Technology and Social Change Program
Iowa State University
Amos, Iowa 50011
In collaboration with
Center for Indigenous Knowledge for
Agriculture and Rural Development (CIKARD)
Iowa State University
Amos, Iowa 50011
The Leiden Ethnosystems and Development Programme (LEAD)
Institute of Cultural and Social Studies
University of Leiden
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(c)1992, Iowa State University Research Foundation
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The definition of "homegarden" varies greatly in the literature (for a discussion of this topic, see Brownrigg 1985). Here we refer to intensive agricultural production systems situated relatively close to the homestead, with the characteristics of multistoried systems already outlined. Such systems can be found worldwide in tropical regions (Boxes 2.1 and 2.3).
Perhaps the most studied homegarden system is that of Java (Box 2.4).
In West Africa, compound farms (Box 2.5) are the most intensive permanent type of homegardens (Brownrigg 1985:36). Lagemann (1977:30) suggests that they developed because land scarcity forced farmers to intensify production on small fields. In addition to population pressure, other authors have identified factors such as convenience, the slave trade and war as influencing the development of compound farms (Cantor 1985:69-71; Okafor and Fernandes 1987:161), while Okigbo and Greenland (1976L69) see it mainly related to two phenomena: (1) the gender division of labor and (2) the need to ensure the production of necessary trees and plants because of their reduction through frequent clearing of forests and bush. Clay and Lewis (1190:155) cite limited access to organic fertilizers as one reason for cultivating bananas and other important crops close to the homestead on Rwandan compound farms. They point out that fields within a 5-minute walk are more frequently fertilized than are more distant fields, and observation confirmed by Allan (1965) for Chagga homesteads (see Box 2.5).
Most researchers view homegardens as promising and sustainable land-use strategies (e.g., Gliessman 1984:197, 1990:161; Michon 1983:14). Beside their favorable ecological characteristics (see section 3.5.1), the advantages of homegardens include the great variety of products and materials they provide (Gliessman 1990:163) and their socio-economic adaptability based on their diversity (Gonzales-Jacome 1981:25; Wiersum 1982:59). They may contribute a considerable proportion to household income, especially in poor families (Stoler 1981:251). Furthermore families can observe newly acquired plants and can grow useful species conveniently close to the house, thus eliminating long walks to distant fields (Ruddle 1974:138; Cantor 1985).
Few of the publications listed in Box 2.3 describe the constraints of multistory systems. Fernandes et al. (1984), Michon et al. (1986) and Wiersum (1982:60) mention the relatively low productivity of Chagga, West Sumatran and Javanese homegardens respectively. Nair and Sreedharan (1986) make similar points when stressing that high levels of production in South Indian homesteads can only be maintained by using inorganic fertilizers, making homegarden cultivation relatively costly. Other constraints presented by Nair and Sreedharan authors include:
The last constraint led to the failure of trials in Indonesia to promote tree gardens on dryland fields in order to combat erosion and rehabilitate the soil. Farmers who received a planting fee planted the trees but neglected to maintain them and continued to grow annual crops (Wiersum 1982:61).
Wiersum (1982:59-60), who regards tree gardens as "systems with remarkable ecological and social stability," points out that gardens well-adapted in the past may be no longer appropriate because of rapid changes in rural areas. Therefore attention should be given to possibilities for their further development. Possible improvements include various technical measures such as the choice of better cultivars and improved soil management. A systems approach is needed to evaluate the effects of such technical measures.
Several other authors call for more research on multistory systems around homesteads (e.g., Jacob and Alles 1987; Tejwani 1987:130). According to Tejwani, these agroforestry systems are little understood. Okafor and Fernandes (1987:166) recognize that the International Institute for Tropical Agriculture (IITA) and the International Livestock Centre for Africa (ILCA) already study crops and animals relevant to compound farming, but they call for more on-farm trials.
Improving homegardens, however, is not only hampered by the lack of research but also requires a reorientation of existing extension services. Fernandes et al. (1984:85), Michon et al. (1986), Nair and Sreedharan (1986) and Wiersum (1982) note that extension work focuses mainly on single crops instead of using the integrated approach needed for such complex and diverse systems.
The improvement not only of homegardens, but also of other multistory systems (Padoch and Denevan 1987: 102) and of the subsistenee sector as a whole (Sharland 1989), needs an integrated and flexible approach. Sharland (1989) blames the dominance of statistics in Western science of favoring certain production methods and ways of evaluating success. As a result, extension recommendations are directed towards the commercial sector which do not take into account the different needs and values of the subsistence sector.
Scientists used to believe that farmers abandon a swidden as its soil fertility drops, weeds invade and trees shade out crops. This belief is wrong. Swiddens often continue to be managed and produce various valuable products over an extended period (Alcorn 1981; Colfer 1983a:6; Denevan et al. 1984; Hiraoka 1989:82; Padoch and de Jong 1987:180; Ohler 1985; Posey 1984, 1985; Treacy 1982: 16). In their brief review of tropical swidden fallow management worldwide, Denevan and Padoch (1987:2) suggest that "any swidden system featuring tree species among the initial crop assemblage will probably have a useful tree-enriched fallow."
Denevan et al. (1984:347 and 356), who studied Bora swidden fields and fallows of different ages in the Amazon, describe abandonment as a process over time whereby a short-term cropping system is converted into a long-term agroforestry system. In fact, the term "sequential variation" may be more appropriate than "phased abandonment" (Denevan and Treacy 1987:40). Factors influencing the composition of managed fallow vegetation include:
Unruh (1988, 1990) provides details on the ecological processes determining the fallow vegetation and enabling the increase of economic tree species during site recovery.
Economic conditions and market opportunities also influence the configuration of managed swidden fallows. Anderson (1988:151) observed that planting and improved management of acai palms seemed to occur most frequently close to major market centers. For other examples see Padoch and de Jong (1987) and Padoch et al. (1985).
The interaction of so many factors means that no two fallows are likely to contain exactly the same species, as Padoch and de Jong (1989:108) noted for plots in Santa Rosa in the Amazon. The spectrum ranges from highly diverse fallows containing many spontaneously occurring species (e.g., Bora fallows of various ages [Flores Paitan 1987; Unruh and Alcom 1987; Unruh and Flores Paitan 1987]) and those enriched through planting of useful domesticated or semidomesticated perennials (Irvine 1989), to fallows which are dominated by one tree species (e.g., damar forests [Michon and Bompard 1987; Torquebiau 1984]). While some produce mainly for subsistence (e.g, Bora Indians [Padoch and de Jong 1987:181]), others are market-oriented (e.g., fallows in Tamshiyacu, Peru [Padoch et al. 1985, 1987]).
Padoch and de Jong (1987) demonstrate the diversity of swidden fallows by describing five traditional swidden-fallow agroforestry systems from the Peruvian Amazon. They conclude (p. 192) that the basic characteristic of such systems is their high flexibility and their adaptability to various environmental and economic conditions.
Gardens elsewhere share this flexibility, as illustrated by the talun gardens of West Java (Box 2.6).
Forest plots, another form of indigenous agroforestry, are established through casual management of natural forest. With the Huastec te'lom, selective weeding is the basic technique (Alcorn 1984:394, 1989a:188). Similar to fallows, the highly diverse vegetation of a te'lom is influenced by historical, topographic, personal and market-related factors (Alcorn 1990). Alcorn (1989a:188) found that a te'lom typically contains over 300 species. These are used for construction materials (33 species), to produce utilitarian items (65 species), for food (81 species) and medicine (221 species), and as livestock feed (8 species).
Other forms of forest plots are described for the Kayapo Indians in Brazil (Posey 1984, 1985) (see also section 5.3.2), Maya Indians in Mexico (Barrera et al. 1977; Gomez-Pompa 1987; Rico-Gray et al. 1985), and briefly for the Ifugao in the Philippines (Conklin 1967:106, 1980:8).
Relatively few publications (e.g., Alcorn 1989a; Eder 1981; Padoch 1987; Padoch and de Jong 1989) provide qualitative or quantitative data about the economic productivity of forest plots and other indigenous agroforestry systems. Alcorn (1989a) points out that such studies are difficult because of the diversity and complexity of traditional farming strategies. Eder (1981) describes how villagers in San Rose in Palawan, Philippines, turn swiddens into orchards. In a sample of 33 farms, he recorded the costs and returns for 10 rice swiddens and five orchards and found that tree cropping provided higher market returns than grain cropping. Padoch and de Jong (1989:110) conclude from their analysis of swidden fallows in Peru that these have the potential for substantial commercial returns. The authors note, however, that this potential cannot be realized unless transport, marketing and export facilties exist. Alcorn (1989a: 198), who assessed the production of the complex Huastec farmstead, views the major advantage of forest groves not in their economic and financial returns, but rather in their subsistence and conservation benefits.
The significance of indigenous multistory systems for environmental conservation is also stressed in other publications (e.g., Christanty et al. 1986: 152; Denevan et al. 1984; Posey 1983a). These authors strongly recommend that development efforts should draw on indigenous knowledge to facilitate ecologically sound change.
Trees often grow scattered in fields devoted to annual crops or pasture. Reasons for this include: convenience, optimal use of available space, shade, timber, food, fodder, and other products, soil improvement, erosion control, regulation of the hydrologic cycle and ritual or religious reasons. The Hopi, for example, encouraged extensive tree growth around their irrigated gardens to reduce evaporation (Forde 1968:233). The Aztecs reinforced the sides of their chinampas (raised platforms) with posts interwoven with branches and willow trees planted along the edges (Armillas 1971, cited in Altieri 1987:87).
Trees are common in and around the edges of fields in the drier areas of East Java, while the talun (Box 2.6) and homegarden (Box 2.4) forms, widespread in West and Central Java, are largely absent. Terra (1953:182, 195) accounts for the difference between Central and East Java in terms of the lower, more seasonal rainfall in the eastern part of the island, and cultural differences between the Javanese, Madurese and Tenggerese in this region.
Farmers in Tlaxcalca, Mexico, cultivate various fruit trees in their maize fields (Altieri and Trujillo 1987:196-197; Altieri et al. 1987:91). Fonzen and Oberholzer (1984) list more than 50 perinnials which Nepalese keep on contour strips across slopes and around fields. Jambulingam and Fernandes (1986) describe the properties of trees and shrubs maintained on farmland in Tamil Nadu, India. The species discussed are Borassus flabellifer, Tamarindus indica, Ceiba pentandra, Acacia lcucophloea, Acacia nilotica, Prosopis juliflora and Delonix elata. In Rajasthan, Prosopis cineraria trees and Zizyphus nummularia shrubs are often grown together with millet, legumes, and oilseeds. However, legumes yield less when intercropped with Z. nummularia, probably because both have a similar height (Malhotra 1981).
In Sudan, Acacia senegal is maintained in fields because it is a source of gum arabic (FAO 1974:43; Freeman and Fricke 1983) (Box 2.7).
In Sri Lanka's dry zone (Ulluwishewa 1991) and in northeast Thailand (Grandstaff et al. 1986), farmers grow trees in and around their rice fields. Grandstaff et al. argue that these trees originally were spared during shifting cultivation. But with the intensification of rice cultivation, more trees are being planted. This process occurs in four stages (Box 2.8).
Some societies traditionally cultivate around large trees because they know from exerience that this improves crop yields (e.g., Felker 1978:108, 116). The Moru in southern Sudan call cultivating around trees "kaetiri" (Sharland 1989). Scientific research has confirmed positive effects by several tree species on yields and soil fertility. Examples are Prosopis cineraria in India (Tejwani 1987:118-120) and Acacia albida in Africa (see also section 3.6.1).
Researchers in Senegal found that millet yielded up to 3 times more per hectare when grown in fields with Acacia albida than in fields without the trees (Felker 1978; Dupriez and Leener 1983:272). Acacia albida sheds its leaves during the rainy season (Farrell 1987:157) but grows leaves in the dry season when shade is much appreciated, a phenomenon known as "reverse folition" (Advisory Committee on the Sahel 1984:20). Campbell (1989), Freeman and Fricke (1983), Miehe (1986), Poschen (1986) and Weber and Hoskins (1983) describe further traditional agroforestry systems based on this species.
Research has also confirmed beneficial attributes for other tree species. Tests in Mexico showed that soil close to capulin (Prunus capuli) tress was richer in available phosphorus, nitrogen, calcium and magnesium and other elements than was soil further from the trees (Farrell 1987: 151; 1990: 172, 173). In the Spanish dehesa (Box 2.9), an agrosilvopastoral system, oak trees have a positive effect on soil condition, nitrogen utilization by grasses, and water balance when compared to grassland outside the tree canopy cover (Joffre et al. 1988).
However, as farmers in the American Midwest know, trees in fields also have drawbacks. They make it difficult to mechanize the cultivation of ground crops. Malhotra (1981) points out that introducing tractors for cultivation reduces the number of trees in fields.
Kater et al. (1992) confirmed that the soil under certain tree species may be richer than the soil further away from the trees, but they interpret this enrichment as a matter of redistribution of available nutrients. They furthermore found that the yields of sorghum and pearl millet were reduced close to Vitellaria padoxa and Parkia biglobosa trees, probably due to shade and other reasons. Reduced yields of wheat, sorghum and rice up to several meters from the tree line at field borders have also been confirmed by other studies (Akbar et al. 1990; Kessler 1992; Sae-Lee et al. 1992; Sharma 1992). Sharma (1992), however, points out that the loss in grain yield was insignificant when compared to the additional income in form of timber, fuelwood and fodder from the trees.
In different parts of the world, certain trees and shrubs are spaced so closely that they form hedges or fences. Howes (1946:51) estimates that in warmer climates probably more than 500 plant species are used for this purpose. He describes about 60 "armed" species (e.g., with thorns). Budowski (1987:170) applies the term "fence" to trees grown in a single row usually as support for wire, while "hedges" are thicker and may consist of several species. This distinction, however, is not always followed in the literature.
Hedges and fences fulfill various functions. Baobab and shea-butter hedges serve as windbreaks in many African savanna farms (Richards 1985:69); Russian olive and hackberry perform the same duty for Hopi Indians (Nyhuis 1981). To provide as much shelter as possible, Malaysian betel growers surround their gardens with hedges of the horse-radish tree (Moringa gterygosperma) or Eughorbia tirucalli (Grist 1936:295). Woody perennials and magueys planted by Peruvian farmers in the Andes protect crops against animals or prevent erosion (Brush 1977:98). Maya Indians in Yucatan fenced out free-roaming cattle by manipulating the outer lines of trees in forest strips between fields (the so-called t'olche'), using a technique called packch'ak (Remmers and de Koeijer 1992:159). Farmers in Tamil Nadu, India, use some 16 tree species for the same purpose (Jambulingan and Surendran pers. comm., cited in Westley 1990). In the upper Rio San Miguel, Mexico, farmers successfully maintain and expand arable land in the floodplains with "woven fences" propagated from cottonwood (Pogulus fremontii) and willow (Salix gooddingii) (Nabhan and Sheridan 1977). In the Sahel and Sudan zones of Africa, certain species---often thorny or prickly---were grown for defense purposes (Sollart 1986:26).
In addition to the functions just described, hedges and fencerows may provide fodder, fuelwood and many other useful products, and serve as habitat for beneficial animals, birds and insects (Altieri and Farrell 1984:15; Harwood 1979:105; Howes 1946). Chavunduka (1976:8) mentions that the Manyika in Afriu plant Boophane disticha hedges around their huts for magical reasons. They believe that these hedges ward off evil dreams and keep out the spirits of the deceased.
Mintz (1962) discusses plants commonly used for hedges in Haiti. Bromelia pinguin, though short, keeps animals out because it has spines. However, it harbors snakes, mongooses, rats and other small animals, and people avoid planting it too close to the house. Euphorbia lactea, a prickly, cactus-like succulent, has the advantage that it forms impenetrable thickets while remaining "clean", i.e., it does not bunch at its base and can be cultivated in orderly lines. According to farmers, its sap can be used as a paste for paper. Parese (probably Polyscias sp.) is another popular hedge plant in Haiti. It prevents trespassing and protects against erosion; however, goats and horses eat its leaves. Farmers plant it either in tight rows or sometimes more widely spaced. In the latter case, they may tie it together with bamboo crossbars.
In Costa Rica and other countries in Latin America, living fences made from large cuttings connected with barbed wire are characteristic features of the landscape. They occur from sea level to well above 2500 m (Budowski 1987:169). The living fences in Costa Rica (Box 2.10) have received more scientific attention than those elsewhere.