By Pedro Sanchez, and Anne-Marie Izac (ICRAF); Bruce Scott (ILRI)

Growing trees alongside crops is an ancient indigenous practice that gained the attention of agricultural researchers about 25 years ago. During the 1980s, agroforestry was considered to be a panacea for solving land-use problems in the tropics. Many development projects pushed agroforestry technologies without the benefits of solid research.

Now, as a result of a more scientific approach, agroforestry research is very much process-oriented. Two agroforestry interventions demonstrate how research and development are helping to improve the environment, reduce poverty, and increase food security for thousands of small farmers in Southeast Asia and Africa.

Soil fertility depletion on small farms is now recognized as the key cause of declining food security in sub-Saharan Africa. The most severely depleted nutrients are nitrogen and phosphorus. Although soils could be improved with imported mineral fertilizers, most farmers cannot afford them.

Africa has ample nitrogen in the air and phosphorus in many rock deposits; the challenge is to transfer these resources to where plants can use them. To restore nitrogen, land can be taken out of crop production and planted with fallows of leguminous nitrogen-fixing shrubs and trees. To increase phosphorus, indigenous rock phosphate combined with the biomass of non-leguminous shrubs can be applied directly to crops.

ICRAF and its partners have shown that two-year leguminous fallows accumulate about 200kg N/ha in their leaves and roots. When these are incorporated into the soil, maize yields double and sometimes quadruple. The greatest impact of this work has been in Southern Africa where more than 10,000 farmers are now using a 2-year fallow, 2 3-year maize rotation. An equivalent amount of mineral fertilizer would cost US$ 240/ha in that region, an unrealistic amount to farmers who make less than 1 US dollar per day.

In many areas of East Africa, smallholder farms need both nitrogen and phosphorus, necessitating the combined use of organic and mineral sources of nutrients. Short-term (6 16 months) improved fallows have proven to be an effective and profitable way of adding about 100kg N/ha and recycling other nutrients in the depleted soils of Western Kenya. Even fallows as short as six months have tripled maize yields in villages where many farmers are now practicing a fallow-crop rotation every year.

In phosphorus-deficient soils, Minjingu phosphate rock from northern Tanzania is as effective and profitable as imported triple superphosphate. Farmers are applying 125 250kg P/ha as a capital investment, and expect a five-year residual effect. In addition, biomass transfers from hedges of the wild sunflower, tithonia, have increased yields of maize and high-value crops such as tomatoes and beans in western Kenya, where about 4,000 farmers are trying these techniques. Most of the dissemination is done at the village scale as a pilot development project, involving government agencies and NGOs.

Improved policies at the national, district, and community levels are emerging in support of these technological breakthroughs. They include making phosphorus fertilizer, high-quality seeds, and microcredit available to farmers. Kenyas government established and funded a pilot project on soil fertility replenishment for western Kenya. As a member of the CGIAR, the government is supporting ICRAF efforts to conduct strategic research underpinning the replenishment practices.

A second example shows how improved policies stem from a sound biophysical base. The complex agroforests in Sumatra, Indonesia are indigenous systems created over generations by people living at the margins of tropical rainforests. After slash-and-burn was carried out, food crops were planted along with coffee, pepper, fruit trees and the resin-producing damar tree. The trees eventually produce high-value products such as fruits, resins, medicinals, and high-grade timber.

Scientists have found that the villagers in Krui, Lampung Province, who depend on these complex agroforests, have a much higher standard of living than those who grow only crops. The problem has been that they did not have land tenure, since their agroforests are classified as State Forest Land. This created a great deal of uncertainty among Krui agroforesters.

The Indonesian Minister of Forestry invited ICRAF scientists, including seconded scientists from ORSTOM (now IRD), France, two local NGOs, and Ministry of Forestry counterparts to document the attributes of the complex agroforests and develop policy options for solving the problem. The research culminated in January 1998, when the Minister of Forestry signed a historic decree that established an official precedent for community-based natural resource management in Indonesia. The decree recognizes the legitimacy of community-managed agroforests over a significant area of State Forest Land.

Already, 7,000 Indonesian farmers have benefited from this prototype, which could benefit millions more at the forest margins, by increasing incomes, improving resource management, and reducing social conflict. Researchers working on similar problems as far away as Cameroon took notice. There is hope that lessons can be shared between Indonesia and Cameroon regarding implementation options.

Agroforestry research can deliver substantial benefits for smallholders. The challenge now is to move beyond this beginning to improve the lives of millions of farming households as soon as possible. ICRAF is now participating actively in pilot projects and large-scale development initiatives, and recently established a Development Division. Working in partnership with NGOs and national extension agencies that have strong developmental capabilities and experience, ICRAF is helping to identify, facilitate, and catalyze agroforestry-based development opportunities around the world.