19. Erythrina (leguminosae: papilionoideae): a versatile genus for agroforestry systems in the tropics.

J. of Sustainable Agriculture, 1, (2), 1991, pp. 89-109

Some of the most common uses of Erythrina species are discussed in this review related to specific agroforestry applications.

Although common throughout the tropics, the many species of Erythrina have not received much attention from researchers or development workers. Yet these trees of the family Leguminosae grow quickly and have considerable potential for supplying fodder, fuelwood and other products, for providing shade to coffee and tea, and for restoring eroded sites.

The genus Erythrina is of special interest in the development of agroforestry systems because of its adaptability to several uses (e.g., live posts for fences, shade trees for perennial crops such as coffe and cacao, forage for livestock, and others).

They thrive in hot climates, with mean annual temperatures from 30 to more than 38 C. Although well adapted to drought, they also grow well in areas with annual rainfall of up to 1200 millimetres. They can survive in soils with a pH of 8.7 and up to 0.11% salt concentration.

With their rapid growth and extraordinary nodulation, the Erythrinas are a good source of organic matter for green manure. Dry foliage contains from 1 to 3% nitrogen. When incorporated into the soil, it improves fertility, moisture, nutrient retention and general tilth.

In Costa Rica, for instance, the use of Erythrina for shading or nursing other crops is a common agricultural practice in both coffee and cacao plantations. There is a great deal of evidence showing its value as a "natural fertilizer" supplier and nutrient cycling helper. The calculated figures show that the return of nitrogen to the soil and nutrient cycle in coffee, cacao, and also in maize, can save up to 200 kg N/ha per year.

A considerable research effort in working with this genus has been done in the Tropical Agricultural Center for Research and Training (CATIE), Turrialba, Costa Rica through the Erythrina Project.

This research project supported by the International Development Research Center (IDRC) from Canada, produced a large amount of research and also compiled a substantial bibliography on the genus.

Field trials would be useful to compare different Erythrina species and varieties in terms of growth rates and fuelwood and fodder quality.

There is also a need to test the potential of different species as sources of good-quality paper and pulp.