AGRICULTURA TROPICA ET SUBTROPICA VOL. 43 (4) 2010 Review Articles THE USE AND INTEGRATION OF INGA EDULIS IN AGROFORESTRY SYSTEMS IN THE AMAZON – REVIEW ARTICLE LOJKA B. 1, DUMAS L. 2, PREININGER D. 1, POLESNY Z. 1, BANOUT J. 1 1Institute of Tropics and Subtropics, Czech University of Life Sciences, Czech Republic 2Ecole Nationale Supérieure Agronomique de Montpellier, Montpellier, France Abstract In Latin America this fast growing, acid-soil tolerant tree, which improves soil fertility through nitrogen [ xation, is tradi- tionally used to shade perennial crops such as coffee and cacao, provide [ rewood and charcoal, and produce a sweet pulp suitable for human consumption. I. edulis is also useful as a green manure with its high biomass production and helps control weeds and erosion, in alley cropping and other agroforestry systems. It has a great potential for restoring degraded soils as a part of agroforestry system. The information about the physiology, the use by local farmers, the silvicultural management and integration into agroforestry systems were collected. The species is commonly used in a large variety of agroforestry systems, however, it is surprising that it is still not the object of any improved breeding program and scienti [ c information about this species are still rather scarce. Key words: Peruvian Amazon, slash-and-burn farming, small farmers, weed control INTRODUCTION species for agroforestry and other environmental improv- ing systems (Weber et al., 2001). The genus Inga ( Leguminosea: Mimosoideae: Ingeae ) Several researchers have described I. edulis as an agro- comprises c. 300 species of trees restricted to tropical forestry tree with an important role for farmers and with America. It is and ubiquitous component of lowland and a great adaptability for agroforestry systems (Szott 1987; montane rainforest throughout the humid tropical zones Alegre 1991; Salazar and Palm 1991; Fernandes et al., from Mexico to Uruguay. The highest species diversity 1991; Ricse and Szott, 1993; Flores 1997; Weber et al ., is concentrated it the Andean foothills of Peru, Ecuador, 1997; Labarta and Weber 1998; Pennington and Fern- Colombia and in southern Central America (Pennington, andes, 1998). In the study of Labarta and Weber (1998) 1997). Inga edulis Mart. is one of the most widely dis- of economic valuation of agroforestry species in the Pe- tributed and economically useful in the whole Amazon ruvian Amazon, I. edulis was ranked as a second most region. Sotelo-Montes and Weber (1997) investigated important trees species used by local farmers. In other farmers’ preferences for agroforestry tree species in the study of agroforestry species prioritization (Villachica, Peruvian Amazon and identi [ ed I. edulis as a high pri- 1995) I. edulis was generally cited as a tree with facili- ority species for agroforestry research and development. ties to integrate agroforestry systems and with excellent This fast growing, acid-soil tolerant tree, which improves characteristics to develop its use in agroforestry. The ob- soil fertility through nitrogen [ xation, is traditionally jective of this review was to collect most relevant infor- used to shade perennial crops such as coffee and cacao, mation about the integration and use of this species in provide [ rewood and charcoal, and produce a sweet pulp agroforestry systems. suitable for human consumption (Pennington and Fern- andes, 1998). I. edulis is also useful as a green manure Physiology and adaptation with its high biomass production and helps control weeds and erosion (Lawrence, 1995). It has a great potential for The native range of I. edulis is in Amazonian Bra- restoring degraded soils as a part of agroforestry system. zil, Bolivia, Peru, Ecuador and Colombia. The species Its presence throughout the Amazon basin sparked inter- has also been introduced across most of tropical South est of scientists in further exploring the potential of this America, Panama and Costa Rica (Lawrence, 1993). It 352 AGRICULTURA TROPICA ET SUBTROPICA VOL. 43 (4) 2010 grows in hot, humid climates between 26°S and 10°N, per cm 3 it is used mainly as a fuel wood but also for rural and up to 2000 m elevation and it is most wide-spread in construction. areas without a dry season or with a dry season of three to four months and annual rainfall of around 1500 mm The use (900–3500 mm). It can tolerate short droughts, although in its natural range some rain falls every month. I. edulis has a wide range of uses among small farmers I. edulis thrives on all the kind of soils presented in in Latin America (Pennington and Fernandes, 1998). Its Amazon from fertile alluvial Entisols to strongly-acid, major products are fruit and [ rewood, and its major serv- infertile Ultisols. Sanchez (1987) described I. edulis as ice functions are shade and soil improvement. Its com- an excellent species for acid soils in the tropics. How- mon uses are as a mulch supply in alley cropping system, ever, its growth is better on the non- \ ooding [ elds a pasture or soil improver, a shade for perennial crops; (TCA, 1997). Rapid growth of this species is also re- its potential is as a fuelwood and timber producer and in ported on highly acidic soil, low in nutrients and high in improved fallows. Other uses are presented in the litera- aluminum toxicity of abandoned pasture in Amazonian ture such as living fence or medicine properties (Weber Ecuador (Neill and Nixon, 1998). Leblanc et al. (2005) et al., 1997). The seeds are valued as a natural purgative [ for human and cattle. have studied the N 2- xing symbiosis with I. edulis . The four strains of symbiotic bacteria were closely related to The pods of Inga edulis are widely marketed and eaten Bradyrhizobium japonicum and to Bradyrhizobium liao- as a fresh fruit in the Amazon. The fruits of low quality ningense . The estimate of the percentage of N [ xed from are consumed by the livestock, pigs, poultry or [ shes. atmosphere out of total N in I. edulis seedlings was about The important content of proteins in the seed confers 40% in the sand media treatments and 10% in the native the potential as a source of animal alimentation (TCA, soil. 1997). The pulp covering the seeds is sweet and tender, Tree can reach a height of 30m and a stem diameter contains over 80% water, is rich in carbohydrates and (dbh) of 60 cm, but usually grows much lower (up to contains a lot of energy. It is eaten usually fresh but juice 15 m) and branches from below 1 m. The branches form can be prepared and it has also a potential for produc- a broad, \ at and moderately dense canopy. The bark is ing alcoholic beverages. The nutritive value of fresh pulp pale grey and smooth, with pale elongated lenticels. The is low, but the embryos of this and other Inga species young twigs are angular in cross-section and covered in can be cooked and are more nutritious than the fruit. line short brown hair. The leaves are once pinnate, up to The cooking probably degrades trypsin inhibitors and 24 cm long, with four to six pairs of opposite lea \ ets. enhances palatability (Leakey, 1997). The fruits, which The terminal pair of lea \ ets is larger than the basal pair can normally be kept for only three to four days, can be and can be up to 18 cm long and 11 cm wide. Between stored in a refrigerator for three weeks. each lea \ et there is a nectary gland on the leaf rachis. Concerning the use of I. edulis as a wood source, it is The in \ orescences are dense axillaries spikes of \ owers, generally appreciated for three reasons (1) it is a fast- each consisting of a calyx tube with 5 lobes (4–9 mm growing tree, (2) its management is easy, and (3) it has long), a corolla tube with [ ve lobes (13–25 mm long) a short fruit production period (6–10 years). The wood and a large number of white stamens up to 4.5 cm long is used as fuelwood or in the rural construction. (TCA, united in a tube in the lower half (Pennigton, 1997). 1997). It has a high calori [ c content and its weak smoke In observations made in Brazilian Amazon (Falcao and derangement, however, the species is not usually culti- Clement, 2000) the majority of plants had four \ owering vated speci [ cally for fuelwood or other woody products periods during the year, with \ owering peaks in March, (Lawrence, 1993). May, August/September, October/December, with some Leblanc et al. (2005) have described I. edulis as tree trees presenting [ ve \ owering peaks, followed by fruit- used traditionally for shade in coffee and cacao planta- ing periods in April, June, September/October, and No- tions throughout tropical America. Indeed it is one of the vember/January. Three to four year old trees produced most popular shade trees for coffee and cacao planta- 20 000–100 000 \ owers (mean 50 000) and 200–800 tions in the humid Neotropics. In Costa Rica, I. edulis is fruits (mean 500). Fruit set varied from 0.4 to 1.8%, chosen in preference to Erythrina poeppigiana (another with a mean of 1.1%. Fruit is a large, cylindrical, ribbed commonly used species for coffee shade trees) because it pod (40–180 cm long), [ lled with 2–3 cm long, usually retains its leaves in the dry season, while E. poeppigiana black, oval seeds, which are covered with white, cottony, does not (Nichols, 1990). In pastoral systems, I. edulis edible pulp. Fruit weight varied from 250 to 600 g, with can provide shade for livestock (Weber et al., 1997). only 22 ± 4% of edible pulp (Falcao and Clement, 2000).