TECHNICAL PAPER # 57
Fred Weber and Carol Stoney
Frederick J. Holman
VOLUNTEERS IN TECHNICAL ASSISTANCE
Boulevard, Suite 500, Arlington, Virginia 22209 USA
Telephone: (703) 276-1800,
Fax: (703) 243-1865
Telex: 440192 VITAUI,
Understanding Agroforestry Techniques
1989, Volunteers in Technical Assistance
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
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
Volunteers Fred Weber and Carol Stoney
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
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
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
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.
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
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.
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
species are found in these dispersed, park-like stands, depending on site
The best known are Acacia albida, Butyrospermum parkii,
Parkia biglobosa, and Borassus
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
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
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
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
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.
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
International Institute of Tropical Agriculture (IITA) has been experimenting
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
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.
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,
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
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
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
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
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
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.
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
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
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
This technique differs from borderline plantations in that shrubbier
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
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.
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:
Easily coppiced (sprout back)
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
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
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.
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
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
the bark or wood when attaching wire for the fence.
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
land, these open spaces are not used for agricultural
production. Trees planted in these
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
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
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
creates traffic hazards.
Additional width is needed around curves, because the trees reduce the
distance ahead that drivers can see.
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
favored for footpaths.
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
growing conditions for trees.
Fruit trees (mangos, citrus) should be given special
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
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
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
Most of the street and road trees mentioned above are
excellent shade trees. Others are
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
necessary wherever animals are corraled or fenced in, and
around watering spots.
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Study, on the Impact of Windbreaks in Majjia Valley, Niger.
CARE/Agricultural University, Wageningen, Holland.
Buck, L.E. (ed.). 1983.
Proceedings of the Kenya National Seminar on Agroforestry,
ICRAF and the University of Nairobi.
Delehanty, J., J. Thomson, and M. Hoskins.
1985 Majjia Valley Evaluation Study:
CARE International Report.
Guidelines for Watershed Management.
Rome: FAO Conservation Guide
Series No. 1.,
Conservation in Arid and Semi-Arid Zones.
Rome: FAO Conservation
Series No. 3.
FAO. 1977. Special
Readings in Conservation Techniques.
Rome: FAO Conservation
Management of Upland Watersheds; Participation of the Mountain
FAO Conservation Guide Series No. 8.
FAO. 1985. Sand Dune
Stabilization: Shelterbelts and
Afforestation in Dry Zones. Rome:
Conservation Guide Series No. 10.
FAO. 1985. FAO
Watershed Management Field Manual:
Vegetative and Soil Treatmentt
FAO Conservation Guide Series No. 13.
Felker, P. 1978. State
of the Art: Acacia albida as a
Complementary Permanent Intercrop with
Crops. Riverside, California:
University of California, 133 pp.
Flannery, R.D. 1981.
Gully Control and Reclamation.
Arlington, Virginia; Volunteers in
Assistance (VITA), 26 pp.
Gulick, F.A. 1984.
Increasing Agricultural Food Production Through Selected Tree
Techniques: A Summary Memorandum with
D.C.: USAID/Bureau for Africa, 149 pp.
Hagedorn, H. et al. 1977.
Dune Stabilisation: A Survey of
Literature on Dune Formation and
Stabilization. Eschborn, W.
Germany: GTZ, 193 pp.
Hoekstra, D.A. and F. M. Kuguru (eds.)
Agroforestry Systerm for Small-Scale
of an ICRAF Workshop.
ICRAF, 283 pp.
IITA. 1986. Alley
IITA Research Report.
ILCA. Pastoral Systems Research in Sub-Saharan Africa:
Proceedings of the IDRC/ILCA
at ILCA, Addis Ababa, Ethiopia. Addis
Ababa: ILCA, 480 pp.
Kunkle, S.H. 1978.
Forestry Support for Agriculture Through Watershed Management,
Other Conservation Actions. Position
Paper, Eighth World
Congress. Jakarta, Indonesia, 28 pp.
Le Houerou, H.N. (ed.) 1980.
Browse in africa: The
Current State of Knowledge. Addis
ILCA, 491 pp.
McGahuey, M. 1986.
Impact of Forestry Initiatives in the Sahel on Production of Food,
Wood. Washington, D.C.:
Chemonics International, 25 pp.
Nair, P.K.F. 1980.
Agroforestry Species: A Crop
Sheets Manual. Nairobi:
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.:
Committee on the Sahel, 86 pp.
USDA/SCA. 1962. Soil
Conservation Manual. Paris:
USAID/Centre Regional d'Editions
pp. (Also available in French).
Vergera, N.T. (ed.) 1982.
New Directions for Agroforestry:
The Potential of Tropical
Trees. Honolulu Environment and Policy
Institute, East-West Center.
Weber, F. and M.W. Hoskins. 1983.
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Conservation du Solss). Moscow,
Idaho: University of Idaho for
Weber, F. and M.W. Hoskins. 1983.
Agroforestry in the Sahel.
Blacksburg, Virginia: Virginia
Institute, Department of Sociology.
The following organizations work in arid forestry, range
management, or agriculture, and can be
contacted for information on specific problems:
Centro Agronomico Tropical de Investigacion y Ensenanza
Department de Recurses Naturale
Turrialba, Costa Rica
Centre Technique Forestier Tropical (CTFT)
45 Bis Avenue de la Belle Gabrielle
94 Nogent Sur Marne
Consultative Group on International Agricultural Research
1818 H Street
Washington, DC 20433 USA
Environment and Policy Institute
1777 East-West Road
Honolulu, HI 96848 USA
International Crops Research Insitute for the Semi-Arid
Andhra Pradesh 502 324
National Academy of Sciences
Board on Science and Technology for International
2101 Consitution Avenue, NW
Washington, DC 20418
Nitrogen Fixation by Tropical Agricultural Legumes (NifTal)
P.O. Box 0
Paia, Hawaii 96779 USA
Overseas Development Natural Resources Institute (ODNRI)
56/62 Gray's Inn Road
London WC1 X8LU