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Page 165 Basul Agroforestry is gaining widespread recognition and research these days. In this agricultural system, shrubs and trees are grown together with food or plantation crops, and sometimes with livestock as a third partner. Such systems can be highly productive and resistant to perturbation, and they represent a major thrust in the programs emphasizing sustainable agriculture. Indeed, agroforestry is seen as one solution to the fact that the developing world will soon contain 500 million more persons than its current land resources can support. 1 One of the least known but perhaps most promising candidates for inclusion in agroforestry is basul (Erythrina edulis). This smallish tree is native to the Andean region from western Venezuela to southern Bolivia. It is vigorous, fast-growing, and precocious, a pioneer species that colonizes newly cleared sites. Basul (pronounced bah-sool) is not widely known even in the Andes. Yet it is found in many backyard gardens and along property boundaries as a beautiful “living fence.” However, since pre-Columbian times it has been grown less for its beauty than for its large, edible seeds. Basul is one of the few trees that provides a basic foodstuff. It is a legume species and its seeds, like those of other legumes (also called beans, grain legumes, or pulses), are important sources of food both for humans and animals. It could be said that basul is the “tree bean of the Andes.” Basul is an important food crop because it grows in areas where seasonal food deficits occur often. In these “famine seasons,” its dried seeds are an important nutritional safety net. They are used particularly in the months just before field crops are ready to harvest—a time when the previous year's harvest is often depleted and food is scarce. This tree-bean can then make the difference between health and malnutrition. Beans are rich in protein, and basul seeds complement the starch-rich cereals or root crops that make up the bulk of food consumed by the poor. Moreover, the amino acids in its protein complement those found in cereals and roots. 1 This outcome was predicted to occur by 2000 A.D., assuming present levels of agricultural inputs, in a recent report of the UN Food and Agriculture Organization.
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Page 166 For all its importance as a food, this tree produces more than just beans. Indeed, it is one of the most versatile of all woody species. It supplies lumber for construction, poles for fencing, and wood for fuel. Its nitrogen-rich leaves are fed to animals and are used to mulch the garden. Its edible young flowers are used to decorate and season foods. And, although basul is mostly grown for home consumption, it is used as a cash crop as well—the pods being exchanged among families or sold in markets. The living trees are also important themselves. Basul is one of the easiest trees to grow. Sections of stem—even large ones—take root readily and become living and long-lasting fence posts. A basul hedge requires little care and, once established, can live for decades. The tree can also be used for shading coffee, cocoa, and other sun-sensitive crops. Vines—such as pepper, betel, and grape—get double benefit because they also use the tree trunks as supports. As a leguminous tree, it supplies nitrogen that fertilizes the soil around it. Because of this it is sometimes called a “nurse tree.” Despite its extreme versatility, basul is so far little known outside the Andes. But—with the desperate need of developing countries for food, forage, firewood, paper, other wood products, reforestation, and erosion control—it is worth much more recognition than it now receives. PROSPECTS The Andes. Agronomic research aimed at regularizing the production of basul would greatly enhance its commercial use and might elevate it to one of the most prevalent and useful trees among the region's rural populations. Because of its “off-season” seed production, basul is potentially vital for health and survival in times of food scarcity. Owing to its robustness, it can be grown on unused patches of land as a source of “famine food,” “famine feed,” and other critical products. Given organized production it could also make some “wastelands” productive. Other Developing Areas. Any crop that can be raised for home consumption to improve nutrition during times of scarcity is worthy of increased attention, not only in the Andes, but in other parts of the tropics as well. Versatile tree crops that yield food as well as other products are extremely useful in the lives of the rural poor, and offer important advantages to farmers in many developing countries.
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Page 167 ~ enlarge ~ Basul is a bean that grows on trees. Its extremely large seeds have a pleasant, slightly sweet flavor and are usually eaten like lima beans. They are also used in candies. (Wilson Popenoe © 1926 National Geographic Society.)
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Page 168 Because bacteria in its root nodules fix atmospheric nitrogen and because its fallen leaves enrich soil, basul is particularly promising for ameliorating the effects of soil impoverishment. It is also promising for use in reforestation, one of the most pressing of all environmental concerns. Industrialized Regions. For regions outside Africa, Asia, and Latin America, basul is not a promising resource. The tree is killed by frost and has little or no potential for cultivation in North America, Europe, or other temperate regions, nor is there much need for its seeds there. USES The large, soft, succulent seeds are usually boiled in water with a little salt and are served as a side dish to corn, cassava, bread, or potatoes. They are sometimes mashed with cheese and are also fried. They should not be eaten raw. The leaves and immature pods of this legume are used to feed cattle, pigs, sheep, guinea pigs, and chickens. In one agroforestry system, basul trees shade the animals while cover crops between the trees provide additional fodder. Meanwhile, the animal droppings help the trees remain productive. As noted, the basul tree is widely used as a living fence. It is fast growing, stout spined, easily planted, and almost maintenance free. NUTRITION The seeds contain about 20 percent protein on a dry-weight basis. 2 Their amino-acid balance is similar to that of other legumes—rich in lysine, for example. Their limiting amino acids are methionine and tryptophan, both of which are also low in other legumes. They have a good balance of inorganic nutrients, particularly phosphorus. AGRONOMY Basul can be easily propagated by several methods. Its mature seeds germinate well and the young plants grow vigorously. Superior specimens can easily be propagated by stem cuttings, and, as noted, 2 Perez et al., 1979.
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Page 169 branches stuck in the ground will sprout. Grafted trees begin producing seeds within 1–2 years of planting. Small birds are the normal pollinators. The brilliant red flowers provide a rich and abundant nectar, an important food and water source for the birds at certain times of the year. HARVESTING AND HANDLING Although basul pods come from trees, they are harvested and processed much like beans. As with most legumes, the pods mature at slightly different times, and several pickings are necessary. However, unlike most plants, basul yields seasonal harvests twice a year. A single tree can yield as much as 200 kg of seed each year. As the seeds dry out, they pull away from the pod wall and can be readily removed. LIMITATIONS Care must be taken to ensure that one is dealing with the right species. In some places the common name “basul” is applied to species other than Erythrina edulis. This could lead to a serious mistake, because the seeds of many other Erythrina species are poisonous even when cooked. (However, these are small and hard and are unlikely to be confused by knowledgeable people.) As already noted, they cannot be eaten raw. The seeds are said to be rarely used in soups because they darken the soup and can give it a bitter flavor. (This is perhaps because of interaction with the metal pot.) All Erythrina species are susceptible to insect borers that invade the heartwood. Proper care (and perhaps use of pesticides) can prevent the young trees from being destroyed. As the tree ages it seems to become resistant to the borers. Basul is susceptible to extended droughts. (Grafting it onto Erythrina falcata rootstock greatly increases its drought tolerance. 3 ) RESEARCH NEEDS Among research topics for this species are the following. Baseline Survey Traditional production methods should be surveyed and analyzed. Topics for investigation include planting density, pest control, pruning, harvesting, and tree maintenance. 3 Information from I. Peralta V.
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Page 170 Genetic Improvement Provenance evaluation for high yield, large seed size, pleasing taste, fast growth, and adaptability should be made. Most erythrinas are self-sterile and require cross-pollination, an impediment for high fruit set. Whether basul requires this has not been reported and should be checked. Nutritional Research Nutritional trials could help demonstrate dietary importance. Details of amino acid and vitamin compositions are lacking. Toxicological analyses should be conducted on the seeds as a precaution. Animal Production Trials All woody plants that provide feed for livestock deserve greater recognition in animal production in tropical regions. Browse shrubs and trees complement (and often benefit) herbaceous pasture species and can be crucial to the nutrition—even the survival—of animals, especially during drought, when shallow-rooted species shrivel to straw. However, cattle are said to eat only limited quantities of erythrina leaves. Exploratory trials using basul are called for. Basul trees fix nitrogen, and with their protein-rich foliage, pods, and seeds as well as their general robustness, they might enormously benefit developing country reforestation and soil-improvement programs in the future. SPECIES INFORMATION Botanical Name Erythrina edulis Triana Family Leguminosae (Fabaceae) Synonym Erythrina esculenta Common Names Spanish: basul, balú, antipurutu, baluy, chachafruto, chafruto, sachafruto, sachapuruto, calú, frísol calú, nopas (Colombia); pajuro (Peru); achaporoto, sacha purutu (Argentina, Bolivia) Origin. Unknown, although the seeds are found in early burial sites. Basul is a semidomesticate, and wild forms are abundant at the transition zone between highland and forest. Description. Basul is a tree 8–10 m tall with trifoliate leaves. The trunk bears stout, conical spines, and the young branches are thorny. The two-petaled, red, fleshy flowers face upward, forming a large cup in which nectar gathers.
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Page 171 The 20–30 cm long seed pod is greenish purple, leathery, and spongy. It is smooth and nearly cylindrical, with constrictions between the 1–10 large, light-brown, glossy seeds (each 2.5–3.5 cm in diameter). Horticultural Varieties. None. Environmental Requirements Daylength. Basul's requirements are unknown, but other members of the genus set seed to the limits of the subtropics. Rainfall. 450–1,800 mm. Altitude. Generally grown between 1,800 and 2,200 m in the central Andes; between 1,100 and 2,700 m in Colombia. Low Temperature. Unknown, but probably about 5°C. High Temperature. Unknown. Soil Types. Apparently widely adaptable.
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