Cover Image
close this book 101 Technologies - From the South for the South
close this folder Forestry
View the document 21. Alley farming
View the document 22. Using paulownia trees for intercropping
View the document 23. Agroforestry seed information clearinghouse
View the document 24. Agroforestry seed centre for southern Africa
View the document 25. Agroforestry in semi-arid areas
View the document 26. Live fences for protecting crops and plants
View the document 27. A windbreak for protecting crops



21. Alley farming

Alley farming is a sustainable farming system that could replace shifting cultivation systems in tropical Africa, reducing deforestation and land degradation. It exploits the potential of trees, primarily for maintaining the fertility of the soil, as well as for improving crop and livestock production.

Multipurpose trees (usually leguminous) are established in rows 4-6 metres apart with crops cultivated in the "alleys" between the tree rows. Trees are pruned at the end of the first year and subsequently managed through periodic pruning of the regrowth so that interplanted food crops get enough light.

Under this system:

· The trees and shrubs protect the soil against water runoff and erosion, particularly on sloping land;

Tree prunings may be applied to the soil surface as mulch or incorporated as green manure;

· A significant amount of nitrogen, mineral nutrients, and organic matter is made available to the topsoil improving soil fertility and reducing the need for inorganic commercial fertilizer;

· The mulch also acts as a weed-suppressor and helps earthworms to multiply;

· The pruned branches can be used as a protein-rich livestock feed leading to improved productivity of sheep and goats;

· The system can also produce fuelwood or poles if desired.

The system increases the length of cropping periods, so the land can produce more, and soil fertility is rapidly regenerated and maintained. Alley farming can be used on farms of any size.


Availability of seeds of multipurpose tree species appropriate to local climate and conditions; training of farmers and community groups interested in trying out the new techniques.

Potential users

Farmers, extension workers, NGOs, and development workers in the agriculture sector. Techniques are useful in areas with erosion problems (such as hill-side farming) and where population pressure and land degradation increasingly limit the availability of fertile land for farming. Alley farming is flexible enough to be used by small farmers as well as by large mechanized farms, and is close to current farming methods. It is also in use in Southeast Asia.

Established in February 1989, the Alley Farming Network for Tropical Africa (AFNETA) promotes and supports alley farming research, on-farm testing, and extension of the concept across diverse environments in tropical Africa. Technical studies are complemented by studies of some of the constraints to alley farming, such as systems of land ownership, labour requirements, gender issues, religious beliefs, ancestral traditions, and socioeconomic pressures.

AFNETA's activities include: information dissemination, and exchange of alley farming techniques; training; and collaborative research with national and international agricultural research centres. A major priority for the network is collaboration between research institutions and development organizations. For example AFNETA co-hosted a training workshop on "Research Institution NGO Linkages" in 1991; an international conference on alley farming held in Ibadan, Nigeria, in September 1992 featured presentations from both research institutions and NGOs.

AFNETA works in Benin, Burkina Faso, Burundi, Cameroon, Côte d'Ivoire, Ethiopia, Ghana, Kenya, Liberia, Malawi, Mali, Nigeria, Rwanda, Senegal, Sierra Leone, Tanzania, Togo, Uganda, Zaire, Zambia and Zimbabwe.


Kwesi (A.N.) Atta-Krah, Coordinator, AFNETA International Institute of Tropical Agriculture Oyo Road, PMB 5320, Ibadan, Nigeria Tel.: (234-22) 400300/400314 Telex: TDS IBA NG 20311 (Box 015) or TROPIB NG 31417/ 31159; Cable: TROPFOUND IKEJA

Resources and publications

· Alley Farming: the Development of Alley Cropping as a Promising Agroforestry Technique, B.T. Lang and G.F. Wilson, IITA Reprints, International Institute of Tropical Agriculture, 1987.

AFNETAN, the official newsletter of the Alley Farming Network for Tropical Africa (see address above).

· Alley Farming with Livestock - Guidelines, International Livestock Centre for Africa, 1988. ILCA, Addis Ababa, Ethiopia, PO Box 5689; Fax: (251-1) 613218; Telex: Ilca Addis 21207.

· Alley Farming in the Humid and Subhumid Tropics, Proceedings of the 1986 International Workshop, Ibadan, Nigeria, available from IDRC.

· Alley Farming, a review by B.T. Kang, L. Reynolds and A.N. Atta-Krah, in Advances in Agronomy, 43: 315-359, 1990.

· Alley Farming Training Manual, resource materials and methodological guides for use in alley farming training programs, AFNETA, IITA, 1991.

· Trees of Plenty, 19-mint film on the use of leguminous trees in farming systems around the world, 1987, IDRC.


22. Using paulownia trees for intercropping

In many Third World countries, the depletion of native forests coupled with the increased demand for timber and fuel is creating serious environmental, economic and social problems. One strategy to deal with this situation is to encourage rural people to integrate trees within existing farming systems.

In China, the Paulownia tree has been used with great success in agroforestry programs, on nearly two million hectares of farmland. This planting has helped alleviate the chronic shortage of timber, fuelwood, and animal fodder, and at the same time has served to increase agricultural production and improve soil conservation. The successful development and use of Paulownia in China can benefit many other countries that face similar problems of competing priorities between agriculture and wood production.

Scientists at the Research Institute of Forestry, Chinese Academy of Forestry, have been studying Paulownia and have developed and distributed several improved varieties to farmers and organizations in China and other countries.

The benefits of Paulownia trees include:

· They are adaptable. They grow on flat or mountainous land, in various types of soil, including: rich humous soil in temperate areas, dry poor soil, rich forest soil, and clay soil in the subtropics, laterite soil in the tropics, and dry steppes.

· Paulownia also adapts to a variety of climates, even temperatures as low as -20°C (different species vary in their resistance to the cold). The optimum mean daily temperature for Paulownia is 24-29°C. Precipitation needs also vary greatly, from as low as 500 mm to a maximum of 2000 or 3000 mm annually.

· They grow extremely quickly (average growth 2 metres per year).

· They have a deep root system that does not compete with the roots of crops.

· Their branches and leaves are sparse, allowing plenty of light to come through.

· Intercropping with Paulownia can improve the microclimate by reducing the effects of drying winds (wind speed can be reduced by 20-50% on average) and increasing air moisture, which considerably increases yields of crops such as winter wheat, millet, and maize.

· Paulownia produces a light yet strong timber useful for furniture, plywood and musical instruments; its sale can considerably increase the income of rural people.

· Its branches can be used for fuelwood (a 10-year-old tree produces 400 kg of branches per year).

· The branches, leaves, and flowers are rich in protein, carbohydrates, and minerals, making them ideal for animal feed and green fertilizer (a 10-year-old tree produces 30 kg of dry leaves per year).

· The leaves, flowers, and wood have medicinal properties.

If the trees are used primarily to improve agricultural production, 40-67 trees are planted per hectare. This will increase yields of wheat, millet, and maize. Crops such as sesame and sweet potato are not suitable for intercropping with Paulownia and their yields may actually decrease. If 50 trees are planted per hectare, they will produce 20-25 cubic metres of timber per tree over 10 years, an important extra income to farmers.

Paulownia trees can also be planted primarily for timber production, with the crops as a secondary activity. In this case 200-400 trees are planted per hectare. The crop yield is reduced after 4-10 years, but can still amount to some 37.5 tonnes per hectare over 10 years. From 80 to 140 cubic metres of timber per hectare can be produced after 10 years.


Access to seedlings or root cuttings of appropriate Paulownia species for local conditions; training in planting and management of the trees and intercropping techniques. The Chinese Academy of Forestry has provided training courses for farmers, technicians, and extension workers.

Potential users

Farmers around the world could benefit from intercropping with Paulownia, especially in areas with poor soils, climate problems such as sandstorms, high winds, and droughts, and timber, fuelwood, and fodder shortages. Paulownia seeds have been introduced in more than 30 countries in Africa, America, Asia, Australia, Europe, Latin America, and with considerable success in Australia, India, and Pakistan.

Cost and availability

Seeds of different Paulownia species are available from the Paulownia Research Group (see below). Cost is approximately US $10 per 100 g plus US $15 to $20 to cover mailing, quarantine, etc.


Paulownia Research Group Forest Research Institute Chinese Academy of Forestry Wan Shou Shan, Beijing 100091 People's Republic of China Tel.: 2582211 ext 672; Fax: 2582317

Resources and publications

· A 27-minute film in English titled Paulownia in China has been produced by the Chinese Agricultural Studio.

· Paulownia in China: Cultivation and Utilization, by the Chinese Academy of Forestry Staff, Asian Network for Biological Sciences and IDRC, 1986, 65 pp.

· Agroforestry Systems in China, Chinese Academy of Forestry and IDRC, 1991, 216 pp. Models, development, research, and experiences of agroforestry in tropical, subtropical, temperate, and semi-arid regions in China.

· Available from the National Paulownia Centre in the United States: Paulownia Information Packet; Kiri Newsletter (Kiri is a subspecies of Paulownia); and Kiri seed. Contact: Dr Peter R. Beckford, 4303 Kenny St, Beltsville, MD 20705, USA.


23. Agroforestry seed information clearinghouse

Agroforestry is quickly becoming an important component of agricultural development in many countries. Expansion of agroforestry systems, however, are hampered by lack of seed. When seeds are available they are too often expensive and of low quality. This situation is aggravated by limited knowledge of seed production, handling, and testing for quality.

The Agroforestry Seed Information Clearinghouse (AFSICH) in the Philippines was established to serve the information needs of NGOs and government. The project collects information on seed sources and technologies for promising agroforestry species and distributes the information to NGOs and government agencies through brochures, newsletters, and training sessions.

Activities of the clearinghouse include:

· A database of seed resources for major agroforestry species in the Philippines, as well as organizations, resource persons, and seed production technologies;

· Training in seed production and handling for planners, NGOs, trainers, and farmers;

· Research;

· Coordination of a network linking NGOs and government agencies involved in uplands development in the Philippines;

· Production and distribution of extension materials.

The following types of information on seeds are being generated by the clearinghouse: information sources, uses of different species, taxonomy, growth habits, adaptation, areas under cultivation, flowering requirements and characteristics, seed setting requirements and characteristics, seed handling, and requirements for establishment of the plants.

Oil application to protect seeds

Information from the project has been used to produce the Agroforestry Technology Information Kit and was highlighted in a special issue of the Sustainable Agriculture Newsletter on agroforestry seeds. Fifteen hundred copies of the newsletter were distributed in 75 countries. The newsletter contains information on seed technology (guidelines for production, seed collection and preparation, seed drying, seed storage and protection, seed quality testing, and pregermination treatments), as well as worldwide lists of seed sources, resource people, agencies, organizations, and projects involved in seed production.

The project works closely with NGOs through the network, and its research agenda is based on farmers" problems as identified by NGOs and extension workers, not by the researchers. It is a model of a successful seed exchange network.

Potential users

Farmers, NGOs, and government agencies who do not have access to information on seeds through usual channels.


Dr Pamela G. Fernandez Agroforestry Seed Information Clearinghouse Department of Agronomy University of the Philippines at Los Baños Laguna, The Philippines 4031 Fax: 63-2-818-2087, c/o Paul Tengirri

Resources and publications

· Agroforestry Technology Information Kit, available from: Dr. Julian Gonsalves, Director, Appropriate Technology Unit, International Institute of Rural Reconstruction, Room 38, Elena Apartments, 512 R. Salas St., Ermita, Manila, The Philippines.

· Sustainable Agriculture Newsletter, Vol. 2, No. 3, Sept. 1990; available from: SAN, c/o Scott A. Killough, IIRR, Km. 39, Silang, Cavite 4118, The Philippines.


24. Agroforestry seed centre for southern Africa

As deforestation becomes an increasingly serious problem in southern Africa, agroforestry programs and community woodlots are in need of reliable sources of good-quality tree seed. There is a need for a wider selection of tree species to meet a variety of uses: improvement of soil fertility, protection of crops, provision of shelter, shade, and forage for domestic animals, provision of wood for fuel and construction, and mitigation of environmental damage.

Current problems facing forestry and agroforestry programs include a lack of available seed (and the need to import seed), inadequate testing and storage of seed, a lack of trained personnel, and inadequate information. For the programs to work, obtaining the best possible seed at the right time is crucial. To address this situation and to promote self-sufficiency in seed supply of multipurpose trees, a regional seed centre has been established in Zimbabwe.

The regional seed centre includes offices, workshop and conference facilities, a seed lab, and cold storage. It aims to provide the Southern Africa region with access to certified and improved seed for research and development programs; to develop standardized techniques for collecting, processing, storing, and testing seed for distribution; to provide training to seed workers in the region; to identify and record existing seed sources and tree stands in the region; to establish resource conservation tree stands for seed production; and to disseminate information (including information on problems of seed importation).

For the first time in Africa, seed stands of major dry-zone species have been established. A system of seed stands has been set up in Kenya, Malawi, Zambia, and Zimbabwe. The regional seed centre has organized various training activities, including a workshop for scientists on taxonomy, seed handling and testing, and a course on indigenous tree seed collection attended by seed workers from Botswana, Burkina Faso, Ethiopia, Kenya, Malawi, Zambia, and Zimbabwe. A computerized list of commercial seedlots has been drawn up, and information on seeds is provided to individuals and organizations both inside and outside the region. As well, the seed centre is identifying seed sources in other countries and on other continents for promising species that can be used in the Southern Africa region.

Potential users

Forestry and agroforestry programs throughout Africa.

Cost and availability

Seed for research is available free or on an exchange basis. A price list in US dollars for different categories of seeds is available. Seeds can be sent to any country by air freight or air mail. An import permit is required for commercial seed orders, but not for seed for research purposes.

Seed species available include:

· Exotic species: various eucalypt and pine species, and small quantities of other species;

· Indigenous species: a range of Zimbabwe acacias and other species.


Forestry Commission

PO Box 8111

Causeway, Zimbabwe

Tel.: (263) (4) 706216; Fax: (263)

(4) 795557

Telex: 22446 FORCOM ZW

General Manager

Forest Research Centre

PO Box HG 595

Harare, Zimbabwe

Tel.: 4687819; Telex: 2446 FORCOM


Resources and publications

· FORMAT, a free newsletter published in English by The Seed Centre.


25. Agroforestry in semi-arid areas

Kenya's semi-arid areas are under increasing ecological pressure due to growing population and a lack of arable land. Grazing lands are under threat in the Kakuyuni catchment area (Machakos district), where the number of cattle, goats, and sheep is now more than twice the recommended maximum for the type of land. Rainfall is low, the land produces little, and there are shortages of fodder.

The Kenya Forestry Research Institute is developing agroforestry technologies to counteract the soil erosion and poor conditions. The technologies include:

· Identification of the most promising species for intercropping (planting trees with crops) and for hedges;

· Establishment of fodder banks;

· Technologies for the rehabilitation and management of grazing lands;

· Identification of appropriate fruit tree species to improve nutrition and provide a small cash crop to local farmers;

· Improved tree-planting techniques;

· Techniques for community participation and dissemination of the new technologies.

The growing of hedgerows of trees among crops can increase productivity and improve and protect the soil. The most promising material includes species of Leucaena, Gliricidia, Cassia, and Sesbania which provide fodder, mulch, and fuelwood while preventing soil erosion and surface water runoff.

Wooden fences in the area are constantly attacked by termites and need to be replaced frequently, using scarce trees to provide the wood. Live fences provide a solution to this problem. Three species are recommended to farmers (Caesalpinia spinosa, Parkinsonia aculeata, and Zizyphus mauritania). The trees are planted less than 50 cm apart and are pollarded at 30 to 50 cm above ground to stimulate the growth of side branches.

Natural vegetation in the grazing lands is prevented from maturing by lack of moisture and constant browsing by animals. A package of treatments has been devised for eroded grazing land, to protect both natural vegetation and newly planted trees and shrubs. This includes: digging a 2-metre-long V-shaped trench upslope of the tree to improve water retention; pruning the tree to one main branch to promote upward growth; surrounding the tree with thorny bush to protect it from animals while the main branch is growing; constructing ditches for erosion control; introducing appropriate tree, shrub, and grass species to enrich the land.

Four species of fruit trees were introduced to increase available food and income: mango, pawpaw, rough lemon, and guava.

Researchers are working with farmers to develop tree-planting and management techniques for particular species and locations. These include: pruning the roots of seedlings and the stems if necessary; digging larger planting holes to encourage rapid root development; and planting promptly at the beginning of the rainy season to take advantage of all available moisture.

Self-help groups of farmers, predominantly women, participated in the trials and were the first to plant the most promising species on their farms. School children and self-help groups are taught the importance and the methods of rehabilitating grazing lands, and given seedlings to start tree nurseries. Information is disseminated mainly through radio programs, newspaper articles, women's groups, and schools.


Access to seeds or seedlings of appropriate species; training in intercropping, building and maintaining live fences, and rehabilitating grazing lands. The technologies need to be adapted to local conditions, including socioeconomic factors and current farming practices.

Potential users

Farmers, co-ops, community groups, NGOs, extension workers, and agriculturalists working in semi-arid areas.


Dr Jeff A. Odera

Director, Kenya Forestry Research Institute

PO Box 20412, Nairobi, Kenya

Tel.: Karuri 32173 or 32220; Cable:

KEFRI Nairobi


26. Live fences for protecting crops and plants

In Burkina Faso, deforestation and soil erosion are having a disastrous impact on the environment. Programs for reforestation and smallholding protection have been introduced to reverse the damage. Much of the reforestation, carried out annually at great cost in terms of financial and local manpower resources, is usually destroyed in its first year by village cattle. It is estimated that the plant survival rate is less than 30%. To reduce losses in the reforestation program, researchers from the Ministry of Environment and Tourism have developed agroforestry methods using live fences.

To protect their vegetable crops and young plants, farmers usually use wire fencing, which is expensive, or enclosures made from branches or other material that rots quickly. In contrast, live fences are cheap and quickly form permanent barriers that cattle find difficult to penetrate.

Researchers have identified the best species and methods suited to local environmental conditions. The species were chosen according to the following criteria:

· The plant's recovery rate after planting;

· The plant's annual growth rate in height and diameter;

· Ramification, which must be low and full to produce an impenetrable fence; and

· The cover, or interpenetration of the branches.

The following species were selected: Acacia senegal, Acacia nilotica, Acacia seyal, Bauhinia rufescens, Ziziphus mauritiana and Prosopis juliflora.

The following instructions should be followed closely to ensure a healthy fence:

· Planting the fence. A system of trenches improves water infiltration and increases root growth. The trenches, which aid plant recovery while minimizing the farmers' work, should measure 50 cm (for single rows) to 80 cm (for double rows) wide and 60 cm deep. The trees are planted in staggered, double rows with 40 cm between the rows and 30 to 50 cm between trees in the same row.

· Upkeep. The fences must be weeded two or three times during the first year after planting, to reduce competition from weeds. During the dry season each plant needs at least 1.5 litres of water per week.

· Pruning. The plants must be pruned once or twice a year, depending on their height, at the end of the dry season or during winter. At first, pruning should be kept low (50 to 80 cm from the ground) to encourage branches to form at the base of the trees. Subsequent pruning depends on the height to be protected, generally around 1.2 metres.

Two major drawbacks to this method became apparent during the research stage: namely, the amount of work required to dig the trenches and the availability of plants in sufficient quantities at the right time. To overcome these problems, the researchers identified species and methods suitable for creating live fences using direct seeding rather than plants.

Producing live fences using direct seeding is an easy, cost-effective method that does not require growing trees in nurseries and eliminates the planting process. The success of direct seeding depends on regular, frequent watering. The species producing best results using direct seeding are: Acacia nilotica, Acacia seyal and Bauhinia rufescens. The seeds must be planted in early winter (June and July) in trenches that have been dug and refilled before seeding.

The live-fence method has proved popular with farmers, especially those growing vegetables. This method is a significant step forward and will improve reforestation and vegetable farming conditions in the country.


Seedlings, potted plants, or cuttings of the appropriate species. In Burkina Faso, the seeds of the forest species used are available from the Centre national des semences forestières (CNSF), PO Box 2682, Ouagadougou, Burkina Faso (Tel.: 30-08-57/30-12-33).

Plants and cuttings are available from the nurseries of the Ministère de l'Environnement et du Tourisme (see above address).

Potential users

Reforestation groups, farming and vegetable programs in dry regions where cattle are causing damage and efforts are being made to halt soil erosion.


Zigani Goudouma Direction de la production Ministère de l'Environnement et du Tourisme PO Box 7044 Ouagadougou, Burkina Faso Tel.: 33-12-13/33-63-11


27. A windbreak for protecting crops

Most of Tunisia is exposed to strong winds that blow in from the sea. These winds cause numerous problems, including soil erosion, increased rainfall, a reduction in the foliation area of plants, flattening of standing grain, drying out flowers, and blowing down fruit. A windbreak that reduces the wind by 40% provides effective protection for crops.

Although windbreaks have been used in Tunisia for some time, the majority of them are incorrectly planted (trees are too close together), poorly maintained, or made up of tree species that are not suitable for the purpose.

Tunisian researchers have shown that, with appropriate species and methods, windbreaks can increase the yield of vegetable and fodder crops by 17 to 100%, depending on the crop and local conditions. Windbreaks can also produce additional income from firewood and poles.

Although the best windbreaks are designed to suit local conditions, they all have some common characteristics:

· It is important to use several tree species (eg, Eucalyptus, Acacia, Cypress) to avoid the entire windbreak being destroyed by harmful insects; trees of varying heights also offer fuller protection.

· Young plants should be protected by plastic-wrapped mulch to minimize humidity loss and to protect them against harmful insects and weeds. They should be watered regularly.

· The windbreak should be permeable to allow a certain amount of wind to get through. An impermeable windbreak raises the temperature in the fields, thereby damaging the crops. The porosity of the windbreak varies according to the farmer's needs.

· Since the windbreak occupies about a tenth of the productive land area, it is important that it produces additional income to compensate for the loss in crops. The species selected should be viable for lumber, firewood, and poles. Small fodder or medicinal plants can also be planted at the foot of the trees to create another source of income.

· Hedges that are not irrigated will compete with the crops; a space or laneway must therefore be left between the windbreak and the crops. Fruit trees should be planted at least 6 metres from the hedge to avoid competition.

· The windbreak should be maintained and pruned regularly.

· Costs can be minimized by planting trees 1 to 1.5 metres apart and hedges 80 to 100 metres apart without reducing the windbreak's effectiveness (trees are traditionally planted 60 cm apart and hedges 50-60 metres apart). The trees also benefit from the irrigation provided for the crops.

In the dry regions of Southern Tunisia, which receive only 100 to 200 mm of rain per year, researchers have studied the optimum methods for protecting crops and structures against the wind and blowing sand. They have tested fences erected perpendicular to the direction of the prevailing winds. The fences that produce the best results are made from either plaited palm-tree leaves or fibre-cement sheets.


Availability of seeds or seedlings of species suitable for local conditions.

Potential users

Farmers growing crops in regions exposed to frequent, strong winds.


A 20-minute videocassette is available, as well as illustrated brochures in Arabic, written in a simple and lucid style. Radio programs have also been produced and extension workshops organized.


Mrs Jelila Benzarti

Laboratoire de climatologie

Institut national de recherche agronomique de Tunisie

PO Box 2, Ariana-Tunis, Tunisia

Tel.: 23-19-23; 23-00-24; Telex: 143570MUVM