Back to Home Page of CD3WD Project or Back to list of CD3WD Publications

Home - English - French - German - Italian - Portuguese - Spanish
                Go to the people,
                  live among them,
                     learn from them,
                        plan with them,
                          work with them.
                Start with what they know,
                build on what they have.
                But with the best leaders,
                when the work is done,
                  the task accomplished,
                the people will say,
                "We have done this ourselves."
                                            International Movement
                                            for Rural Reconstruction
                      AGRICULTURAL PROJECTS
                     GUIDELINES FOR PLANNING
                     Revised Edition Prepared
                          Miguel Altieri
                 University of California, Berkeley
                          Helen L. Vukasin
                            CODEL, Inc.
                CODEL, Inc. (Coordination in Development)
                VITA (Volunteers in Technical Assistance)
                               CODEL, Inc.
                   Environment and Development Program
                      475 Riverside Drive, Room 1842
                     New York, New York 10115, U.S.A.
                             Order books from:
                      1600 Wilson Boulevard, Suite 500
                        Arlington, Virginia 22209 USA
                  Tel:   703/276-1800 * Fax:  703/243-1865
                  Permission received to reprint as follows.
                       (See Appendix A for citations.)
        International Council for Research on Agroforestry, page 129-134
                     MacMillan Publishing Company, page 76
                        Mujeres en Desarrollo, page 121
                         Praeger Publishers, page 124
                         Prentice-Hall, Inc., page 104
                           Westview Press, page 17
                         Worldwide Neighbors, page 138
                              VITA, page 34, 126
                           Drawings by Linda Jacobs
                           Diagrams by Linda Schmidt
                       Cover Design by Susann Foster Brown
                             CODEL 1990
                           ISBN No. 0-86619-283-2
                 TABLE OF CONTENTS
                PART I:   INTRODUCTION
Chapter 1 - USERS AND USES                         
The Purposes of the Manual                                
Who Should Use This Manual                                
What the Manual Provides                                   
AND ENVIRONMENT                                          
What Is Meant By Ecology and Environment                        
How Agriculture and Environment Are Related                     
Why Ecological Concepts Are Important for Agricultural Development
What Ecosystems Are and Why They Are Important                  
What Happens When Natural Systems Are Altered                   
  The Food Web                                                  
How Stability Relates to Diversity                                 
Succession and Agroecosystems                                     
Limiting Factors                                                  
How Knowledge of Environmental Concepts and Impacts
  Can Be Used to Ensure More Successful Projects               
                PART II:   PLANNING FOR
Chapter 3 - THE PLANNING PROCESS                                      
Who Plans                                                         
The End is the Beginning                                      
Flexible Planning                                                 
1.   Identify and Assess Needs and Constraints                     
2.   Community Profile and Natural Resource Profile               
    Community Profile                                             
    Natural Resource Profile or Inventory                         
       Learning from Local Agricultural Experience                
       Agricultural Practices                                     
       Land Tenure                                              
3.   Define Goals and Objectives                                    
4.   Design Project with Consideration of Trade-Offs               
5.   Implement the Activity                                         
       Training Programs                                          
6.   Monitor the Project                                          
7.   Evaluate the Project                                           
A Summary Checklist                                            
Legal Considerations                                           
Socio-Cultural Considerations                                 
Women and Agriculture                                          
Economic Considerations                                       
REDUCTION OF EROSION                                                
Erosion:   What Is It?                                         
   Sheet Erosion                                               
   Rill Erosion                                                
   Gully Erosion                                                
   Laterite Formation                                          
Soil Loss                                                   
Erosion By Wind Action                                      
Soil Cover and Why It Is Important for Control of Erosion
How Erosion Can Be Controlled                              
How Plant Residues Combat Erosion                           
Improved Tillage Methods for Erosion Control                
   Reduced Tillage                                             
   Conservation Tillage                                        
Crop Rotation and Erosion Control                          
Some Support Practices for Erosion Control                 
   Contour Strip Cropping                                      
The Effects of Soil Management/Erosion Control             
Some Alternatives                                            
Summary of Erosion Control Practices                        
Chapter 6 - WATER SUPPLY AND MANAGEMENT                            
The Major Sources of Water                                     
   Surface Water                                                
The Water Balance in Croplands                              
How Water Moves and the Effects                             
   Physical Transport                                          
   Chemical Transport                                          
The Importance of Irrigated Agriculture                     
Why It Is Necessary to Plan Irrigation
   Projects Carefully                                          
Using Surface Water for Irrigation                         
   Effect on the Aquatic Environment          
   Effect on Farmland                                         
   Salinization and Alkalinization                              
Using Groundwater for Irrigation                           
Irrigation Return Flows and Their Effects                 
Irrigation and Human Health               
Determining the Effects of Water Supply and Management Projects
What Alternatives Exist                                        
Chapter 7 - SOIL NUTRIENT MANAGEMENT                                 
Sources of Plant Nutrients                                    
   Natural Soil Fertility                                        
   Organic Matter                                               
      The Significance of the C/N Ratio                          
      Plant Residues                                             
      Animal Wastes                                             
   Precipitation and Run-on Water                             
   Inorganic Fertilizers                                      
Evaluating the Source of Nutrients                        
The Effects of Fertilizers on the Environment                 
The Effects of Movement or Loss of Soil Nutrients             
   Health Effects                                                
Management of Nutrient-Related Factors                    
   Managing Fertilization                                         
   Crop Rotations                                               
   Animal Wastes                                                
   Plowing-Under Green Legumes                                  
   Controlling Surface Applications                             
The Effects of Nutrient Management                           
Alternatives for Nutrient Control                           
Chapter 8 - PEST MANAGEMENT                                             
Environmentally Sound Pest Management Practices                   
Alternatives to Pesticides                                        
   Local Plants                                                  
   Crop Management Practices                                      
      Resistant Varieties
      Planting Time
      Planting Space
      Destruction of Alternate Host Plants
   Mechanical and Traditional Control Practices
   Biological Control Methods
Integrated Pest Management:  What Is It?
Definition of a Pesticide
Effects of Pesticide Use
   Effects on People
   Effects on Soil Fertility
   Effects of Pesticides on the Balance of Nature
   Some Other Effects of Pesticides                               
   Effects on the Aquatic Environment
   Pesticide Persistence
How Pesticides Move About the Environment
   Pesticide Pathways
   Distribution in Soil
   Distribution in Water
Some Factors That Should Be Considered Before Applying Pesticides
   Local Experience
   Alternative Pest Control Measures
   Timing of Application
   Pesticide Movement
   Precautions Necessary
Checklist for Projecting the Impacts of Chemical
   Pesticide Use and the Potential For Alternatives
Definition and Classification
   Ecologic or Climatic
   Socio-Economic Scale and Level of Management
Some Advantages of Agroforestry Systems
   Ecological Advantages
   Economic and Socio-Economic Advantages
Some Constraints of Agroforestry Systems
Role of Women in Agroforestry
The Role and Effect of Trees
Examples of Traditional Agroforestry Systems
Design of Agroforestry Combinations
   1.  Alley Cropping in High Potential Areas
   2.  Contour Planting
   3.  Fodder Bank - Cut and Carry
   4.  Fodder Bank - Grazing
   5.  Fruit Improvement
   6.  Hedges/Living Fences
   7.  Mixed Intercropping
   8.  Multistorey Planting of Domestic/Industrial Tree Crops
   9.  Tree Planting Around Water Places and Dams
  10.  Selective Clearing
  11.  Woodlot Planting for Fuelwood and Poles
A Checklist for Developing Sustainable Agricultural Projects
Examples of Traditional Resource Management Systems
Long Term Evaluation of Local Agro-Ecosystems
Additional Assistance or Information
Appendix B - Appendix C - GLOSSARY
    The original manuscript for this manual was a creative idea that
developed during a conference in 1977, sponsored by the Mohonk
Preserve, that brought together the US environmental nongovernmental
organizations (NGOs) with those groups that work with
development assistance in the Third World.  Peter Freeman, Robert
Tillman and Ann LaBastille created a document that provided the
basis for the original edition.  Paul and Marilyn Chakroff worked on
a subsequent draft and Laurel Drubin, formerly with VITA, and
CODEL staff edited the manuscript for publication in 1979.  Since
that time CODEL has published four additional volumes on forestry,
water, energy, and livestock.  Each volume has relied heavily on
input from technical experts and potential users in the field.
    The revised edition of the agriculture manual is indebted to
many persons for constructive and helpful comments on a review
draft prepared by Miguel Altieri.  CODEL acknowledges with thanks
contributions from the following:
      Ms. Becky Andrews, Rodale Press, Pennsylvania
      Mr. William R. Austin, Van Wingerden International, Inc.,
        North Carolina
      Mr. Fabio Bedini, Undugu Society of Kenya, Kenya
      Ms. Joan Brinch, Kenya Institute of Organic Farming, Kenya
      Mr. Richard Carpenter, East-West Center, Environment and
        Policy Institute, Hawaii
      Professor Gordon R. Conway, International Institute for Environment   
        and Development, England
      Ms. Margaret Crouch, Volunteers in Technical Assistance,
        Washington, D.C.
      Professor Peter F. Ffolliott, University of Arizona, Arizona
      Mr. Peter Freeman, Development Ecology Information Service,
        Washington, D. C.
      Mr. George Gerardi, Hermandad, Dominican Republic
      Mr. Terry Gips, International Alliance for Sustainable Agriculture,
      Mr. Matthias Quepin, Kenya Institute of Organic Farming,
      Mr. Lawrence Hamilton, East-West Center, Environment and
        Policy Institute, Hawaii
      Ms. Susanna B. Hecht, University of California at Los Angeles,
      Mr. John Michael Kramer, CARE, New York
      Dr. Bede N. Okigbo, International Institute of Tropical Agriculture,
      Rev. John Ostdiek, OFM, Franciscan Missionary Union,
      Mr. W.J. Pape, Swaziland Farmer Development Foundation,
      Ms. Caroline Pezzullo, Pezzullo Associates, New York
      Mr. Coen Reijntjes, Information centre for Low External Input
        Agriculture, The Netherlands
      Mr. Raniari Sabatucci, Kenya Freedom from Hunger Council,
      Rev. Kenneth F. Thesing, MM, Maryknoll, New York
      Dr. Norman Ulsaker, Institute for Alternative Agriculture,
      Mr. Napoleon T. Vergara, Participatory Forestry Development
        Through Extension, FAO Thailand
      Mr. Peter von der Lippe, Christian Children's Fund, Virginia
      Mr. Fred R. Weber, International Resources Development and
        Conservation Services, Idaho
      Bro. Andrew Winka, Christian Brothers Conference, New York
      Mr. Ben Wisner, Hamshire College, Massachusetts
      Dr. Timothy Wood, Wright State University, Ohio
      Mr. Charles S. Wortmann, CIAT Regional Bean Programme of
        Eastern Africa, Uganda
    Miguel Altieri, with assistance from Helen L. Vukasin, CODEL
Environment and Development Program, spent many hours integrating
the useful technical and user suggestions in order to make the
text more useful to the field staff to which it is addressed.
    In addition to the above named persons there are some special
acknowledgments that should be mentioned.  International students
in a forestry class at the University of Arizona each wrote extensive
comments on the Agroforestry chapter that provided useful local
examples and perspectives.  Terry Gips, author of the newly published
book, Breaking the Pesticide Habit, commented helpfully on the
Pest Management chapter.  The candid comments of colleagues in
Africa have helped to reduce the Northern perspective of the text.
    Finally, a special word of gratitude is due to Debra Decker who
contributed her talents to the preparation of the text for printing
with dedication - from the initial draft of the author through all the
subsequent changes.
    We welcome comments from readers of the book.  A questionnaire
is enclosed for your convenience.  Please share your reactions.
      Rev. Boyd Lowry, Executive Director
      Sr. Mary Ann Smith, Environment & Development Program
                      ABOUT CODEL
Coordination in Development (CODEL) is a private, not-for-profit
consortium of forty Christian-related development agencies working
in developing countries.  CODEL funds community development activities
that are locally initiated and implemented.  These activities
include agriculture, water, forestry, health, appropriate technology,
and training projects.
The Environment and Development Program of CODEL serves the
private and voluntary development community by providing workshops,
information, and materials designed to document the urgency,
feasibility, and potential of an approach to small-scale development
that stresses the interdependence with human and natural resources.
This manual is one of several materials developed under the Program
to assist development workers in taking the physical environment
into account during project planning, implementation, and
evaluation.   For more information, contact CODEL, Environment and
Development Program at 475 Riverside Drive, Room 1842, New York,
New York 10115 USA.
                      ABOUT VITA
Volunteers in Technical Assistance (VITA) is a private non-profit
international development organization.  It makes available to
individuals and groups in developing countries a variety of information
and technical resources aimed at fostering self-sufficiency:  needs
assessment and program development support; by-mail and on-site
consulting services; information systems training; and management of
fields projects.  VITA promotes the use of appropriate small-scale
technologies, especially in the area of renewable energy.  VITA's
extensive documentation center and worldwide roster of volunteer
technical experts enable it to respond to thousands of technical
inquiries each year.  It also publishes a quarterly magazine and a
variety of technical manuals and bulletins.  For more information,
contact VITA at 1815 N. Lynn Street, Suite 200, Arlington, Virginia
22209 USA.
                    PART I:   INTRODUCTION
                      CHAPTER 1
                        USERS AND USES
                  THE PURPOSES OF THE MANUAL
    This manual is designed to assist those who plan and implement
small-scale agricultural projects.  By promoting awareness of
environmental concerns, the manual can increase the development
worker's ability to design projects that are both environmentally
sound and potentially more sustainable.
    This manual has two objectives:
    1.  To promote well-planned and environmentally sound small-scale
        agricultural projects.
    2.  To introduce environmental concepts into technology development
        and alternative management techniques, and encourage
        the transfer into training programs.
    Environmentally sound planning requires more than finding the
right technology and a source of funds.  Planning involves consideration
of the social, cultural, economic, and natural environments in
which the project occurs.  The challenge is to develop sustainable
food systems that have reasonable production but do not degrade the
resource-base and upset the ecological balance.  Development workers
are in a position to pass on awareness of environmental concerns to
community groups, government planners, village residents, farmers,
and students.  For example, a development worker may use this
manual in a training course to increase students' awareness of erosion
control methods and alternatives.  As a project planner or implementor,
a development worker may wish to use the book for planning
or on-the-job training of project workers or for technical training
of farmers and local residents.
    By providing guidelines to planning, this manual can assist
development workers to view projects as part of larger environmental
systems.   It offers a perspective that can assist users to ask the
right questions and to look for and find information about local
resource availability and use, traditional methods, weather patterns,
social, and cultural traditions.
    Many issues of importance to small-scale agricultural projects
that need to be considered are beyond the scope of this manual.
These include: land use patterns; inability of small landless farmers
to take risks; lack of credit and money; and access to technical
personnel and appropriate agricultural expertise.  Finally, this
manual cannot address all of the environmental conditions or implications
associated with individual project sites.  The use of the
general concepts and principles outlined here should enable development
workers to recognize environmental issues and to consider
them in the planning process.
    This manual has been prepared for those who are actively
engaged in planning and implementing small-scale agricultural
projects.   It will be most useful for those who wish to:
    - learn more about environmental considerations and their
      relationship to small-scale agricultural projects
    - approach agricultural projects, even though small, from an
      environmentally aware perspective through the promotion of
      technologies appropriate to the situation
    - integrate environmental and socio-economic factors into
      agricultural planning activities, so that recommended technologies
      fit the resource base, perceptions, and needs of local
    The manual covers the following subjects:
    * Introduction to important ecological concepts relevant to the
      development of agricultural projects.
    * Technical information related to environmental issues.
    * Some suggestions for planning small-scale agricultural
    * Guidelines for using knowledge of environmental effects to
      determine positive (benefits) and negative (costs) factors in a
      given small-scale agricultural effort.
    Consideration of these factors can lead to well-informed decisions
on alternative project designs.  In addition, this background
information can be used as the basis for planning environmentally
sound projects in the areas of water supply and management, nutrient
management, soil conservation, pest management, and related
                    CHAPTER 2
                        AND ENVIRONMENT
    Agriculture is defined as the science, business, and art of growing
crops and rearing animals in order to produce food, fodder, fiber,
and other products useful to people.  A customary goal of agricultural
projects is to enhance food production for growing populations.
Such projects should also be concerned with the farm as a
multiple-use system that includes animals and plants other than food
crops.   However, this manual emphasizes crop production.  Other
volumes in the series deal with livestock, forestry, water, and energy.
    Crop production can be increased by one or more of the following:
     - expanding the area planted to crops
     - increasing the yield per unit area of individual crops
     - growing more crops per year (in time and/or space) on the
       same unit of land

03p04y.gif (600x600)

03p04z.gif (486x486)

Agriculture is essentially an environmental activity.  It is a process
of adapting the natural ecosystem in order to channel energy to
people in the form of food.  The process works by modifying the
environment by the addition of energy and resources.  The greater
the degree of modification of the natural system, the more energy
can be channeled to humans.  At the same time, modification may
also decrease the stability and sustainability of the system.   (Altieri
    Agricultural systems that have greatly modified the natural
system are thus dependent on high energy and resource inputs to
achieve and maintain a desired level of yield.  In the tropics commercial
cash crops (monocultures) and tree-based plantations require
more human intervention than annual multi-crops (polycultures) and
combinations of ground and tree crops (agroforestry systems).

03p05y.gif (540x540)

03p05z.gif (600x600)

    Systems that require more input and intervention are usually
associated with higher resource depletion and negative social impacts
than low-input, diversified agricultural systems.  Modification, however,
also implies the possibility of enhancing the environment for
humans in addition to the negative impact on the environment
resulting from altering the natural system.  The fundamental objective
of agricultural development should be to balance these two
possibilities in the search for environmentally sound and socially
acceptable agricultural production techniques.
    Environmental problems in some areas have developed because
of the misapplication of temperate-zone technologies to the tropics.
Sustaining yields in these areas will only be achieved through
farming methods unique to the ecological and socio-economic conditions
of the tropics.  (Dover and Talbot 2.5)
    Many environmental concepts have their basis in the science of
ecology.   Ecology is defined as the study of the structure and function
of nature, or the interactions among and between the living and
non-living components of the place being studied.  Ecology, then,
includes aspects of the sciences of biology, physiology, geology,
chemistry, meteorology, and others in the study of natural systems
or ecosystems.
    In agriculture, the appropriate level of organization to be
studied and managed is the agroecosystem and the corresponding
discipline is agroecology.  All that ecologists study--such as the
distribution, abundance, and interactions between organisms and
within the physical environment, succession, and the flows of energy
and materials--are important for an understanding of agroecosystems.
These ecological processes can shed light on the development of
sustainable agricultural technologies.  In agricultural studies, the
social sciences also are critical in understanding the relation between
natural and social systems.  (Altieri 2.1, King 2.6)
    Environment, on the other hand, defines the natural, social,
cultural, and economic surroundings of a project.  Agricultural
projects influence and are influenced by environmental factors.
    Each agricultural project takes place within a complex system
of social attitudes, cultural framework and practices, economic
structures, and physical, chemical, and biological factors.   This total
system is the environment in which a project occurs, and every
agricultural project, no matter what its size or scope, affects and is
affected by these factors, i.e., by its environment.  The many forms
of agriculture found throughout the world are the result of variations
in local climate, soil, economics, social structure, and history.   Water
availability, solar radiation, temperature, and soil conditions are the
main determinants of the physical ability of crops to grow and
farming systems to exist.  Human factors that play dominant roles
include social, economic, and political considerations.   Among these
are: traditional and religious practices; cost and ease of transport;
existence of marketing channels; inflationary tendencies; availability
of capital and credit; and stability of the government, accompanied
by continuity and consistency in policies, programs, and commitment.
In other words the environment of any one area consists of the
biosphere in the area, including the time, customs, and practices of
the people.  (Briggs and Courtney 2.2)
    Farming systems also depend heavily on the character of
production, i.e., whether the crops are produced in a subsistence or a
commercial economy.  The subsistence farmer produces crops primarily
for family consumption.  Consequently, there may be resistance to
change in production methods because livelihood and survival are
threatened if the changes turn out to be unproductive.  Commercial
farmers, subject to market conditions, may also resist change because
they are not willing to take the risk or because they are not willing
to sacrifice short-term gains.
    The way crops are grown further depends on the availability
and level of technology, the availability of suitable land area, and
other resources.  High levels of technology and large land units are
generally accompanied by a high degree of mechanization, and
uniformity of land, soil fertility, and genotype.  On the other hand
low levels of technology and small parcels of land are usually associated
with varying soils, intensive cropping systems, and less

03p08y.gif (600x600)

03p08z.gif (540x540)

    All agricultural development projects, whether they involve
irrigation, pest control, fertilization, or the introduction of new
varieties of crops and cropping methods, have positive and negative
effects upon the environment.
    Some of the interactions between parts of the total environment
can be easily forecast.  For example, it is clear that the
amount of rainfall, the money available for the project, and the
involvement in the project of local people are factors that can affect
the success of an agricultural project.  Other factors, however, such
as the effect of using certain pesticides over a long period of time are
much harder to predict.
    Environment in the agricultural setting has been defined here
to include the people of the region, the animals, the plants, soil,
water, nutrients, the weather, ways of planting and cultivating, and
so on.   Those planning and implementing small-scale projects must
consider all of these influences.  Interactions between agroecosystems
and social systems involve exchanges of energy, materials, and
information between both systems.  The decisions that farmers make
in using a cropping system or technology depend not only on the
technology and local resources available but numerous aspects of the
surrounding social system as well.
    Agricultural development implies continuing change in the
system toward an improved system.  Therefore, in order for development
to occur as a result of agricultural project activities, the alterations
or changes made as a result of the project must have more
positive effects than negative.  Because they are principles explaining
how ecosystems function, ecological concepts can provide assistance
with judging how the natural environment may be affected by
agricultural projects.  Moreover, understanding the ecological
mechanisms that underlie basic processes in natural ecosystems
(such as nutrient cycling, succession, and others), can provide important
information for developing appropriate low input alternatives for
soil management, pest and disease management, development of
technologies for various activities from planting to post-harvest
phase, and other needs.
                      WHAT ECOSYSTEMS ARE AND
                      WHY THEY ARE IMPORTANT
    A planner viewing a potential project site is looking at an
ecological or natural system--an ecosystem.  An ecosystem is defined
as the complex of organisms interacting among themselves and with
the non-living environment in processes such as competition, predation,
decomposition, feeding, habitat, and so on.  The structure of the
ecosystem is related to species diversity.  The more complex the
structure the greater the diversity of species.  The function of the
ecosystem is related to the flow of energy and the cycling of materials
through the structure.  The relative amount of energy needed to
maintain the system depends upon its structure.  The more complex
and mature it is, the less energy it needs to maintain the structure.
When an agricultural project interferes with the flow of energy
and/or materials through the natural system or ecosystem by adding
fertilizers or eradicating pests, ecological patterns may be changed.
    Whether an area is farmland under rice cultivation for many
years, or a virgin forest, it is a functioning system.  Any decision
made to introduce change, such as replacing the rice with a new crop
or cutting down the forest for agriculture, should be made with an
awareness of the characteristics of the existing system and of the
potential effects such a decision would have.
    A good example is the substitution of tractor for buffalo power
in rice fields of Sri Lanka.  At first sight, the substitution of tractor
for buffalo seems to involve a straightforward trade-off between more
timely planting and labor saving, on the one hand, and the provision
of milk and manure, on the other.  But associated with buffaloes are
buffalo wallows and these in turn provide a surprising number of
benefits.   In the dry season these mud holes are a refuge for fish
who then move back to the rice fields in the rainy season.  Some
fish are caught and eaten by the farmers and by the landless,
providing valuable protein; other fish eat the larvae of mosquitoes
that carry malaria.  The thickets harbor snakes that eat rats that
eat rice, and lizards that eat the crabs that make destructive holes
in the ricebunds.  The wallows are also used by the villagers to soak
coconut fronds in preparation for thatching.  If the wallows are lost
because of mechanization, so are these benefits.  Moreover, the
adverse consequences may not stop there.  If pesticides are brought
in to kill the rats, crabs or mosquito larvae, then pollution or pesticide
resistance or both can become a problem.  Similarly if tiles are
substituted for the thatch this may hasten forest destruction since
firewood is required to bake the tiles.
    In forest ecosystems there are also dynamic relationships
among the components.  Trees protect forest soils by serving as
wind-breaks, by breaking and cushioning the beating action of
raindrops so that rainwater can be absorbed slowly and prevent
runoff.   Trees also provide shade and cooler temperatures underneath
the tree canopy.  This protection of the soil allows dead organic
matter to decompose, releasing important nutrients used for growth
by the forest plants.  Forests also provide habitat for wildlife and
certain trees produce valuable fuelwood, construction materials, and
medicinal substances--all resources used by local farmers.   When a
development worker makes the decision to assist the farmer to
increase yields by substituting another crop for rice or cutting down
all or part of the forest, it is also a decision about interacting with
the ecosystem.  For that reason the environmental ramifications
should be taken into account.
                        ARE ALTERED
    A look at the forest ecosystem will show what can happen

03p12y.gif (486x486)

03p12z.gif (486x486)

when the protection of the trees is taken away and not replaced by
other cover:
    * Wind can pick up the organic matter and dry out the soil so
      that it is not good for cultivation.
    * Nutrient-rich soil particles may be dislodged by raindrops
      during rain storms.   Both soil particles and nutrients in
      solution may be carried away.
    * Protection against flooding may disappear.  Forests maintain
      soil porosity, aid the infiltration of rain, and retard the
      surface movement of water, thereby protecting villages from
      floods and retaining moisture in the soil.
    * Sources of firewood, lumber, and tree crops for domestic
      needs are no longer available.
    * Diversity of plant and animal life is affected.  Many birds,
      mammals, reptiles, amphibians, and insects that prey upon
      agricultural pests disappear with the loss of the forest
The Food Web
    Plants, plant-eating animals, predators, scavengers and decomposers
interact in what is commonly called a "food web."   Through

03p13.gif (486x486)

the food web, food energy moves in one direction:  from producers to
    With a knowledge of the dynamics of the food web, the quantity
of food available to us can be increased by:
    - reducing the number of organisms that compete for the same
    - converting forests and rangelands into cropland
    - increasing the efficiency of food use by livestock by improving
      animal husbandry practices
    - growing crops that put more photosynthetic energy into
      edible parts
    - eating less meat and more fruits, vegetables, and cereals
    All these efforts are limited by the energy inefficiencies that are
inherent in food webs, since there is energy lost at each transfer
from one trophic level to another trophic level.
    When land is cleared for agricultural crops, usually the numbers
and kinds of plants and animals living there are greatly reduced.
It is often best to design projects that will maintain the diversity
of the plants and animals insofar as possible.  Ecological theory
holds that diversity is often related to stability, implying that ecosystems
that contain many different kinds of species are more stable
than those containing only one (as in monoculture).
    It is clear, however, from recent evidence that agricultural
ecosystems cannot be made more stable by simply increasing complexity.
Instead biological interactions with potential stabilizing
effects must be encouraged.  For example, it is known that diversification
of the vegetational component of agroecosystems with
certain plant associations often significantly lowers pest population,
even below economic thresholds and result in agronomic benefits.
The challenge is to evaluate which crop assemblages will result in
such benefits.
    For example, forest ecosystems tend to be very diverse and
usually stable.  Severe stress on the physical environment (e.g., by
drought) is less likely to adversely affect such a system because
numerous alternatives exist for the transfer of energy and nutrients
through the system.  Similarly, internal biological or biotic controls
(such as predator-prey relationships) prevent destructive shifts in
pest population numbers.  Hence, the system is capable of adjusting
and continuing to function with little if any detectable disruption.
    Agricultural ecosystems, on the other hand, (particularly those
that promote the use of monoculture cropping systems) are likely to
be less stable because a single species represents a high proportion
of the total number of plants on the site.  Such systems, despite
their initial high yields, carry with them the disadvantages characteristic
of new, young, and developing ecosystems.  Particularly, they
are unable to perform protective functions such as soil conservation,
nutrient cycling, and population regulation.  The functioning of the
system depends on continued human intervention in the form of
chemical inputs, mechanization, and irrigation.  Nevertheless, monoculture
systems may be easier to plant and less time-consuming to
tend, and also lend themselves more readily to mechanization, use of
chemical inputs, manipulation in various ways, and the advantages
ofeconomies of scale.  On the other hand, some polyculture systems
developed by small farmers throughout the Third World may also
require less effort to tend.  For example, corn, bean, and cassava
crop combinations in Costa Rica have been found to be less labor
demanding because of reduced weed growth in the multi-crop fields.

03p14.gif (600x600)


03p15.gif (600x600)

    One of the major reasons that small farmers choose to use
multi-crop systems (polycultures) is that frequently more yield can be
harvested from a given area sown in polyculture than from an
equivalent area sown in separate patches of a single crop (monoculture).
Over the long term, single crop systems tend to be more
susceptible to major crop failure than a multi-crop farm.  For example,
look at a multi-crop farm containing equal numbers of pea,
maize (corn), and bean plants compared with a monoculture maize
farm.   If both farms were attacked by a disease or insect that
destroyed 80 per cent of the corn, the multi-crop farmer would still
have a 73 per cent yield.
    These considerations must be evaluated in view of local situations,
therefore small-scale experimentation is recommended whenever
farmers are considering changing present crops or cropping
methods.   (Bunch 3.4)
    Ecosystems tend toward complexity as they approach maturity.
Immature ecosystems are less diverse and have a high energy in-flow
per unit of biomass.  In mature ecosystems that are more complex,
there is less accumulation of energy because the energy flows
through more diverse channels.  This flow or change is called succession.
Succession refers to the process in which plant and animal
species enter a site, change the site, and are later replaced by other
types of plants and animals.  The repeated invasion and replacement
continues until the site is dominated by types of plants and animals
that replace themselves and are not forced out by other species.   The
final stage is known as the "climax community" for the site.   The
climax species will remain relatively unchanged until the site is disturbed
by fire, changes in climate or water table, or by human
activities, such as clearing land by logging or for farming.   (Cox and
Atkins 2.4)
    The succession process can take hundreds of years, but the
early stages can be seen much more quickly.  If a field is left fallow
for one growing season, weeds, legumes, grasses, and wildflowers will
invade the field, along with various insects, rodents, and birds.   Left
alone for many years, the field will eventually become a forest or
some other climax community, but not necessarily similar to the
community that previously existed on the site.  Succession may be
occurring under different conditions than previously and produce a
different climax.  This makes conservation of existing ecosystems
even more important.
    The observation and study of succession in local natural ecosystems
has apparently guided many traditional farmers in the design
and structuring of their agricultural systems.  For example, farmers
in West Java follow a system comprised of three stages--kebun, a
mixture of annual crops; kebun-campuran incorporates some perennials;
and the talun, a climax dominated by perennials, closely
mimicking the successional sequence of neighboring tropical rainforests.
(Marten 2.7)

03p17.gif (600x600)

    Succession tends to restore agricultural sites to the original
ecosystems--if not prevented from doing so by the farmer.  To prevent
natural succession, the farmer has to interfere with the process
continuously by weeding (manually or by applying herbicides), or by
mulching or flooding.  In many cases, succession would return a site
to forest, secondary bush, woodland, or thicket vegetation within
decades, or even years, thereby reversing negative effects of certain
activities and induced changes in the environment.  Thus the impact
is reversible.  However, if a project has had major impacts on the
site, such as altering the water table or resulting in massive erosion
of topsoil, natural succession can take centuries or may never return
the site to its previous condition.  The impact may be irreversible.
For example, sites exist where humans cleared out forests centuries
ago only to have the unprotected site remain as a barren desert.
The development worker should consider seriously the magnitude of
the project and whether its effects are reversible or irreversible by
natural processes.
    In the well-known traditional practice of slash and burn
agriculture, farmers clear a patch of forest and burn the biomass to
release nutrients before planting their crops.  Once the soil fertility
that was built up over many years is exhausted by continuous
cropping, the farmer moves to a new site and begins the cycle again.
On the uncropped (fallow) land, succession takes over.   If enough
time is allowed to elapse the land may again take on the characteristics
of the original community and nutrients will be restored to the
    Population growth and land tenure problems have caused
fallow years to be reduced or eliminated in many areas, thus, over
time decreasing the soil fertility.  Because the decision to cultivate a
certain area requires a continuous supply of nutrients, organic or
inorganic fertilizers will have to be added to the site.  Inorganic
fertilizers supply necessary chemical nutrients, but do not supply
organic matter to the soil or contribute to the maintenance or improvement
of soil structure over the long term.  The use of manure
and organic fertilizer should be considered in the planning process
from the beginning.  Care should be taken that sufficient nitrogen is
present, which may have to be supplied by chemical sources.
    In areas of Nigeria where the fallow period has become progressively
shorter, an improved fallow system was developed by the
International Institute for Tropical Agriculture.  (See Appendix B for
address.)   Leguminous shrubs and trees (e.g., Leucaena leucocephala)
are planted in association with food crops to restore soil nutrients.
In these "alley cropping systems" food crops are grown in rows (2-4
m. wide) between strips of Leucaena which are pruned during
cropping.   The prunings provide green manure and mulch for the
companion crops, erosion control, fodder, firewood, and staking
material.   In a trial, Leucaena rows averaged 100-162 kg. of soil
nitrogen per meter, increasing maize yields about 23 per cent.   It
has been observed that Leucaena prunings are a more effective
nitrogen source when incorporated in the soil than when applied as

03p19.gif (600x600)

                      LIMITING FACTORS
    Agricultural projects are undertaken in all kinds of environments--forest,
flatland, mountainside, or coastal plain.  In each area
there are factors that will determine crop distribution and performance.
In some agricultural projects, crop production can be improved
by increasing or decreasing one factor.  For example, in a
given project area, climate, nutrient availability, and soil type may
be perfect for the growth of rice.  However, there is not enough
water for rice plants to grow.  In another field, conditions may be
good for corn but there is so much water the corn will drown.   In
both cases, water availability is the limiting factor:  it dictates both
the type and the quantity of growth on the site.
    The physical environmental conditions of an area--temperature
range, amount, timing, and intensity of rainfall, soil characteristics,
and availability of nutrients--dictate the variety and density of plant
and animal species that can live in an ecosystem.

03p21.gif (600x600)

    In rainfed areas, the distribution and amount of rainfall are
perhaps the most critical determinants of the types of cropping
systems that can be adopted.  In some areas where rainfall is limited,
irrigation is not feasible.  Crops that require less water are the
obvious choice for such areas.  Water-conserving measures such as
mulching, fallowing, and terracing can often conserve enough water
to make the difference between profit and loss.  In areas where
annual rainfall is over 600 mm, cropping systems are generally based
on maize.  In areas where rainfall is over 1,500 mm per year, cropping
systems are often based on rice.  Other crops grown with the
latter rainfall pattern are roots, cocoyams, tubers, plantains, and
bananas among others.  For example in Southeast Asia, various crop
systems fit the rainfall pattern, which is a single annual rainy
season.   Since rice needs more water than other cereal crops, and
because it is the only major crop that tolerates flooding, only rice is
grown at the peak of the rains.  Upland crops can be planted at the
beginning and/or end of the rains to utilize residual moisture and
higher light intensities during the dry season (System I).  Mixed
cropping systems, such as, maize and groundnuts, are often best
reserved until the end of the rainy season (System II).
    Natural sites are able to support a number of plants and
animals.   The limits of this support are determined by the availability
of the elements needed for life.  This limit is known as the site's
biological potential or carrying capacity.  Obviously, the biological
potential of a fertile flood plain is much greater than that of arid
lands of the same size because more water, better soil, and more
nutrients are available to organisms living there.
    Biological potential can be increased by adjusting the limiting
factors.   Crop production can be increased by adding limiting elements.
These might be fertilizer, organic matter, water, or some
form of pest control.  Improved technology can also affect limiting
    When considering limiting factors, remember:
    * Satisfying the most obvious limiting factor may not solve the
      problem.   In fact, satisfying one limiting factor may reveal
      yet another.   For example, when nitrogen is lacking in a
      corn field, the farmer may add a nitrogenous fertilizer.  He
      may then find that nitrogen-induced crop growth attracts a
      greater pest attack, thus revealing a new limiting factor.
    * There are upper and lower limits to the amounts of nutrients
      plants can use.
    * Changing present conditions by adding limiting factors may
      harm currently adapted organisms.
    Understanding the concept of limiting factors and knowledge of
how ecosystems function constitute a basis for drawing up appropriate
and ecologically sound guidelines for planning agricultural projects
that are more sustainable.
    A feasibility study of a project should consider potential ecological
change, as well as economic, social, and cultural factors that may
influence the project.  If this process indicates a number of possible
good and/or bad effects, the development worker then looks for
acceptable alternatives or makes what seem to be acceptable
trade-offs or compromises based on the situation.  For example, if
people are starving and increased crop production seems to require
use of a pesticide that may be harmful, the decision will depend on
the urgency of the situation, but the planners and the community
need to be aware of the implications of pesticide use and take
    In order for small-scale agricultural efforts to benefit from an
environmentally sound approach, planners should be aware of the
environmental factors impinging on the type of agricultural project
being considered, and then utilize this information to design management
options that limit environmental impacts.
                             PART II:
                     CHAPTER 3
                   THE PLANNING PROCESS
    This book contends that all development activities must have a
substantial basis of local participation in planning, decision making,
and implementation.  Planning is often described as a linear process
of identifying needs, proceeding to project objectives, and designing a
project to meet those objectives.  In reality the process is and should
be more complex.  Effective planning of a project is a dynamic
process involving the beneficiaries, the implementors, and any outsiders
who are assisting.  The initiator may be the community itself
or it may be an outside development assistance agent or organization.
In either case the partnership relations between the community
and outside assistance must be balanced if the development
activity is to belong to the community.
                      WHO PLANS
    Planning can be done on an international, national, regional, or
local level.  It may be initiated by the local community people on
their own initiative, by nongovernmental organizations, by regional
government officers, or personnel of national universities or ministries.
Whatever the level or whoever the initiators, the sustainability
of the activities will be depend on the involvement in the planning
and decision making of those the project is intended to benefit.
                THE END IS THE BEGINNING
    Meeting the needs of beneficiaries is both the beginning and
the end goal of development activities.  If the initiator is a community
group, group members need to sit together and explore their
needs and the resources available to meet those needs.  If the
initiators are external to the community, they need to sit with the
community and identify needs and resources from the local perspective.
    A local group organizing a project must establish a clear
picture of itself and the natural resource base.  External agencies
must also gather a profile of the community and a profile of the
resource bases of the activity.
    The next step is for the community to define the goals and
objectives of the activity being undertaken to meet identified needs.
If there is an external agency involved the process should be collaborative.
Plans for the activity can be made based on the ultimate
goal and the specific objectives.  This part of the planning process
needs to be done with conscious recognition of the tradeoffs involved
in meeting needs with limited resources and the realities of politics,
cultural values, and preservation of the natural resource base.
    The project may need input of a technical nature in design,
implementation, monitoring, and redesigning.  If there is external
assistance, the evaluation should not be external but participatory.
    Various quantitative techniques may be used to help complete
the basic phases of the planning process.  Such techniques will help
establish a baseline against which to measure accomplishments.
Some of these quantitative techniques can be quite detailed, requiring
the use of computer programs and simulation techniques.  Customarily,
a development worker will not have ready access to computer
programs and simulation techniques.  In that case, it is helpful
to have a checklist for a guide as planning proceeds.  Some checklists
that may be useful can be found later in this chapter.  A
framework outlining this planning process is on the following page.
                   FLEXIBLE PLANNING
    Flexible planning is the ability to use a framework and the
information and perspective provided by it creatively in designing a

03p26.gif (600x600)

    A planning framework/methodology presents a logical, step-by--step
method for defining and integrating project variables and for
choosing among project opportunities.  Because the steps in the
planning process have been lifted out of a "real context," they may
appear neat and well ordered.  In reality, the steps to be taken in a
given project are not likely to be clear-cut (at least initially) and the
variables and components may be difficult to categorize.  A good
methodology helps the user work through the mass of information
available to structure steps that are possible and feasible.   For
example, a planner can use this methodology to determine priority
among a number of possible projects and to decide when a project
design, perhaps because of a likely imbalance in benefits/costs terms,
should be changed.
    The key to good planning is applying a problem-solving approach
flexibly within pre-determined boundaries.  The boundaries,
or guidelines, are things that should not be changed--except for very
good reasons.  Certain aspects of a project can be altered easily
because they represent different methods of accomplishing the project
within the same boundaries.  Alterations that do change the boundaries
must be made only with great caution.  These guidelines, once
set, can provide the basis for an environmentally sound, small-scale
agricultural project in various local situations and with alternative
project designs.
    When community members participate in all phases of project
planning, execution, and evaluation, they will be more committed to
the project and have a sense of ownership.  Arousing and maintaining
community participation is a challenging task.  It is not
difficult to communicate with one or two leaders or a small group.
However, involving the whole community and helping them to realize
what can be achieved is more difficult.  Some references on the
subject are included in Appendix A.
    Planners and community members may not always agree on
the priority needs of a community.  Each is looking at the problem
from their own point of view.  If planners begin a project that addresses
needs that are not identified by the community, there will be
insufficient support from the community.  With the participation of
local people, planners can learn which issues are critical to the
    Communities are groups of individuals that may have conflicting
goals.   If the project satisfies only the goals of certain members
of the community, planners should make sure that the project does
no harm to those who are not participating.  A project that satisfies
the needs of several different groups within the community will be
more sustainable.
    Where commercial sales of agricultural products are involved,
wholesalers, retailers, and transporters should be included in planning.
These groups are experienced with marketing problems and
with past successes and failures.  If all related groups are included
in the development process, they can explore the reasons why projects
have failed, so that mistakes are not repeated.
                      RESOURCE PROFILE
Community Profile
    A community profile can be an important tool for the development
worker from outside the community as well as a community
group planning a project.  The profile should be structured so that it
will provide easy-to-use data on key social, economic, cultural, and
natural characteristics of the community or region.  The profile does
not have to be prepared in great detail, nor should it take weeks and
months to complete.  The topics suggested here for inclusion highlight
agricultural activities.  The user will want to gear the profile so
it yields data relevant to the primary area of concern.
    * Determine the social structure and kinship relationships of
      the community.   Note these particularly as they pertain to
      agricultural activities such as cultivating, harvesting, marketing,
    * Understand the traditional roles of men and women in relation
      to the agricultural system.   Include all related activities
      such as land preparation, planning, harvesting, storage, sale
      and other aspects of crop management.
    * Note the cultural traditions and folkways of the community
      associated with food production.
    * Identify community leaders, their spheres of influence, and
      how these may or may not affect agricultural activities.
    * Analyze the economy of the community and the area, especially
      as it relates to phases of agricultural production, such
      as cultivation, harvest and post-harvest activities.
    * Consider marketing opportunities or lack of markets.
    * Note land use and ownership patterns.
    * Note availability of such services, as credit mechanisms,
      agricultural extension, and agricultural information.
    * Determine people's ability to put more time into crop production
      or to take risks.
    * Include a range of perspectives among community members
      on agricultural and personal needs and the priority of each
    * Verify all of the above with the community.
    The planner will also want to be sure that the community
profile encompasses all the information that is relevant to the community
and the project.
Natural Resource Profile or Inventory
    A survey of the natural environment (climate, soil, topography,
rainfall, soil fertility, pests, etc.) provides information necessary for
assessing project feasibility and for determining potential benefits
and costs as well as required modification.  For small-scale projects,
the inventory need not be turned into an intensive study, but rather
a rapid rural appraisal method.  It can be a useful tool providing a
baseline to which to refer after the project is underway.
    There are at least two levels at which inventories should be
done.   The first consists of creating an overview picture of the area
ecosystem.   As part of this inventory, the planner should look at
such things as watershed characteristics, significant topographical
features, general rainfall distribution patterns, general climatic
information.   This information may be available through local
sources, by observation, or discussion with local people.
    The second inventory is a localized biophysical and socio-economic
review.   The biophysical evaluation entails an identification of
land types, cropping systems, farming systems determinants, and the
interactions among farm components.  The socio-economic review
analyzes the resources needed for the farming systems (human
resources, land, credit, capital, etc.) on a seasonal basis.
Learning from Local Agricultural Experience.  Learning from local
agricultural experience is important because agricultural practices in
many countries are already well-adapted to prevailing environmental
conditions.   Over many years of trial and error, farmers have developed
systems that work.  As more research is conducted, many
farming practices, once regarded as primitive or misguided are now
recognized as sophisticated and appropriate.  Confronted with specific
problems of slope, flooding, droughts, pests and diseases, and low soil
fertility, small farmers throughout the world have developed unique
management systems aimed at overcoming these constraints.
    By learning about local practices, it is possible to obtain further
information on (Chambers 3.5):
    - local crop varieties that have shown particular resistance to
      disease and pests
    - cropping methods, such as intercropping and multiple cropping,
      that are designed to get the most out of small land
    - availability and use of organic fertilizers (e.g., manure and
      compost) that do not have to be purchased
    - agricultural methods that conserve water, soil, and nutrients
    - agricultural methods that may require less time, money, and
      labor than some other alternatives
    - agricultural tools which are made locally and are suited to
      local needs
    All this information can serve as a starting point to develop
appropriate agricultural systems and technologies adapted to local
    This inventory should also cover the following among other
Agricultural Practices
    * What crops are grown and why?
    * Who is growing which crops (men or women)?
    * Are crops grown for consumption, cash, medicine or other?
    * What local resources are available for food production?  Are
      they used efficiently?
    * Are there food shortages or surpluses?
    * What are the major causes of crop loss?
    * Are pests a serious problem?   Which ones?  Which pest
      control methods are in use?
    * Do current crops provide adequate nutrition for human diet?
    * Do current cropping systems improve or lessen the nutrient
      content of the soil?
    * Do local agricultural practices promote or otherwise enhance
      watershed management and soil conservation?
    * What types of soils dominate?
    * What is the organic and nutrient content of the soil?
    * Are there signs of degradation, such as compaction, erosion,
      light colored soils?
    * Is wind erosion a problem?
    * What is the topography and how does it affect soil quality
      and water/soil relations?
    * What kinds of organisms does the soil contain?  Are earthworms,
      protozoa, grubs present?
    * What fertilizing practices are used, if any?  What ingredients
      are available for composting?
    * What are the major local sources of water?  Is the same
      water source used by both animals and people?
    * Is the water of good quality?
    * What water-carrying methods are used to bring water to
    * Is the water table relatively stable?
    * What kind of vegetation exists around the water source?
    * Is the supply of water steady year round?
    * Is there much fluctuation in water supply due to heavy
      flooding or drought?
    * What type of watershed management is used?
    * What are the rainfall/sunshine patterns?
    * Do floods and droughts present serious seasonal problems?
    * Is altitude an important factor?
    * Is wind a predominant feature?
Land Tenure
    * Who owns the land in the community?
    * How many are landless and engage in day-labor on other's
    * What are the characteristics of the land available for farming,
      for example size, existence of or potential for irrigation,
      topography, land cover?
    * Is the land titled or registered?
    * Can additional land be acquired?
    * Who owns or controls water sources and water rights?
    * Is land being priced out of the agricultural market?
    The above checklists of questions should help to meet the
ultimate objectives of the survey which are to:
    * Define the productive potential of each agroecological zone.
    * Delineate the limiting factors (i.e., zones of moisture surplus
      or deficit) so that appropriate techniques of resource conservation
      are developed.
    * Identify other areas with similar ecological environments and
      social contexts, so that technology developed in one environment
      can be transferred.
    * Facilitate the choice of appropriate agricultural inputs and
      technologies and quantify the levels of risks associated with
    * Promote development of sustainable farming systems with
      well defined inputs, calendars, and outputs.
                 3.   DEFINE GOALS AND OBJECTIVES
    After the community has identified needs with the highest
priority, the goals and objectives that address these needs can be
formulated by the group.  A goal is an overall purpose for undertaking
the project.  The objectives help direct action toward this
general purpose.   
    Objectives are the more specific targets that will be achieved
by the project.  Objectives should be clearly defined, measurable, and
feasible.   An objective should indicate what is to be achieved, when
it will be completed, and how success will be measured.  The objective
should state actual numbers, such as, the number of hectares
involved, the kind of crops to be produced, the number of wells to be
constructed, and so forth.
    If the objective states when achievements are expected, it
provides the time line for achieving the objective.  A valuable outcome
of formulating objectives is that information needs become
    Once project objectives have been established, the ways to
reach these objectives can be considered.  It may assist in developing
objectives for the community to answer the following questions.
    * What is the overall purpose or long range goal?  (example:
      increase income, improve nutrition)
    * Who will be responsible for achieving that goal?
    * How do the relations between and responsibilities of both
      men and women affect that achievement?
    * Who will benefit from the project?   Are they the same people
      who are responsible for achieving the benefits?
    * How can progress toward achievement of the goal be measured?
    * What results would indicate that the goal was reached?
    * In what time frame can these results be expected?
    * Over what geographical area will the project extend?
    Answers to these questions can be combined into several
coherent objectives.
                          OF TRADE-OFFS
    Once objectives are defined, members of the community in
consultation with development workers and technical personnel can
design means to achieve the objectives.  Informed and constructive
opinions can be helpful in reaching decisions.  Some of the key
elements in designing agricultural activities are listed in the box on
this page.
                    KEY ELEMENTS FOR DESIGNING
                     AGRICULTURAL ACTIVITIES
  - start small
  - include local participation at every stage
  - start with knowledge and information from the community
    enhanced with technical information
  - seek technical information on soil, water, crops and seeds
  - include training in the basic plan
  - consider integration of conflicting land uses (agriculture, forestry,
    livestock) to maximize productivity of the farm system
  - consider alternatives to chemical pesticides and fertilizers
  - where tree planting is involved plan for maintenance and
    harvesting of the trees
  - benefit the whole community
  - build evaluation into the dynamic of implementing the planned
                        Source:   Weber 3.8
    In preparing alternative courses of action predictions should be
made of probable impacts, both negative and positive, of the proposed
activity.   Choices often involve trade-offs.   A choice that has strong
positive benefits may also have negative effects.  For this reason, the
costs and benefits of each alternative are often compared with each
other, using a standardized format.  This is called a cost-benefit
analysis.   References that can provide methodology for analyzing
trade-offs and cost benefit analysis can be found in Appendix A.     
                 5.   IMPLEMENT THE ACTIVITY
    After alternative designs have been examined, the sequential
steps needed to put the plan into action can be finalized and a
tentative timeline established.  Meeting the objectives of the project
depends upon continuous community participation, development of
local leadership, and consideration of community dynamics.   A plan
that is adapted to the local environment should utilize local materials
and local expertise.  It also should include training in new
management methods and other skills needed for project realization,
while taking advantage of local knowledge of the environment.
    Case studies have shown that farmers and their families have
a good understanding of their immediate environment.  Farmers
throughout the world have developed traditional calendars to time
agricultural activities.  Thus many farmers sow according to the
phase of the moon, believing that there are lunar phases of rainfall.
Other farmers cope with climatic seasonality by utilizing weather
indicators based on the vegetative stages of local vegetation.
Training Programs
    Training is almost always needed when innovation is being
introduced.   It is essential when larger or more complex systems are
planned, when new crops or trees are to be introduced, or when new
methods are to be adopted.  It may be necessary to identify some
farmers who are willing to risk being innovative.  These producers
are more likely to achieve increased yields and are often easily
identifiable.   If such people are given special training, and encouraged
by follow-up support, they can often help in the training of other
members of the community and can demonstrate project benefits.
    Funding of projects is not always necessary but sometimes it is
critical.   Small farmers usually have few resources and little money
or time to risk in a new enterprise.  They may be reluctant to enter
a loan agreement in an untried venture.  However, the more sustainable
projects are those in which the beneficiaries have made
some sacrifice of time or have contributed resources.   Financial
assistance sometimes may be needed from the local community,
government, or other organizations in the form of loans and/or
                   6.   MONITOR THE PROJECT
    Plans for monitoring the project should be part of the original
design.   Systematic monitoring often detects unexpected positive or
negative impacts and modifications of project design can be made.
    Because environmental and human interactions are complex,
all project effects cannot be predicted and changes may not be immediately
apparent.   Therefore, it is important to continue to monitor
the project in operation to observe both expected and unexpected
    Planners may want to monitor effects on vegetation, water
quality, soil fertility, land use, diet and cultural practices.   Such data
also will help to identify maintenance procedures that will ensure
project continuation.
                   7.   EVALUATE THE PROJECT
    The project plan should outline the evaluation methods to be
used, and ensure that the evaluation is carried out.  Too often this
process is ignored, especially when the project may not appear to be
achieving its objectives.  However, project evaluation is important for
all who were involved in a project.  Every project involves a certain
amount of risk for project participants.  In the event of project
failure, these participants must not be abandoned by planners or
they will hesitate to try any future projects.
    Evaluation must be a joint effort of planners and community
members.   Outside evaluators may add fresh insight or see solutions
to problems overlooked by those close to the project.  However, they
also may judge the project from their own value system that may not
fit project purposes.  The point is to observe and measure how well
objectives have been achieved and to determine if there have been
other expected or unexpected results.  Investigation of the causes of
success and failure will help future planners to improve project
    Evaluations are especially helpful if the project methods have
been experimental, with no past history of success or failure in a
similar environment.  Planners and project managers should exchange
information with those in nearby regions in order to compare
methods and results.
                    A SUMMARY CHECKLIST
    * Are project objectives measurable and realistic?
    * Are they compatible with community needs?
    * Were community members involved in establishment of project
    * Was a cost-benefit analysis which includes an environmental
      analysis used to help select the best project design to achieve
    * Is an effective technical assistance and training program
      integrated into the project design?
    * What assistance can be provided by financial, governmental,
      and other institutions or groups?
    * Is there a reasonable plan to monitor and evaluate the
    This chapter has outlined a planning process.  Chapter 4 contains
some suggestions about the broad framework of understanding
needed for planning.  The chapters following explore some of the
technical issues that might be encountered in planning an agricultural
project.   Chapter 10 concludes with a checklist for sustainable
projects, examples of traditional systems, and a look at long term
                        CHAPTER 4

03p38.gif (437x437)

    Chapter 3 reviewed the process of planning.  The suggestions
in that chapter, however, are not a prescription.  They need to be
adapted to the local situation.  In addition, there are some other
considerations that affect planning a project.  There are some natural
limitations, involving biological and physical relationships.   These
will be discussed in the chapters providing technical background for
planning.   This chapter will discuss legal constraints to agricultural
activities; socio-cultural considerations; and related to these, the
special considerations of women's activities in agriculture.
    Legal limitations, unlike natural limitations, are established by
people to meet specific conditions and, therefore, can be modified by
people in response to changes in legal, social, and economic situations.
Socio-cultural conditions have been established over time by
practical use.  Considerations concerning women in agriculture are
not new but their importance is newly recognized.
                     LEGAL CONSIDERATIONS
    Among the important institutional considerations in planning
small-scale agricultural projects are the laws that affect the use of
land and other resources.
    Often in the rural areas of developing countries the legal
status of land ownership is ambiguous.  Vast areas of farm land
used by low-income farmers is unregistered, with usage passing from
generation to generation without legal protection.  These lands are
usually marginal, lacking fertility and irrigation, and otherwise
undesirable for agricultural production.  Where statutes are clear
with respect to land ownership and distribution, for example, in a
land reform program, enforcement is always mixed.  There may be a
correlation between the level of poverty of the low-income farmer and
the issue of security of land titles.  Political considerations color the
execution process producing uneven results.  Also land prices can
make it difficult for governments to acquire land for distribution.
    As regards laws that address ownership, use, and the sale of
the products of natural resources, the development worker may be
faced with dual legal systems in some jurisdictions:  a common law
system inherited from the colonial period and customary law deriving
from indigenous concepts of ownership and usage.  In parts of Africa,
for example, land ownership may reside in the person of the tribal
chief.   Accordingly the use of the land and distribution of products
will be subject to his regulation.  At the national level a price
structure established by the government to hold down the cost of
food in the urban areas may make a small-scale commercial agricultural
project unprofitable.  Law always affects development projects
at some level, too often with negative results.
    A development worker should consult with local authorities to
be sure that a small-scale agricultural project can be implemented
within the existing land tenure jurisdiction and patterns of land
    Legal considerations, as discussed above, are formal rules that
guide social conduct.  Less explicit, but equally important, are
guidelines derived from other cultural practices of a society--from
tradition, religion, and folklore.  As with laws, these social considerations
must be reflected in the decision-making process.  Failure to do
so can lead to adverse reactions that can severely affect the project.
    Cultural considerations determine, in part, the options available
to a planner of environmentally sound small-scale agricultural
projects.   From the flood plains of the Mekong River Basin to the
fragile desert environments of northwestern Africa, situations can be
found in which social patterns affect implementation of particular
agricultural practices.
    Social constraints are often difficult to assess.  They are not
usually susceptible to easy solution and are often ignored.   However,
to do so is folly.  To increase the possibility of environmentally sound
resource management in agriculture, it is essential to include local
people in planning objectives of the project.  Training and public
education are also important.
    Other socio-cultural factors such as household relationships,
division of labor between men and women, and decision making in
relation to agricultural activities are sometimes critical to project
planning and should not be overlooked.  Some projects increase the
burden on women by increasing their responsibilities and working
time involved, when the objective of the project is to reduce the
                 WOMEN AND AGRICULTURE
    In many areas of the developing world, women constitute
one-half or more of the agricultural labor force and may be responsible
for producing as much as 90 per cent of the food.  It is essential
to recognize this in those regions where women traditionally are
the farmers, producing food crops, managing small livestock, and
sometimes cultivating cash crops.  Women need to have a role in
decision-making about agricultural innovations and development
interventions.   They need to have access to training, extension
programs that are sympathetic to their traditional role, and they
need credit.
    In the past, when new options existed, they have been more
often available to men rather than women.  For a large majority of
women, especially in rural areas, innovation, training, and development
interventions have not improved their quality of life.  In
many cases just the opposite effect has been the result.
                            BY SEX:   ALL AFRICA
                                            of Total
                                            Labor in Hours
                                            Men    Women
Cuts down the forest; stakes out fields     95      5
Turns the soil                              70     30
Plants the seeds and cuttings               50      50
Hoes and weeds                               30      70
Harvests                                     40      60
Transport crops home from the field         20     80
Stores the crops                            20      80
Processes the food crops                    10      90
Markets the excess                          40      60
Carries the water and the fuel              10      90
Cares for the domestic animals              50      50
Hunts                                        90      10
Feeds and cares for the family              5      95
    Source:  UN Economic Commission for Africa, 1975, Women in
    If there is to be a shift to a better understanding, the following
are some of the constraints that need to be addressed:
    * Most of the power is in the hands of men; therefore men
      have access to new opportunities.
    * Women tend to be viewed as consumers rather than as producers.
    * Women's chores such as food processing, fetching water and
      fuelwood, child care, and cooking are generally not considered
      to be productive contributions to the economy.
    * When these chores offer income-producing potential, they are
      usually undertaken by men.
    The preceding table demonstrates the division of labor between
men and women in Africa, where women traditionally play a dominant
role in agriculture.
    The local people and the development worker must select from
alternative plans of action.  Choosing among alternatives requires
some economic considerations.  Economics involves patterns of
analysis, sometimes referred to as benefit/cost analysis.
    To make an economic analysis of alternative courses of action,
three general objectives form a basis of choice.  The objectives are to:
    - provide the greatest possible benefits for the costs incurred
    - bring the best possible rate of return on investment
    - achieve a specified "production goal" at the least cost
    Analysis of these objectives can give the local people and the
development worker a better understanding of the economic implications
of selecting a particular course of action.
    To analyze the first two objectives, likely consequences of
alternative courses of action and costs of implementation must be
determined to the extent possible.  Some information can be obtained
from previous local experience.  If the course of action is newly
adopted, the development worker can seek available prediction
    To satisfy the third objective, goals should be established for
various levels of production.  These goals are most effective if set
according to values of local residents, coupled with long-range goals
derived through the political process.
    Benefits/costs analysis has often been viewed as a purely
financial approach rather than as a tool to use in a more
human-centered development process.  This view can be dangerous
for at least two reasons:  1) it can cause the planner to overlook the
importance of economic effects; 2) it can lead to a failure to recognize
that cultural, social, and ecological factors also can (and should) be
considered in benefits and costs terms.  Planners must be able to
bring a benefits/costs approach to all facets of the planning process if
they are to be able to judge project feasibility in terms of impact on
the community.
                         CHAPTER 5
                          SOIL MANAGEMENT

03p44.gif (437x437)

    Soil contains the nutrients and water that plants need for
growth and serves as the medium or substrate in which they grow.
The primary purpose of soil management is to provide a continuously
supportive and productive soil for plant growth through proper
provision of water and nutrients and soil conservation practices.
    When the soil is left without vegetative cover, erosion may
result.   Since erosion is the most serious environmental problem
facing many farmers around the world, this chapter provides background
for planning agricultural projects in areas that are prone or
subject to erosion, and need controls to reduce erosion.  Before
beginning a project, it is necessary to understand the process of
erosion and its effects both upon the project and the environment.
                    EROSION:   WHAT IS IT?
    Erosion is movement of soil by water, wind, ice, or other
geological processes.  It is a function of climate, topography (slope),
soils, vegetation, and human actions, such as cropping methods,
irrigation practices, and equipment use.  Usually erosion control
becomes more necessary as the slope of the land increases because
the slope helps the soil to move.
    There are three stages of water-caused erosion:  sheet erosion,
rill erosion, and gully erosion.
Sheet Erosion
    Intense rainfall or large rain drops displace particles of soil.
Topsoil is dislodged by this impact.  As water accumulates, it begins
to remove soil more or less uniformly over a bare sloping surface.
Moving down the slope, the water follows the path of least resistance,
such as channels formed by tillage marks, stock trails, or
depressions in the land surface.  Sheet erosion is the first stage of
damage and as such can be hard to identify.  Those seeking to
develop a piece of land should check carefully for signs.   One simple
method for assessing erosion problems is to observe from the low end
of the field what is happening during a heavy rainstorm; i.e., is the
run-off water dark with accumulated soil?
Rill Erosion
    Concentrated runoff may remove enough soil to form small
channels, tiny gullies, or rills in a field.  While rills are often the
first visible sign of erosion, they can be covered up by tillage practices.
Learn to recognize the signs of rill erosion and watch for
them.   Under continued rainfall, rill erosion increases rapidly.
Steeper or longer slopes increase the depth of the rill.  The erosion
potential of flowing water increases as depth, velocity and turbulence
increase.   Sheet and rill erosion together account for most of the soil
movement on agricultural lands.
Gully Erosion
    As water accumulates in narrow channels, it continues to move
soil.   This is the most severe case of erosion and can remove soil to
depths of 1 to 2 feet, or up to several hundred feet in extreme cases.
Laterite Formation
    There is a widespread belief that tropical soils, once cleared,
are irreversibly transformed into hardened plinthite or laterite.
Actually, only a small proportion of tropical soils (for example, only 4
per cent of the land in the Amazon) is subject to laterite formation.
Where there is soft plinthite in the subsoil, and when the topsoil has
been removed by erosion, hardening to laterite can take place.
Therefore laterization is more likely to occur in soils where erosion is
                         SOIL LOSS
    The main factors that affect erodability of a soil are the physical
structure and chemical composition of the soil, the slope of the
land and the management (how is it used) of the land.  (FAO 5.3)
Soil loss is directly related to the following:
    - intensity and amount of rainfall
    - quality of the soil and how much it is subject to erosion
    - length of slope
    - degree of gradient (steepness) of the slope
    - quantity of vegetation cover
    - kind of crop system (monoculture or crop associations and/or
    - system of soil management (especially related to soil cover)
    - erosion control practices (discussed later in this chapter)
These factors determine how much water enters the soil, how much
runs off, and the potential impact for erosion.  It is essential to
evaluate present and potential erosion in planning a project.
                   EROSION BY WIND ACTION
    In arid and semi-arid regions, wind erosion can be extremely
serious.   Topsoil blown away from the land can leave the land
unproductive and increase the number of particles in the atmosphere,
thus affecting local climate.  Wind erosion can also:
    - cover and kill plants
    - disturb organisms living in the area
    - increase labor and cost of cleaning those areas which are
      covered by soil
    - reduce amount of solar energy (sunlight) available to plants
    - increase evaporation, surface drying
    Extreme wind erosion, coupled with climatic changes and
human activities, can contribute to the formation of deserts.   For
example, people contribute to increased wind erosion and hasten
desertification by cutting woody species for firewood, overcultivation,
and other practices such as improper cattle management that leads
to overgrazing.  In many cases, such practices are the result of
increased population pressures, but also because impoverished farmers
are pushed to adopt these practices by social, political, and
economic factors.
                      FOR CONTROL OF EROSION
    A good soil cover is the most important control of both wind
and water erosion.  A cover directly on the soil or close to it is the
most effective.  Soil cover serves the following functions:
    - interrupts rainfall so that the velocity is slowed down before
      it hits soil particles thereby reducing splash and dislodging
      effects of rain
    - decreases runoff velocity by physically restraining water and
      soil movement
    - increases ability of the soil to store water by providing
      shade, humus, and plant mulch
    - improves surface soil porosity by root systems that help
      break up the soil and facilitate water infiltration
    The leaves and branches of a crop provide a canopy or cover
over the soil and protect the soil from heavy rainfall and wind.   For
example, corn forms a canopy several feet above the ground.  However,
this crop leaves soil bare before seed germination and during
early crop establishment.  Shorter crops, such as some grasses or
legumes (beans, vetch), and crops such as sweet potatoes and squash,
provide cover closer to the ground surface and have an even better
potential to reduce erosion.  Soil loss from a grass and legume
meadow is substantially lower than in a cornfield.

03p48.gif (486x486)

    Ideally, projects should be designed so that some kind of
vegetative cover remains in place at all times.  This may not be
possible in all ecosystems.  If an area is cleared, plan to cover the
cleared area with vegetation as soon as possible.  If this is not
possible at least take time to check, and encourage weeds to grow
naturally in the fallow field.  This is helpful in three ways:
    * The cover reduces the possibility of soil erosion.
    * The weeds can be plowed under to provide nutrients (green
      manure) for later crops and improved soil structure.
    * The balance of the ecosystem may be reestablished to
      ensure that the disturbance will not have lasting, negative
    Erosion can be controlled by reducing the mechanical forces of
water or wind, by increasing the soil's resistance to erosion, or by
doing both.  Water erosion can be controlled by preventing splash
erosion by providing crop cover or a layer of mulch (crop residue or
other organic materials) through which the rainfall then trickles
(infiltrates) into the soil.
    Another means of preventing erosion by water is to constrain
any run-off that continues to exceed the rate of infiltration.   This can
be done with physical barriers such as contour-bunds, tied-ridges,
terraces reinforced by rocks, ridges, or living barriers composed of
natural or planted grasses or shrubs.  Strip cropping with furrows in
between using sprinkler irrigation or trickle irrigation can also help
control water erosion.  Mulches and cover crops sometimes deter both
water and wind erosion.  Wind erosion can also be reduced by
planting trees and/or shrubs as a windbreak.  (See figure below) A
windbreak in addition can provide other benefits (firewood, fodder,
food, wood poles) if multiple-use trees are planted.  Stubble mulching
is also used in some areas to control wind erosion.

03p49.gif (437x437)

   There are several ways to control erosion caused by water.  The
implementation of each of these control measures may be a project in
itself, or the measures may be included in agricultural projects.
Some common methods are:
    - increasing vegetation cover
    - using plant residues to protect soil (mulching)
    - using improved tillage techniques such as conservation
    - rotating crops and planting cover crops
    - reducing erodability of soil, for example, by adding organic
    - planting deep rooted trees for slope stability
    - using mechanical support carefully
    - and other practices such as terracing, using diversion channels,
      contour plowing and planting, strip cropping, contour
      strip cropping, tie-ridging, and reducing of field lengths
    Plant residues are, for example, corn stalks, wheat chaff,
weeds, and similar remains left in the field after crops have been
harvested.   They can provide effective erosion control by reducing the
raindrop impact on the soil and reducing runoff.
    The practice of leaving plant residues on the field is called
mulching.   Mulching is particularly useful for protecting young
plants from high soil temperatures, retaining soil moisture, and
contributing to soil fertility as the residues decompose.
    Mulch can be left on the surface, or it can worked into the
topsoil by plowing, discing, or harrowing.  When this latter practice
is followed, the amount of organic matter in the soil increases and
the soil structure or composition and water infiltration improve as
well as does the water-holding capacity of soil.  On the other hand,
working mulch into the soil reduces the percentage of surface cover
and loosens soil so that it is somewhat more susceptible to wind and
water erosion.  Some pests as well as disease-causing fungus and
bacteria may thrive in the mulch and can be difficult to control.
    The decision to plow plant residues into the soil or to leave
them on the surface depends upon the erodability of the soil in the
area, the kind of organic materials, the amount of runoff expected,
and the tillage practices used.  The cost and availability of the labor
to do the plowing are also factors.  Greatest protection from erosion
may be provided by not plowing mulch into the soil.  Yet, even when
mulch is worked into the soil, more soil can be saved than would be
possible if mulch were not used at all.
    Some crop residues may have negative effects as a mulch.
Local farmers can be a good source of information on this point.

03p51.gif (600x600)

    As farmers are well aware, conventional tillage methods leave
a bare soil surface and expose soils to erosion until the crop is
    Tillage methods can affect the runoff velocity of water, the rate
of infiltration of water into soil, and the degree of soil compaction.
Compaction, which occurs naturally in soils with a high clay content,
and hampers root and plant development, can be worsened by the
use of heavy field machinery, thus further increasing the chances of
    Following are three tillage techniques that can reduce erosion:
reduced tillage, conservation tillage, and no-till.
Reduced Tillage
    Soil is tilled as little as possible to produce crops under existing
soil and climatic conditions.  Fields may be plowed or harrowed,
but with chisel plow rather than with moldboard plow.
Conservation Tillage
    Plant residues are usually left on the surface as a mulch to
control weeds and to conserve soil and water.  Plowing and planting
are done in one operation with crop residues mixed into the soil
surface between rows.
    Crops are planted directly into the field or plot left untilled
after the last harvest.  No-till is done by planting in narrow rows
between previous crop residues.  The surface mulch of weed and crop
residues is vital to the sustained success of 'no-till' and reduced
tillage systems.  In the tropics, in addition to protecting the surface
soil against the impact of raindrops, the mulch helps develop and
maintain the soil surface and ensure rapid infiltration of water.
    In some regions no-till needs to be supplemented by carefully
designed chemical weed control programs and increases in the rate of
fertilizer application.  Such additions require more capital and also
sophisticated management and planning.
    Studies indicate that erosion associated with conventional
tillage can be reduced 50-90 per cent by a switch to any of the above
conservation tillage practices.
    Most development workers who work with farmers in rural
situations and plan projects should become familiar with these
practices, and new advances in this area.  For example, improved
tillage practices have been hampered in many areas by lack of
low-cost, efficient tools for planting through the plant residue.
However, new implements have been designed and tested to overcome
this limitation such as the stick, the punch planter and the
single row rolling injection planter (RIP), developed by the International
Institute of Tropical Agriculture in Ibadan, Nigeria.
    Crop rotation is one way to reduce soil erosion.  Since the use
of different crops in rotation reduces the amount of time a field is
left without an adequate vegetative cover, erosion is reduced.   In
rotation of legume forage crops with non-forage crops, erosion can be
reduced 25-30 per cent over continuous cropping.  The forage crops
can also supply nitrogen for the crops that follow.  In addition, if the
rotation is planned wisely, certain crops can be chosen for their
ability to assist the resistance of soil to erosion under succeeding
crops.   The greatest of these residual effects is derived from grass
and legume meadows.  Because they are sod-farming crops, they
provide cover and help build up the soil even when they are later
plowed during conventional tillage.  There may also be residual
effects in rotations using non-sod-forming crops.  For example, corn
leaves soil less erodible than soybeans, but more erodible than small
grains.   In addition to planting crops with different harvest times,
crops can be planted between rows of permanent plant barriers such
as broomstraw, elephant grass, or tree crops such as Leucaena.   This
technique, called "alley cropping," will be discussed in Chapter 9.
    Support practices for erosion control may require moving the
soil, sometimes using machinery.  The most common practices--contour
plowing and planting, and terracing--are practiced on long and
steep slopes.  These practices reduce erosion by slowing down the
velocity of water and its soil transporting capacity.  In semi-arid
regions, these practices or variations of them can be used for conserving
    Crops are planted horizontally on the contour of the slope,
rather than up and down the slope.  This practice has the effect of
creating ridges across the land which reduce the rate of runoff.
Because small barriers are provided by the rows the water moves
less quickly, erosion is reduced, and the soil is able to absorb more
water.   Average rates of erosion on contour-farmed land are about 61
per cent less than on similar cropland planted without contours.
    However, contour planting needs to be planned carefully.  On a
very steep slope or in areas of heavy rainfall and easily eroded soils,
water can build up in each contour, spill over, and break across
contour lines.  The volume of water can build up with each broken
row, and the result can be more erosion, not less.
Contour Strip Cropping
    Contoured strips of crops are alternated to reduce the effect of
row breakage.  For example, when sod and crops are planted in
alternating strips, the sod reduces water flow and serves as a filter
to catch much of the soil washed from a strip crop row.  Strips
structured close to land contours give good erosion control.
    Terracing is a very old practice, especially in mountainous
areas.   Terraces are costly in terms of the labor needed to build
them and require constant maintenance.  When used with contour
farming practices, terraces are more effective for erosion control than
strip cropping alone.  Terraces reduce effective slope length and
retain much of the soil moved between terraces.  They can trap up
to 85 per cent of the sediment eroded from a field.  Terraces are also
used in semi-arid regions for conserving both water and soil.   However,
in tropical climates where topsoil is thin, poor soil is sometimes
brought to the surface.  Raised beds also help control erosion.
    It is important to understand the relationship among soil,
water, and methods for erosion prevention and control, in order to
develop alternative land management techniques.  The following
questions are provided as a starting point for considering projects in
which susceptibility of the soil to erosion is a significant limiting
factor for crop production:
    * Would improved tillage practices provide better erosion
      control?   If so, would there be obstacles--money, customs--or
      other constraints to changing practices?
    * Is the site subject to wind or surface water erosion or land-slipping?
      For example, does the site have a steep slope?  Is
      it a windy area without protective windbreaks?  Is there
      evidence of past landslides?
    * Are there periods during the year when the soil of the
      project site is unprotected by vegetative cover and subject to
      sheet, rill, or gully erosion?
    * Will erosion cause silt to form in downstream water bodies
      such as streams, lakes, and reservoirs?
    * Will use of mechanical equipment on the project site damage
      the soil structure and leave the soil more susceptible to
    * What is the major factor limiting agricultural production in
      the area?   Is erosion a major constraint to increased agricultural
    * What are the social, cultural, physical and economic costs of
    * Can the project be set up to include a training course for
      local project participants?
    * How have farmers traditionally adapted to erosion problems?
    * What other soil management practices may be appropriate?
                      SOME ALTERNATIVES
    Other tillage methods can be undertaken to protect soil from
erosion.   These include:
    - improving soil fertility
    - timing of field operations
    - plow-plant systems
    - grassed outlets and grass waterways
    - ridge planting with tie-ridges
    - construction of ponds for runoff collection
    - changes in land use
    - long low bunds, e.g., in the Sahel
    These practices are described in the following table, which is
based on material from the U.S. Department of Agriculture and the
U.S. Environmental Protection Agency.  The left-hand column gives
the name of the practice; the right-hand column describes the advantages
and disadvantages of each as an erosion control method
and describes the potential effects of such a practice.
Practices Highlights of Practices
No-till                Most effective for grasses, small grains, and with
                      crop residues; reduces labor and time required for
                      agriculture; provides year-round control.  Not
                      effective when soil is too hard to allow root development.
Conservation tillage  Includes a variety of no-plow systems to retain
                      some crop residues on surface; more adaptable
                      than no-till but less effective.
Sod-based rotations    Good meadows lose almost no soil and reduce
                      erosion of the next crop; total soil loss is greatly
                      reduced but is unequally distributed over rotation
                      cycle; may aid in disease and pest control.
Crop rotation         Much less effective than above; can provide more
                      soil protection than a one-crop system; aids in
                      disease and pest control.
Improved soil         Reduces soil loss as well as increasing production
fertility              of crops.
Plow-plant systems    Rough, cloddy surface increases the infiltration
                      rate and reduces erosion; seedlings may be poor
                      unless moisture is sufficient; mulch effect is lost
                      by plowing.
Contouring(*)          Can reduce soil loss up to 50 per cent on moderate
                      slopes, less on steep slopes; less effective if
                      rows break; cannot use large farming equipment
                      on steep slopes; must be supported with terraces
                      on long slopes.
Graded rows           Similar to contouring but less likely to have
                      breaks in rows.
Contour strip         Rowcrops and hay in rotation in alternate 15 to
cropping               30 meter strips reduce soil loss to about 50 percent
                      of that with the same rotation that is only
                      contoured; area used must be suitable for across-slope
Terraces               Reduce erosion and conserve moisture; allow
                      more intensive cropping; some terraces have high
                      initial costs and maintenance costs; cannot use
                      large machines; support contouring and agronomic
                      practices by reducing effective slope length
                      and runoff concentration.  In tropical climates
                      where the topsoil is usually very shallow, terracing
                      often leads to bringing to the surface, soil
                      which is very poor.   This can have worse effects
                      than erosion.
Bund terracing        A technique for terracing by creating bunds along
                      contours, then planting seedlings on the bunds to
                      create a terrace.   This technique is used to replace
                      labor-intensive terracing in Kenya and is
                      called Fanya Juu (does by itself).
Alley cropping        Rotations of crops are grown in between hedgerows
                      of fast-growing leguminous shrubs or non-leguminous
                      fallow shrubs planted along the contour
                      with the hedgerows pruned from time to
                      time to provide mulch and organic residues.
Live mulch system     Where crops are grown in rows on ground covered
                      by leguminous cover crops that are killed by
                      an herbicide along the rows where the crops such
                      as maize are planted.  Can minimize erosion on
                      steep slopes; most suitable where there is adequate
Grassed outlets       Facilitate drainage of graded rows and terrace
                      channels with little erosion; are costly to build
                      and maintain.
Ridge planting        Reduces erosion by concentrating runoff in mulch-covered
                      rows; most effective when rows are across
                      slope; earlier drying and warming of root zones.
Contour listing       Minimizes row breakover; can reduce yearly soil
                      loss by 50 per cent; disadvantages same as contouring.
Change in land        May be the only solution in some cases.  Where
use                    other control practices fail, may be better to
                      change to permanent grass or forest; lost acreage
                      can be supplanted by intensive use of less erodible
                      land.   Leaving the land to fallow is a common
                      practice in some areas.
Other practices       May use contour furrows, diversions, sub-surface
                      drainage, closer row spacing, intercropping, and
                      so on.
(*) A simple means of finding the contour is with the "A" frame technique.
This method is described in a brochure by World Neighbors
(see list of agencies in Appendix B).  World Neighbors also has slides
or filmstrip about the technique.
                           CHAPTER 6
                      WATER SUPPLY AND MANAGEMENT
    An understanding of the relationship between water and
agriculture is key to planning environmentally sound projects.   With
this knowledge a development worker can judge a proposed water
supply or control practice in terms of its impact on the environment
in which the agricultural project is taking place.
    As the primary transport medium on agricultural lands, water
can be both friend and enemy.  Water carries or moves nutrients
through the soil to plants and within the plants themselves.   Water
removes soil particles by the process of erosion.  It also moves
agricultural chemicals from the fields into the surrounding environment
where they can cause serious problems.  An understanding of
how water moves and what its effects are on agricultural lands is
the key to knowing how, when, and where a given project may
interfere with these processes.

03p59.gif (600x600)

Surface water
    Lakes, ponds, streams, and rivers provide water to plants
either indirectly through evaporation and later condensation over
agricultural lands as rain, or directly, by tapping and channeling for
irrigation purposes.
    Rainfall is the climatic factor that most drastically affects
agriculture in the tropics.  Rain falls directly on plants and moves
down, or percolates, through the soil to the roots and on to groundwater
    The important characteristics of rainfall that affect agricultural
growth are the amount, intensity, variability, and lengths of dry
spells and of rainy seasons.  The amount of rain varies greatly from
season to season and from area to area.  In many places, records--if
kept--of the amount of rainfall can be used to identify patterns in
the amounts of water available and to identify both flooding and
drought cycles.  It is helpful to establish the amount of rainfall and
the amount of evaporation/transpiration (see glossary).  In a climate
with a well-defined wet and dry season, the growing season will
begin when rainfall exceeds evaporation/ transpiration and continue
until the soil water reserve is exhausted.  Understanding the moisture
patterns and any changes in the patterns is of crucial importance
for developing cropping systems adapted to local rainfall
    Water accumulates in the soil at various depths depending
upon soil and geologic structures.  These groundwater supplies are
relatively permanent.  Groundwater can move up through the soil by
capillary action to become available to plants at times when there is
not enough rain.  Under drought conditions, however, this source
may not help.  Water held in deep pockets, called aquifers, can be
made available by digging wells.
    The water balance or amount available to the farming system
over a specific period of time reflects factors affecting sources of
water.   What water is left in the soil around the root zone of the
crops can be calculated by balancing the following:
    - what is left of the water from the rainfall after runoff (water
      moving below the surface soil, for example, on top of an
      impermeable layer of clay, towards a stream)
    - percolation below the root zone (water seeping down through
      the soil to the water table or the groundwater supply)
    - evaporation (from the soil)
    - transpiration (moisture given off by the crop)
    The balance between rainfall and evapotranspiration initially
determines the amount of water available for crop growth.  When
rainfall exceeds evapotranspiration the root zone is charged with
water.   As evapotranspiration begins to exceed rainfall, water available
for crop growth decreases.  Runoff and percolation also will affect
the amount of water remaining in the root zone.
    The objective of water management in agriculture is to minimize
and utilize the runoff, percolation, and evapotranspiration.
Practices such as mulching and no-tillage can reduce evapotranspiration,
whereas terracing can reduce runoff.
    Regardless of the source, water moves materials to and from
the project site physically and chemically.
Physical Transport
    Raindrops falling on unprotected soil dislodge soil particles and
carry them over the surface of the land.  This surface water runoff
can be a major cause of erosion.  Erosion has three negative effects:
    - loss of valuable topsoil, making land less productive where
      runoff takes place (however, nutrient laden sediment may
      enrich soil in lowland areas)
    - pollution of streams and lakes downstream from the project
      site by soil particles that accumulate and become sediment
    - washing of fine particles into spaces between larger soil
      particles creating a physical block which reduces water
    Sediment from this process chokes streams, decreases the
amount of light that can penetrate the water, and clogs the gills of
fish and shellfish.  Nutrients and pesticide chemicals adhering to
eroded soil particles increase their polluting effects in the water.
    On the other hand, physical movement of the soil can have
beneficial effects.  For example, in flood plains many agricultural
lands receive fertile top soil as a result of annual floods that transport
soil from sites upstream.
Chemical Transport
    Many minerals, nutrients, and pesticides or fertilizers and
other chemicals are dissolved and carried in water (or leached) out of
the soil.  This occurs by surface and sub-surface runoff, and also by
water seeping down through the soil (percolation).  Sub-surface
runoff picks up chemicals, nutrients, and sediment, and deposits
them in surface waters.  A number of negative effects can result
from this chemical transport.  For example, pesticides can kill
aquatic organisms and fertilizers promote growth of algae that may
pollute the water.  The extent of the impact depends upon the
amount of runoff, the chemicals carried, and their concentration in
the surface water.  Through percolation, water may carry soluble
agricultural chemicals directly to wells or to surface streams as part
of the groundwater.  Percolation may move nutrients beyond the root
zone of plants.  The amount and frequency of deep percolation
depends upon the water storage capacity of the soil, the vegetative
cover, the amount of runoff and rainfall, and the type of soil and
geologic conditions below the root zone.
    Percolation has beneficial effects as well.  One of these is moving
dissolved salts deeper into the soil.  When this does not occur,
salts can accumulate in the topsoil and eventually become toxic to
agricultural plants.
    Water management seeks to ensure the best use of available
water.   In many areas and in many small-scale agricultural projects,
the major problem, at least initially, is inadequate water supply.   A
common answer is irrigated agriculture, although water conserving
cropping systems and drought tolerant crops might also be appropriate.
    Before a decision is made about irrigation it is important to
know the amount and timing of rainfall that can be expected during
the growing season and how rapidly this water will be depleted.
Many times even though rainfall appears to be adequate, its monthly
distribution should be considered in relation to potential evapotranspiration.
For example, although total annual rainfall as shown in
the figure below, is adequate for crop growth, moisture is in excess
from September to May but inadequate from May through August, so
irrigation is recommended during the period of peak evapotranspiration.
    Agricultural lands are irrigated in many ways.  The best
method to use depends upon:
    - supply of water available
    - quality of water
    - slope of the site
    - infiltration and percolation rates of the soil
    - water-holding capacity of the soil
    - chemical characteristics of the soil (salinity, alkalinity, and
      so forth)
    - moisture requirements of the crop
    - weather conditions of the area
    - economic resources of the farmers, especially for moving
      water to the field
    - techniques for moving water to the field

03p64.gif (600x600)

    Irrigation projects can have far-reaching effects on the environment
of a vast area.  Irrigation can affect the water-table depth,
water quality, soil characteristics, crop productivity, human health
(the spread of diseases such as malaria and schistosomiasis), family
structures and mobility patterns, economic status of farmers, water
rights, and land ownership patterns.  The land ownership issue is
very important because once land is irrigated its value is increased
dramatically and what was once marginal land, now becomes quite
productive and desirable.  If the land title is not secure in the hands
of the low-income farmers, they could lose the land to an unknown
registered owner.  These possibilities should be carefully considered.
    Irrigation projects also can be affected by other factors.  Control
of water sources needs to be considered.  For example, the
watershed that will be providing water for the project should be
checked to determine if the watershed is protected adequately to
ensure water of the quality and quantity needed for proposed crops.
Watershed development upstream from the project site could alter
the water supply drastically, causing flooding, drought, fluctuations
in seasonal flow, or water contamination.  Other uses of water closer
to the source can affect the supplies and possibly pollute the water.
    Using surface water for irrigation can have far-reaching effects.
Irrigation water usually is diverted via canals, ditches, and channels
from surface waters nearby.

03p65.gif (540x540)

Effect on the Aquatic Environment
    * Removal of water for irrigation can result in reduced flow
    * Reduced flow can cause the death of aquatic plants and
    * Water returned to the stream after irrigation is often of
      poorer quality than the original water, and may cause death
      of plants and animals.
Effect On Farmland
    Water carried to irrigated fields is also subject to evaporation
from open canals or seepage from canals in areas where the soils are
permeable.   On the other hand, when irrigation from surface waters
spreads out over the land surface, the water percolates downward
and can accumulate underground.  Over a period of time accumulated
subsurface water can raise the water table until it is within a
meter or even a few centimeters of the soil surface.  High water
tables can inhibit the growth of plant roots by waterlogging the soil.
Irrigation may also change the wet-dry cycle and increase pest
problems and incidence of certain diseases.  Many insect populations
die back to low levels during the dry season.  With irrigation, pests
may continue to breed throughout the year.
Salinization and Alkalinization
    Improper irrigation can have various negative impacts on the
soil that will affect crops.  Among these are salinization and alkalinization.
Soils that contain more or fewer salts are better for different
kinds of crops.  The measure for whether soil is alkaline or acid is
called pH.  The normal pH balance in soils is around 7.  If the soil
is above normal acidity the pH reading will be higher than 7.   If the
soil is below normal or alkaline, the pH reading will be less than 7.
Salinization.   In soils with drainage problems and improper irrigation
the soil surface can become very salty as water evaporates from
it leaving deposited salts in the upper layers of the soil (salinization).
Salinization is the concentration of salts--sodium, calcium, magnesium,
and potassium--in the upper soil layers or on the surface in the
form of a white crust or powder.  Salinization if uncorrected can
drastically reduce crop productivity.  When drainage is adequate,
salts usually present no problems.  Salts can be washed out of the
soil by applying water in excess of the rate of evapotranspiration of
plants.   Where drainage is poor, concentration of mineral salts can
occur when surplus water accumulates and raises the water table to
within one meter or less of the surface so that increased evaporation
leads to salinization.
    Inadequate drainage and elevated water tables are the underlying
cause of salinization problems in irrigation projects.  Awareness
of the nature of this problem and its causes is another planning tool.
Development workers must check drainage and water table characteristics
before developing an agricultural project using surface
waters for irrigation.  The saline problem can be corrected through
drainage, which could cause saline contamination of groundwater and
surface waters elsewhere.  An alternative to transporting the saline
drainage water elsewhere would be to use it on-site for irrigation of
salt-tolerant crops such as barley, cotton, sugar beet, wild rye.
Sensitive crops are beans, onions, and most fruit trees.
    Salinization can also be caused by small amounts of water if
the water is of poor quality.  It is a common problem where water
supply is limited and there is a need to save it.
Alkalinization.   Another possible consequence of improper irrigation
is alkalinization which is of particular concern in arid and semi-arid
regions.   Alkaline soils are those with a high content of exchangeable
sodium whether or not in combination with substantial quantities of
soluble salts.
    Alkalinization is more serious than salinization because it is
harder to remedy.  Salinization can be remedied by applying water;
leaching alkaline soils may worsen their condition.  Sodium, unlike
other soluble salts, does not leach away because it is adsorbed (clings
to the surface of soil particles and combines with water in a chemical
reaction) to clay and organic matter.  While salts may be leached
away by runoff or irrigation water, the sodium remains in the form
of sodium hydroxide or sodium carbonate.  The presence of the
sodium hydroxide causes the organic matter in the soil to dissolve
and destroys the soil structure, making it difficult to till and almost
impermeable by water.  Expert technical assistance is needed to
correct this soil condition.
    Technical assistance is required to determine whether or not
these conditions exist and how serious they are.  One easy way to
get help is to take a soil sample to a government office.  World
Neighbors has a pamphlet describing "How to Take a Soil Sample."
See Appendix B for the address.
    When water for large-scale irrigation is drawn from groundwater
supplies by sinking wells and pumping, the water table is often
lowered.   This has several possible effects that must be considered by
the project planner:
    * Local vegetation may no longer be able to draw on the water
    * Marshes, springs, and wet places may dry up.
    * River and stream flow may be reduced.
    * The land may sink, or subside, if too much water has been
      pumped out too quickly from natural underground water
      storage areas, or aquifers.   This phenomenon is irreversible
      (that is, it cannot be restored to its former state by natural
    * Heavy withdrawal of groundwater can also lead to saltwater
      contamination of the fresh water in the aquifer.
    * If too much water is applied, waterlogging may occur in
      certain areas.
    Water used for irrigation flows back to water sources through
transport processes.   This return flow from irrigation can be a
significant polluter of surface waters, groundwater, and soil.   Small-scale
projects usually do not exert excessive withdrawal of water,
since normal discharge of groundwater may occur through springs,
and through seepage along the sides of streams.  However, reduced
surface water availability forces areas with marginal water supplies
to pump groundwater, which increases water mining and costs of the
project due to high energy requirements.  Dissolved salts, for example,
can be carried to the subsoil or groundwater.  Water percolating
through the ground carries with it the salts accumulated in the
root zone and moves them up or down in the soil profile.  Some salts
also wash into drainage systems and are returned to main streams.

03p69.gif (486x486)

    When irrigation water returns to main streams it may have
adverse effects:
    * Because of leaching and evaporation in the fields and canals,
      the salt content of the irrigation return flow may be much
      greater than that of the initial water used.   Too much salt
      can kill fish and other aquatic organisms downstream from
      the point of return.
    * Return flows can carry pesticides, which can be lethal to
      beneficial aquatic organisms that provide food for higher
      organisms in the food web, including humans.
    * Irrigation flows can carry sediment or silt, which raises the
      beds of irrigation canals, changes the direction of canals
      (causing them to meander), clogs drains, and fills the
      streambeds of reservoirs and lakes downstream.

03p70.gif (486x486)

    The human health implications of irrigation can be extremely
serious and can include the following:
    * Irrigation canals can carry chemical pollution from one place
      to another.
    * Canals and ditches can provide new places for the growth,
      breeding, and reproduction of various disease organisms, or
      their vectors, and can be instrumental in spreading these
      diseases, especially if water is used for drinking and/or
    * Slow-flowing or stagnant storage ponds, supply canals, or
      deeper drainage ditches are ideal habitats for disease organisms.
      This occurs particularly when canals become choked
      with aquatic weeds, which slow-the flow of water and offer a
      feeding ground for mosquitoes and other aquatic organisms
      that transmit disease.   Many of the most serious human
      diseases (for example, malaria, yellow fever, and schistosomiasis)
      are carried by organisms such as snails and mosquitoes.
    * Although snails and mosquitoes that spread disease can be
      controlled by pesticides, these pesticides may also kill the
      eggs, larvae, and adults of many other species of aquatic
      animals.   Control of disease organisms with chemicals can
      also harm fish-raising efforts in irrigation canals and reservoirs.
      Mosquitoes that transmit malaria can develop resistance
      to specific insecticides over time.   Pesticides also
      accumulate in the food web and can cause harm to humans
      who use the water or eat fish grown in contaminated water.
    Note:  Alternatives to pesticides for mosquito control include
promoting pathogens (i.e., Bacillus turringiensis var.  israelensis)
insect-eating fish (Gambusia, the mosquito fish), birds and other
predators (See Chapter 8 for information on biological pest control
    By formulating and answering a series of questions like those
given below for each project and site, development workers may be
able to anticipate a few of the potential effects of irrigation projects:
    * Is there adequate water for the project, either from precipitation
      (rainfall), surface water, groundwater, or aquifers?
    * Are cycles of floods and droughts accounted for in the project
      design?  What would be their impacts on the project when
      they occur?
    * Does the project design minimize surface runoff that might
      carry away valuable nutrients and topsoil and cause pollution
    * Do upstream resource uses (construction and forestry
      activities) affect the quality of the water to be used by the
    * Will the project involve irrigation?  If so, the planner should
      be particularly careful to assess the impact of the project
      downstream and the possibility for increasing habitat for
      aquatic pest insects including vectors of waterborne diseases,
      and abundance and quality of the project water source.
    * Will the project affect water-flow patterns of the area?
      Would these alterations affect the water supply needed by
      other users?
    * Are malaria, yellow fever, schistosomiasis, or other waterborne
      diseases carried by organisms associated with water,
      prevalent in the region?   And will the project in any way
      result in increased incidence of the diseases?
    * Will the project reduce downstream water flows and thus
      affect fisheries, aquaculture projects, the growth of aquatic
      weeds, the habitat for mosquitoes and other vectors of
      disease-causing insect pests?
    * If habitat is increased for disease vectors, could this result in
      increased use of insecticides or molluscicides with the possible
      result of chemical poisoning of fish and water supplies?
    * Could irrigation cause waterlogging of the soil?
    * Is the soil susceptible to salinization?
    * Does the soil have a characteristically high pH and could
      irrigation result in soil alkalinization?
    * Does the site have lateritic soil or is laterization a potential
      problem?   (See Chapter 5).
    * Will new wells be sunk?   If so, could this affect the water
    * If the water table is affected how will stream levels and
      wetlands be affected?
    * Is the project site near the sea?   If so, could lowering the
      water table allow salt water to intrude, contaminating
      freshwater supplies?
    * Could downstream water or groundwater quality be affected
      by high salinity in the return flows from the project site?
    * What other water supply and management options should be
    * What alternative designs could minimize possible water
      supply impacts?
    Other appropriate questions may be added.  By considering
these questions, the trade-offs necessary to minimize the negative
affects of the project can be evaluated.
    A number of practices are available to reduce the amount of
water used for irrigation (and thus decrease possible negative impacts)
or to conserve water.  These management methods can be
used to lessen water loss from runoff, evaporation, deep percolation,
irrigation, and stored soil water.  Practices are also available to
maximize the efficiency of irrigation and the use of stored soil water:
    - control of runoff losses through contour tillage, terracing, use
      of crop residues, and water spreading (the diversion of
      surface runoff to sites where the water infiltrates and is
      stored in the soil)
    - control of evaporation losses through mulching
    - reduction of deep percolation through the use of horizontal
      barriers (i.e., asphalt)
    - conservation irrigation such as drip irrigation (See Appendix
      A for references)
    - water harvesting (i.e., through construction of small ponds to
      capture excessive water during rainy season)
    - use of drought tolerant crops
    - no-tillage agriculture (see Chapter 5)
    - relying on summer fallows for dryland farming areas currently
      being irrigated
    There are also several ways to avoid or mitigate negative
effects of irrigation on human health.  When canals are used, people
can take extra care to draw water from uncontaminated stretches of
the canal, or from safer sources such as deep wells if such possibilities
exist.   If alternative waste disposal methods are adopted, disease
organism life cycles can be interrupted, preventing the spread of
disease.   More research on the natural enemies of snails and mosquitoes
can identify possible predators such as ducks, geese, or fish.
There may also be local plants that serve as molluscicides, such as
the soapberry (berry of the dodecandra plant in Ethiopia).  The best
method may be to deprive disease vectors of a suitable habitat by
conveying water in pipes or tile aqueducts and by using buried tiles
to drain excess water from fields.  On a small scale, the use of
enclosed systems for irrigation would not only protect humans from
disease but would also prevent seepage and evaporation of water
used for irrigation.  However, these solutions may be costly or
beyond the control of small-scale project operators.
                     CHAPTER 7
    Nutrients, such as Nitrogen (N), phosphorus (P), potassium (K)
and others, are essential to plant growth.  Planners of agricultural
projects should have an understanding of the dynamics and cycles of
nutrients in the natural environment in order to devise wise soil
nutrient management plans.  Understanding the inputs and outputs
of nutrients in a crop field will help in devising techniques that keep
a good balance of nutrients in the soil.  For example, the figure
below illustrates how nitrogen is added and withdrawn from the soil
through the nitrogen cycle.

03p75.gif (437x437)

    In crop lands there are six primary sources of nutrients:
natural soil fertility, plant residues, animal waste, legumes, water,
inorganic fertilizers.
Natural Soil Fertility
    All cropland has a degree of natural soil fertility.  Soil fertility
refers to the inherent capacity of a soil to supply nutrients to plants
in adequate amounts.  Some soils, such as the flood plains of rivers,
are usually very fertile.  On the other hand, loose sandy soils, which
contain little or no organic matter, and usually not very fertile.

03p76.gif (600x600)

Organic Matter
The Significance of the C/N Ratio.  There is a close relationship
between the organic matter and nitrogen content of soils, expressed
as the ratio of Carbon to Nitrogen or C/N.  C/N is important in
controlling the available N and the rate of organic decay in soils.   The
relationship of these two elements in organic material added to the
soil is crucial for two reasons:  a) Keen competition among micro-organisms
for available N results when added crop residues have a
high C/N ratio (more carbon in relation to nitrogen).  This means the
rate of decomposition will be faster and the availability of nitrate to
plant will be depressed until the activity of decay organisms slows
down.   b) Because the C/N ratio is relatively constant in the soil, the
organic matter content of the soil depends largely on the nitrogen
level.   The figure above shows the trend to be expected when
materials with high and low C/N ratio are added to the soil.
Plant Residues.  Leaves, roots, and other plant debris build up the
soil structure by providing organic matter.  As these materials
decompose, nutrients are released.  The amounts of nutrients vary
greatly depending upon the type of plant, temperature, rainfall, and
whether the material is plowed into the topsoil or not.
Animal Wastes.  Animal wastes such as manure are organic matter
that may decompose to provide nutrients to the soil.  Manure has
been used as fertilizer for centuries and is useful and environmentally
sound, if excessive amounts are not used.
    The nutrient content of manure depends upon the animal, the
type of feed given, and the amount of water consumed by the animal.
Disease organisms that affect humans can be carried in animal
excrement, therefore, only manure from healthy animals should be
used.   Extra precaution is necessary when using animal manures if
these diseases are a problem in the area.  Local authorities usually
are aware of these problems and can provide information.  Aerobic
composting, as discussed below, can kill the pathogenic bacteria, eggs
and spores found in animal manures.  Other by-products that may
be used for fertilizer are bone meal, blood meal, and fish meal.
    Cover new manure as soon as possible and mix it with the soil.
As much as 1/4 of the nitrogen content can be lost in one day due to
ammonia volatilization if the manure is not handled properly.
    Temperature and moisture affect decomposition of manures.
Therefore timing of the application of manure may vary with climatic
zone.   In a semi-arid area, for instance, where high temperatures are
coupled with high aeration of the soil, manure applied too early
before the onset of rains, can lose a large part of its nutrients from
rapid oxidation of the organic matter.
   Animal                          % of Dry Weight
                                          N      P       K
Dairy Cattle                              2.4    0.6     3.0
Beef Cattle                               2.0    0.8     1.7
Poultry                                    3.7     1.7    1.9
Swine                                     5.9     2.5    4.1
Sheep and Goat                            3.0     1.1    4.8
Legumes.   Legumes, including peas, beans, groundnuts, and alfalfa,
contain nitrogen-fixing bacteria in their root systems.   These plants
fix nitrogen from the air into proteins that become available to the
plants when the bacteria die.  Bacteria can fix enough nitrogen to
support a grass and legume meadow if no other nitrogen source is
available.   The nitrogen usually is produced as the plant needs it.
Plants with poor growth will not fix much nitrogen.  If there is a
high level of nitrogen available in the soil, the bacteria fix less.
Nitrogen then is not a limiting factor.
    Legumes are often grown in association with other crops in
intercrop or crop rotation systems to provide nitrogen for other
plants.   For example, peas or beans are often grown with maize in a
mutually beneficial system.  Such multi-cropping, or polyculture
practices can reduce or eliminate the need for chemical fertilizers.   It
is important to exploit the ability of the cropping system to reuse its
own stored nutrients.  In complex crop mixtures, closed canopies and
larger root areas usually promote nutrient conservation and cycling.
    In addition to their compatibility in the field, maize and
legume combinations complement each other nutritionally.   By eating
both, human beings can receive nearly their complete protein requirements--without
adding meat or dairy products.  Other plants
have similar relationships, both symbiotic and nutritional.  Often,
traditional crop patterns adapted by local farmers turn out to be the
best use of the land as well as the best combination for providing
essential proteins for human diets.  Development workers planning
to introduce new species should consider the potential of indigenous
crop mixtures as a starting point for the design of soil management
practices.   In combination with other crops grown locally, indigenous
crop mixtures can provide adequate nutrition and even improve local
Precipitation and Run-on Water
    Rainfall can provide nitrogen and phosphorus to cropland, but
in very low amounts compared to other sources.  The nutrient
content of precipitation is influenced by the weather, and by the
presence of industry, cities, disposal sites, power plants, feedlots, etc.
For example, phosphates, that may be present in dust, ash or smoke,
are made available to plants when dissolved in rain.
    Nutrients in soil and organic matter that are suspended in
run-off water, that is, eroded and carried from elsewhere, may be a
significant input in certain situations.  For example, rice-growing
areas subject to inundation or flooding from silt-laden rivers or
riverain cropping systems that involve planting on previously inundated
land, may have sufficient nutrients from this source when the
seasonal river flow declines.
Inorganic Fertilizers
    Inorganic fertilizers consist of chemicals with little or no
organic matter.  Chemical fertilizers supply nutrients that are
readily available after application, in amounts and ratios that are
more readily controlled.
    Inorganic fertilizers are expensive, often unavailable, and
generally do little to improve the structure of the soil.  Many farmers
have difficulty calculating how much chemical fertilizer to apply.
This can lead to under-fertilization or over-fertilization either of
which do not produce desired results.  Many tropical soils cannot
hold the chemical nutrients long enough for the plants to use them.
Often the first rain washes them out of the soil.  However, in some
areas organic fertilizers are not available or not in sufficient quantities.
In that case, correct application of inorganic fertilizers is
necessary and critical.
    The choice of nutrient source depends on the situation.  Even
soils that are naturally very fertile may be depleted of nutrients by
continuous cropping.
    The need for fertilizer, i.e., anything added to the field to
increase the natural fertility of the soil, depends on:
    - ability of the soil itself to provide essential nutrients to
      crops (soil fertility)
    - nutrient demands of the crops
The choice of fertilizers depends on availability, costs, and the
fertilizer's effect on the soil.  Whether nutrients are organic or
inorganic does not matter to the plant.  Plants can use fertilizers
from any source.  However, other effects of inorganic fertilizers are
often unknown.  In the long-term perspective they can reduce the
diversity of microbes in the soil.  They may also be hard to obtain
and/or expensive.  Wherever possible it is best to use organic fertilizer.
Potential organic fertilizers exist wherever there are animal
and plant wastes.  They are relatively cheap although they require
larger inputs of labor.  They have the added advantage of contributing
organic matter to the soil.  In the warmth and moisture of the
humid tropics most soils are very highly weathered, sandy, and
coarse textured.  In such highly weathered soils, organic matter, in
addition to adding nutrients to the soil, plays a very dynamic role in
the colloidal complex that holds nutrients and retards leaching.   In
these soils, organic matter decomposes rapidly so that its nutrients
are available quite quickly.  One of the best practices for fertilizing
with organic materials is composting.

03p81.gif (486x486)

    Composting is a natural process whereby organic wastes are
microbially decomposed.  It has the following advantages:
    - uses waste material and is of low cost
    - can yield organic matter for fertilizer within several weeks,
      depending upon the ingredients used, the climate, and so
    - generates heat sufficient to kill insect eggs, larvae, weed
      seeds, bacteria, and other pathogens that may cause human
    - stabilizes the volatile nitrogen fraction of manure by fixing it
      into organic forms
    - the final product is easy to store and handle
    Composting also has some disadvantages:
    - is labor intensive to produce
    - requires space to store
    - requires water
    - is bulky and less convenient to transport and handle than
      solid inorganic fertilizers
    - is dependent on supplies of manure and organic matter
    - is more feasible for smaller areas, such as, kitchen gardens
      or small plots
    In many countries, composting in some form or another is
practiced traditionally.  Examination of local methods can provide
good guidelines for project planning in terms of available ingredients,
length of preparation time, receptivity of residents to the practice,
and so on.
                 Carbon:nitrogen       ----- kilos/ton-----
Material                Ratio         N        [P.sub.2][O.sub.5] [K.sub.2]O
Grass Hay              80:1          9-11      2-5                11-16
Legume Hay             12-24:1       20-27    5-7                16-21
Straw                   75-150:1      5-9      1-3                9-14
Cow Manure & Bedding   15-25:1       3        .5                 2
Seaweed                 19:1          .5       .35                 2
Human Faeces           5-10:1        2-3       1-2                .5-.9
Sugarcane Fiber        200:1         .11       .01                +
Filter Mud             22-28:1       .5       .9                 .05
Maize Stalks           60:1            -         -                  -
Fish Scrap               -           1-3       .9-3                 -
Vegetable Wastes       12:1            -        -                   -
Groundnut Shells         -           .35       .06                  -
    Both fertilizers and naturally occurring nutrients are subject to
all the natural processes that tend to reduce nutrient levels--leaching,
runoff, and erosion. In addition, other sources of nutrient loss
in agricultural systems are:
    - nutrients in the crop material that leaves the farm
    - nutrients in stock or stock products that leave the farm
    - leaching of nutrients below the root zone
    - loss of nitrogen to the atmosphere through volatilization
      (escaping as a gas) or through burning of vegetation or crop
    - losses through run-off water (erosion)
    If these processes can be halted or slowed, the chances are
greater that the nutrients present in the soil and those applied in
the form of fertilizers will remain available for plant growth.   Ensuring
that nutrients remain in the soil for crop use lessens the likelihood
of excessive nutrients entering the larger environment and thus
causing pollution.

03p83.gif (486x486)

    Leaching is the process by which soluble chemicals move downward
through the soil in water that is percolating through the soil.
Nitrates are the most easily leached nutrients and are commonly
found in drainage waters.  Leaching from cropland depends upon the
type of crop grown, as well as the soil type and its drainage characteristics,
and on the amount of available water passing through the
crop root zone.  Leaching effects are particularly important early in
the rainy season in the humid and subhumid tropics, when the main
flush of mineralization of soil organic matter occurs.  Under perennial
crops with permanent, deep root systems, leaching is of minor
    Runoff occurs when it rains so hard and fast that the ground
cannot absorb the moisture fast enough.  When fertilizers are left on
the soil surface, the first rainfall can carry away a substantial
portion of the nutrients.  Fertilizers during periods of light rains
move into the soil dissolved in the available water.  The loss of
fertilizer may be much less if the fertilizer is incorporated into the
top few inches of the soil before rains begin.  Being soluble, nitrates
are easily leached into the soil.  The concentration of nutrients in
runoff water will vary greatly from field to field, depending upon soil
characteristics, slope, crops grown, type of manure or fertilizer used,
and rainfall conditions.  Organic fertilizers mixed with the soil can
increase the soil's capacity to absorb water.
    Although sediment transport through erosion depends upon the
volume and velocity of water flow, it can be the major transport
process for phosphorus and organic nitrogen clinging to or adsorbed
on sediment particles.  When the velocity of water is reduced, the
large particles of sediment fall out of solution.  The remaining
sediment is usually finer and has a higher capacity (more surface
area to which to adhere) to adsorb phosphorus, so that transported
sediment is richer in phosphorus and nitrogen than the original soil.
    Organic matter is often transported along with sediment, causing
further nutrient losses from the fields.  Nutrient losses from
cropland can be controlled by proper management practices such as
those described in Chapter 5 for sound erosion control.
    For example, leaving plant residues on a field can reduce
erosion rates of 25-65 tons/hectare/year to 12.5 tons/hectare/year, and
at the same time provide nutrients to the field and thereby reduce
the need for inorganic fertilizer.  Other soil management/erosion
control methods, such as crop rotations with sod, contouring, and
terracing, can reduce nutrient losses as well.
                       OF SOIL, NUTRIENTS
    Nutrients, including fertilizers, in solution or suspension in the
groundwater or surface water bodies, can result in two problems:
    * Nutrients may reach toxic levels and become a health hazard
      to humans and animals.
    * When added to water systems (i.e., ponds, small lakes),
      nutrients may accelerate the eutrophication rate to the
      extent that it becomes harmful to the environment.
    Eutrophication is the enrichment of a body of water by nutrients
with resulting increases in growth of aquatic plants.   When
nitrogen and phosphorus enter the water in high levels as a result of
runoff or other transport methods from agricultural lands, over-fertilization
of the water systems stimulates an exploding growth of algae
    Algae can:
     - cause taste and odor problems
     - create obnoxious conditions in impounded water such as
       small ponds
     - block passage of the sun's rays and interfere with photosynthesis
       of bottom vegetation
     - clog the screens of water treatment systems
When these massive algae populations suddenly die off, their decomposition
releases gaseous substances and depletes oxygen levels in
the water, with harmful effects to fish and other aquatic organisms.
Health Effects
    Fertilizers usually contain nitrogen, phosphorus, and potassium.
Of these, nitrogen in particular has been associated with
health problems.  Nitrogen, which occurs as nitrites, nitrates, and/or
ammonia, may be converted to another form by chemical reactions
occurring naturally in the environment.
Nitrites.   The nitrite form of nitrogen is very toxic; if taken by
humans in drinking water or in food, it enters the bloodstream
where it interferes with the ability of the blood to carry oxygen.
Nitrites can also combine in compounds that may cause cancer in
Nitrates.   Nitrates are much less toxic than nitrites.  Healthy,
mature animals with single stomachs are able to expel nitrates in
their urine.  However, cattle, young animals, and children can
convert some nitrates to nitrites in their stomachs, a condition that
can be harmful.
    Both nitrites and nitrates occur naturally in foods and water,
but only in small amounts.  Only small amounts can be tolerated by
humans.   The World Health Organization has fixed the Drinking
Water Standard for nitrates at 0 to 50 parts per million (ppm) as
recommended levels, and 50 to 100 ppm as acceptable.  In many
developing countries, however, these levels are exceeded, especially
where drinking water supplies are contaminated by nearby concentrations
of nitrogen, such as manure piles in farm barnyards.
    Obviously project plans must include consideration of fertilizing
practices in terms of the location of compost piles, manure accumulations,
and slope of fertilized fields in relation to housing and water
Ammonia.   Ammonia, like nitrate, can be converted by specialized
bacteria to toxic nitrite.  Ammonia occurs naturally.  It is generated
by micro-organisms as they break down organic matter on the
bottom of stagnant lakes.  Dissolved ammonia can occur at levels
that are toxic to fish.  Another problem with nitrogenous fertilizers is
that the addition of a common fertilizer, sulfate of ammonia, may
acidify an already acid soil.  However, this may benefit a basic soil.
Phosphorus.   Phosphorus usually enters water as a soluble phosphate
compound that is completely available for algae growth.  Phosphate
may also enter the water adsorbed on sediment or on particles of
organic matter.  The phosphates are then slowly released.  These
phosphates then contribute to problems associated with eutrophication.
    Erosion control practices may be an that is needed to control
the loss of phosphorus and nitrogen.  If nutrient losses persist,
however, other nutrient management practices may be necessary
such as fertilizer management, crop rotation, legume cropping etc.
    One must be careful that solving one problem does not create
another. As an example, in certain areas of the state of Texas, USA,
terraces were built to retain moisture.  While the terraces did hold
water, this moisture control caused nitrate leaching, which contaminated
the groundwater supplies of the area.
Managing Fertilization
    To prevent the build up of nutrients in soil and their subsequent
loss through leaching, farmers should apply only the needed
amount of fertilizer to croplands.  Failure to estimate fertilizer
requirements accurately leads many people to over-fertilize.   The best
way to prevent overfertilization and the leaching that results is to
estimate the need for fertilizers and apply only that which will be
used by the crop.  The table below provides general guidelines for
the nitrogen requirements of selected crops.  It should be kept in
mind, however, that most of these generalizations must be evaluated
for each locality.
                                           Kilos of nitrogen
Crop                                per hectare per year
Grass (2-3 times as a top dressing)        100-150 (maximum)
Small grains                               20- 40
Potatoes                                    120-160
Leafy vegetables                           120
Root crops                                 80
General home vegetables                    100
    Symptoms of lack of fertilizer will emerge when the seedlings
are a few inches tall.  Fertilizer can be applied at this time in
between the rows.  At this point, when the soil is deficient in a
particular nutrient, the  crop plants will develop specific symptoms.
Thin stems and yellowing of leaves is typical of nitrogen deficiency,
whereas purpling of leaves signals phosphorus deficiency.   The effects
of some elements are greatest when fertilizer is applied near the
time of fastest vegetative growth, that is, several weeks after the
plant emerges from the soil.  This is not true for phosphorous, which
needs to be applied early for root development.  With late application,
less fertilizer is used and it is used more efficiently.   However,
late application can set back development of the crop.   One practice
is to put half the fertilizer on the field at one time early in the
growing season and the rest later.
    Soil fertility and physical conditions may be estimated by
observing certain biological indicators such as the prevalence of
specific weeds.  Although weed growth may be determined by more
factors than just soil conditions, at times the dominance of one
specific weed species can be well correlated with salinity, drainage,
nutrient levels, or soil texture characteristics.  The development
worker is advised to consult local farmers, extensionists, or technical
experts to interpret the indicators.
    Project planners who are not agricultural experts will probably
want to consult others for advice on actually choosing fertilizers and
using them in crop production.  Local farmers, extensionists, and
agricultural experts have experience in determining what kind and
how much fertilizer is needed.
Crop Rotations
    The average amount of fertilizer needed on fields often can be
reduced by rotating crops.  Crops that require high nitrogen levels,
such as maize, sorghum, and cotton, can be rotated with legumes
such as soybeans, beans, or alfalfa, or with crops that require
smaller amounts of nitrogen such as small grains.  Crops can be
alternated by growing season to reduce the need for other fertilizers.
The particular cropping sequence appropriate in a rotation will vary
with the climate, soil, tradition, and economic factors.   Some crop
yields are affected by the previous crop.  For example, yields of
almost any crop after barley are usually lower than after corn,
soybean or wheat.

03p89.gif (486x486)

Animal Wastes
    Animal manures can be good fertilizers, but there are problems
associated with them.  If manure is applied as it becomes available
nitrogen will be released slowly before planting.  This is not always
possible.   Storing manure, however, is difficult and costly.  It is also
difficult to determine how much nitrogen is being applied when
animal wastes are used, especially since the nitrogen amount varies
with the animal and its diet.  The best way to use animal manures
to prevent nitrogen loss to volatilization is to plow it into the soil
directly, or add it as a slurry, so that it soaks into the soil.   One of
the advantages of animal wastes as fertilizers is that they release
nitrogen slowly enough that little is lost through leaching.
Plowing-Under Green Legumes
    Before chemical fertilizers were developed, many farmers would
grow a legume on a field and then plow it into the soil to serve as a
nitrogen source for later crops.  The main disadvantage is an economic
one--no crops can be harvested from the field that season.
However, compared with the cost of using chemical fertilizers and
their potential impacts upon the environment, this practice is useful
when a farmer has enough land to leave fields fallow.  In areas
where chemical fertilizers or animal wastes are not available, this is
one way to add nitrogen and organic matter to the soil.  In general,
immediate benefits from incorporation are only observed with young
legume green manures.  Most other residues have high C/N
(Carbon/nitrogen ratio, see beginning of this chapter for explanation)
and "tie-up" nitrogen during a period of time.
Controlling Surface Applications
    The type of fertilizer must be chosen carefully, and it must be
applied at the right time.  For example, nitrogen, which moves
quickly through the soil, should be applied just before or during the
growing season.  Phosphorus and potassium fertilizers can be applied
after the growing season or sometime before the next one.   It is
usually best to mix fertilizers into the soil right after application to
reduce loss of nutrients to erosion.
    By answering questions such as those below for each project
and site, the development worker can estimate the potential effects
of fertilization projects on the environment.  If the answers are not
readily apparent, go back and think about the project site again.
Consult local experts in the field if the answers point out major
problems.   Use the questions as guidelines to plan projects that will
be both environmentally sound and successful.
    * Is manure available for use as a fertilizer in the project?  If
      used, would this practice result in the spread of weeds
      and/or disease through human contact with the manure?
    * Will plant residues be used for fertilizers and soil structure
      enhancement?   What is the C/N ratio of these materials?
    * Will new plant species or varieties be introduced?  This could
      have long-term environmental repercussions and the potential
      effects should be carefully reviewed.
    * Could the new species out-compete traditional crops in the
    * Do the new varieties need more fertilizer than traditional
    * Will the new varieties require more pesticides, and/or the
      use of heavy farm machinery, which could lead to other
    * Could new pest species be attracted into the region along
      with the new crop?
    * Will the project involve the use of inorganic fertilizers?
    * Could this practice lead to nitrite toxicity for people or animals?
    * Are precautions being taken to avoid over-fertilization?
    * Could the project enhance loss of nutrients via runoff,
      erosion, or leaching?
    * Could nutrient transport cause eutrophication?
    * Are there other nutrient management considerations?
    * Does the success of the project depend on inorganic fertilizers?
      If so, do farmers have a reliable source?  Have they
      been trained in its use?   What are the projected costs of
    * What alternative project designs could be used at the site to
      minimize nutrient loss?
    The following table lists ways to manage nutrients in agricultural
projects.   The left-hand column names the practice; the
right-hand column describes the advantages, disadvantages, and
potential effects of each as a nutrient control method.
                     CONTROL OF NUTRIENT LOSSES
Practice                Advantage/Disadvantage
Timing nitrogen application    Reduces nitrate leaching; increases efficiency
                               of nitrogen use.  However, may
                               encounter labor shortages.
Rotating crops                 Reduces fertilizer requirements; reduces
                               erosion and need for pesticides.  But may
                               decrease production of saleable crops.
Eliminating excessive          Reduces cost of fertilizers; can cut nitrate
fertilization                   leaching.
Using animal wastes            Enables slow release of nutrients; economic
                               gain for small farms; improves soil
                               structure; extends the period of residual
                               effects of applied nutrients on subsequent
                               crops.   However, there are labor costs and
                               problems with spreading.
Plowing under green            Reduces need for nitrogen fertilizer; not
legume crops                   always feasible; amounts of nitrogen difficult
                               to determine; ties up available land.
Controlling fertilizer         May decrease nitrate leaching; not yet
release time                   economically feasible.
Incorporating surface          Decreases nutrients in runoff; may add
applications                    costs; not always possible; no effect on
Timing fertilizer plow-down    Reduces erosion and nutrient loss; may
                               not be convenient.
Source:   U. S. Department of Agriculture, 1975.
Adapted from Control of Water from Cropland, Vol. I, A Manual for
Guideline Development.
                   CHAPTER 8
                    PEST MANAGEMENT
    "Pest" is a human-oriented term.  It has been defined as "an
organism that reduces the availability, quality, or value of some
human resource.  This resource may be a plant or animal grown for
food, fiber, or pleasure (or) a person's health, well-being, or peace of
mind."   (Gips 8.8, Flint 8.7)   What is considered a "pest" then is
based on human needs and values and thus can change from situation
to situation.  Most organisms and animals are not pests and are
considered beneficial.
    The use of chemicals that control pests and herbs developed in
the 1940s and accelerated in the following decades.  The use of
pesticides and herbicides has now spread throughout the world.   It is
only in the past twenty-five years that the horrors of using pesticides
have become known and documented.  Balancing against the great
benefits that pesticides and herbicides offer is the negative impact of
direct contact in applying the chemicals, and of secondary effects on
humans through the water, food, and meat that we eat, as well as
damage to the environment.
    Pests, however, are a particular problem in farming systems.
Changes in cropping systems often lead to changes in the numbers
or kinds of pests and associated natural enemies (predators and
parasites) in the agricultural ecosystem.  Planning environmentally
sound agricultural projects requires looking beyond the types of pests
and predators present and considering how measures used to control
pests will affect the total ecosystem.  Too often failure to take this
broad approach has resulted in damage to the environment and in
less than successful projects.
    In many agricultural projects, pests are controlled only by the
use of chemical pesticides.  Some chemical pesticides, however, cause
environmental problems as a result of their toxic or residual effects
and are a cause of sickness and death to humans.  In a small-scale
project, it may be possible to control pests by using less damaging
alternatives such as promoting biological control, planting different
crop mixtures, using less persistent and less toxic pesticides, finding
more species-specific pesticides, or growing resistant crop varieties.
It should be recognized, however, that some alternative methods
require more sophisticated management.

03p95.gif (534x534)

    Some birds and rodents if they reach pest proportions can
cause great damage and losses in agricultural systems and thereby
significantly reduce the amount of food available for people and
livestock.   Various methods can be used to control pests--from scarecrows
and netting to trapping and killing them individually.  It is
more common, however, to poison these animals, even though poisoning
is potentially a far more dangerous practice to people and other
non-target organisms.  Whenever possible, trapping and other mechanical
control practices should be used to control larger pests.
When properly managed, the pests that are edible can provide an
important source of protein and income to local people.
                       MANAGEMENT PRACTICES
    The best way to lessen or avoid unwanted environmental
effects from pesticide use is to minimize their use.  Feasible alternatives
to pesticides often exist and should be investigated by the
development worker.  For example, there may be combinations of
local plants that can control pests.  In some areas, the use of resistant
varieties and delayed or early planting can reduce crop damage
by pests.  It is important for the development worker to understand
how to use alternative control methods.  In the long run, it may be
better to protect and enhance the natural predators and parasites of
pest species than to use chemical pesticides.  Insect pests can become
resistant to certain pesticides and may do so after only a few applications.
Predator species, on the other hand, may have longer
life-cycles and may be more sensitive to repeated pesticide applications.
Find out what kinds of pests are a problem before using a
pesticide and try to use pesticides that are both species-specific and
short-lived.   Broad spectrum pesticides kill beneficial as well as pest
organisms and are not recommended.  Also find out what other
pesticides are being used locally to control disease vectors or other
pests.   If pesticides are already in use some resistance may already
exist among pest species.
    If possible consult local specialists and authorities before deciding
on a particular pesticide for use on agricultural lands.   Some
countries have very specific laws governing the use of particular
pesticides, and these should be taken into account before any time or
money is spent obtaining or using chemical pesticides.  Some countries
outlaw certain pesticides and export them to other countries.
Contact government agencies and local universities or the regional
office of the Pesticide Action Network (PAN) for information on local
pest species and alternative control practices.  A list of regional
offices of the Pesticide Action Network (PAN) that can provide
technical information or answer specific questions is in Appendix B.
    Because of the potentially harmful effects of chemical pesticides,
development workers should take care to investigate alternative
measures and use them wherever possible.
Local Plants
    Many farmers know the plant species in their area that have
insecticidal properties.  There are about 1,600 plant species known to
possess pest-control properties.  Try to find indigenous plant materials
and use them rather than chemical pesticides.  Two such plants
with insecticidal properties are tobacco and pyrethrum (derived from
chrysanthemums).   Both are now widely distributed throughout the
tropics.   Another plant used is the derris root.   It produces a chemical
called rotenone which is used as a poison especially for ridding
fish ponds of trash fish.  Some plants, like the neem tree have
multiple types of pest-control action.  When a local plant which has
insecticidal properties is pointed out, try making a solution from
crushed leaves or stems and spray it on a small test area.   If this
seems successful, it may be cheaper to use than commercial pesticides,
easier to get, and environmentally safer.  Even if the test is
not successful there may be other ways of utilizing the tree or plant
for pest-control.  Local farmers often have this information.
Crop Management Practices
Rotation.   Crops usually are rotated for economic and nutrient
management reasons.  Crop rotation also can be used as a method to
control insects, weeds, and plant diseases.  Many traditional agricultural
practices rely upon crop rotations to provide weed, disease and
insect control.  Crop rotations, including non-host crops, have proven
effective against soil-borne pathogens (cabbage black rot, bean bacterial
blight) and corn rootworms and should be explored with local
experts, and with local farmers who rotate their crops.
Resistant Varieties.  There are also crop varieties that are resistant
to attack by disease or insects.  These varieties sometimes need the
help of pesticides, but in greatly reduced quantities.
Intercropping.   Intercropping and polyculture can also reduce the
spread of pests and disease organisms.  By interspersing non-susceptible
crop plants with host plants in the same field, the spread of the
pest and disease organisms among susceptible crops can be considerably
reduced.   Moreover, the intercrop may also provide a more
favorable habitat for the growth and reproduction of pest and disease
organisms than the primary crop.  It may also provide habitat for
beneficial insects and other organisms.  For example, alfalfa strips
interplanted among cotton rows attract lygus bugs away from cotton,
avoiding damage.  Surrounding melon or squash fields with a few
rows of corn, acts as a trap crop for melon flies.
Planting Time.  Another crop management practice is to change
planting times to prevent attack by insects and disease.   Insect
reproduction cycles are often attuned to the growth of plants.   If
crops can be planted a few weeks before or after the normal time,
farmers may be able to by-pass the stage of the insect that causes
the most damage to the crop.  Early maturing varieties may escape
insect attack.
    Early planting can be effective in avoiding the egg-laying
period of a pest by allowing crop maturation before pest attack
occurs.   However, because it requires knowledge of insect species and
their life cycles, the advice of entomologists or other scientists from
local universities and government agencies may be needed.
Plant Spacing.  Modifying the spacing of crop plants by decreasing or
increasing plant densities may provide a measure of pest control by
affecting the micro-environment of the pest, the vigor of the plant,
and the duration of crop growth.  For example, densely planted
stands of grain crops suffer less from chinch bug attack, whereas
narrow-row planting of cotton can discourage boll weevil infestations.
Destruction of Alternate Host Plants.  It may be found that the crop
pests are breeding or spending part of their life cycle on another
plant species.  If the alternate host is another crop, it may be best
not to grow both in the same area.  If the alternate host is a weed,
it may be possible to control it and thus reduce the pest population.
Control of the sugar beet curlytop virus involves destruction of the
Russian thistle, the alternate host of the insect vector, the beet
leafhopper.   Many weeds, however, especially flowering Compositae
(sunflower family) and Umbelliferae (carrot family), can provide
alternate food (pollen, nectar) to a number of important parasites
and predators.  For example, biological control of crickets in Puerto
Rico depended on the presence of two weeds that provided nectar to
the parasitic wasps.  In this case, it was desirable to have more
weeds of this type.  On the other hand, if a certain type of crop is
preferred by a pest, one way to control the pest is to plant that crop
along with the desired crop and sacrifice the alternate crop that
serves as a trap to the pest.  Pests and diseases can also be controlled
by growing, in sequence or rotation, crop plants that are not
susceptible or do not constitute alternative hosts.
Mechanical and Traditional Control Practices
    Sometimes the easiest, least costly, and most environmentally
sound means of controlling pests on agricultural lands is by using
mechanical and traditional control methods.  Some of these methods
for weed control, for example, involve:
    - pulling weeds by hand or cutting them down
    - covering weeds with mulch to prevent growth
    - burning a field prior to planting
    - flooding the field
    - normal tillage practices such as plowing and harrowing
    Mechanical and traditional practices can be very effective in
those countries where labor is available and money and pesticides
are not.   For example, insects can be killed by trapping; rats can be
smoked out, trapped or clubbed; and birds can be shot or trapped in
nets and removed from the field.  Hunting and/or simply shooting
nuisance birds or game animals can also be effective.
Biological Control Methods
    Pests can be effectively controlled by supporting the resident or
introduced natural enemies of pests.  Many of these methods are
"new" as far as research is concerned.  However, in agricultural
areas that retain a diversified environment, biological control is an
everyday occurrence.   Birds eat insects, cats eat birds, and so on.
Each predator has its prey and helps control the population of that
prey.   In practice, biological control is the use or encouragement of
natural enemies for the reduction of pest organisms as well as
introducing crop varieties that are resistant to pests discussed
    Natural enemies act as mortality agents that directly respond
to the size of the population.  Thus natural enemies act as density-dependent
factors.   This relationship between pest density and
the intensity of attack by natural enemies is called a functional
response.   For density-dependence to happen in agroecosystems it is
necessary to let the insect pest population build up sufficiently to
stimulate the corresponding build-up of the beneficial predator or
parasite population.  This will not happen if pesticides are used on
the pest as soon as it appears.  Thus, a certain amount of injury to
the crop may occur.  A small test plot may demonstrate the effectiveness
and the negative possibilities before introducing the technique
widely.   Observation and discussion with farmers can help to determine
the maximum pest population that can be tolerated at a
particular time without crop damage becoming too serious before
other controls are sought.  Natural controls may take over before
this happens.
    Research into the use of biological suppression controls has
expanded to include other methods, including the use of sex attractants,
insect growth regulators, sterilized male insects, repellants,
and warning or aggregating chemicals (pheramones) that influence
the behavior of insect colonies.  These methods have worked well in
some small-scale applications but may or may not work in other
situations.   They should be considered as alternatives that may be
used alone or in combination with other pest control practices.
    The best way to control pests on agricultural lands may be a
combination of the chemical, biological, cultural, and mechanical
control techniques described here.  Using a combination of these pest
control practices has the following advantages:
    - prevention of adverse impacts upon the environment from
      the continuous use of pesticides
    - prevention of the development of resistance to particular
      pesticides in pest species
    - provision of a backup pest control system in the event that
      any one method fails

03p101.gif (437x437)

    Ideally integrated pest management requires well-trained pest
managers who understand the complex factors of ecosystem interrelations.
However, even without such resource persons there are merits
to introducing and experimenting with some alternative means of
control as described in the previous sections, when the results of
pesticide use are sickness and death to people.
    Some of the most characteristic features and goals of the integrated
pest management Approach are:
    * The focus is on the entire pest population and their natural
      enemies operating within an ecosystem.  The agroecosystem
      is the management unit.
    * The objective is to maintain pest levels below a
      pre-established economic threshold.   The goal is to manage
      rather than eradicate the pest population.

03p102.gif (540x540)

    * Control methods are chosen to supplement the effects of
      natural control agents (parasites, predators, weather, etc.).
    * Alleviation of the problem is long-term and regional, rather
      than localized and temporary, and the harmful side effects
      on the environment are minimized.   Thus, integrated pest
      management should be part of government policy.
    * Monitoring is essential.   Pest population numbers need to be
      regularly monitored, and also the environmental factors
      influencing pest abundance in order to determine when to
      apply control actions.   How monitoring is conducted depends
      on the crop, the pest species, the climate, the human skills,
      and economic resources.   Simple monitoring procedures that
      involve no special equipment or expenses have been designed
      for farmers with limited resources.   For example, with rice, a
      system based on plant tapping can be used to sample for the
      green leafhopper.   Each week a farmer randomly picks 20
      hills across the paddy.   He slaps the plants with force
      several times with the palm of the hand.  He then counts
      both adults and nymphs that fall on the water.  Finally, he
      calculates the average green leafhopper numbers per hill,
      and based on this data makes decisions whether or not the
      pest needs to be controlled.

03p103.gif (540x540)

                   DEFINITION OF A PESTICIDE
    "Pesticide is an umbrella term used to describe any chemical
that controls or kills a pest, be it insect, weed, disease, or animal.
Pesticides are generally classed by the type of pest they control:
insecticide (insects), herbicide (weeds), fungicide (fungus), rodenticide
(rodents), nematicide (nematodes), acaricide (mites, ticks and spiders).
Pesticides are also defined by their method of dispersal
(fumigant) or mode of action, such as an ovicide, which kills the eggs
of pests.  Although they do not specifically kill pests, insect growth
regulators are considered pesticides because they modify the insect's
growth in such a way as to halt its deleterious effects."   (Gips 8.8)

03p104.gif (600x600)

    Pesticides used today belong to three principal groups of
    * Organochlorides are derivatives of chlorobenzene that are
      highly toxic and have long-lasting effects.  Included in this
      type of chemicals are DDT, chlordane, aldrin, dieldrin,
      endrin, toxaphene, lindane, heptachlor, among others.
    * Organophosphates are highly toxic to men and other
      warm-blooded animals.   Examples are phosdrin, parathion,
      methyl parathion, azodrin or nuvacron, lorsban.
    * Carbamates are derived from carbonic acid.  Like organophosphates,
      they have inhibitive or disruptive effects on the
      central nervous system, which controls all bodily functions,
      they are very poisonous and take immediate effect.  Examples
      are temik, furadan, lannate, sevin, baygon.  (Source:
      Secretariat for Ecologically Sound Philippines.)
                    EFFECTS OF PESTICIDE USE
    The use of pesticides should be limited to epidemic situations
in which all other measures fail to provide control.  Pest management
programs should seek to reduce both the frequency of application
and the dosage.  Following are some of the common effects of
dependence on pesticides.
Effects on People
    Pesticides can be inhaled by humans or taken into the body
through the skin.  Body contact is a particular problem during the
application of pesticides.  Failure to take safety precautions and to
handle certain pesticides carefully may even result in death.   Thousands
of individuals suffer from pesticide poisoning every year.
Many die annually.  Fatalities have mainly occurred among people
who handle pesticides--farmers, crop dusters, farm workers, and
workers in pesticide manufacturing factories.  More and more concern
is also focussed on the issue of poisonings attributed to eating
food crops and meat containing pesticide residues.
Effects on Soil Fertility
    Each square meter of fertile agricultural soil contains millions
of life forms--insects, earthworms, oligochaete worms, nematodes,
protozoa, algae, fungi, bacteria, and yeast cells.  All these organisms
are absolutely necessary for soil fertility maintenance.   The organisms
are involved in:  the conversion of bound nutrients into
forms available to plants; the break up of organic matter; the fixation
of nitrogen; and the aeration of the soil.  Their presence ensures
that ecological balance or equilibrium is maintained.  Continuous use
of pesticides that do not decompose rapidly can alter this soil organism
community and, ultimately, may reduce soil fertility.  Populations
of earthworms, critical to some ecosystems, may be drastically
decreased by chlordane, endrin, parathion, carbametes and most
nematicides.   Some fungicides and herbicides seem to affect mostly
the microflora, thus upsetting the dynamics of most nutrients in the
Effects of Pesticides on the Balance of Nature
    Most organisms in nature are regulated by natural enemies
keeping them in a state of balance with their environment.  Overuse
or misuse of pesticides can interfere with this natural control system.
When this happens, pest problems can actually be worsened.
    During the last three decades, despite a tenfold increase in
insecticide use, crop losses to insect pests have nearly doubled.   Two
major factors account for this near doubling of crop losses:
    - more than 300 species of insects, mites and ticks have developed
      genetic resistance to pesticides
    - pesticides have inadvertently destroyed natural enemies of
      certain insect pests, resulting in pest resurgence and/or
      secondary pest outbreaks
Some Other Effects of Pesticides
    Certain pesticides can also alter the chemical makeup of
plants.   Some organochlorines can increase amounts of particular
mineral elements in corn and beans.  Herbicides, especially 2,4-D,
can induce accumulation of nitrates in plants, with possible toxic
effects on livestock and other animals.  These changes in plant
constituencies can alter the physiology of certain crop plants, such as
corn, making them more susceptible to insect or pathogen attack.   In
particular, 2,4-D can render some crops more susceptible to pests
and disease.
Effects on the Aquatic Environment
    Pesticides transported from treated fields into the aquatic
environment by runoff and erosion are distributed throughout water,
mud, and the organisms living in both.  The buildup of pesticides in
a given body of water depends on:
    - how much pesticide is entering the aquatic system
    - the persistence of the pesticide
    - the tendency of the pesticide to bioaccumulate, or build up
      within an organism and food chains
    - the sites or organisms in which the pesticide concentration is
      being measured
Pesticide Persistence
    Pesticide persistence is the length of time a pesticide remains
biologically active, or toxic, to target pests.  Most pesticides are rated
according to their persistence, as indicated in the table below.
                     PERSISTENCE OF CHEMICALS
                  Duration of    Chemical   Examples
                  Activity       Group
Non Persistent    1-12 weeks             Organo-phos-        Malathion,
                                        phorous com-       methyl para-
                                        pounds;            thion, para-
                                        Carbamates         thion carbaryl
Moderately         1-18 months            --                 2,4-D, atra-
Persistent                                                  zine
Persistent         2-5 years              Organochlor-       DDT, BHC,
                                        ine(1) comp-        lindane, al-
                                        ounds              drin, dieldrin,
                                                           endrin, chlor-
                                                           dane, hepta-
                                                           chlor, cam-
Permanent          Degraded to            Compounds          Phenyl mer-
(residues)         (permanent res-        containing          cury acetate,
                  idue                   mercury,            arsenate of
                                        arsenic or lead    lead
(1) A number of organochlorine compounds are in the "non-persistent"
or "moderately persistent" classifications, e.g., methoxychlor, dicofol,
    In general, persistent pesticides (those which remain biologically
active for longer periods) are less soluble and volatile but have a
strong tendency to become adsorbed (attached to particles of soil).
The best known of the persistent pesticides are the organochlorine
insecticides (DDT, Aldrin, Endrin, Heptachlor, etc.), the herbicide
simazine, and the fungicide benomyl.  These can remain up to 14-17
years in the soil.  The longer the pesticide persists, the greater the
likelihood that it will move from the target area via soil, water, air,
or organisms, and influence adjoining ecosystems.
Pesticide Pathways
    Pesticides are applied in either liquid or powder form.  Both
forms can be sprayed on the soil or plants.  During application, some
of the pesticide is lost to the air through drifting or volatilization.
After application, the pesticides can travel in various ways in the
    - biological degradation by soil microorganisms, chemical
      degradation on the soil surface, or foliage photo-decomposition
      as a result of sunlight
    - volatilization
    - absorption by plants (which may be eaten by animals and/or
    - adsorption onto soil particles (especially clay and organic
      matter) that may move with erosion
    - dissolution in water (rain or irrigation) that becomes surface
      runoff or that infiltrates into the soil, later appearing in
      surface water or groundwater supplies.
    Pesticides take one pathway rather than another depending on
a number of factors.  Principal among these are:  characteristics of
the pesticide itself; the soil type; the strength and amount of rainfall;
the type of erosion control measures being used; and the temperature.
In general, pesticide compounds that are more water-soluble
and less persistent will move primarily in runoff water.   Those that
are more firmly adhered or adsorbed to soil particles will generally
move with sediment.
Distribution in Soil
    Organic content and texture are the most important soil
characteristics influencing how pesticides move in the soil.  Other
soil properties--pH, moisture content, temperature, mineral content--may
also influence pesticide persistence and movement.  For
example, the greatest persistence of organochlorines is found in soils
rich in organic matter, with high clay content and with acid pH.
Water and pesticides compete for adsorption sites on soil particles;
therefore, as moisture in the soil decreases, the amount of pesticide
adsorbed may increase.  Some pesticides in the soil are subject to
leaching.   Leaching of pesticides is influenced by the amount and
rate of water flow, and the formulation, concentration, and rate of
degradation of the pesticide.  Pesticides may move laterally through
soil as well, appearing in surface or sub-surface runoff.  Cultivation
of the soil can also enhance loss of volatile pesticides.
Distribution in Water
    Pesticides enter lakes, ponds, rivers, and other waterways from
runoff of treated areas, from drift, or from direct pesticide (mainly
herbicide) applications.  The quantity of a pesticide that moves into a
water course from treated areas depends upon topography, intensity
and duration of rainfall, soil erodability, and land management
practices.   Improved erosion control practices can be very important
for keeping pesticides from entering the larger environment.   Sound
project planning requires consideration of the methods for erosion
control in light of their applicability for pesticide control.
    If pesticides enter a body of water in a dissolved state, the
pesticide in solution will move as the water moves.  The pesticide
may:  remain in solution in the water; precipitate out of the water
and end up in bottom silt; be taken up by aquatic organisms; be
biologically or chemically degraded; or more commonly become
adsorbed onto live or dead particulate matter which eventually
settles to the bottom as sediment.  Pesticides adsorbed on sediment
will disperse with the sediment.  The finest particles (those carrying
the greatest concentration of pesticide) will be transported the
farthest and will typically be the last to settle out of the water to
the bottom in lakes or quiet water.  Systems with running water
which flushes away pesticide pollutants tend to be more resilient
than those where water is static.

03p110.gif (486x486)

    Until they chemically degrade, pesticides will not disappear.
Because the system is dynamic, even those deposited in bottom muds
may be later churned up and carried downstream.  Also, pesticides
continually separate from muds and remain in the water.  Once in
the water, the pesticides may reach the surface and volatilize
(become gaseous) or be degraded by sunlight.  On the bottom of a
water body, there is often a lot of microbial activity in the organic
matter.   At the bottom, biological decomposition consumes oxygen,
thereby creating anaerobic (without oxygen) conditions that favor the
degradation of many pesticides.
    If pesticides must be used, try to use those that will degrade
rapidly in water in order to protect nearby aquatic environments.
Also, keep in mind that the products of pesticide degradation may be
toxic.   Information appropriate for your region is available by writing
to the Pesticides Action Network (PAN).  Addresses of the regional
offices of PAN are in Appendix B.
Local Experience
    Check with local farmers or extension agency personnel to see
what local experience has been with given pesticides.  There is no
prescription for the persistence and potency of pesticides.  It can
vary depending upon local conditions.
Alternative Pest Control Measures
    Check the variety of alternative non-chemical control measures
that may meet project needs.  Become familiar with possible negative
effects of the pesticides you may be considering.  Some of these
alternatives are described elsewhere in this chapter.
    Consider the possibility of relationships between two or more
pesticides used in the same area before applying more than one to a
field.   When two or more pesticides are applied at the same time,
their combined toxicity may actually be greater than the sum of their
individual toxicities.  This is called synergism.
Timing of Application
    If possible, apply pesticides well before heavy rains if they are
to do the most good in controlling target organisms.  The rate at
which pesticides are washed off the land is usually high at first.
This rate of loss, however, decreases reaching a steady rate, unless
changed by weather, soil, temperature, soil moisture level, acidity, or
cultural practices.  Some pesticides have greater losses if they are
applied to wet soil rather than dry, especially if runoff occurs soon
after application.  When pesticides are incorporated into the soil, the
loss to runoff is not as great as when they are just left on the soil
Pesticide Movement
    Explore the ways in which pesticides might move through the
environment to help design projects that will contribute less to
pollution.   Runoff travelling from cropland to open water can carry
pesticides.   As the water crosses other lands, some pesticide is left
behind.   While the total amount entering the water is decreased,
nearby land may also be contaminated by pesticides.  This pollution
can have damaging impacts on animals and humans.
Precautions Necessary
    If you are going to introduce pesticides it is important to
provide training to those who will be applying them.  Include precautions
regarding bodily exposure of those applying chemicals and
exposure of others in the area.  At the very least, read the directions
on the label carefully.  These will instruct on the way in which the
chemical can be safely applied, the time that needs to elapse following
application before the area is safe, and the relation of using the
chemical to the maturing of the crop.  Also, read the precautions on
the label and understand the steps to take in case of emergencies
such as swallowing some, or coming in physical contact with the
chemical.   Never reuse pesticide or herbicide containers.
    Addressing questions such as the following will provide the
project planner with a background for making informed judgments
concerning environmentally sound pest control.
    * Are chemical pesticides suggested for the project?
    * Have all pest management options been considered?
    * Are alternative pesticides available that are relatively safer
      to use?
    * Are there plants with pesticidal properties which could be
      used?  Are they locally available?
    * Are the pesticides to be used in the project recommended for
      use on these particular crops by the manufacturers?  By the
    * Are similar pesticides being used locally for health purposes,
      such as malaria control?
    * Can a species-specific pesticide be used?
    * Does the project design recognize the possibility that target
      species will develop resistance to the pesticide and larger
      quantities may be required each year to control the pest?
    * Is it possible to change pesticides to reduce the likelihood of
      target species developing resistance to an important pesticide?
      If so, can a schedule for implementation be developed?
    * Is the pesticide persistent in soil?  Will it tend to accumulate
      in the soil?
    * Might the pesticide suggested for use kill beneficial soil
    * Does the pesticide tend to bioaccumulate (biologically increase)
      or biomagnify (biologically grow) in organisms?  If
      so, which organisms would it affect in the immediate area, if
    * Is there a body of water nearby?   If so, are people downstream
      highly dependent upon aquatic resources such as
      fisheries, aquaculture, and drinking water which might be
      contaminated by an accidental discharge of pesticides because
      of the project?   What effect would contamination of the
      water have on health, finances, and other?
    * Is it likely that erosion will carry pesticides into downstream
      water bodies?   If so, could such pesticides affect fisheries,
      aquaculture projects, and domestic water use?
    * Have adequate precautions been taken to protect workers
      from pesticide poisoning during transport, storage, and
      application of pesticides?   Are instructions available in local
      languages with culturally sensitive symbols?
    * Can pesticide applications be timed to avoid rapid loss to
      wind and rain?
    * Is it possible to develop plans that can be put into effect
      easily and simply in case of an emergency, such as accidental
      pesticide pollution or physical contact?
    * What alternative project designs could be used at the site to
      minimize environmental impacts from pesticide use?
                      CHAPTER 9
                    AGROFORESTRY SYSTEMS
    Agroforestry systems are production strategies designed to
promote a more varied diet, new sources of income, stability of
production, minimization of risk, reduction of the incidence of insects
and disease, efficient use of labor, intensification of production with
limited resources, and maximum returns with low levels of technology.
Some form of agroforestry has been practiced by many traditional
agriculturalists.   For a number of reasons such as commercial
plantation development, cattle raising, deforestation, and population
pressures, these practices may have been abandoned.  Recognizing
the value of combining trees with crops and livestock as a means of
conserving soil, increasing the multiple uses of land, rehabilitating
degraded sites, and diversifying to reduce risk is leading development
workers to consider introducing or reintroducing agroforestry practices
with improvements based on research and experience.
    This recognition has grown out of a combination of acknowledging
traditional experience and scientific research.  Traditional bush
fallow and shifting cultivation could be said to be a precursor of the
modern understanding of agroforestry.  The clearing of woody vegetation
for crops for a period of years and reestablishment of forest in
the fallow period was a combination of agriculture and forest in
sequence that has been practiced in many regions.  Taungya is an
early form of agroforestry that introduced tree seedlings planted by
foresters combined with growing of crops in the cleared area until
the tree canopy provided too much shade.  Traditional kitchen
gardens have typically been a mixture of shrubs, food crops, and
medicinal plants in a multistoried arrangement.  For some species of
coffee and cacao interplanting with shade trees has been a necessity.
Some more purposeful combinations of trees and crops practiced
today are introduction of fodder trees in fields; dispersing indigenous
species in fields for nutrients and fodder, as for example Acacia
albida in millet fields; use of trees for shelter belts and hedgerows.
Alley cropping is a recently introduced system that involves planting
and intensive management of relatively close-spaced rows of nitrogen-fixing
trees and shrubs such as Leucaena and Gliricidia, with a crop
such as maize in between.  (Winterbottom 9.19)
    Agroforestry denotes a "sustainable land and crop management
system that strives to increase yields on a continuing basis, by
combining the production of woody forest crops (including fruit and
other tree crops) with arable or field crops and/or animals simultaneously
or sequentially on the same unit of land, and applying management
practices that are compatible with the cultural practices of the
local population." (International Council for Research in Agroforestry,
    There are several ways to classify and group agroforestry
systems (and practices).  The most commonly used are:  structure
(composition and arrangement of components); function (the use of
trees); ecologic (ecosystem or climatic zone); and socio-economic scale
and level of management.
    Agroforestry systems can be grouped as:
    - agri-silviculture:   the use of land deliberately for the concurrent
      or sequential production of agricultural crops  field and
      tree crops) and forest crops (woody forest plants)
    - silvo-pastoral systems:   land management systems in which
      forests are managed for the production of wood, food and
      fodder, as well as for the rearing of domesticated animals
    - agro-silvo-pastoral systems:   systems in which land is managed
      for the concurrent production of agricultural (field and
      tree crops) and forest crops (woody forest plants)and for the
      rearing of domesticated animals
    - multipurpose forest tree production systems:  in which forest
      tree species are regenerated and managed for the ability to
      produce not only wood, but leaves and/or fruit that are
      suitable for food and/or fodder
    The functional basis for classifying agroforestry systems refers
to the main output and role of various trees, especially the woody
ones.   These would be productive functions (production of "basic
needs" such as food, fodder, fuelwood, and other products), or protective
roles (soil conservation, soil fertility improvement, protection
offered by windbreaks and shelterbelts, and so on).  The functional
basis is discussed in detail later in this chapter.
Ecologic or Climatic
    On an ecological basis, systems can be grouped for any defined
agro-ecological or climatic zone such as lowland humid tropics, arid
and semi-arid tropics, tropical highlands.  They can also be based on
climatic zones defined by rainfall patterns or other groupings that
serve the purpose.
Socio-Economic Scale and Level of Management
    The socio-economic scale of production and level of management
of the system can be used as the criteria to designate systems as
commercial, intermediate, or subsistence.
    Each of these ways of looking at agroforestry systems is useful
and applicable in specific situations, but for each there are limitations
so that no single way of grouping is universally applicable.
Classification depends upon the purpose for which it is intended.
    By combining agriculture and forestry/tree crop production, the
various functions and objectives of forests and food crops production
can be better achieved.  There are advantages of such integrated
systems over agriculture and/or forestry monocultures.  (Wiersum
Ecological Advantages
    * A more efficient use is made of the natural resources.  The
      several vegetation layers provide for an efficient utilization of
      solar radiation, different kinds of rooting systems at various
      depths make good use of the soil and short-lived agricultural
      plants can profit from the enriched topsoil as a result of the
      mineral cycling through treetops.   By a three dimensional
      use of space, total growing capacity is increased.  By including
      animals in the system, unused primary production can
      also be utilized for secondary production and nutrient recycling.
    * The protective function of the trees in relation to soil, hydrology,
      and plant protection can be utilized to decrease the
      hazards of environmental degradation.
It should be kept in mind, however, that in many agroforestry
systems the components may be competitive for light, moisture, and
nutrients; trade-offs must be considered.  Good management can
minimize this interference and enhance the complementary interactions.
Economic and Socio-Economic Advantages
    * By ecological efficiency the total production per unit of land
      can be increased.   Although the production of any single
      product might be less than in monocultures, in some instances
      production of the base crop may increase.  For
      example, in Java it has been demonstrated that after introduction
      of the tumpang-sari or taungya system, dryland rice
      production increased significantly.
    * The various components or products of the system might be
      used as inputs for production of others (for example, wooden
      implement, green manure) and thus the amount of commercial
      inputs and investments can be decreased.
    * In relation to pure forestry plantations, the inclusion of
      agricultural crops with trees, coupled with well-adjusted
      intensive agricultural practices, often results in increased
      tree production and less costs for tree management (e.g.,
      fertilization and weeding of agricultural crops may also
      benefit tree growth), and provide a wider array of products.
    * Tree products can often be obtained throughout the year
      providing year-round labor opportunities and regular income.
    * Some tree products can be obtained in the agricultural
      off-season (e.g., dry season), when no opportunities for other
      kinds of plant production are present.
    * Some tree products can be obtained without much active
      management, giving them a reserve function for periods of
      failing agricultural crops, or special social necessities (e.g.,
      building a house).
    * By the production of various products a spreading of risk is
      obtained, as the various products will be affected differently
      by unfavorable conditions.
    * Production can be directed towards self-sufficiency and
      marketing.   The dependency on the local market situation
      can be adjusted according to the farmer's need.  If so desired,
      the various products are entirely or partially consumed,
      or delivered to the market, when conditions are right.
    There are a number of limiting conditions or constraints to
implementing agroforestry systems.  These constraints should be
recognized and efforts made to overcome them, if agroforestry is to
be applied successfully.
    * A major ecological constraint is that agroforestry systems are
      ecosystem-specific and on certain low grade soils the choice
      of suitable plant species might be limiting, although many
      trees are better adapted to poor soils than annual crops.
    * The competition between trees and food crops, and the
      priority that must be given to them to meet basic needs,
      may exclude poor farmers, who have very little land, from
      tree growing.
    * In promoting tree planting, short term benefits as well as
      long term benefits are needed.   Economic or production
      incentives need to be included.
    * A common economic constraint is that some newly
      established agroforestry systems might need substantial
      investment costs to get started (e.g., planting material, soil
      conservation, fertilizer).   For these investments, credit may
      be needed.   In most agroforestry systems one may need a
      few years before the first yields are obtained.  In some cases,
      financial support is needed to provide for this waiting period.
    * Size of plot may affect the kind of inputs.  In areas with a
      high population pressure and poor soils, the private landholdings
      might be too small as viable production units.  In
      this case some kind of cooperative effort might be necessary.
    * Availability of seeds and/or seedlings is a critical variable for
      agroforestry projects.   Check with government offices, university
      forestry or botanical departments, or nongovernmental
      organizations involved in species research for the best species
      to meet your needs.   Then check on availability of seeds
      and/or seedlings.   In most cases, longer run planning includes
      developing small nurseries along with planting and
      maintaining trees.
    * Management of livestock sometimes can conflict with agroforestry
      ventures especially in areas where cattle or goat
      herding is being practiced.
    * Wildlife is a problem in some areas.  Where elephant herds
      still exist they have threatened forestation projects.
    * Pests may also threaten agroforestry projects--both tree and     
      ground crops.   Current infestation of locusts in some areas of
      the Sahel in Africa are a problem.
    * In areas with complex clan or communal land systems,
      developing agroforestry systems may be difficult.  Tenure
      rights are a fundamental consideration in agroforestry.  They
      may be a limiting factor.
    * Tree tenure is also a possible constraint.  In many cases,
      land on which trees may be planted and protected is not
      owned by those who planted them.   The planters, then, may
      not be legally entitled to harvest the trees or the produce of
      the trees.   Further, in some countries there are laws that
      restrict the harvesting/cutting of trees for any purpose
      regardless of who owns the land on which they are planted.
      It is therefore necessary to check before undertaking a tree
      planting project to see:
    - who owns the land
    - what are the regulations about protecting the seedlings
    - what are regulations about harvesting the trees and/or
      produce of the trees
    * Factors that may limit the participation of people and affect
      their motivation need to be considered.  In addition to land
      and tree tenure these include other socio-political policies of
      the government as well as some traditional social mores.
    * In all cases, it is essential that the local population is
      directly involved and traditional farming knowledge taken
      into account in the planning and design of the system.  (See
      Chapter 3) Agroforestry is a complex form of land-use and
      requires adequate farming knowledge.  Local knowledge and
      experience is still available about traditional agroforestry
systems.   For developing new agroforestry techniques, knowledge
of traditional land use and farming systems and
additional education and/or extension work is essential.

03p121.gif (540x540)

    Women have traditionally been involved in both agriculture
and in the use and management of trees.  Most often women harvest
the products of trees.  Yet women have often been ignored in the
design of agroforestry projects.  There are significant examples of
women taking the initiative to create possibilities for tree planting
and relating trees to the farm system.  Notable among these are the
Green Belt Movement of the National Council of Women, Kenya, The
Forestation and Ecological Education Project of Mujeres en Desarrollo
(MUDE) in the Dominican Republic, and the Chipko movement in
India.   Projects that involve participation of women from the outset
have been more sustainable.  (Fortmann and Rocheleau 9.2)

03p122.gif (486x486)

    Agroforestry systems are multiple use systems in which the
tree components provide most of the multiple benefits.   The management
of the tree component can affect, directly or indirectly, the
other ecosystem components, for example soil conservation, nutrient
recycling, the hydrological cycle, as well as bio-components (other
crops, weeds, insect populations, micro-organisms).  Thus, through
management of trees these other components can to some extent be
    Perhaps the most important ecological role of trees in farmlands
is their effect on soil conservation.
Effect on Soil Conservation
    Inclusion of trees usually increases organic matter content, and
improves physical conditions of the soil.  (Wiersum 9.18)

03p123.gif (540x540)

Effect on Nutrient Recycling
    Below is a schematic presentation of nutrient relations and
advantages of ideal agroforestry systems in comparison with common
agricultural and forestry systems.

03p124.gif (600x600)

Effect on Hydrological Cycle and Erosion
    Trees also influence hydrological characteristics from the micro-climate
level up to the farm and local levels.

03p125.gif (540x540)

    A summary of linkages between agroforestry, land management,
and soil conservation is found in the table on the following
    Traditional agroforestry represents centuries of accumulated
experience of interaction with the environment by farmers without
access to scientific information, external inputs, capital, credit, and
developed markets.  Shifting cultivation (swidden agriculture and the
slash and burn system) was among the earliest forms of agroforestry
systems.   These methods were sustainable under conditions of low
population pressures and long fallow periods.
Factors                     AGROFORESTRY                                FARM/RANGE    MANAGEMENT                             SOIL CONSERVATION
  and                                                               FARM                           RANGE
Soil Moisture          - Alley cropping, line plantations      - Use of compost, cover-        - Controlled grazing        - Incorporating organic matter into
Retention                 and dispersed trees to provide:         crops                                                      the soil
                           * Organic matter                    - Crop-residue left in fields   - Rotational grazing       - Preparing micro-catchments,
                                                                                                                           contour ridges or other micro-site
                           * Shade to reduce surface           - Mulch                          - Fire Management            improvements.
Soil Fertility         - Nutrient cycling and Nitrogen         - Crop rotation (including      - Use of Animal            - Contour vegetation strips
                             fixation                             legumes)                         Manure
Water Erosion          - Surface Runoff reduction              - Contour farming               - Range rotation          - Berms, ditches, ridges
Control                   through:
                            * Establishment of trees/          - Maintaining soil tilth        - "Grazing reserves"      - Benches or terraces
                              shrubs along physical                                                                       - Waterway and gully control
                              conservation features            - Maintaining maximum           - Contract grazing        - Protection of stream banks
                                                                 plant cover                     linked to vegetation
                            * Trees along canals and                                              rehabilitation or
                              waterways                                                           protection.
Wind Erosion           - Wind reduction through:               - Maintaining maximum           - Controlled lopping       - Windbreaks
Control                                                           plant cover                     for fodder
                            * Dispersed Trees                  - Natural vegetation strips                               - Palisades, other physical
                                                                 left when clearing new land                                treatment in extreme cases
                            * Borderline Trees                 - Minimum till cultivation                                - Dune stabilization
Access                  - Live fencing                           - Stock driveways left          - Herding as opposed       - Layout of soil conservation
Control                                                           when laying out fields.         to letting animals         plantings to reinforce
                                                                                                 roam freely               fencelines and livestock trails.
                       - Alignment of livestock trails          - Borderline Trees               - Tethering or
                                                                                                  corraling livestock
                                                                     Source:   Weber and Stoney 3.8
    Throughout the tropics, traditional agroforestry systems may
contain well over 100 plant species per field.  These are used for
construction materials, firewood, tools, medicine, livestock feed, and
human food.  In Mexico, for example, Huastec Indians manage a
number of agricultural and fallow fields, complex home gardens, and
forest plots totalling about 300 species.  Small areas around the
houses commonly average 80-125 useful plant species, mostly native
medicinal plants.  Management of the noncrop vegetation by the
Huastecs in these complex farm systems has influenced the evolution
of individual plants and the distribution and composition of the total
crop and noncrop communities.  Similarly, the traditional pekarangan
system in West Java commonly contains about 100 or more plant
species.   Of these plants, about 42% provide building materials and
fuelwood, 18% are fruit trees, 14% are vegetables, and the remainder
constitute ornamentals, medicinal plants, spices, and cash crops.
    Javanese agroforestry systems usually consist of three
stages--kebun, kebun-campuran and talun--each stage serving a
different function (Christanty 9.1).  The first state, kebun, is usually
planted with a mixture of annual crops.  This stage has a high
economic value since most of the crops are sold for cash.   After two
years, tree seedlings have begun to grow into the field and there is
less space for annual crops.  The kebun gradually evolves into a
kebun-campuran, where annuals are mixed with half-grown perennials.
The economic value of this stage is not as high, but it has a
high biophysical value, as it promotes soil and water conservation.
After harvesting the annuals, the field is usually abandoned for two
to three years to become dominated by perennials.  This stage is
known as talun, the climax stage in the talun-kebun system.   The
talun has both economic and biophysical values.
    To begin the process after clearing the forest, the land can be
planted to dryland rice (huma) or wet rice paddy (sawah), depending
on whether irrigation water is available.  Alternatively, the land can
be planted with a mixture of annual crops, the first stage (kebun).
In some areas the first agroforestry stage (kebun) is developed after
harvesting the dryland rice (huma) by following the dryland rice with
annual field crops.  If the kebun is mixed with tree crops or bamboo,
it becomes second stage (kebun campuran), a mixed garden.  After
several years perennials will dominate and create the third stage, a
perennial crop garden (talun).  (See figure on page 17.)
    Agroforestry systems are also widespread among many tribal
groups, for example, in the Amazon region, the Himalayas, the
Philippines, and the Sub-Saharan countries of Africa.  Unlike other
shifting cultivators, the Bora in Brazil do not have a transition
between cropping and fallow, but rather a continuum from a cropping
system dominated by crops to an old fallow composed entirely of
natural vegetation.  This process may take as long as 35 years or
more.   Given current population pressure trends and deforestation
rates in the area, this system may not be sustainable in the future.
    Arrangement of component plant species in space and time is
also an important but difficult factor in agroforestry because of the
many variations in the types of agroforestry practices and the conditions
under which they are practiced.  When attempting to improve
such systems or to devise new ones, it is therefore necessary to know
about both the short-term productivity of the plants and the
long-term sustainability of the system.  Thus, depending on whether
the tree/crop interaction is favorable or not, plant arrangements have
to be devised to maximize the beneficial interactions and minimize
the undesirable ones.  There are also several other factors to be
taken into account, such as:
    - growth habits and growth requirements of the component
      species when grown near other species
    - simplicity of management procedures for the whole system
    - realization of additional benefits such as soil conservation
Species and plant arrangement patterns in agroforestry are very
situation specific.
    One way to develop agroforestry is to imitate the structure and
function of natural communities.  In the humid tropics successional
ecosystems can be particularly appropriate models for the design of
agricultural ecosystems.  In Costa Rica, plant ecologists conducted
spatial and temporal replacements of wild species by botanically
and/or structurally/ecologically similar plants.  Thus, successional
members of the natural system such as Heliconia species, cucurbitaceous
vines, Ipomoea species, legume vines, shrubs, grasses, and
small trees were simulated by plantain, squash varieties, yams,
sweet potatoes, local bean crops, Cajanus cajan, corn/sorghum/rice,
papaya, cashew, and Cassava species, respectively.  By years two
and three, fast-growing tree crops (for example, Brazil nuts, peach,
palm, rosewood) may form an additional stratum, thus maintaining a
continual crop cover, avoiding site degradation and nutrient leaching
and providing crop yields throughout the year.
    Some agroforestry systems are given below based on materials
published by the International Council on Agroforestry (ICRAF),
Kenya.   (Spicer 9.12) Information about the choice of species and
their planting and management schedule needs to be sought locally
or regionally.  Some of the techniques discussed below are described
on pages 53-58.
1. Alley Cropping in High Potential Areas
    Alley cropping is appropriate for home gardens and for cultivated
arable land.  This system can be helpful in the following
    - providing green manure or mulch for companion food crops;
      in this way plant nutrients are recycled from deeper soil
    - providing prunings, applied as mulch, and shade during the
    - suppressing weeds
    - providing favorable conditions for soil macro- and micro-organisms;
      when planted along the contours of sloping land,
      to provide a barrier to control soil erosion
    - providing prunings for browse, staking material and firewood
    - providing biologically fixed nitrogen to the companion crop
    Trees and shrubs suitable for alley cropping should meet most
of the following criteria:
    - can be established easily
    - grow rapidly
    - have a deep root system
    - produce heavy foliage
    - regenerate readily after pruning
    - have good coppicing ability
    - are easy to eradicate
    - provide useful by-products
Multipurpose species are generally preferable because they give the
alley cropping system flexibility.  Leguminous trees and shrubs,
because of their ability to fix atmospheric nitrogen, are preferred
over non-leguminous species.
2.   Contour Planting
    Contour planting is useful where there are the following
    - poor or easily depleted soils
    - sloping (erodible) land as well as non-erodible land
    - medium to high population density
Contour planting can help in the following ways:
    - to restore/improve soil nutrient and increase organic material
    - to reduce soil and water run-off
    - to spread the risk of crop failure during extremely dry
      seasons by moderating the effects of excessive moisture
      evaporation on exposed land
    - to add wood products for home consumption or sale
    The appropriate farming systems in which to utilize this
system are permanent crop cultivation, medium to small farm size,
and medium to high labor input available per unit of land.  Fast
growing species can be established at the start of the growing season
which gives them the opportunity to establish while livestock are
kept out of the arable areas.
3.   Fodder Bank - Cut and Carry
    Establishment of fodder banks is useful where there is high
population density and nearby markets for livestock products.
Fodder banks can improve fodder availability and quality, particularly
during the late dry and early wet season.  They also seem to
restore/improve soil nutrients and organic matter content.
    Creating these banks of trees will facilitate ease of fencing.
Pure stands (blocks, strips, lines) of trees (mainly leafy fodder) can
be planted near cattle kraals, in homestead gardens, in arable lands
and grazing areas, along watercourses and around the margins of
watering places.
    The appropriate farming system for fodder banks is on the
small farm where there is intensive land use, a kraal feeding system
and high labor input per animal.
4.   Fodder Bank - Grazing
    Fodder banks for grazing are usually located in grazing
areas.   They may be on hills (especially pod species), on uplands,
along watercourses, and on borders of watering places.
    Fodder banks for grazing will improve fodder availability and
quality in low to medium population density areas, and restore/improve
soil nutrients and level of organic materials.
    A mixture of trees (pods and leaves) and grasses (fenced) can
be planted in blocks.  Pod and foliar species should be planted in
hedges.   Scattered trees need to be protected by thorns.  The pod
species will provide a feed supplement for cattle during the early
    Species selected must be adaptable to local climate and soil as
well as having other attributes such as palatability, high protein
content, ease of establishment by direct seeding, transplanting or
truncheon setting.  Pod trees for hills and uplands seed from August
to December.  Self-seeding varieties in watering places must be
tolerant of up to 6 months waterlogging.  They should have a limited
water uptake rate in order not to have a detrimental effect on the
hydrology of the area.  Foliar species should be maintained at the
lower levels.
5.   Fruit Improvement
    In the homestead arable area and garden it is useful to
add fruit-producing trees.  Scattered trees, planted near the home
will allow for protection from animals.  Fruit trees may also be
planted to create boundaries around the homestead.  This will
improve nutrition, produce fruit for sale, provide shade, and firewood.
    Use of the system is limited by the availability of improved
fruit varieties.  There needs to be adequate extension support to help
with choice of varieties and management, e.g., propagation, grafting
and budding, planting, mulching, watering, and control of weeds,
pests, and diseases.
6.   Hedges/Living Fences
    Hedges and living fences are useful in areas with medium to
high population density and where animals roam freely in the area.
Live fences or hedges provide an alternative to constructed fencing
    * The demarcation of boundaries; for example between/around
      schools, farms and fields (particularly paddocks in grazing
    * Protection from the ravages of free-grazing livestock; for example
      crop lands, orchards, nurseries, woodlots, dams,
      protein banks (grazing schemes), vegetable gardens and
In addition hedges can offer secondary benefits, such as reducing the
adverse influence of wind, and they provide not only organic material
to adjacent soils but also multiple tree products (firewood, poles,
fruit, fibre, medicines, etc.) to the local community.
    The appropriate farming system for living fences is the small
to medium sized farm with permanent crop cultivation.
7.   Mixed Intercropping
    Mixed intercropping is most useful in poor or easily depleted
soils, on flat to gently sloping land, in areas of medium population
density.   This system will serve to restore/improve soil nutrients and
increase organic materials.
    The appropriate farming system is that with permanent crop
cultivation, medium to small farm size using medium labor input per
unit of land and no animal cultivation (at high tree densities).
8.   Multistorey Planting of Domestic/Industrial Tree Crops
    Multistorey tree crops are best suited to home gardens and as
the upper storey of productive trees in hedges or plantations.
Multistorey planting fits well in areas with high population density
and high rainfall.  It will contribute resources for tree products, some
of which will supply household requirements.  This may also reduce
cash expenditures, and add to cash income.  Multistorey tree crop
systems are appropriate for small sized farm systems with high labor
input per unit of area.
9.   Tree Planting Around Watering Places and Dams
    Tree planting around watering places and dams is appropriate
where there is a high population density or presence of animals in
the area.   Planting trees will reduce the damage to the watering
place and dams that is caused by livestock.  It will also provide
materials for wood products for home consumption or sale.  Trees
can be laid out in strips or planted in woodlots.  A mixture of trees
and grasses is helpful.  Planting can also be spaced and mixed with
multistory species.  The appropriate farm system is a small to
medium sized farm with permanent crop cultivation.
10.   Selective Clearing
    Selective clearing is useful in areas with substantial acreage of
native woodlands.  It is particularly useful in resettlement areas
where there is a low population density.  Selective clearing will
conserve functional indigenous vegetation, biodiversity, and help to
ensure future supplies of woodland products and germ plasm.  In
this system selected trees are left in croplands.  Strips of trees and
shrubs are left around newly opened plots, between fields and along
roads, tracks and watercourses.  The appropriate farm system is the
medium to large farm with low labor input per unit area.
11.   Woodlot Planting for Fuelwood and Poles
    Woodlot planting for fuelwood and poles is appropriate for
deforested areas, and for all areas with a market for poles and/or
firewood.   Such woodlots can produce fuelwood/poles to meet household
and/or household industries requirements.  They may also add
to the cash flow of the family.  Woodlots should be fenced.  Where
possible "live fences" should be established within the protection
offered by the fence.  Firebreaks are recommended.  The appropriate
farm system is the medium to large farm with low to medium labor
input per unit area.  The system is also appropriate for tobacco
farms (for barn construction as well as curing) and small industries
e.g., brick works or small mines.
    More detail about these systems is available from the International
Council for Research in Agroforestry, Nairobi, Kenya.  (See
Appendix B for address.)
                   PART IV:   CONCLUSION
                    CHAPTER 10
    This manual has reviewed the relation between the environment
and agricultural projects.  With a framework for planning, the
background technical information and other considerations have been
provided.   This is only a start.   Now you have to adapt the information
here to the local situation and seek the specific technical assistance
and information identified with the help of this manual.
    The technical guidelines and information are designed to give
the development worker a better understanding and to indicate the
possible effects.  In most cases the decisions to be made involve
trade-offs.   For example, should the community introduce high priced
inorganic fertilizer that will produce quick results but is expensive
and does not improve the quality of the soil; or alternatively, should
they try to introduce techniques for organic fertilizing that will
improve the soil but incur increased labor costs and sometimes
sacrifice alternative uses of the local materials?
    The ideals sometimes advocated here also may not be possible.
Decisions about trade-offs should be made by those who will bear the
benefit or burden of the results.  The enlightened development
worker will contribute to community understanding through consciousness
raising and training.
                    AGRICULTURAL PROJECTS
    This checklist of concepts helpful for developing ecologically
sustainable projects has been prepared to assist you in utilizing the
information in this book.
    * Use land according to its use capabilities, thus avoid if
      possible slopes prone to landslides.   Where these are in use,
      maintain cover to conserve the soil.
    * Ensure that, with the exception of edible and useful products
      harvested or taken out of the system from time to time, as
      much recycling of materials and wastes as possible occurs.
    * Control pests by biological and mechanical methods insofar
      as possible.
    * Utilize local resources, including human and animal energy,
      without increasing the level of technology significantly
      wherever possible.
    * Do not overlook local varieties of crops, and conserve local
      wild plants and animals that may be important food sources,
      as well as genetic resources.
    * Satisfy local consumption first in utilizing production.
    * Focus on species with multi-use potentials in combining
      nutritional needs (legumes, fruits, vegetables, animals with
      high protein yields per unit weight) with other uses for
      example, crafts, construction materials, and drugs, especially
      in densely populated areas).
    * Combine a variety of species with different properties,
      products, and contributions.
    * Exploit the full range of ecosystems which may differ in soil,
      water, temperature, altitude, slope, fertility, etc., within a
      field or region.
    * Involve community and farmers in the design, implementation,
      management, and evaluation of the program.
    * Involve women, as well as men, in decision making and
    * Include cultural values (religious or other) and beliefs in the
      development of plans for conservation of species and undisturbed
      wild spaces.
    * Build upon existing social organizations and mutual assistance
      customs for environmental rehabilitation and conservation.
    * Consider the non-quantifiable and indirect benefits and costs
      in any economic analysis for decision making.
    * In all cases, focus on minimizing negative impacts while
      trying to introduce improvements.
    * Check the land tenure problems of the farmers and include
      consideration of them in planning.
    * Ensure the program has a sufficiently long-term horizon.
    To this checklist, however, the development worker may want
to add others.  Other guidelines may be based on such things as:  1)
the goals or philosophy of the the local residents and the sponsoring
agency or individual, and 2) the realities of the context within
which the project will occur (limits of time, funding, scope).
    For small-scale, community-based efforts that emphasize
low-input appropriate technology and/or appropriate development
philosophy, some points that should be considered are:
    - optimal use of locally available material and human
    - strong community involvement and support
    - community-identified and/or community realized needs
    - high potential for enhancing community self-reliance in both
      short and long-range terms
    - technologies that can be taught from one farmer to another
      so that a multiplier effect is achieved
    - availability and allocation of funds
    - high priority on use and adaptation of traditional technologies
    - necessity to complete activity during a certain time frame
The sequence of principles developed by World Neighbors (Bunch
10.2) is reproduced on the next page.  These principles can help
achieve the main goals of any agricultural program which are:
    - that farmers develop the ability to solve their own problems
    - that they learn about and adapt appropriate technologies
      that build on traditional practices
    - that the program achieves early but relevant success
    As boundaries within which the project must operate regardless
of specific design aspect, these principles serve two major purposes:
first they provide a framework for designing projects; second, they
can be used to enable the planner to make wise choices regarding
feasibility among possible project designs.  For example, the planner
following these guidelines knows that any design he or she comes up
with must include a strong community participation and/or involvement
component; the planner judging a project against these guidelines
must take a closer look at an effort which does not indicate
community support.

03p138.gif (600x600)

                        Source:   Bunch 10.2
                     MANAGEMENT SYSTEMS
    The following table provides examples of resource management
strategies followed by traditional farmers in developing countries, to
cope with environmental constraints in a variety of circumstances.   It
is important that you consider the perspective of traditional systems
that have already solved some of the resource management questions
raised in the earlier chapters.  (Altieri 10.1)
                        SOME EXAMPLES OF SOIL, SPACE, WATER
                            TRADITIONAL AGRICULTURALISTS
                                THROUGHOUT THE WORLD
                        Objectives or                     Stabilizing Agricultural Systems
Environmental            Processes                         or Practices
Limited space           Maximum utilization               Intercropping, agroforestry, multistorey
                        of environmental                  cropping, home gardens,
                        resources and                     altitudinal crop zonation, farm
                        sources and                       fragmentation, rotations, etc.
Steep slopes            Erosion control,                  Terracing, contour farming, living
                        soil improvement                  and dead barriers, mulching,
                        water                             levelling, continuous crop,
                        conservation, diversification    and/or fallow cover, stone walls,
                        of                                integrated land use (planting so
                        production                        that each crop has maximum
                                                         location advantage)
Marginal soil           Sustain soil fertility           Natural and/or improved fallow,
fertility                and recycle                       crop rotations and intercropping
                        organic                           with legumes, litter gathering,
                        matter                            composting, manuring, green
                                                         manuring, grazing animals in
                                                         fallow fields, night soil and household
                                                         refuse, mounding with
                                                         hoe, ant hills used as fertilizer
                                                         sites, use of alluvial deposits,
                                                         use of aquatic weeds and muck,
                                                         alley cropping with legumes,
                                                         plowed leaves, branches, and
                                                         other debris, burning vegetation,
Flooding or excess      Utilization of                    Raised field agriculture (i.e.,
water                    water bodies in                   chinampas, tablones), ditched
                        an integrated                     fields, diking, etc.
                        manner with
Salinity or             Lowering of                       Planting of appropriate tree
water logging           water table                       species.
due to high                                                                                              
ground water                                                                                              
Excess water            Optimum use of                    Control of floodwater with
                        available water                   canals and checkdams.   Sunken
                                                         fields dug down to ground water
                                                         level.  Splash irrigation.   Canal
                                                         irrigation fed from ponded
                                                         groundwater, fed from wells,
                                                         lakes, reservoirs, etc.
Unreliable rainfall     Best utilization                  Use of drought tolerant crop
                        of available                      species and varieties, mulching,
                        moisture                          use of weather indicators, mixed
                                                         cropping that best utilize end of
                                                         rainy season, use of crops with
                                                         short growing period
Wind velocity,          Microclimatic                     Shade reduction or enhancement,
temperature, or         amelioration                      plant spacings, thinning,
radiation extremes                                       use of shade tolerant crops, increased
                                                         plant densities, mulching,
                                                         management with
                                                         hedges, fences, tree rows; weeding,
                                                         shallow plowing, minimum
                                                         tillage, intercropping, agroforestry
                                                         alley-cropping, etc.
Pest incidence          Crop protection                   Overplanting, allowing some
(invertebrates,          maintenance of                    pest damage, scaring away
vertebrates)             low pest popula-                  pests, setting traps, hedging
                        tion levels                       and/or fencing, use of resistant
                                                         varieties, mixed cropping, enhancement
                                                         of natural enemies,
                                                         hunting, direct picking, use of
                                                         poisons, repellents, planting in
                                                         times of low pest potential, etc.
    The long-term performance of local agricultural systems can be
evaluated by four properties:  (See Conway 10.4)
     * Sustainability:   Relates to the ability of an agricultural
       system to maintain production through time in the face of
       long-term ecological and/or socio-economic constraints.
       Sustainability of small-scale farming systems depends on the
       accessibility to resource poor farmers of technologies and
     * Stability:   Expresses the consistency of production of a
       cropping system through time under a given set of environmental,
       economic, and management conditions.  Production
       trends can be expressed as yield by area, season, or year.
     Both stability and sustainability have two dimensions--time and
     disturbance.  These terms then have two connotations--persistence
     and resistance.   Persistence is the tendency of the system
     to look the same through time; resistance is its capacity to
     withstand disturbance.
     * Resilience:   Relates to the ability of a system to recover from
       disturbances of perturbations.   Perturbations can be salinity/acidity
       problems, pests, flood/drought, etc.
     * Equity:   Is a measure of how equitably the products of the
        farm (income, productions, etc.) or the inputs used (labor,
        land, etc.) are distributed among the local producers and
        consumers and between men and women.
     At this or any point in the planning process, there may be
reasons for seeking additional assistance.  For example, preliminary
investigation may show clearly that the area requires access to more
specialized expertise, as in the case of working with a degraded
watershed.   Consultation with specialists such as local or regional
water resource managers, ecologists, sociologists, resource economists
or agricultural extension officers would be recommended before going
very far with the planning process.
     Second, even when and if the project seems to be relatively
simple and easily tackled, it is a good idea to seek an objective
appraisal.   The development worker can do this by summarizing the
findings to date, making recommendations based on those findings,
outlining planned activities, and getting in touch with experts who
are familiar with community based projects.  If possible, the development
worker should provide a community profile and natural environment
information.   These can provide an excellent base from
which to offer assistance even from a distance.
     There are a number of other ways to bring valuable technical
expertise and insight to the planning process:
     * Seek advice from local residents.   Their knowledge of local
       conditions and past environmental impacts is not usually
       available elsewhere and is a resource that is much too
       important to be overlooked.
     * Contact local universities and government agencies, and local
       representatives of international organizations as well as local
       NGOs, churches and missionaries.   Often they have a great
       deal of pertinent information on local soils, climate, terrain,
       and upon plants and animals native to the region.  Or they
       may have insights and valuable suggestions about other
     * Using local resource people, organize an interdisciplinary
       team to observe possible project sites.  The team can then
       discuss the project from their respective viewpoints.  Collectively,
       the team may be able to identify potential effects that
       will have to be accounted for in the project design.  Depending
       upon the type of project, the team might include representatives
       from several of these fields:   ecology, hydrology,
       soil science, entomology, and so on.
     * As planning and investigation continues locally, get in touch
       with other organizations.   Network with nongovernmental
       organizations in the area or region.
     Through outside assistance the planner can test the reality and
feasibility of the project.  Some planners may prefer to have the
project reviewed only after the needs identification and assessment
process is complete.  Other planners may choose to have the material
reviewed at several points.  For those who wish to use such services,
they may be available locally, or through international non-governmental
organizations.   A list of organizations that can help is
included in Appendix B.
                    APPENDIX A
Chapter 2:  The Relation of Agriculture and Environment
1.   Altieri, M.A.   1987.  Agroecology:   The Scientific Basis of
    Alternative Agriculture.   Boulder, CO:   Westview Press.
2.   Briggs, D.J.   and F.M.  Courtney.   1985.  Agriculture and
    Environment.  London:  Longman.
3.   Conway, G.R.   1986.  Agroecosystem Analysis for Research and
    Development.   Bangkok:  Winrock International Institute for
    Agricultural Development.
4.   Cox, G.W. and M.P. Atkins.   1979.  Agricultural Ecology:  An
    Analysis of World Food Production Systems.  San Francisco, CA:
    W.H. Freeman and Co.
5.   Dover, M. and L.M. Talbot.   1987.  To Feed the Earth:
    Agroecology for Sustainable Development.  Washington, DC:
    World Resources Institute.
6.   King, B.T. et al.   1984.  Alley Cropping:  A Stable Alternative to
    Shifting Cultivation.   Ibadan, Nigeria:   IITA, 22 p. Permission
    granted to reprint figure.
7.   Marten, G.G.   1986.  Traditional Agriculture in Southeast Asia:
    A Human Ecology Perspective.   Boulder, CO:   Westview Press.
    Permission granted to reprint figure.
Chapter 3:  Planning for Sustainable Development
1.   Bryant, C. and L.G. White.   1984.  Managing Rural
    Development with Small Farmer Participation.  CT:   Kumarian
2.   Buhler, R.G., M. Ochoa, and S. Tobing.   "A Primer for Planning
    Development Projects."   Interface, Second/Third Quarter 1987.
    Washington, DC:   ADRA International.
3.   Buhler, R.G. and K. Flemmer.   "A Primer for Planning
    Development Projects - II."   Interface, Fourth Quarter 1987.
    Washington, DC:   ADRA International.
4.   Bunch, R.  1982.  Two Ears of Corn:   A Guide to
    People-Centered Agricultural Development.  Oklahoma City, OK:
    World Neighbors.
5.   Chambers, R.   1983.  Rural Development:  Putting the Last
    First.  London:  Longman.
6.   Richards, P.   1984.  Indigenous Agricultural Revolution.  Boulder,
    CO:  Westview Press.
7.   Rugh, J.  1986.  Self-Evaluation:   Ideas for Participatory
    Evaluation of Rural Community Development Projects.
    Oklahoma City, OK:   World Neighbors.
8.   Weber, F. with C. Stoney.   1986.  Reforestation in Arid Lands.
    Arlington, VA:   VITA.  Permission granted to reprint table.
Chapter 4:  Other Considerations for Planning
1.  Brokensha, D. and A.P. Castro.   1984.  Fuelwood, Agro-Forestry,
    and Natural Resource Management:   The Development
    Significance of Land Tenure and Other Resource
    Management/Utilization Systems.   Binghamton, NY:   Institute
    for Development Anthropology.
2.   Collins, J.  1984.  Land Tenure, Institutional Factors and
    Producer Decisions on Fragile Lands.   Binghamton, NY:
    Institute for Development Anthropology.
3.   Dixon, R.  1980.  Assessing the Impact of Development Projects
    on Women.  AID Program Evaluation Discussion Paper No. 8.
    Washington, DC:   Agency for International Development.
4.   Dankelman, I. and J. Davidson.   1988.  Women and
    Environment in the Third World.   Alliance for the Future.
    London:  Earthscan.
5.   Pezzullo, C. 1982.   Women and Development.  Guidelines for
    Programme and Project Planning.   Santiago, Chile:   Economic
    Commission for Latin America and the Caribbean, United
6.   United Nations.   1980.  Rural Women's Participation in
    Development.   Evaluation Study No. 3.  New York:  United
    Nations Development Programme.
7.   Weinstock, J.A.   1984.  Tenure and forest Lands in the Pacific.
    Working Paper.   Honolulu, HI:  East-West Environment and
    Policy Institute.
8.   Zimbabwe Women's Bureau.   1981.  We Carry a Heavy Load.
    Rural Women in Zimbabwe Speak Out.   Harare, Zimbabwe:
    Zimbabwe Women's Bureau.
Chapter 5:  Soil Management Through Erosion Control
1.   Beets, W.C.  1982.  Multiple Cropping and Tropical Farming
    Systems.  Boulder, CO:  Westview Press, Inc.
2.   Catholic Diocese of Nakuru.   Report on Sustainable Agriculture
    Workshop held at Baraka F.T.C. Molo, July 27 - August 16,
3.   FAO.  1978.  Methodology for Assessing Soil Degradation.
4.   FAO.  1984.  Improved Production Systems as an Alternative to
    Shifting Cultivation.   FAO Soils Bulletin 53.   Rome.
5.   Greenland, D.J. and R. Lal.   1977.  Soil Conservation and
    Management in the Humid Tropics.   NY:  John Wiley and Sons.
6.   Hudson, N. 1981.   Soil Conservation.  Ithaca, NY:  Cornell
    University Press.
7.   Poincelot, R.P.   1986.  Toward a More Sustainable Agriculture.
    Westport, CT:   AVI Publishing Company.
8.   Sommers, P.  1983.  Low Cost Farming in the Humid Tropics:
    An Illustrated Handbook.   Manila, Philippines:   Island
    Publishing House, Inc., 38 p.
9.   Troeh, F.R. et al.   1980.  Soil and Water Conservation for
    Productivity and Environmental Protection.  Englewood Cliffs,
    NJ:  Prentice-Hall.
10. Weber, F. and M. Hoskins.  1983.   Soil Conservation Technical
    Sheets.  Moscow, ID:  Forest, Wildlife and Range Experiment
    Station, University of Idaho.
11. Wolman, M.F. and F.G.A. Fournier.  1987.   Land
    Transformation in Agriculture.   SCOPE.  NY:  John Wiley and
Chapter 6:  Water Supply and Management
1.   Darrow, K. and M. Saxeniah.   1986.  Appropriate Technology
    Sourcebook, A Guide to Practical Books for Village and Small
    Communities.   Washington, DC:  Volunteers in Asia.
2.   Szeremi, M. and T. Pluer.   Drip Irrigation for Family Garden.
    Available from CODEL, Inc.   See Appendix B.
3.   Tillman, R.  1981.  Environmental Guidelines for Irrigation.
    Washington, DC:   U.S. Man and the Biosphere Programme and
    U.S. Agency for International Development.
4.   Tillman, R.  1981.  Environmentally Sound Small-Scale Water
    Projects.  Guidelines for Planning Series.  Arlington, VA:
Chapter 7:  Soil Nutrient Management
1.   Bornemiza, E. and A. Alvarado.   1975.  Soil Management in
    Tropical America.   Raleigh, NC:   North Carolina State
2.   Brady, N.C.  1984.  The Nature and Properties of Soils.  9th
    edition.  New York, NY:  MacMillan Publishing Co.  Permission
    granted to reprint figure.
3.   FAO.  1971.  Improving Soil Fertility in Africa.  FAO Soils
    Bulletin 14.   Rome.
4.   FAO.  1975.  Organic Materials as Fertilizers.  FAO Soils
    Bulletin 27.   Rome.
5.   FAO.  1977.  Soil Conservation and Management in Developing
    Countries.   FAO Soils Bulletin 33.  Rome.
6.   FAO.  1978.  Organic Materials and Soil Productivity.  FAO
    Soils Bulletin 35.   Rome.
7.   Lal, R.  1987.  Tropical Ecology and Physical Edaphology.  NY:
    John Wiley.
8.  Rodale Institute.   Composting; Green Manure; Manure Handling.
    (pamphlets) Emmaus, PA:   Rodale Press, Inc.
9.   Sanchez, P.A.   1976.  Properties and Management of Soils in the
    Tropics.  NY:  John Wiley and Sons.
Chapter 8:  Pest Management
1.   Altieri, M.A. and D.K Letourneau.   1982.  "Vegetation
    Management and Biological Control in Agroecosystems".  Crop
    Protection 1:405-430.
2.   Bottrell, D.R.   1979.  Integrated Pest Management.  Washington,
    D.C.:  Council on Environmental Quality.
3.   Brown, A.W.A.   1978.  Ecology of Pesticides.  NY:   John Wiley
    and Sons.
4.   Chaboussou, F.   1986.  "How Pesticides Increase Pests."  The
    Ecologist, Vol. 16, No. 1, p. 30.
5.   Environment Liaison Centre.   1987.  Monitoring and Reporting
    the Implementation of the International Code of Conduct on the
    Use and Distribution of Pesticides (The FAO Code) Final Report.
    Nairobi, Kenya:   Environment Liaison Centre.
6.   Flint, M.L. and R. vanden Bosch.   1977.  A Source Book on
    Integrated Pest Management.   NY:  Plenum Press.
7.   Flint, M.L. and R. vanden Bosch.   1981.  Introduction to
    Integrated Pest Management.   NY:  Plenum Press.
8.   Gips, T. 1987.   Breaking the Pesticide Habit - Alternatives to 12
    Hazardous Pesticides.   Minneapolis, MN:   International Alliance
    for Sustainable Agriculture.
9.   Hansen, M.  1988.  Escape From the Pesticide Treadmill:
    Alternatives to Pesticides in Developing Countries.  Mt. Vernon,
    NY:  Institute for Consumer Policy Research Consumers Union.
10. Huffaker, C.B. and P.S. Messenger.  1976.   Theory and Practice
    of Biological Control.   NY:  Academic Press.
11. International Organization of Consumers Unions.   Problem
    Pesticides, Pesticide Problems:   A Citizens' Action Guide to the
    International Code of Conduct on the Distribution and Use of
    Pesticides.   Penang, Malaysia:  IOCU Regional Office for Asia
    and the Pacific.
12. Litsinger, J.A. and K Moody.  1976.   "Integrated Pest
    Management in Multiple Cropping Systems."  In Multiple
    Cropping.  P.A. Sanchez, ed.  American Soc. Ecol. Management
    2:  161-168.  pp. 293-316.
13. Metcalf, R.L. and W. Luckman.  1975.   Introduction to Insect
    Pest Management.   NY:  John Wiley and Sons.
14. Moses, M.  1988.  A Field Survey of Pesticide-Related Working
    Conditions in the U.S. and Canada.   Monitoring the
    International Code of Conduct on the Distribution and Use of
    Pesticides in North America.   San Francisco, CA:   The Pesticide
    Education and Action Project.
15. Nebel, B.J.  1987.   Environmental Science:  The Way the World
    Works.  2nd edition, p. 414.  Englewood Cliffs, NJ:
    Prentice-Hall, Inc.   Permission granted to reprint figure.
16. Pimentel, D. (ed.) 1981.  CRC Handbook of Pest Management in
    Agriculture.   Vol. I. Boca Raton, FL:  CRC Press.
17. Rabb, R.L. and F.E. Guthrie.  1970.   Concepts of Pest
    Management.   Raleigh, NC:  North Carolina State University.
18. Reissig, W.H. et al.  1985.   Illustrated Guide to Integrated Pest
    Management in Rice in Tropical Asia.   Manila, Philippines:
    International Rice Research Institute.
19. Smith, R.F. and R. vanden Bosch.  "Integrated control."  In Pest
    Control, R.L. Doutt (ed).   NY:  Academic Press, pp. 295-340.
20. vanden Bosch, R., P.S. Messenger, and A.P. Gutierrez.  1982.
    An Introduction to Biological Control.  NY:   Plenum Press.
Chapter 9:  Agroforestry Systems
1.   Christanty, L., O. Abdoellah and J. Iskander.  1986.   "Traditional
    Agroforestry in West Java:   The Pekarangan (Homegarden) and
    Talun-Kebun (Shifting Cultivation) Cropping Systems."  In
    Traditional Agriculture in Southeast Asia, G. Marten (ed).
    Boulder, CO:   Westview Press.
2.   Fortmann, L. and D. Rocheleau.   1985.  Women and
    Agroforestry:   Four Myths and Three Case Studies.   Nairobi:
    ICRAF, Reprint No. 19.
3.   Gholz, H.L.  1987.  Agroforestry:   Realities, Possibilities and
    Potentials.   Dordrecht:  Martinos Nijhoff Publishing.
4.   Kamweti, D.  1982.  [I\]Tree Planting in Africa South of the
    Sahara.  Nairobi, Kenya:  Environment Liaison Centre.
5.   Kenya Energy Non-Governmental Organizations.  The Value of
    Indigenous Trees.   Nairobi, Kenya:   KENGO.
6.   Lal, R.  1987.  Tropical Ecology and Physical Edaphology.  NY:
    John Wiley and Sons, 732 p.
7.   Lockevetz, W. ed.   1983.  Environmentally Sound Agriculture.
    New York, NY:   Praeger Publishers.  Permission granted to
    reprint figure.
8.   Mujeres en Desarrollo Dominicana, Inc.   1988.  Cojan la Mocha
    Mujeres, Vamos a Reforestar.   Santo Domingo, Dominican
    Republic:  MUDE.  Permission granted to reprint drawing.
9.   Nair, P.K.R.   1984.  Soil Productivity Aspects of Agroforestry.
    Nairobi, Kenya:   ICRAF.
10. Nair, P.K.R.  1985.   "Classification of Agroforestry Systems."
    Agroforestry Systems 3:97-128.
11. Nair, P.K.R.  1987.   Agroforestry Systems in Major Ecological
    Zones of the Tropics and Subtropics.   Nairobi, Kenya:   ICRAF,
    Working Paper No. 47.
12. Spicer, N.  1987.   "Agroforestry Systems in Zimbabwe."   Paper
    prepared for the NGO Agroforestry Workshop, Nyanga,
    Zimbabwe, June 1987.   Based on information from International
    Council for Research in Agroforestry, Kenya and Forestry
    Commission, Zimbabwe.
13. Teel, W.  1984.   A Pocket Directory of Trees and Seeds in Kenya.
    Nairobi, Kenya:   KENGO.
14. Vergara, N.T.  1987.   Agroforestry in the Humid Tropics.   Its
    Protective and Ameliorative Roles to Enhance Productivity and
    Sustainability.   Honolulu, HI:  Environment and Policy institute,
    East-West Center and Laguna, Philippines:  Southeast Asian
    Regional Center for Graduate Study and Research in
15. von Carlowitz, P.G.  1986.   Multipurpose Tree and Shrub Seed
    Directory.   Nairobi, Kenya:  International Council for Research
    in Agroforestry.
16. Weber, F. and M. Hoskins.  1983.   Agroforestry in the Sahel.
    Blacksburg, VA:   Virginia Polytechnic Institute and State
17. Wijewardene, R. and P. Waidyanatha.  1984.  Conservation
    Farming for Small Farmers in the Humid Tropics.  Sri Lanka:
    Department of Agriculture, 38 p.
18. Wiersum, K.F.  1981.   Viewpoints on Agroforestry.  Wagerringen:
    Hinkeloord, Agricultural University.
19. Winterbottom R. and P.T. Hazlewood.  1987.   "Agroforestry and
    Sustainable Development:   Making the Connection."   Ambio, Vol.
    16 No. 2-3, pp. 100-110.
Chapter 10:  Conclusion:   A Checklist for Sustainable
Development, Examples of Traditonal Systems, and Long
1.   Altieri, M.A.   1987.  Agroecology:   The Scientific Basis of
    Alternative Agriculture.   Boulder, CO:   Westview Press.
2.   Bunch, R.  1982.  Two Ears of Corn:   A Guide to
    People-Centered Agricultural Improvement.  Oklahoma, OK:
    World Neighbors.   Permission granted to reprint diagram.
3.   Chambers, R. and B.P. Ghildyal.   1985.  "Agricultural Research
    for Resource-Poor Farmers:   The Farmer--First and--Last Model".
    Agricultural Administration 20:   1-30.
4.  Conway, G.R.  1986.  Agroecosystem Analysis for Research and
    Development.   Bangkok:  Winrock International Institute for
    Agricultural Development.
5.   Richards, P.   1984.  Indigenous Agricultural Revolution.
    Boulder, CO:   Westview Press.
6.   Tull, K and M. Sands.   1987.  Experiences in Success:  Case
    Studies in Growing Enough Food Through Regenerative
    Agriculture.   Emmaus, PA:  Rodale International.
7.   Zandstra, H.G. et al.   1981.  A Methodology for On-Farm
    Cropping Systems Research.   Los Banos, Philippines:   IRRI.
                          GENERAL REFERENCES
Carlier. H.  1987.   Understanding Traditional Agriculture,
    Bibliography for Development Workers.   Netherlands:   ILEIA.
Child, R.D., H. Heady, W. Hickey, R. Peterson, and R. Pieper.   1984.
    Arid and Semiarid Lands, Sustainable Use and Management in
    Developing Countries.   Morrilton, AR:   Winrock International.
Child, R.D., H. Heady, R. Peterson, R. Pieper, and C. Poulton.   1987.
    Arid and Semiarid Rangelands:   Guidelines for Development.
    Morrilton, AR:   Winrock International.
Food and Agriculture Organization of the United Nations.   1983.
    Food and Fruit-Bearing Forest Species:  1.   Examples from
    Eastern Africa, Forestry Paper 44/1; 2.  Examples from
    Southeastern Asia, Forestry Paper 44/2; 3.  Examples from
    Latin America, Forestry Paper 44/3.   Rome:  FAO.
Goodland, R., C. Watson, and G. Ledec.  1984.   Environmental
    Management in Tropical Agriculture.   Boulder, CO:   Westview
Huston, P.  1978.   Message from the Village.  NY:  The Epoch B
Leonard, D.  1983.   Traditional Field Crops.  ICE Manual Number
    M-13.  Washington, DC:  Peace Corps.
Nanda, M. ed.  Resource Guide to Sustainable Agriculture in the
    Third World.   Minneapolis, MN:  International Alliance for
    Sustainable Agriculture.
National Research Council.  Ecological Aspects of Development in the
    Humid Tropics.   Washington, DC:  National Academy Press.
Vickery, D. and J.  1978.   Intensive Vegetable Gardening for Profit
    and Self-Sufficiency.   Program and Training Journal, Reprint
    Series, Number 25.   Washington, DC:   Peace Corps.
Wade, I.   1986.  City Food.  Crop Selection in Third World Cities.
    San Francisco, CA:   Urban Resource Systems, Inc.
                            APPENDIX B                               
                         LIST OF RESOURCE AGENCIES
Apartado Postal 163C
Tegucigalpa, HONDURAS
African NGOs Environment Network (ANEN)
P.O. Box 53844
Nairobi, KENYA
Ground Floor
Philippine Social Development Center
Magallanes Corner Real Street
Intramuros, Manila
Center for Education and Technology (CET)
Casilla 16557 Correo 9
Santiago, CHILE
Centro Agronomico Tropical de Investigacion y Ensenanza (CATIE)
Turrialba, COSTA RICA
Coordination in Development, Inc.
475 Riverside Drive, Room 1842
New York, New York 10115, USA
Environment Liaison Centre (ELC)
P.O. Box 72461
Nairobi, KENYA
Environment and Development in the Third World
     Box 3370
     Dakar, SENEGAL
   P.O. Box MP 83
   Mt. Pleasant
   Harare, ZIMBABWE
African Institute for Economic and Social Development
   08 BP 8
   Abidjan 08, IVORY COAST
   P.O. Box 14022
   Nairobi, KENYA
Information Centre for Low External-Input Agriculture (ILEIA)
Kastanjelaan 5
P.O. Box 64
Institute for Alternative Agriculture, Inc.
9200 Edmonston Road, Suyite 117
Greenbelt, Maryland 20770
Institute for Consumer Policy Research
Consumers Union
256 Washington Street
Mt. Vernon, New York  10553, USA
International Alliance for Sustainable Agriculture (IASA)
Newman Center
University of Minnesota
1701 University Avenue, S.E., Room 202
Minneapolis, Minnesota  55414, USA
International Council for Research in Agroforestry (ICRAF)
P.O. Box 30677
Nairobi, KENYA
International Institute for Environment and Development (IIED)
1717 Massachusetts Avenue, N.W.
Washington, D.C.  20036, USA
International Institute of Tropical Agriculture (IITA)
PMB 5320
International Organizaton of Consumers Unions (IOCU)
P.O. Box 1045
10830 Penang, MALAYSIA
International Rice Research Institute (IRRI)
P.O. Box 933
Kenya Institute of Organic Farming (KIOF)
Box 34972
Nairobi, KENYA
Pesticide Action Network International (PAN)
Regional Centers:
   AFRICA (English)
   Environment Liaison Centre
   P.O. Box 72461
   Nairobi, KENYA
   AFRICA (French)
   B.P. 3370
   Dakar, SENEGAL
   International Organization of Consumers Unions
   Regional Office
   P.O. Box 1045
   10830 Penang, MALAYSIA
   22, rue des Bollandistes
   1040 Brussels, BELGIUM
   Fundacion Natura
   Casilla 243
   Quito, ECUADOR
   Pesticide Education and Action Project
   P.O. Box 610
   San Francisco, California   94101, USA
Rodale Institute
222 Main Street
Emmaus, Pennsylvania 18098, USA
Sahabat Alam Malaysia (Friends of the Earth)
37 Lorong Birch
Volunteers in Technical Assistance (VITA)
1815 North Lynn Street, Suite 200
Arlington, Virginia  22209, USA
                           APPENDIX C
absorb - To suck in as in a blotter.
adsorb - To adhere to the surface of as ions on molecules.
aerial biomass - Total weight and molecules of living materials.
aquifer - An underground layer of rock that is porous and permeable
enough to store significant quantities of water.
artificialities - Mechanisms, techniques, and processes introduced
by humans.
biodegradable - Refers to substances that can readily be decomposed
by living organisms.
biodiversity - The critical multiplicity of species that creates and
maintains ecosystems.
biomass - The total weight of all the living organisms in a given
biotic - Living or derived from living things.
capillary action - The movement of water upward against the force
of gravity, through small openings.  The liquid is pulled upward by
electrical attractions between the water molecules and the sides of
the holes.
carrying capacity - The maximum number of individuals of a given
species that can be supported by a particular environment.
climax community - A natural system that represents the end, or
apex, of an ecological succession.
colloidal - Made up of solid, liquid, or gaseous substances of very
small, insoluble particles.
denitrification - Reduction of nitrates to gaseous state by certain
organisms that produces nitrogen.
desertification - The process whereby lands that have been disturbed
by natural phenomenon (e.g., drought, flooding) or people
initiated processes (e.g., improper farming practices) are converted to
double cropping - Growing two crops in the same year in sequence,
seeding or transplanting one after the harvest of the other (same
concept for triple cropping).
ecological niche - The description of the unique functions and
habitats of an organism in an ecosystem.
ecosystem - A group of plants and animals occurring together plus
that part of the physical environment with which they interact.   An
ecosystem is defined to be nearly self-contained, so that the matter
flowing into and out of it is small compared to the quantities that
are internally recycled in a continuous exchange of the essentials of
eutrophication - The enrichment of a body of water by nutrients,
with the consequent deterioration of its quality for human purposes.
evaporation - Vaporization of water from surfaces.
evapotranspiration - The conversion of liquid water to water vapor
by transpiration followed by evaporation from the leaf surface.
externalities (economic) - The portion of the cost of a product that
is not accounted for by the manufacturer but is borne by some other
sector of society.  An example is the cost of environmental degradation
that results from a manufacturing operation.
farming system - The manner in which a particular set of farm
resources is assembled within its environment, by means of technology,
for the production of primary agricultural products.  This definition
thus excludes processing beyond that normally performed on the
farm for the particular crop or animal product.  It includes farm
resources used in marketing the product.
food chain - An idealized pattern of flow of energy m a natural
ecosystem.   In the classical food chain, plants are eaten only by
primary consumers, primary consumers are eaten only by secondary
consumers, secondary consumers only by tertiary consumers, and so
forth.   See also food web.
food web - The pattern of food consumption in a natural ecosystem.
A given organism may obtain nourishment from many different
trophic levels and thus give rise to a complex, interwoven series of
energy transfers.
green revolution - The realization of increased crop yields in many
areas owing to the developing of new high-yielding  strains of wheat,
rice, and other grains in the 1960s.  The second green revolution is
use of the techniques of genetic engineering to improve agricultural
groundwater - Water that has accumulated in the ground and is
replenished by infiltration of surface water.
growing season - Used in a general way to refer to the period of
the year when (most) crops are grown, e.g. the rainy season.
growth cycle - The period required for an annual crop to complete
its annual cycle of establishment, growth and production of harvested
habitat - Place where plant or animal lives.
hectare - A metric measure of surface area.  One hectare is equal to
10,000 sq. m. or 2.47 acres.
herbicide - A chemical used to control unwanted plants.
humus - The complex mixture of decayed organic matter that is an
integral part of healthy soil.
hydrological cycle (water cycle) - The way water moves in a
cycle in all its forms, on the earth.
infiltration - The process whereby water filters or soaks into soil as
opposed to running off the surface.
intercropping - Two or more crops grown simultaneously in the
same, alternate, or paired rows in the same area.
laterite - A soil type found in certain humid tropical regions that
contains a large proportion of aluminum and iron oxides and only a
small concentration of organic matter.  Laterite soils cannot support
sustained agriculture.
leaching - The extraction, usually by water, of the soluble components
of a mass of material.  In soil chemistry, leaching refers to
the loss of surface nutrients by their percolation downward below the
root zone.
legume - An plant of the family Leguminosae, such as peas, beans,
or alfalfa.  Bacteria living on the roots of legumes change atmospheric
nitrogen, [N.sub.2], to nitrogen-containing salts that can be readily
assimilated by most plants.
limiting factors (law of) - A biological law that states that the
growth of an organism (or a population of organisms) is limited by
the resource that is least available in the ecosystem.
litter - The intact and partially decayed organic matter lying on top
of the soil.
mineralization - The process of gradual oxidation of organic matter
present in soil that leaves just the gritty mineral components of the
mixed cropping - Two or more crops are grown simultaneously in
the same field at the same time, but not in row arrangements.
(Sometimes called mixed intercropping.)
monoculture planting - Growing a single crop on the land at one
time, particularly the repetitive growing of the same crop on the
same land year after year.
mulch - Leaves, straw, peat moss, or other material spread around
plants to prevent evaporation of water from soil and roots.
multiple cropping - Growing more than one crop on the same land
in one year.  Within this concept there are many possible patterns of
crop arrangement in space and time.
natural selection - A series of events occurring in natural ecosystems
that eliminates some members of a population and spares those
individuals endowed with certain characteristics that are favorable
for reproduction.
organic farming - A system of farming using no chemical fertilizers
or pesticides.
outputs - The products (for rainfed agriculture, crops), services (e.g.
water supply, recreational facilities) or other benefits (e.g. wildlife
conservation) resulting from the use of land.
percolation - The process of water seeping through cracks and
pores of soil and rocks.
photosynthesis - The process by which chlorophyll-bearing plants
use energy from the Sun to convert carbon dioxide and water to
pollution - The impairment of the quality of some portion of the
environment by the addition of harmful impurities.
population - The breeding group to which an organism belongs in
practice.   A population is generally very much smaller than an entire
species, because all the members of a species are seldom in close
proximity to each other.
predator - An animal that attacks, skills, and eats other animals;
more broadly, an organism that eats other organisms.
primary consumer - An animal that eats plants.
rainfed farming - The growing of crops or animals under conditions
of natural rainfall.  Water may be stored in the crop field by bunding,
as with lowland rainfed rice, but no water is available from
permanent water storage areas.
salinization - When irrigation water is applied to farmlands, much
of it evaporates, leaving the salts behind.  Salinization is the process
whereby these minerals accumulate until the fertility of the soil is
severely impaired.
shifting cultivation - Several crop years are followed by several
fallow years with the land not under management during the fallow.
The shifting cultivation may involve shifts around a permanent
homestead or village site, or the entire living area may shift location
as the fields for cultivation are moved.
slash and burn - A specific type of shifting cultivation in high
rainfall areas where bush or tree growth occurs during the fallow
period.   The fallow growth is cleared by cutting and burning.
soil-moisture belt - The layer of soil from which water can be
drawn to the surface by capillary action.
soil structure - The manner in which soil particles are loosely stuck
together to form larger clumps and aggregates usually with considerable
air space in between.
strip cropping - Growing two or more crops in different strips
across the field wide enough for independent cultivation.  The strips
are wide enough to give greater association among the crops in the
strips than between the different crops.
structural diversity - A measure of the way in which the canopy
or soil cover is organized in layers in a cropping or forestry system.
substrate - The foundation provided by the soil to support plant
succession - The sequence of changes through which an ecosystem
passes during the course of time.  Primary succession is a sequence
that occurs when the terrain is initially lifeless, or almost so.
Secondary succession is the series of community changes that takes
place in disturbed areas where some regrowth is taking place.
surface water - Includes all bodies of water--lakes, rivers, ponds,
streams - on the surface of the earth in contrast to ground water that
lies below the surface.
sustainable - A measure of the constancy of agricultural production
in the long term.
sustainable use - Continuing use of land without severe or permanent
deterioration of the resources of the land.
symbiotic - The intimate association of two organisms that provides
a mutual benefit to both.
temperature inversions - A meteorological condition in which the
layers of cool air remain stagnant leading to concentration pollutants.
threshold - The level of population of insect pests beyond which any
increase will cause damage.
threshold level - The minimal dose of a toxic substance that causes
harmful effects.
toxic substance - Any substance whose physiological action is
harmful to health.
transpiration - The passage of water through the tissues of plants,
especially through leaf surfaces.
trophic level - Level of nourishment.  A plant that obtains its
energy directly from the sun occupies the first level and is called an
autotroph.   An organism that consumes the tissue of an autotroph
occupies the second trophic level, and an organism that eats the
organism that had eaten autotrophs occupies the third trophic level.
vector - An animal, such as an insect, that transmits a disease - producing
organism from one host to another.
volatilization - Process of a liquid or solid becoming gaseous.
water pollution - The deterioration of the quality of water that
results from the addition of impurities.
                  ABOUT THE AUTHOR
Miguel Altieri is an Associate Professor and Associate Entomologist
at the University of California, Berkeley.  Dr. Altieri, a native of
Chile, earned a Ph.D. in Entomology at the University of Florida in
1979 and studied agronomy and agroecology in Latin America.
Dr. Altieri's research has centered on methods to enhance naturally
occurring and introduced biological control agents of pests, and
interactions of plants and pests, in annual agricultural systems and
orchards.   His research has been based in North, South, and Central
Dr. Altieri has published extensively in the fields of agroecology,
sustainable agriculture, entomology, alternative agriculture, and pest
management.   Among his publications are the following books:
Agroecology:   The Scientific Basis of Alternative Agriculture, Weed
Management in Agroecosystems:  Ecological Approaches, and Agroecology
and Small Farm Development.
                  ABOUT THE EDITOR
Since 1977, Helen Vukasin has been active in the field of environment
and development.  In 1979 she became associated with CODEL
and helped to develop the CODEL Environment and Development
Program.   Working with indigenous organizations in developing
countries, the Program fosters natural resource management in
small-scale development projects particularly emphasizing people's
participation in the process.
In addition to serving as a consultant to CODEL, Ms. Vukasin is
currently a Program Associate with the Development Institute of the
University of California at Los Angeles.  She is actively interested in
gender issues in natural resource management and in contributing to
knowledge about ways to foster people's participation in development
and environment activities.