Cacao grown under banana trees.Photo by Danny Blank

In simplest language, agroforestry is the production of trees and of non-tree crops or animals on the same piece of land. The crops can be grown together at the same time, can be grown in rotation, or can even be grown in separate plots when materials from one are used to benefit another. However, this simple definition fails to take into account the integrated concepts associated with agroforestry that make this system of land management possibly the most self-sustaining and ecologically sound of any agricultural system. Thus, a second definition of agroforestry would be the integration of trees, plants, and animals in conservative, long-term, productive systems. Agroforestry can be considered more as an approach than as a single, finished technology. Although several finished systems have been devised and tested, such technology may require adjustment for particular situations. The flexibility of the agroforestry approach is one of its advantages.

Why Agroforestry?

Agroforestry systems make maximum use of the land. Every part of the land is considered suitable for useful plants. Emphasis is placed on perennial, multiple purpose crops that are planted once and yield benefits over a long period of time. Such benefits include construction materials, food for humans and animals, fuels, fibers, and shade. Trees in agroforestry systems also have important uses such as holding the soil against erosion and improving soil fertility (by fixing nitrogen or bringing minerals from deep in the soil and depositing them by leaf-fall).

Furthermore, well-designed systems of agroforestry maximize beneficial interactions of the crop plants while minimizing unfavorable interactions. The most common interaction is competition, which may be for light, water, or soil nutrients. Compe- tition invariably reduces the growth and yield of any crop. Yet competition occurs in monoculture as well, and this need not be more deleterious in agroforestry than monoculture systems. Interactions between components of an agroforestry system are often complementary. In a system with trees and pasture, with foraging animals, the trees provide shade and/or forage while the animals provide manure.

Thus, agroforestry systems limit the risks and increase sustainability of both small- and large-scale agriculture. Agroforestry systems may be thought of as principle parts of the farm system itself, which contains many other sub-systems that together define a way of life.

Definitions

Alley Cropping:

Growing annual crops between rows of trees or shrubs

Beautification:

Planting trees for ornamental purposes

Boundary Plantings:

Trees planted along boundaries or property lines to mark them well

Dispersed Trees:

Trees planted alone or in small numbers on pastures or otherwise treeless areas

Earthworks:

Constructions made of earth, usually to conserve or control water

Improved Fallows:

Areas left to grow up in selected trees in trees-crop rotation systems

Individual Trees:

Trees occurring alone, whether spontaneously emerging or planted

Living Fences:

Fences in which the posts are living trees, or in which the entire fence consists of closely-spaced trees or shrubs

Nectar Crop:

Trees valuable as a source of nectar for honey bees

Terraces:

Level areas constructed along the contours of hills, often but not necessarily planted with trees

Vegetative Strips:

Long, narrow areas of any type of vegetation, usually planted along contours for erosion control; may include trees

Woodlot:

An area planted to trees for fuel, or timber

Summary Of Benefits Of Agroforestry

• Improved year-round production of food and of useful and salable products
• Improved year-round use of labor and resources
• Protection and improvement of soil (especially when legumes are included) and water sources
• Increased efficiency in use of land
• Short-term food production offsetting cost of establisment of trees
• Furnishing of shade for vegetable or other crops that require or tolerate it
• Medium and long-term production of fruits
• Long-term production of fuel and timber
• Increase of total production to eat or to sell

Components Of An Agroforestry System

Land

Agroforestry is not a system of pots on a balcony or in a greenhouse. It is a system by which land is managed for the benefit of the landowner, environment and long-term welfare of society. While appropriate for all landholdings, this is especially important in the case of hillside farming where agriculture may lead to rapid loss of soil. If the farmer owns the land, s/he has a vested interest in thinking conser- vatively, how the land can be maintained over long periods of time. Unfortunately, farmers who rent land may have less interest in the long-term benefits of agroforestry and may even fear that making improvements will raise the rent or result in the lease being terminated.

Trees

In agroforestry, particular attention is placed on multiple purpose trees or perennial shrubs. The most important of these trees are the legumes because of their ability to fix nitrogen and thus make it available to other plants. The roles of trees on the small farm may include the following:

• Sources of fruits, nuts, edible leaves, and other food
• Sources of construction material, posts, lumber, branches for use as wattle (a fabrication of poles interwoven with slender branches etc.)and thatching
• Sources of non-edible materials including sap, resins, tannins, insecticides, and medicinal compounds
• Sources of fuel
• Beautification
• Shade
• Soil conservation, especially on hillsides
• Improvement of soil fertility

In order to plan for the use of trees in agroforestry systems, considerable knowledge of their properties is necessary. Desirable infor- mation for each species includes its benefits, adaptability to local conditions (climate, soil, and stresses), the size and form of the canopy and root system, and suitability for various agroforestry practices. Some of the most common uses of trees in agroforestry systems are:

• Individual trees in home gardens, around houses, paths, and public places
• Dispersed trees in cropland and pastures
• Rows of trees with crops between (alley cropping)
• Strips of vegetation along contours or waterways
• Living fences and borderlines, boundaries
• Windbreaks
• Improved fallows
• Terraces on hills
• Small earthworks
• Erosion control on hillsides, gullies, channels
• Woodlots for the production of fuel and timber

Some very good food-bearing trees for agroforestry are given in Table 1. Table 2 lists some of the best of the non-food producing trees used in agroforestry. Some successful uses of trees in isolation are given in Table 3. Note that any tree can be used; however, in actual practice, very large trees are not key components of most agroforestry systems.

Non-trees

Any crop plant can be used in agroforestry systems. The choice of crop plants in designing such systems should be based on those crops already produced in a particular region either for marketing, feeding animals, or for home consumption, or that have great promise for production in the region. In keeping with the philosophy of agroforestry, however, other values to be considered in crop selection include proper nutrition, self-sufficiency and soil protection. Thus, selection of crops requires a judgment based on knowledge of the crops, adaptations, production uses, as well as family needs, opportunities for barter, and markets.

Any farm animal can be used in agroforestry systems. The choice of animal will be based on the value the farmer places on animal- derived benefits including income, food, labor, non-food products, use of crop residues, and manure. Some examples of the use of trees, crops, and animals together are given in Table4.

Getting Started With Agroforestry Systems

Steps in the decision-making process

1. Decide whether agroforestry systems are appropriate
   • Describe family and community needs
   • List the needs that could be met with an agroforestry system
   • List the potential benefits, and their relative importance, of an agroforestry system in the region in question
   • Find the limiting constraints in agriculture, including markets and marketing
   • Consider whether the people of the region are willing or capable of adopting a system
   • Then decide if it is worth the effort to develop one
2. Design a system
   • Select the area
   • Characterize its strengths and weaknesses with respect to existing soil, water, and crops
   • Select the trees, shrubs, or grasses to be used (see Tables 5-7; consider similar local plants)
   • Characterize the minimum space requirements, water and fertilizer needs, and shade tolerance of the desired crops

Further decisions as influenced by anticipated duration of the system

1. If the system is temporary
   • Plan the features of soil erosion control, earthworks, and gully maintenance first
   • Plan spacing of fruit trees according to final spacing requirements
   • Plan a succession of annual or short-lived perennials, selecting the most shade tolerant crops for the final years of intercropping
2. If the system is permanent
   • Plan the proportion of the permanent fruit and lumber trees on the basis of relative importance to the farmer
   • Plan the spacing of long-term trees on the basis of final space requirements times 0.5
   • Plan succession of annual and perennial understory crops, including crops for soil protection and enrichment
   • As large permanent trees grow, adjust planting plan to place shade tolerant crops in most shady areas
3. With both temporary and permanent systems
   • Always keep the ground covered, using various crops-to protect soil from sun and erosion
   • Try the system on a small scale first
   • Measure the inputs and outputs of the system
   • Evaluate whether the benefits expected have been achieved
   • Expand or extend any new system cautiously

Seed And Information Sources For Agroforestry Species

ECHO provides sample (not bulk) packets of seeds of most of the agroforestry species listed in this publication. See our online (www. echonet.org) overseas seed listing. Seed requests can also be emailed (echo@echonet.org) or mailed (17391 Durrance Road, N. Ft. Myers, FL 33917). Other seed sources are listed in Table 5 below. Be aware that many trees that are able to survive under difficult condi- tions may also have considerable potential to become weeds. Management can be critical. For example, pruning minimizes the ability of Leucaena spp. to produce seeds.

Table 7. Adaptation and Photos of Principle Tree Species.

Bursera simaruba hot, dry tropics	Callindra calothyrsus wet tropics	Erythrina berteroana intermediate tropics
Faidherbia albida hot, dry tropics	Gliricidia sepium intermediate tropics	Leucaena leucocephala intermediate tropics
Moringa oleifera intermediate tropics	Senna siamea intermediate tropics	Sesbania grandiflora intermediate tropics
Sesbania sesban intermediate tropics	Photos by Tim Motis

BibliographyandUseful Publications

Buck, L. 1988. Agroforestry Extension Training Sourcebook Cooperative for American Relief Everywhere. (CARE) International New York, N.Y., 540 pp.

Fernandez, Pamela G., guest ed. Sustainable Agricultural Newsletter (September 1990 issue dedicated to agroforestry seeds with an extensive listing of suppliers around the world). CUSO, 17 Phaholyothin, Golf Village, Phaholyothin Road, Bangkhen, Bangkok 10900 Thailand.

Folliot, Peter F. and Thames, John L. 1983. Environmentally Sound Small-Scale Forestry Projects, Guidelines for Planning. Volunteers in Technical Assistance (VITA). Arlington, VA, 109 pp. $9.75 (see CODEL below)

Forestry/Fuelwood Research and Development Project. 1992. Growing Multipurpose Trees on Small Farms. Bangkok, Thailand: Winrock International. 195 + ix pp. (including 41 species fact cards). To order in the USA, call: 703/351-4006 and request book order no. PNABR667.

IITA. (no date) Alley Cropping, A Stable Alternative to Shifting Cultivation. International Institute of Tropical Agriculture, Ibadan, Nigeria, 25 pp. (available for $1.00 from NFTA, see resources).

IIRR. 1990. Agroforestry Technology Information Kit. The International Institute of Rural Reconstruction, 475 Riverside Drive, Room 1270, New York, NY 10115 ($20.00). Kits are probably available as well from their office in the Philippines: IIRR, Silang, Cavite 4118, Philippines.

MacDicken. 1988. Nitrogen Fixing Trees for Wastelands. FAO Regional Office for Asia and the Pacific, Maliwan Mansion, Phra Atit Road, Bangkok, Thailand.

Nair, P.K.R. Classification of Agroforestry Systems. Agroforestry Systems 3: 97-128.

National Academy of Sciences. 1980. Firewood Crops, Shrub and Tree Species for Energy Production, Vol I, Washington, D.C., 236 pp. (available free to those actively working in develop¬ment: BOSTID (JH 217D), National Research Council, 2101 Constitution Avenue, Washington, D. C. 20418, USA).

National Academy of Sciences. 1983. Firewood Crops, Shrub and Tree Species for Energy Production, Vol II, Washington, D.C., 92 pp. (see vol I).

Rockeleau, D., Weber, F. and Field-Juma, A. 1988. Agroforestry in Dryland Africa. International Centre for Research in Agroforestry (ICRAF). Nairobi, Kenya, 311 pp. $31.00

Save The Children/US, Thailand. 1992. Collection, Storage, and Treatment of Tree Seeds: A Handbook for Small, Farm Tree Planters. The FAO Regional Wood Energy Development Programme in Asia, Bangkok, Thailand.

Shankarnarayan, R. A. (ed.). 1984. Agroforestry in Arid and Semi-arid Zones. Jodphur, India, ICAR Central Arid Zone Research Institute, 295 pp.

Teel, W.A. 1984. A Pocket Directory of Trees and Shrubs in Kenya. Kenyan Energy Non-Governmental Organization (KENGO). Nairobi, Kenya, 151 pp.

Thuvesson, D. (ed.). Forests, Trees and People Newsletter, Swedish University of Agricultural Sciences/IRDC, Box 7005, S-750 07 Uppsala, Sweden. (Quarterly publication distributed to those interested in and/or working with community forestry activities).

USAID. 1987. Windbreak and Shelterbelt Technology for Increasing Agricultural Production. United States Agency for International Development, Washington, D. C. 219 pp.

Liegel, Leon H., Venator, Charles R. 1987. A technical guide for forest nursery management in the Caribbean and Latin America, Gen. Tech. Rep. SO-67. New Orleans, LA: U.S. Department of Agriculture, Forest Service, southern Forest Experiment Station. 156p.
Von Carlowitz, P. 1986. Multipurpose Tree and Shrub Seed Directory. International Center for Research in Agroforestry, Nairobi, Kenya. 265 pp. $24.00

VSO. (no date). If a Tree Falls: A VSO Guide to Raising and Planting Trees in Kenya. Voluntary Services Overseas.

Wesley, S.B. (ed.) Agroforestry Today, ICRAF. Nairobi, Kenya, quarterly.

Citethis article as:

Martin, F.W. and S. Sherman 1992. Agroforestry Principles. ECHO Technical Note no. 25.