.org/10.1007/978-3-319-93209-5

433

434 Critical shift, 247 Crop-over-tree agroecosystems, 84, 94, 99, 247–248 Cut-and-carry, 35, 249, 253, 274, 292, 309, 340, 366, 371, 387, 407 D Decoy plants, 216, 251, 309, 310, 405 Decision theory, 185, 187, 250, 256, 297 Drip irrigation, 100, 129, 375 Deer, 34, 39, 103, 215, 216, 289, 294, 327, 375 Density, 251 Design packages (defined), 64–66, 255 Desirable plant characteristics, 91–92, 213–214, 246, 252–254, 262, 379 Diagnosis and design, 167, 229, 254, 256, 257 Diet, 10, 11, 126, 176, 178, 179, 180, 268, 308, 365 Disarray, 258 Disruptive-crop hypothesis, 260 Domestication, 93, 261–262 Domestic fowl, viii, 36, 86, 103, 216, 220, 221, 250, 308, 363, 365, 375 Dovecote, 103 Drip zones, 262 Duration, 263

Index Fire, 290–291 Firebreaks, 43, 46, 69, 71, 122, 142, 291 Fish, 104, 111, 114, 132 Floating gardens, 59, 291 Food, 2, 4, 5, 11, 101, 104, 113, 126, 131, 132, 145, 165, 173–179, 182, 187, 192, 198, 202, 203 Food forests, 113, 198, 211 Food kilometers/miles, 291–292 Food sovereignty, 178, 179, 180 Food storage, 132 Forage banks, 101, 292, 352 Forest gardens, 110, 112–114, 152, 198, 202 Forestry, see Silviculture Free-form plots, 139, 293, 322 Free-range grazing, 101, 293–294, 299 Frogs, 104, 217 Frost, 295–296 Fungicides, 6, 39, 55, 203, 275, 296, 330, 352 See also Pathogens

E Earthworms, see Vermiculture Eatable insects, see Entomo-agriculture Economic orientation, 263 Eco-services (defined), 1, 39–48 See also Rules Elephants, v, 39, 40, 216, 289, 327 Enemies hypothesis, 268 Energy, 5, 129, 145, 177, 231, 291, 354, 405 Entomo-agriculture, 103, 268–269, 306, 308 Erosion (water), 35, 139, 144, 157, 269, 270, 300, 320, 332 Erosion (wind), 46, 209, 213, 215, 245, 269, 271, 332

G Gabons, 42, 46, 69, 71, 122, 142, 146, 296–297 Game theory, see Decision theory Gathering, 5, 108, 110, 132, 219, 249, 283, 300 Geese, 220, 350, 363, 413, 416 See also Domestic fowl Genetically improved/modified crops, 3, 10, 297 Genetic modification, 3, 5, 10–11, 72, 180, 203, 278, 297–299, 329, 416, 420 Genetic resources, 180–183, 303 GM, see Genetic modification Goats, 89, 102, 111, 159, 294, 295, 331, 350, 352, 375, 386, 387 Grazing, see Pastures/Free-range grazing Grafting, 254, 298–299 Green revolution model, 299 Guidelines, see Rules Guide species, 224, 299–300, 380

F Facilitation, 271–277 See also Rules Factory farming, 12, 278–280, 335 Fallows, 280–282, 416 Family farms, 106, 140, 143, 164, 165, 167, 168, 169 Fencing, 285–289 Field margins, 289–290

H Harvests, 300 Hawthorne effect, 189, 301–302 Hedgerow alley cropping, see Alley cropping Hedges, 302 See also Living fences Heirloom varieties, 181, 303–304 Herbicides, 5, 6, 8–12, 39, 55, 155, 200, 203 Herds, 130, 138, 294, 295, 331, 351

Index Hogs, see Pigs Honeybees, 9, 39, 86, 216, 267, 361–362, 363 See also Pollination Horqueta trees, 304, 320 Horses, 102, 241, 289, 331, 375, 386 Hunting, 5, 39, 132, 216, 221, 294, 314 Hybrid farms, 169 I Industrial farming, 144, 208 See also Commercial farming; Factory farming Infiltration, 304–306 Infiltration (water), 35, 46, 59, 63, 70–71, 90, 128–130, 139, 157 Insect control, 306–314 Insecticides, 314–318 Insects (eatable), see Entomo-agriculture Integrated pest management, 318 Intercropping (seasonal examples), 80–82 Interplant interface, 25, 318–319 Irrigation, 6, 8, 10, 39, 55, 71, 118, 119, 121, 177 See also Drip irrigation Isolated tree agroecosystems, 319–320 L Lakes, 9, 119, 132, 217, 291, 370, 409 Land equivalent ratio (defined), 33 Landscape agroecology, 45, 135–153, 322–324 Landscape economics, 143, 324 Landscapes (categories of), 137–138, 323 Landscape land equivalent ratio (LLER), 325 LER, see Land equivalent ratio Light dynamics, 25, 110, 227, 379 See also Canopy patterns Living fences, 40, 43, 98, 243, 285, 288 See also Hedges Lodging, 277, 296, 380 Low-input agriculture, 31, 121, 209 M Malthus, 174–178 Manure, 5, 12, 42, 43, 46, 101, 155, 162, 209, 229, 240, 241, 249, 292, 312, 329, 332, 340, 344, 388, 409 Matrix equations, 52, 326–328 Microbes, 328–330 Micro-catchments, 42, 46, 69, 70, 146, 305, 330

435 Mimicry, 97, 101, 108, 142, 147, 211, 216, 331, 332, 376 Modeling, 54, 184, 185, 326, 332, 345–346, 389 Monocultures, 335–338 Mounds, 338–339 Mulch, 339–340 Multi-participant agroecosystems, 340, 397 Multi-purpose trees, 42, 46, 158, 194, 341–342 N Natural ecology, vi, vii, 4, 108, 266, 283, 294, 297 Niches, see Competitive partitioning Non-harvest option, 64, 65, 92, 108, 111, 283, 301, 344–345 No-till, see Till/no-till O Opportunity costs, 157–159, 165 Optimization, 345–346 Orchards, see Plantations; Streuobst Organic agriculture, v, 208–210, 239 Oceans, 9, 217, 370, 409 P Paddies, 347 Parklands, 348 Pastures, 350–352 Pathogens, 352–353 Permaculture, v, 209, 353 Pigs (hogs), 103, 114, 215, 289, 294, 331, 350, 375 Pitfalls, 188–189, 306 Plantations, 354–356 Planting methods (shrubs and trees), 357–359 Planting ratios, 21, 23, 24, 78, 184, 260, 359, 361, 369 Pollination, 34, 37, 158, 219, 306, 314, 328, 361–363 Ponds, 363 See also Lakes Population ecology, 4, 318 Precepts (agroecological), 40, 49, 52, 265, 267, 364, 407 Predator-prey, 365 Primary species, 365 Profitability, 29, 31, 55, 142, 143, 162, 279, 319, 326, 332, 334, 346, 347

Index

436 Profit (defined), 28 Pruning (trees), 365–366 Push-pull (insects), 368 Q Quality-of-life, 142, 145, 181, 208, 292, 322, 368–369 R Ratio lines, see Planting ratios Relative value total (RVT), 369 Repellent plants, 36, 41, 49, 216, 218, 267, 306–311, 314, 370, 371, 405, 407 Resource concentration hypothesis, 370 Revenue orientation, 370 Rice paddies, see Paddies Riparian buffers, 370–371 Rivers, 8, 9, 59, 98, 119, 291, 296, 370, 409, 412 See also Streams Robins, 219 Rocks, see Stones Rotations, 371 See also Rules Row orientation, 25, 215, 227, 372–373 Rules (for) below ground interactions, 77 complex agrosystems, 109 eco-services, 40–41, 49, 169, 194 facilitation, 90–91 intercrops, 76–77 landscapes, 139, 324 risk reduction, 125, 126 rotations, 272 shade systems, 78 S Salt, 145, 181, 374, 375 Scarecrows, 38, 215, 216, 220, 251, 368, 375 Scattering (risk), 127–128 Secondary species, 19, 59, 68, 91, 92, 212, 222, 223, 252–254, 271, 365 Semi-husbandry, 375–376 Shade systems, 376 See also Rules Shelterbelts, 43, 46, 69, 71, 122, 142, 374, 380 See also Windbreaks Shrub gardens, 110–113, 211, 212, 371, 393 Sigmoidal equations, 381 Sigmoid functions (illustrated), 18, 50, 125, 160, 232, 235, 237, 274

Silviculture, 110, 114, 202, 381–382 Slash and burn, 338 Slash and char, 388 Slash and mulch, 388, 389 Solution theory (landscape), 147, 389–390 Sparrows, 219 Spatial patterns, 18, 24–26, 42, 57, 72, 77, 108, 192 Starvation, 5, 120, 126, 132, 175, 177 Stones (clusters, walls, etc.), 69, 70, 141, 393–394 Streams, 71, 98, 211, 225, 279, 296, 297, 370, 412 Streuobst, 83, 345, 356, 390 Strip cropping, 391–393 Subsistence farming, 5, 15, 103, 125, 140, 143, 153, 165, 167–169 Support (physical), 90, 94, 100, 277, 395, 410 Surplus ecology, 157 T Taungyas, 396–399 Temperature, 34, 37, 48, 49, 62, 71, 118, 121, 128, 129, 185 Terraces, 399–400 Threat counters, see Eco-services Tierra prieta, 46, 219, 388, 404, 409 Till/no-till, 174, 345, 404–405 Trade, 180, 275, 389 Tradition agriculture, 209 Trap crops, 40, 71, 92, 251, 309, 310, 405–406 Traps (birds and animals), 406–407 Traps (insect), 40, 306, 307, 310, 318 Traumatic release, 309, 407 Tree-over-crop agroecosystems, 167, 282, 408–409 Treerow alley cropping, see Alley cropping Tropical homegardens, 106, 211, 241, 408 Truant resources, 9, 409–410 V Vermiculture, 240–242 Vines, 67, 87, 90, 91, 92, 100, 277, 282, 288, 395, 410 See also Support von Liebig hypothesis, 326 W Wades, 225, 296, 305, 371 Waterbreaks, 43, 69, 71, 122, 142, 411

Index Water channels, 43, 69, 71, 122, 217, 243, 410–411 Water harvesting, 118, 119, 136, 142, 229, 347, 411–412 Weed control, 412–414 Windbreaks, 37, 46, 47, 50, 69, 71, 97, 122, 129, 140, 142, 146, 148, 417 See also Shelterbelts

437 Wind tunnel effect, 37, 418, 419 Woodpeckers, 220, 221, 308 Y Yield functions, see Sigmoidal equations Yield gap analysis, 162, 163, 420