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The Chagga home gardens: A multi-storeyed agro-forestry cropping system on Mt. Kilimanjaro, Northern Tanzania

E. C. M. Fernandes, A. Oktingati, and J. Maghembe International Council for Research in Agroforestry (ICRAF), Nairobi, Kenya

INTRODUCTION

The Chagga are Bantu speakers descended from various tribes who migrated into the once-forested foothills of Mt. Kilimanjaro, and who began the process of transforming the native forest. Trees that provided fodder, fuel, and fruit were retained while the less useful ones were eliminated and replaced with new tree and crop species. This process is still continuing on Mt. Meru, a neighbouring mountain.

Mt. Kilimanjaro is one of the most densely populated areas in Tanzania, largely because of the ecological and economic success of the Chagga cropping system. The home gardens enable the farmer to sustain production with a minimum of external inputs, and they thus provide a good model of land use for extrapolation to other areas with similar ecological and socio-economic characteristics.

But although the Chagga home gardens are often cited as an example of model land use [1, 8], the system has not been described in any detail. This article identifies the major components, describes their interactions and management aspects, and presents an evaluation of the system's ecological stability, productivity, and sustainability.

GENERAL DESCRIPTION OF THE AREA

Geographic Location

The Chagga home gardens are found on Mt. Kilimanjaro in northern Tanzania (fig. 1). The bulk of the mountain cover about 3,000 km² and the highest peak is 5,895 metres above sea level. The area above the 1,900 m contour is a designated forest reserve and national park.

Biophysical Environment

The Mt. Kilimanjaro region has a bimodal rainfall pattern; 'short rains' from October to December and 'long rains' from March to May. The average annual rainfall ranges from 1,000 to 1,700 mm with marked variation depending on elevation, exposure, and aspect. Thus, Kilimanjaro gets more rainfall on its south-eastern and eastern flanks (where the Chagga home gardens are) than on its northern and western sides, which are sheltered from the wet south-east winds.

The soils in the region fall into four major groups [2]:

1. Humic nitosols and associated humic andosols.
2. Chromic cambisols and associated eutric cambisols.
3. Orchric andosols and associated chromic cambisols and vitric andosols.
4. Mollic andosols and associated eutric nitosols. In general, these volcanic soils are fertile with a high base saturation and cation exchange capacity. A major limitation is the steep slopes which prevent mechanization and require substantial erosion control work. Other limitations include stoniness or a shallow petrocalcic horizon.

Climax vegetation is montane rain forest. The forest varies in composition and structure along attitudinal and rainfall gradients. On the wetter south-eastern slopes, there is a zone of Ocotea usambarensis and Podocarpus usambarensis, which occurs at an altitude of 1,900 to 2,400 metros above sea level and a rainfall of 1,500 to 1,800 mm. The drier end of Ocotea forest sometimes grades into a forest with much Cassipourea malosana associated with Myrica salicifolia. At lower altitudes what little remains of the forest is characterized by the following species: Newtonia bucha nanii, Macaranga kilimandscharica and Parinari excelsa. At around 1,200 metres above sea level and 1,300 mm rainfall, species include Albizia spp., Bombex schumanianum, Chlorophora excelsa, Diospyros mespiliformis, Khaya nyasica, Newtonia paucijuga, and Terminalia kilimandscharica. In contrast, the drier north-western slopes ( 1,000 to 2,800 m) have Juniperus procera as the dominant species in association with Olea africana and Olea welwitschli, and sometimes in pure stands.

FIG. 1. Location of Mt. Kilimanjaro in Northern Tanzania

Land-use Systems

The south-eastern and eastern slopes are characterized by intensive smallholder production of both subsistence and cash crops. Individual homesteads are densely grouped and food crops are grown under the canopies of banana and coffee. In addition, there are state-owned coffee estates and farms. The drier northern and western slopes are used mainly for extensive grazing by the Masai.

Major plantation species are Cupressus lusitanica and Pinus patula, of which there are about 3,000 ha in the west and 3,500 ha in north-eastern Kilimanjaro. The Forestry Department carries out various silvicultural operations in natural forests to encourage the regeneration of root suckers of Ocotea usambarensis, Podocarpus gracilior, Podocarpus milanjianus and Juniperus procera.

The intensive cropping system of the Chagga involves the integration of several multi-purpose trees and shrubs with food and cash crops and livestock on the same unit of land. Within this cropping system several agro-forestry practices can be identified, including the use of multipurpose trees and shrubs:

- to provide shade for coffee,
- as live fences,
- for fodder and mulch production,
- for bee forage, and
- for anti-pest properties.

STRUCTURE OF THE SYSTEM

The Chagga home gardens (vihamba) cover about 1,200 km² (120,000 ha) on the southern and eastern slopes of Mt. Kilimanjaro. Recent estimates indicate that the southern slopes have a population density of 500 per km² and an annual population growth rate of at least 3 per cent. Marketing facilities are fair: Moshi town (fig. 1), the nearest major market, is linked by a good road with Arusha, Tanga, and Dar es Salaam.

The home gardens are located mainly between 900 and 1,900 metres above sea level. In addition, each family has another plot (kishamba) 10 to 16 km away in the drier plains below the southern and eastern slopes. The kishamba has only very few trees and is used mainly for growing annual crops.

Components of the Home Garden

Banana (Muse spp.), beans (Phaseolus vulgaris), cabbage (Brassica oleracea), cow pea (Vigna unguiculata), chill) (Capsicum spp.), eggplant (Solanum melongena), maize (Zea mays), onion (Allium cepa), potato (Solanum tuberosum), sweet potato (Ipomoea batatas), taro (Colocasia spp. and Xanthosoma spp.), tomato (Lycopersicon esculentum), and yam (Dioscorea spp.) are food crops grown in the home garden.

FIG. 2. Typical Vertical Zonation in a Chagga Home Garden

Coffee (Coffee arabica), cardamom (Elettaria cardamomum), surplus bananas and other food crops are sold as cash crops. Women are responsible for marketing the surplus bananas, vegetables and milk, and they keep the proceeds. Men get the money from coffee, poultry, and egg sales.

There are at least 15 different types of banana grown in the home gardens, including cultivars for food, brewing, and fodder. In addition to the fruit, the leaves and pseudostems are also used for fodder while the stem sheaths and dried leaves are used as mulch for coffee bushes.

Although a little maize is grown in some home gardens, the bulk of the crop is grown inter-cropped with beans on the lowland kishamba. Finger millet (Eleusine coracanal) an important crop used for brewing and making porridge, is also grown in the lowlands.

Chagga farmers grow numerous species of trees and shrubs in home gardens. Table 1 gives an idea of the different species and their uses. The men are responsible for lopping the fuel and fodder trees while the women harvest the fodder grasses and herbs.

Cattle are kept for milk, while goats and pigs are reared for meat, either for sale or home consumption, Recently some farmers have started keeping improved cattle; the more popular breeds are Fresian, Jersey, Ayrshire, and crosses between these and local breeds. Farmers on average have three cows, two goats, and six chickens [7]; in some cases a pig is also kept. Livestock are stall-fed with fodder from trees and shrubs, banana plants and grasses grown on the homestead. Supplementary fodder is harvested from the kishamba in the plains or bought at Tsh 20 a headload (30 to 50 kg).

The spatial arrangement of components is irregular and looks very haphazard, with the trees, shrubs and food crops closely intermingled. Vertically, however, several distinct zones can be distinguished (fig. 2). In terms of canopy depth, the lowest zone (O to 1 m) consists of food crops like taro, beans, and fodder herbs and grasses. Included in this zone is the regeneration of the overstorey trees and shrubs. The next zone (1 to 2.5 m) is mainly coffee, with a few young trees, shrubs and medicinal plants. Next is the banana canopy (2.5 to 5 m) with some fruit and fodder trees. Above the "banana" layer, vertical zonation is less distinct with a diffuse zone (5 to 20 m) of the preferred fuel and fodder species and another zone (15 to 30 m+) of the valuable timber trees and other fodder and fuelwood species. There is considerable overlap of the storeys with continuous recruitment to the various zones.

The intimate arrangement of components results in interactions between components in both time and space. The nature of interactions varies and can be:

- direct. fodder trees and shrubs and livestock; trees and shrubs and bees; cattle manure and crops, trees and shrubs.
- cyclic: crop residues and cattle.
- competitive: bananas and coffee; trees and shrubs and crops.

No data are available to indicate the magnitude of the direct or cyclic interactions. Trials conducted at the Coffee Research Station, Lyamungu, and over a part of the main coffee area on Mt. Kilimanjaro showed that bananas interplanted with either young or mature, or lightly shaded or unshaded, Coffea arabica significantly reduced coffee yields [9]. Other trials elsewhere showed that, provided farmyard manure was applied to the banana clumps, the yield of bananas planted at 960 stools per ha was not greatly affected by the presence or absence of interplanted coffee. Reduction of the density of bananas interplanted in coffee from 960 to 480 stools per ha resulted in a lower total banana production, which was partially offset by the higher rate of fruiting and larger bunches from the more widely spaced plants [3]. This is significant, since bananas and not coffee are the Chagga's primary crop.

Management Aspects

The Chagga have an intimate knowledge of the various crops and plants and their ecological requirements. Management techniques applied today have been continuously refined and tested over the ages and handed down from one generation to the next. Thus, when the farmers think the time is right, they carry out various operations such as opening up the canopy to ensure better fruiting of the coffee, spacing out the banana stools, and manuring the different crops. They maintain plant species (e.g. Datura arborea, Rauwolfia caffra) that repel or eradicate various pests and know the best fodder trees and shrubs and when and how to lop them.

Each home garden has a network of irrigation and drainage furrows linked to other home gardens in the vicinity. The farmer is thus able to tap and use runoff from the forest reserve and other home gardens on the slopes above.

The number of banana clumps and coffee bushes on a home garden varies not only with altitude and aspect but also with the management capabilities and preferences of the owner. In general, the range of banana clumps per home garden varies from 200 to 800 (330 to 1,200 per ha) and coffee trees from 300 to 1,000 (500 to 1,400 per ha).

There is, in addition, an average of 39 other trees and shrubs retained and managed in the home garden. Shade-tolerant crops, e.g. taro, yams, and beans, are inter-cropped between the coffee and bananas, while the more light-demanding species are grown in a section of the home-garden over which the canopy has been thinned to minimize shade.

Coffee extension services provide advice on pruning and spraying against coffee-berry disease and leaf rust. Most of the coffee trees have a single stem, while each banana clump is maintained with three to five pseudostems of different ages so as to encourage a continuous banana harvest.

Most Chagga farmers either plant new trees or encourage the natural regeneration of valuable timber species (table 1). These young trees in the understorey are well shaded, and this encourages straight stems with few branches. When appropriate, the overhead canopy is thinned to allow the trees to grow into the upper storeys. They are allowed to grow to a size approaching 0.6 to 1 m³, i.e. a rotation of 60 to 80 years. A large tree (about 1 m³ ) of Olea welwitschli can fetch a price of Tsh 10,000. If such a tree is felled during the lifetime of the present owner, then he in turn plants a new one, so that the next owner will also inherit a valuable tree.

It is important to note that although the great majority of home gardens are intensively cultivated and well managed, one also encounters some that are neglected, overgrown and sometimes abandoned.

TABLE 1. Woody Species Commonly Found in the Chagga Home Gardens and Their Uses^a

a. Over 100 crop and other plant species that appear in the Chagga home gardens have been listed in a separate publication [5].

THE FUNCTIONING OF THE HOME GARDEN SYSTEM

The average size of a home garden is 0.68 ha with a range of 0.2 to 1.2 ha. Traditionally, the land was divided only between the sons, but nowadays daughters can also inherit all or part of the home garden. Land tenure is based on a strongly held traditional belief that there is a close spiritual link between one's ancestors and the soil [1] . Thus, once a member of the immediate family has been buried in the home garden, tenure is assured for the current owner and his descendants and such a plot may even be abandoned for several years without the danger of someone else assuming ownership. This is in contrast to the lowland kishamba (allocated by the state and whose size is proportional to family size) where tenure is on an annual and usufructuary basis. If this land is not used for one or two years it may be claimed by another person.

An average household size of 9.9 people provides a workforce of four family members. In the home gardens, planting, tending and harvesting of bananas, taro and yams occurs throughout the year. Coffee harvesting usually starts in August and continues till January. The peak labour period is between January and March [4]; this is because coffee harvesting coincides with land preparation and planting of crops both in the home gardens and on the lowland kishamba. In contrast, April to June is a slack labour period before the harvesting of maize, beans, and finger millet from the lowlands. In the home gardens all operations are performed by human labour, whereas in the lowlands tractors are sometimes used for ploughing. Each farmer has an average of Tsh 560 worth of farm implements (axes, hoes, and pangas). Only a few farmers own tractors, which they lease to others for ploughing the lowland kishamba.

Seeds are obtained mostly from previous crops, although it is possible to buy seed from the Tanzania Farmers' Association. Dung from the stall-fed livestock and other household wastes are spread around the banana clumps and coffee bushes, but chemical fertilizers are generally not used. The Kilimanjaro Uremi Co-operation (KUCl, a co-operative concerned with the production and marketing of coffee, supplies pesticides free of charge for use against coffee-berry disease and leaf rust. In addition, the Chagga use a variety of plant species with antipest properties (see table 1). Credit facilities are offered by the KUC and the Tanzania Rural Development Bank (TRDB). The TRDB also offers soft loans for dairy cattle and pig production.

An average home garden of 0.68 ha produces about 125 kg of beans (184 kg per ha), 280 kg of parchment coffee (412 kg per ha) and 275 bunches of bananas (404 per ha) annually. In August 1983, coffee fetched Tsh 16.85 per kg while the average price of a bunch of bananas was Tsh 30.

The maize harvest from the lowland plot averages 360 kg per year. Almost all the coffee produced is sold, although the poorer quality beans obtained towards the end of the harvest are retained for home consumption. No production data are available for taro, yams, cardamom, and onions. Local sources indicate that crop failure involving coffee and/or maize and beans occurs once every three or four years. However, total failure involving in addition bananas, other fruits, root crops, and livestock has never occurred.

Each farmer keeps between three and five traditional beehives, and it is conservatively estimated that each hive produces at least 5 kg of honey per year. Milk production by traditional breeds under stall feeding conditions is low (1 to 4 litres per day), whereas improved cattle produce between 8 and 16 litres per day. Pigs are fattened up and sold within a period of 6 to 12 months. It is difficult to estimate the quantity of fodder produced in the home garden, but most of the Chagga farmers are almost self-sufficient in fodder production for their livestock.

Fuelwood production in home gardens is estimated at 1-2 m³ per year (1.5-3 m³ per ha per year). If we assume a minimum consumption of 1 m³ per adult per year, then each family requires 4-6 m³ per year. Thus a home garden supplies one-quarter to one-third of the fuelwood requirements. The rest is obtained from the forest reserve or from the kishamba in the form of Acacia spp. and Combretum spp.

THE DYNAMICS OF THE HOME GARDEN SYSTEM

There is no more land (outside the forest reserve) on Mt. Kilimanjaro that is suitable for the Chagga home gardens and thus expansion is no longer possible. Furthermore, the existing home gardens are reaching the limit of intensive use at the present level of management. They are also becoming increasingly fragmented due to subdivision. This land scarcity has led to the migration of some Chagga to Mt. Meru (70 km south-west of Mt. Kilimanjaro), an area that has ecological conditions similar to those on Mt. Kilimanjaro. Local sources indicate that there has been some intermarriage between the Chagga and Meru (the indigenous tribe on Mt. Meru), and this has probably been an important factor in enabling the Meru, who were formerly pastoralists, to adopt successfully the complex Chagga home garden system within a period of about 50 years.

Although the Chagga cropping system has been stable for at least a century, it is only recently that it has come under pressure from rapid population growth, diminishing land resources and changes in dietary habits (maize replacing bananas as the staple food). The migration of

youngsters to urban areas not only leads to labour shortages but also disrupts the traditional transmission from one generation to the next of the knowledge and experience required for the successful management and perpetuation of the complex multi-cropping system. In recent years, coffee prices declined markedly on international markets and this, combined with the labour-intensive nature of the crop, resulted in some Chagga farmers threatening to remove the coffee bushes from their home gardens. Despite these pressures, however, the system still appears to be working well for the majority of farmers. Nevertheless, if the system is to remain sustainable, then its productivity will have to be increased to cater to the rapidly increasing population.

EVALUATION

The following are the primary advantages of the Chagga home gardens:

1. Because of the continuous ground cover and high degree of nutrient cycling, the Chagga home gardens have remained sustainable on the erosion-prone slopes of Mt. Kilimanjaro.

2. Coffee produced by the Chagga contributes significantly to Tanzania's foreign exchange earnings. Over 52 per cent of Tanzania's export coffee comes from Kilimanjaro, and in 1982 this represented an earning of US$65 million.

3. The various crop species and varieties in the home garden represent years of both natural selection for survival and farmer selection for easier production and better quality. These species have a good resistance to prevalent pests, compete well with weeds, and have a generally high level of genetic variability. The Chagga home gardens thus represent a valuable gene pool for use in breeding programmes that seek to improve crop varieties for multi-storey cropping systems.

4. There are many advantages claimed for the multi-species, multi-storey home gardens, including soil conservation, nutrient cycling and efficiency, microclimate enhancement [5], and other benefits such as labour efficiency, risk minimization, and continuous production.

The home gardens also have several weaknesses.

1. Although the Chagga home gardens are stable land-use systems, their productivity is relatively low, and must be increased if they are to meet the demand for food of a rapidly growing population. The problem lies in the need to increase productivity while retaining the stability of the present system.

2. With the present trend of young people migrating to urban areas, it is mostly the older people who are left to manage the home gardens.

3. The present extension workers focus on individual crops and components. The absence of an integrated approach and consequent lack of awareness of the possible interactions of the various components and the repercussions of altering these interactions can result in problems for the farmer and a loss of faith in the extension service.

Development Potential of Home Gardens

On Mt. Kilimanjaro, the home garden's potential as a productive and sustainable system can be enhanced by:

1. Replacing the less productive trees and shrubs with fast-growing, nitrogen-fixing species, e.g. Leucaena leucocephala, Calliandra calothyrsus, Gliricidia septum, and Lespedeza bicolor. These would provide increased fuel, fodder, and green manure in the home garden and would reduce the time spent in travelling long distances to gather supplementary fuel and fodder.

2. Improving animal husbandry so as to achieve, for example, a lactation period for cows of around 300 days per year.

3. Improving apiculture by, for example, the use of top bar hives, better bee strains, and improved harvesting and honey-extraction methods.

4. Introducing new crop species and breeding for higher yielding crop varieties using the gene pool developed by natural and farmer selection not only in Tanzania but also in home gardens in other parts of the world.

5. Using fertilizers for which credit could be provided by the Tanzania Rural Development Bank. Purchasing, storage, and distribution of the fertilizer could be carried out by the Tanzania Farmers' Association or the Kilimanjaro Uremi Co-operation.

Extrapolability

Despite the need for an intimate knowledge of the components and a high level of management capability, the Chagga home gardens can be extrapolated to upland areas, such as the Kenyan highlands, South-West Ethiopia, and South-West Rwanda, where ecological conditions are similar and farmers now practice less intensive multiple cropping. Preferences for local species and varieties can be catered to by appropriate substitution or introduction. A demand for maize cultivation in such home gardens could be accommodated by growing the maize between rows of trees. Shade could be minimized by an east-west orientation of the rows and ground cover maintained by inter-cropping the maize with beans or cow peas.

Research Needs

Information is required on the following possibilities for improving the overall productivity of the home gardens.

1. Optimal spatial and temporal arrangement of the various components.

2. Optimal crop associations. This includes component crops and varieties differing in morphology, maturity period, shade tolerance, rooting depth, and photoperiod sensitivity.

3. Since chemical pest control is no real alternative in smallholder cropping systems, information is required on crop and species combinations with a greater potential to reduce pests, diseases, and weeds. The effectiveness of the plant species with anti-pest properties that are already used by the Chagga could be investigated as a first step.

4. Better soil management techniques, such as using green manure and mulches, and applying them only at the most appropriate times.

5. Appropriate fertilizer prescriptions for the intimate multi-species associations existing in the Chagga home-gardens.

ACKNOWLEDGEMENT

The authors would like to thank Ms. Lucille Majisu, ICRAF, Nairobi, for her valuable comments on the traditions and customs of the Chagga.

REFERENCES

1. M. von Clemm, "Agricultural Productivity and Sentiment on Kilimanjaro," Econ. Sot., 18: 99-21 (1963).

2. FAO/Unesco, Soil Map of the World, Group VI, Sheet 3 (Unesco, Paris, 1976).

3. H. W. Mitchell, ``Results of a Coffee and Banana Interplanting Trial in Bukoba," Tanganyika Coffee Board Research Report (1963).

4. M'lambiti, "Agricultural Sector Analysis for Kilimanjaro Region: A Basis for Decision Making and Planning," unpublished Ph.D. thesis (University of Dar es Salaam, 1982).

5. P. K. R. Nair, Soil Productivity Aspects of Agroforestry, Science and Practice of Agroforestry, No.1 (ICRAF, Nairobi, in press).

6. A. Oktingati, J. Maghembe, E. C. M. Fernandes, and G. H. Weaver, "An Inventory of Plant Species in the Kilimanjaro Agroforestry System," Agroforestry Systems (in press).

7. A. Oktingati and H. Mongi, "Agroforestry and the Small Farmer. A Case Study of Kilema and Kirua Vunjo in Kilimanjaro," unpublished (1983).

8. K. Openshaw and J. Morris, "The Socio-economics of Agroforestry," in T. Chandler and D. Spurgeon, ads., International Co-operation in Agroforestry. Proceedings of an international Conference (ICRAF, Nairobi, 1979), pp. 327 - 351.

9. J. B. D. Robinson, The Influence of Interplanted Bananas on Arabica Coffee Yields, Annual Research Report (Coffee Research Station, Lyamungu, 1961).

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