TECHNICAL PAPER # 57
 
                     UNDERSTANDING AGROFORESTRY
                            TECHNIQUES
 
                                  By
                      Fred Weber and Carol Stoney
 
                           Illustrated By
                          Frederick J. Holman
 
                             Published By
                   VOLUNTEERS IN TECHNICAL ASSISTANCE
       1600 Wilson Boulevard, Suite 500, Arlington, Virginia 22209 USA
                 Telephone:  (703) 276-1800, Fax:  (703) 243-1865
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                  Understanding Agroforestry Techniques
                         ISBN:  0-86619-276-X
                [C] 1989, Volunteers in Technical Assistance
 
                            PREFACE
 
This paper is one of a series published by Volunteers in Technical Assistance to provide an
introduction to specific state-of-the-art technologies of interest to people in developing countries.
The papers are intended to be used as guidelines to help people choose thechnologies that are
suitable to their situations.   They are not intended to provide construction or implementation
details.  People are urged to contact VITA or similar organizations for further information and
technical assistance if they find that a particular technology seems to meet their needs.
 
The papers in the series were written, reviewed, and illustrated almost entirely by VITA Volunteer
technical experts on a purely voluntary basis.   Some 500 volunteers were involved in the
production of the first 100 titles issued, contributing approximately 5,000 hours of their time.
VITA Staff included Suzanne Brooks handling typesetting and layout and Margaret Crouch as
editor and project manager.
 
Co-author Fred Weber, a pioneer in the community forestry concepts presented here, has advised
projects for over 20 years.  He wrote the original edition of the VITA publication Reforestation
in Arid Lands based on a training manual he prepared for Peace Corps volunteers in Niger.
Carol Stoney collaborated with Mr. Weber on the revisions for the new edition of Reforestation,
which is the basis for the techniques in this technical paper.  Frederick J. Holman, a landscape
architect, provided the illustrations in this paper, which are taken from Reforestation.
 
VITA is a private, nonprofit organization that supports people working on technical problems in
developing countries.  VITA offers information and assistance aimed at helping individuals and
groups to select and implement technologies appropriate to their situations.  VITA maintains an
international Inquiry Service, a specialized documentation center, and a computerized roster of
volunteer technical consultants; manages long-term field projects; and publishes a variety of
technical manuals and papers.
 
                  UNDERSTANDING AGROFORESTRY TECHNIQUES
             by VITA Volunteers Fred Weber and Carol Stoney
 
I.  INTRODUCTION
 
Agroforestry refers to the integration of trees and shrubs as essential elements of agricultural
and other land use systems, with the idea of improving the fertility and productivity of the soil.
In this concept, trees and shrubs can be deliberately managed (that is, established, tended, protected,
harvested, etc.) and considered as one of the resource elements used by people or their livestock,
even though the trees may appear to be randomly dispersed in the landscape.  Trees and shrubs,
then, need not be forests, woodlots, orchards, or other discrete stands especially set aside for
a single purpose or product.   Rather, they can be planted wherever people have not allocated
the space to some other use.   In many situations this makes much more sense than setting aside
specific areas of usable farm land for woodlots--where the most acute problem is lack of food,
for example, not lack of wood.   Certain tree species may provide food (fruit, leaves, edible seeds,
etc.) not only for people but also for livestock, particularly during seasons when food supplies
from other sources are low.
 
In addition to producing wood for fuel, construction, implements, tools, and art objects, other
important and locally appreciated by-products of agroforestry include fiber for mats, baskets,
and rope, or plant materials for medicines, dyes, tannin, cosmetics, and glue.  These raw materials
were easily obtainable a few generations ago when extensive woodlands still existed throughout
dry regions.  Today they are scarce because much of the "useless brush" has been converted
to farm fields or plantations of rapid growth species, the use of which is usually limited to only
a single product.
 
Agroforestry or soil conservation techniques, often combined, can help to stabilize cultivation
on a given piece of land.  Certain of these methods help prevent or reverse environmental damage
in areas where fallow cropping is no longer practical.   Adding trees and shrubs as permanent
features in the landscape in the form of field trees, border and alignment plantings, windbreaks,
and live fencing can protect the soil against erosion and improve nutrient cycling.  Proper
maintenance of trees in agroforestry or soil conservation systems may allow permanent cultivation
of farm fields that previously could only be fallow cropped.
 
Many of the techniques described in this paper are based on farming systems that have evolved
to allow long-term sustainable production systems to take the place of shifting cultivation.  Most
can be used by anyone who wishes to make better use of trees and shrubs to restore or improve
their land.  The techniques have been drawn largely from VITA's publication Reforestation in
Arid Lands by Fred Weber and Carol Stoney.
 
II.  AGROFORESTRY TECHNIQUES
 
A wide assortment of different agroforestry techniques is being used today.  Many are based
on traditional practices that have been carried on for generations.  Others are relatively new,
"invented" by technicians working with local farmers or pastoralists and still being adapted to
varying site conditions.  The methods described here provide a practical guide for use in the
field, rather than extensive coverage of background information, theory, and reference sources.
As a practical measure they have been divided into two categories:  on-farm, which includes
those most directly related to agricultural operations, and off-farm, which includes non-agriculture
techniques.
 
ON-FARM TECHNIQUES
 
Trees can be integrated with crops in a number of ways.   They may be dispersed randomly across
a field, planted in careful rows between rows of other plants, or planted as separate stands for
orchards or woodlots.  Trees may also be used to mark borders or as live fencing.
 
Dispersed Trees
 
Intensive interaction between crops and trees occurs when they are grown together.  The classic
farm/park landscape that covers large parts of the Sahel is a perfect example of a traditional
agroforestry arrangement where trees dispersed in farm fields form an integral part of a cropping
system.  Different species are found in these dispersed, park-like stands, depending on site conditions.
The best known are Acacia albida, Butyrospermum parkii, Parkia biglobosa, and Borassus
aethiopum.
 
In traditional systems these trees regenerate naturally, and so they are more or less homogeneously
distributed across fields in random patterns.   Where they have been regenerated through human
efforts they are planted in lines (normally 10m x 10m).   Regular spacing is particularly important
if mechanized cultivation, such as animal traction, is practiced.  The main feature of this approach
is that the trees are more or less uniformly dispersed either in a natural, irregular pattern or
more systematically in a grid pattern.
 
Some problems do arise.  The seedlings are difficult to protect from grazing when they are young
(up to five years).  Brush fences or woven baskets can be placed around individual trees, but
this is expensive.  Birds are also attracted to the trees, especially when they are established near
rivers and lakes.  The birds can cause problems for farmers if they eat crops and seed.
 
Efforts to introduce Acacia albida in farm fields in the Sahel have been particularly successful,
however, because this species drops its leaves during the rainy season and does not leaf out
again until well into the dry season.   Cereal crops can be grown under the leafless trees during
the rainy season.  The crowns of almost all other tree species compete with light-demanding
crops for space, thus the areas shaded by the trees cannot be used for crop production.  Even
small trees can create enough shade during the rainy season to take a significant part of a farmer's
land-holding out of production.
 
<FIGURE>

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Alley Cropping
 
Small trees or shrubs, pruned frequently to prevent them from producing too much shade, are
grown in relatively compact rows (between 2 and 4m, never more than 6m apart).  Crops are
grown in the space--the "alley"--between the rows of trees.  This method was developed in
more humid areas of the tropics, and it is being tried in drier regions of Africa, Asia, and Latin
America.  The International Institute of Tropical Agriculture (IITA) has been experimenting with
alley cropping in Nigeria for a number of years, as has the Centro Agronomico Tropical de
Investigation y Ensenanza (CATIE) in Turrialba, Costa Rica, in Central America.  Most research
is focused on obtaining the right species combination, but the question as to which crops respond
best to which tree species also varies according to site conditions.
 
Leguminous trees, such as Calliandria calothrysus, Leucaena leucocephala, Mimosa species,
Prosopis cineraria, and Acacias, are often used in alley cropping schemes because their nitrogen-fixing
ability enriches the soil.  Such diverse crops as corn, millet, cowpeas, yams, and manioc
can be grown in the alleys.  The trees/shrubs are pruned as often as five times per year.   The
clippings are laid down as a mulch around both trees and crops, gradually decomposing and
becoming incorporated into the soil as organic matter.   The shade and mulch from the tree rows
also reduce weed growth.  Yields of some crops are higher between the mulched rows than in
comparable fields that are not being alley cropped.   The IITA found that yields from maize were
three times greater after four years of mulching with Leucaena leucocephala clippings (IITA,
1986).
 
<FIGURE>

03p03.gif (600x600)


 
Farmers may want to use the pruned branches for poles or firewood.  The clippings can also
be used as fodder for livestock.   If the leaves and branches are not used to mulch the crops,
alley cropping may not have the effect of increasing crop yields, but it will still be an effective
technique for controlling soil erosion, increasing the availability of tree products, and maintaining
agricultural sustainability.
 
In addition to the increased complexity of matching compatible crop and tree species to specific
site conditions, several other problems may limit the widespread adoption of alley cropping.
A major consideration of farmers who are considering various intercropping schemes is the amount
of arable land that the trees will take up.   Farmers tend to favor methods that will take as little
land out of crop production as possible.   Alley cropping requires fairly close placement of tree
rows, which can substantially reduce the amount of land left for the crop rows.  Where land
scarcity is a problem, therefore, alley cropping is probably not the best method to use.
 
Alley cropping also requires fairly strict adherence to planting and pruning schedules in order
for the technique to give good results.   If the trees are not cut back at regular intervals, they
will create too much shade for the intercropped plants.   For light sensitive crops like corn, too
much shade over a period of just a few days can interrupt flowering and fruiting processes.
Other crops simply do not thrive in excess shade.   Trained extension personnel are needed to
work closely with farmers on crop and tree species selection and on setting up planting and
pruning schedules.
 
Line Plantations
 
Another alternating row arrangement involves planting larger trees at a wider spacing (7 to 10m)
with crops planted between the rows.   In this system, species that provide fuelwood, and timber,
Grevillea robusta, or fruit trees like avocado and citrus, are often used.  As much as 60 percent
of the species composition of the line plantations may be shrubs.  Other possibilities such as
Markhamia platycalyx, Inga vera, Trema orientalis, and Maesopsis eminii are being studied on
trial sites, where they serve as shade trees for coffee plantations.  Several species of Acacia or
Cacao and Gmelina arborea can also contribute to honey production.  The species mix should
include trees that provide different products as well as nitrogen fixing plants.
 
<FIGURE>

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Borderline Trees
 
Borderlines consist of trees, shrubs, and grasses established to delineate individual farm fields.
They serve as property markers while they provide wood and other products for various purposes.
They do not occupy too much space, nor do they shade large areas of the fields.  Because the
tree rows are not actually in the fields, they do not interfere with regular farming operations.
As in line plantations, wood and other products can be harvested from the trees.
 
The promotion of additional species for borderline plantation has potential, if species selection
takes into consideration local preferences.   Protection of young trees is necessary unless the species
being used are unpalatable to livestock.   Issues of land and tree tenure should be carefully researched
and discussed with a community before this technique is tried.  If the trees are planted on a
borderline between two farmers' property, to whom do the trees and the harvesting rights belong?
There may be several alternative approaches to resolve this question, but all parties involved
should agree in advance as to how the situation will be handled.
 
<FIGURE>

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03p05z.gif (600x600)


 
Live Fencing
 
Live fencing consists of dense hedges or thickets usually planted around a garden or farm field
to protect it from free ranging livestock.   They are also planted around family compounds and
other buildings.  This technique differs from borderline plantations in that shrubbier species are
used, the shrubs or trees are tightly spaced (0.5-1m), and they are intensively pruned to maintain
a compact, dense barrier.  This is a very important alternative to traditional fences that are constructed
and annually repaired using interwoven thorny branches.
 
A number of species have shown that they adapt well to use as live fences.  Members of the
Euphorbia family are especially good because animals will not eat them (people too must be
careful--when Euphorbias are cut, the milky sap can cause severe irritation if it touches the
skin).  A number of Acacia and Prosopis species as well as Leucaena, Gliricidia sepium, and
Cajanus cajun, are also useful for this purpose.
 
<FIGURE>

03p06.gif (600x600)


 
Frequently, the main function of a hedge is to keep animals out.  If this is the case, plants must
be spaced tightly and kept well pruned.   Select species that are:
 
       *   Thorny
       *   Easily coppiced (sprout back)
       *   Relatively unpalatable
       *   Fast growing
 
No one species will meet all these requirements.   Trade-offs are inevitable although a mixture
of species may provide the most protection.   Final choice depends much on specific site conditions.
If protection from animals is not a primary concern, the spacing between plants can be wider.
Hedges can have many other advantages and functions besides keeping out animals:
 
       *   Demarcation of property boundaries
       *   Protection against wind
       *   Addition of organic matter from leaf litter
       *   Fruit and forage, when combined with borderline trees
       *   Privacy
 
As garden fences, or wherever irrigation is possible, trees for a live fence can be started by
direct seeding.  The seeds should be planted in furrows or in small pockets placed at intervals
along the fence row.
 
<FIGURE>

03p07a.gif (600x600)


 
Live fences can also be established from cuttings, especially from some species such as Gliricidia
sepium, members of the Euphorbia and Commiphora genera, and some perennial legumes.  Freshly
cut branches from these species are likely to make root and sprout if they are planted at the
beginning of the rains.  These species are therefore, particularly useful for establishing live fences.
Normally, one would not wait until the beginning of the rainy season to build fences, but this
might be done when using post materials that may take root.  Care should be taken not to damage
the bark or wood when attaching wire for the fence.
 
<FIGURE>

03p07b.gif (600x600)


 
OFF-FARM TECHNIQUES
 
In most rural areas as well as in towns and urban areas, there are unused spaces along roads
and water courses, and around houses and public buildings.  While they may traverse agricultural
land, these open spaces are not used for agricultural production.  Trees planted in these spaces
can enhance the environment by providing erosion control and shelter from the sun and wind
for both people and animals.
 
Road and Trail Alignment
 
A long-standing tradition in many tropical areas is to line roads with trees, mainly for shade,
but also for wood and other tree products.   This practice can be extended to include foot paths
and trails.  Certain species such as Albizia lebbek and Syzygium cumini are common street trees
in India, Sesbania grandiflora is often found in the Philippines, and Prosopis alba in South
America.
 
A frequently made mistake has been to plant trees too close to the road.  On major roadways,
enough room must be left for two vehicles to pass with additional space on the roadside for
vehicles to pull over in an emergency.   A space of less than seven meters between tree rows
creates traffic hazards.  Additional width is needed around curves, because the trees reduce the
distance ahead that drivers can see.
 
<FIGURE>

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Trees are also established along livestock and bicycle trails and footpaths, sometimes in combination
with live fencing or rock walls to control access to adjacent fields.  Shade and fruit trees are
favored for footpaths.
 
<FIGURE>

03p09.gif (600x600)


 
Water Course Alignment
 
The banks of streams are frequently cleared for cultivation of cereal crops or irrigated gardens.
They are extremely susceptible to erosion once the natural vegetation has been removed.  These
areas can be protected by restoring tree and shrub cover along the stream banks.  Water course
alignments also create good habitats for wildlife.
 
Trees and shrubs can be established around water sources in much the same way as alignment
plantings along roads.  Rivers, ponds, or drainage canals in irrigation schemes provide excellent
growing conditions for trees.   Fruit trees (mangos, citrus) should be given special consideration
because of their value as food sources.   Dry river beds (wadis) provide a suitable site for species
such as Tamarix, Anogeissus leiocarpus, Prosopis spp., or other more drought-resistant varieties
 
<FIGURE>

03p10.gif (600x600)


 
<FIGURE>

03p11.gif (600x600)


 
Shade Trees
 
Shade trees planted in public places around government buildings, schools, market places, churches,
and mosques serve an important function.   These are areas where people congregate during the
day, and shade is an essential part of the environment.   These are also places where trees can
be established and maintained quite easily by local people themselves with minimal assistance
from outside.
 
Most of the street and road trees mentioned above are excellent shade trees.  Others are Pithecellobium
dulce, Azadirachta indica (neem), and Grevilla robusta.
 
Trees planted in public places usually need individual tree fences to protect them until their
branches are out of reach of free-ranging animals.   Even after they are no longer threatened by
livestock, good local cooperation is needed to keep people from over-harvesting the trees.  For
example, the twigs of the neem tree are very popular in Africa for toothpicks.  A seemingly
harmless practice like breaking off an occasional twig can, however, stunt the growth of young
neems if the stems are continuously stripped by passers-by.
 
Although farmers generally try to restrict the amount of shade in areas where crops are grown,
shade trees are used to protect livestock from intense heat during the day.  Shade trees are particularly
necessary wherever animals are corraled or fenced in, and around watering spots.
 
<FIGURE>

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                             REFERENCES
 
Bognettau-Verlinded, E. 1989.   Study, on the Impact of Windbreaks in Majjia Valley, Niger.
      Niamey/Wageningen, Holland:  CARE/Agricultural University, Wageningen, Holland.
 
Buck, L.E. (ed.). 1983.  Proceedings of the Kenya National Seminar on Agroforestry,
      Nov. 1980.   Nairobi:  ICRAF and the University of Nairobi.
 
Delehanty, J., J. Thomson, and M. Hoskins.   1985 Majjia Valley Evaluation Study:
      Sociology Report.  Niamey:   CARE International Report.
 
FAO. 1977.  Guidelines for Watershed Management.  Rome:  FAO Conservation Guide
      Series No. 1., 298 pp.
 
FAO. 1977.  Conservation in Arid and Semi-Arid Zones.   Rome:  FAO Conservation Guide
      Series No. 3.
 
FAO. 1977.  Special Readings in Conservation Techniques.  Rome:  FAO Conservation
      Guide Series No. 4.
 
FAO. 1983.  Management of Upland Watersheds; Participation of the Mountain
      Communities.  Rome:   FAO Conservation Guide Series No. 8.
 
FAO. 1985.  Sand Dune Stabilization:  Shelterbelts and Afforestation in Dry Zones.  Rome:
      FAO Conservation Guide Series No. 10.
 
FAO. 1985.  FAO Watershed Management Field Manual:  Vegetative and Soil Treatmentt
      Methods.   Rome:  FAO Conservation Guide Series No. 13.
 
Felker, P. 1978.  State of the Art:  Acacia albida as a Complementary Permanent Intercrop with
      Annual Crops.  Riverside, California:   University of California, 133 pp.
 
Flannery, R.D. 1981.  Gully Control and Reclamation.  Arlington, Virginia; Volunteers in
      Technical Assistance (VITA), 26 pp.
 
Gulick, F.A. 1984.  Increasing Agricultural Food Production Through Selected Tree
      Planting Techniques:  A Summary Memorandum with Selected References.
      Washington, D.C.:  USAID/Bureau for Africa, 149 pp.
 
Hagedorn, H. et al. 1977.  Dune Stabilisation:  A Survey of Literature on Dune Formation and
      Dune Stabilization.  Eschborn, W. Germany:  GTZ, 193 pp.
 
Hoekstra, D.A. and F. M. Kuguru (eds.)   Agroforestry Systerm for Small-Scale Farmers:  Proceedings
      of an ICRAF Workshop.   Nairobi:  ICRAF, 283 pp.
 
IITA. 1986.  Alley Cropping.  Ibaden:   IITA Research Report.
 
ILCA. Pastoral Systems Research in Sub-Saharan Africa:   Proceedings of the IDRC/ILCA
      Workshop Held at ILCA, Addis Ababa, Ethiopia.  Addis Ababa:  ILCA, 480 pp.
 
Kunkle, S.H. 1978.  Forestry Support for Agriculture Through Watershed Management,
      Windbreaks and Other Conservation Actions.  Position Paper, Eighth World
      Forestry Congress.  Jakarta, Indonesia, 28 pp.
 
Le Houerou, H.N. (ed.) 1980.   Browse in africa:  The Current State of Knowledge.  Addis
      Ababa:   ILCA, 491 pp.
 
McGahuey, M. 1986.  Impact of Forestry Initiatives in the Sahel on Production of Food,
      Fodder, and Wood.  Washington, D.C.:   Chemonics International, 25 pp.
 
Nair, P.K.F. 1980.  Agroforestry Species:  A Crop Sheets Manual.  Nairobi:   ECRAF,
      83 pp.
 
Niar, P.K.F. 1982.  Soil Productivity Aspects of Agroforestry.   Nairobi:  ICRAF, 336 pp.
 
National Academy of Sciences. 1983.   Agroforestry in the, West African Sahel.  Washington, D. C.:
      NAS/Advisory Committee on the Sahel, 86 pp.
 
USDA/SCA. 1962.  Soil Conservation Manual.  Paris:   USAID/Centre Regional d'Editions
      Techniques, 359 pp. (Also available in French).
 
Vergera, N.T. (ed.) 1982.  New Directions for Agroforestry:  The Potential of Tropical
      Legume Trees.  Honolulu Environment and Policy Institute, East-West Center.
 
Weber, F. and M.W. Hoskins. 1983.   Soil Conservation Technical Sheets (Fiches
      Techniques de Conservation du Solss).  Moscow, Idaho:  University of Idaho for
      USDA (OICD), 112 pp.
 
Weber, F. and M.W. Hoskins. 1983.   Agroforestry in the Sahel.  Blacksburg, Virginia:  Virginia
      Polytechnic Institute, Department of Sociology.
 
                        INFORMATION SOURCES
 
The following organizations work in arid forestry, range management, or agriculture, and can be
contacted for information on specific problems:
 
Research Organizations
 
Centro Agronomico Tropical de Investigacion y Ensenanza (CATIE)
Department de Recurses Naturale
Turrialba, Costa Rica
 
Centre Technique Forestier Tropical (CTFT)
45 Bis Avenue de la Belle Gabrielle
94 Nogent Sur Marne
France
 
Consultative Group on International Agricultural Research (CGIAR)
1818 H Street
Washington, DC 20433 USA
 
Environment and Policy Institute
East-West Center
1777 East-West Road
Honolulu, HI 96848 USA
 
International Crops Research Insitute for the Semi-Arid Tropics
Patancheru P.O.
Andhra Pradesh 502 324
India
 
National Academy of Sciences
Board on Science and Technology for International Development (BOSTID)
2101 Consitution Avenue, NW
Washington, DC 20418
 
Nitrogen Fixation by Tropical Agricultural Legumes (NifTal) Project
P.O. Box 0
Paia, Hawaii 96779 USA
 
Overseas Development Natural Resources Institute (ODNRI)
56/62 Gray's Inn Road
London WC1 X8LU
United Kingdom
 
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