|Amaranth to Zai Holes, Ideas for Growing Food under Difficult Conditions (ECHO, 1996, 397 p.)|
|Principles of agroforestry|
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 foods.
Sources of construction material, posts, lumber, branches for use as wattle (a fabrication of poles interwoven with slender branches etc.), thatching.
Sources of non-edible materials, including sap, resins, tannins, insecticides, and medicinal compounds.
Sources of fuel.
Soil conservation, especially on hillsides.
Improvement of soil fertility.
In order to plan for the use of these trees in agroforestry systems considerable knowledge of their properties is necessary. Desirable information includes the uses described above, the climatic adaptations of the species, including adaptations to various soils and stresses, the size and form of the canopy as well as the root system, and the 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.
Lines of trees with crops between (alley cropping).
Strips of vegetation along contours or water ways.
Living fences and borderlines, boundaries.
Terraces on hills.
Erosion control on hillsides, gullies, channels.
Woodlots for the production of fuel and timber.