Documento(s) 11 de 15

Résumé

Abstract

Introduction

Waste dumped into storm drainage channels, creeks, lagoons and other water impoundment points create serious environmental problems which can escalate into disastrous situations. The devastation of lives and property which occurred due to the 1982 floods in Ibadan, Lagos, Port Harcourt and Aba in Nigeria (Kinako 1979; Filani and Abumere 1992) and Accra, Ghana in 1995 (Daily Graphic, July 5, 1995) were attributed partly to an accumulation of refuse which blocked these cities' drainage channels. The ineffectiveness of contemporary municipal solid waste management practices, which culminates in a number of health and environmental problems, has prompted the need to find effective and pragmatic solutions to waste management problems in African cities.

This paper argues that there is a need to unite waste reuse and urban cultivation in African cities, because opportunities to integrate the two sectors exist in Africa's urban areas. Within this context, certain pertinent questions have to be addressed. Why emphasize organic solid waste recycling? Is urban farming a permanent enough activity in African cities to be able to sustain organic solid waste recycling? What are the constraints and implementation challenges of waste reuse urban cultivation to urban planning in African cities?

This paper considers these issues in three parts. The first examines the basis and role of re-using organic solid waste in African countries; the second reviews the history and status of urban cultivation; the third considers the constraints and implementation issues surrounding waste reuse urban farming (WRUF) for urban planning.

1. Basis and rationale of WRUF

Organic material forms 50-90% of urban refuse in African cities. The organic fraction includes raw kitchen waste generated in the preparation and consumption of food: food leftovers, rotten fruit, vegetables, leaves, crop residues and animal excreta and bones. The bulk of organic waste is generated by households, restaurants and markets. In the Accra-Tema metropolitan area in Ghana, 75% of urban solid waste comes from domestic sources, 15% from commercial and industrial sources, and the rest from institutional sources (Asafo-Boakye and Partners 1992). Fantola and Oluwande (1983) estimate that the Dugbe market in Ibadan, Nigeria generates 827 802 kg of organic solid waste per year. In Accra, Ghana, restaurants and markets combined generate 60 000 m³ of organic solid waste yearly (Lardinos and Klundert 1993).

Table 1 (based on Edmundson 1981; Sridhar et al. 1985; ILO/UNDP 1991; Bertolini 1992; Kramer et al. 1994) shows the composition of municipal solid waste in some selected African cities. It is apparent that the biodegradable organic content is very high, due to the fact that reusable materials such as glass, hard plastics, metal scraps, paper and cardboard are retrieved and reused or recycled into valuable items such as lamps and sandals (Enfo News 1990; Asomani-Boateng 1994). The waste is of high density and has a moisture content ranging between 30-50%. Because the solid waste has an abundant organic content, much of it can be recovered for reuse as fertilizer. In these cities, there are many urban cultivators who are in need of such organic matter for soil conditioning. This provides an impetus for organic waste recovery. The ever-growing quantities of urban organic wastes in African cities - which at present amount to 0.5 to 0.6 kg per inhabitant, per day (Cointreau 1982) - as well as the low organic matter content of soils in most parts of Africa caused by severe drought, the cost of mineral fertilizers, and their relative scarcity, have increased the need to recycle organic waste materials as a source of crop nutrients. There is an inexhaustible and readily-available supply of organic matter: left alone, it constitutes a major health and environmental hazard. Used as an organic fertilizer, however, it ceases to be the environment's principal contaminant.

Table 1. Municipal solid waste (MSW) composition in selected African cities
 

Composition (% by weight)	Cities
	Kumasi	Accra	Ibadan	Kampala	Kigali
Organic	84.0	85.1	55.8	75.0	94.0
Plastic	-	3.4	6.3	-	-
Glass	-	1.9	1.8	-	-
Metal	-	2.6	-	-	-
Paper	-	4.9	12.9	-	-
Inert	-	-	-	-	-
Cloth	-	3.0	-	-

 

Promoting the use of organic waste in food cultivation will not only benefit urban cultivators but also it will minimize the need for expensive imported chemical fertilizers, which in Ghana averaged 46 684 tonnes from 1987-1990 (Ministry of Agriculture 1991). The question remains: is urban agriculture a permanent-enough activity in African cities to be able to sustain organic solid waste recycling? This question is examined in the discussion which follows.

2. History and status of urban farming

Historically, urban farming has been a major activity in African cities since pre-colonial days. According to Winters (1983), in hot, often humid regions such as tropical Africa, the problem of storing food compounded the problem of transporting it. The fact that urbanization was so independent of trade was one more reason for cities to be self-sufficient in food.

Agricultural activities have influenced and determined urban land use and the morphology of cities in Africa. Cities such as Kumasi, Ghana and the Yoruba towns of western Nigeria were surrounded by a zone of intensive farming in which the majority of residents worked each day (Bowditch 1819; as quoted in Winters 1983). The fact that urban farming constituted an activity in which a significant proportion of the population in pre-colonial African cities participated, is one of the reasons why these cities were classified as non-urban (Bascom 1955), and hence referred to as a "group of villages" (Winters 1983). Urban cultivation played a more important role in eastern and central African cities. The quarters of these cities were separated and the spaces between them used for farming (Winters 1983). As one observer said of Kampala, "it was less of a city than an immense garden" (Gutkind 1963). The capital of Loango in the Congo was so green that an eighteenth-century missionary remarked that "a missionary who was a bit nearsighted could have traversed the whole town without seeing a single house" (Balandier, as quoted in Winters 1983).

Colonial administrators' response to urban cultivation in African cities could be described as negative and hostile. This was reflected in their colonial urban planning, which modernized African cities by removing any vestiges of "backward" and "filthy" activities. Urban cultivation was seen as a manifestation of rural habits or "a remnant of bush life," as Naipul (1981) described it. The colonizers who controlled African cities had "concepts of grandeur, percepts of cleanliness and a firm intent to distinguish themselves from the bush" (UNDP 1996). Consequently, urban cultivation and the rearing of animals were not permitted. Colonial administrators thought urban farming would compromise town and city health, and distract the so-called "natives" from working in the emerging formal economy. In addition, it was assumed that since rural agriculture could provide the food needs of towns and cities, cultivation in cities was not necessary. The only plants that urban residents were permitted to grow were ornamental plants, plants that could beautify African cities and towns.

Urban farming in contemporary African cities is largely unrecognized, unassisted, and in some cases, outlawed because of the supposed hazards associated with it. Furthermore, urban farming is seen as not conforming to zoning regulations because in planning African cities colonial administrators ignored urban cultivation. Therefore, "there has been a remarkable continuity from colonial practice in this sphere across the continent" (Simons 1979). Contemporary urban planners and city managers associate development and modernization with industrialization, and ignore farming in urban areas, viewing food production as being "external to cities" (Guyer 1987) and "real agriculture" as taking place in rural areas (Drescher 1994). Subsequently, hostility and repression have confronted the activities of urban farmers in a host of African cities. In Bamako, Mali, the authorities banned the cultivation of cereals in 1989 on the grounds that the tall stalks provide hiding places for bandits (Diallo 1993). Kenyan authorities view urban cultivation as a blight on the urban landscape. In Zambia, the harsh repression of urban cultivation in the 70s and 80s was justified on the grounds that urban farming facilitated the breeding of malaria-carrying mosquitoes (Rakodi 1988).

Despite the official neglect from the colonial period to the present day, it is clearly apparent across contemporary Africa that urban farming is widespread and is becoming a permanent feature of the landscape of many cities. Proof of its persistence and stability is reflected in the acreage of land farmed within and around the built-up space of African cities and by the number of urban residents engaged in urban agriculture.

A significant proportion of urban land in African cities is being cultivated (Mosha 1991). In Dar-es-Salaam, Tanzania, satellite imagery has revealed that 23% of the metropolitan area is used for agricultural production; nearly 34 000 ha are devoted to crop production, with vegetables accounting for 500 ha (DSM/ARDHI 1992). In Harare, Zimbabwe, land under cultivation increased from 5 000 ha in 1990 to 9 000 ha in 1993, representing between 15% and 20% of the city's total area (Mbiba 1995). In Daloa, Ivory Coast, land under urban cultivation increased from 52 ha in 1954 to 624 ha in 1988 (Mougeot 1994). An increasing number of urban residents are engaged in urban agriculture: two thirds of urban Kenyans are farmers (Lee-Smith et al. 1987; Freeman 1991); in Accra, Ghana, Amuzu and Leitmann (1991) estimate that 3% of the city's labour force is engaged in urban farming (including fishing) and 90% of the city's vegetable supplies (including radishes, cabbage, and cauliflower) are supplied by urban farmers. The words of the Accra Metropolitan Assembly (Tetteh and Botchwey 1989) reveal the importance of urban agriculture in the city: <dir>Subsistence farming manifests itself in nearly every home and any unused space in the city. Vegetables and food crops which are commonly planted combine effectively with poultry, piggery and fish farming to supplement the income of the metropolitan dweller. </dir> In Dar-es-Salaam, urban farming is the largest employer in the city, engaging 11% of the total urban population (Bureau of Statistics 1988). In Lusaka, Zambia, urban farming is so extensive that the city has been described as "the world capital of urban cultivation" (Sanyal 1984).

The foregoing discussion establishes the fact that urban farming is an age-old activity which continues to expand. Current conditions prevailing in African countries, including rapid urbanization, ineffective agricultural policies, crippled domestic food distribution, constrained government spending, removal of subsidies, wage cuts, soaring inflation, rising unemployment, natural disasters, and civil strife, will likely accelerate the growth of urban farming (Mougeot 1994). A growing number of African countries have recognized the importance of urban farming and have taken steps to incorporate urban agriculture in their city plans. The new national capitals of Ivory Coast, Malawi and Tanzania have been planned to accommodate urban agriculture (DGIP/UNDP 1992) and local governments in Maseru, Lesotho (Greenhow 1994), Kampala, Uganda (NEIC 1994) and Dar-es-Salaam, Tanzania (DSM/ARDHI 1992) have commissioned special sectoral studies on urban agriculture as part of their master planning process.

It is against this background that promoting WRUF is seen as a practical opportunity for organic solid waste to be part of a "closed loop" within African cities. Is the concept of WRUF in African countries new?

Waste reuse urban farming

Kitchen garden

Figure 1. Kitchen garden (not to scale)

Compound gardening

Figure 2. Compound garden (not to scale)

Community gardening

Figure 3. Community garden (not to scale)

In Kano, Nigeria, the practice of using taki (compost from manure, household waste, street sweepings and ash) as fertilizing material by the city's peri-urban farmers has gone on for centuries (Lewcock 1995). Mortimore (1972) revealed that in 1969 and 1972, 1 137 and 1 447 donkeys respectively carried "taki" out of the old walled city of Kano. This represented between 140 and 1180 tonnes of compost per day for peri-urban farms. It is estimated that in a 7.5 km radius, 25% of farmers' fertilizer needs were met by waste from Kano at an average application of between 3.25 and 5.0 tonnes per hectare per annum (Mortimore 1972).

Emphasis on recycling waste in food cultivation shifted in the 1960s to the use of artificial fertilizers. With their newly gained independence, African countries vowed to modernize their economies based on the model of western, industrialized countries. Ultimately, indigenous practices were discouraged - including agriculture which involved reusing organic waste. Emphasis was placed on modem agricultural practices, including the use of chemical fertilizers. The indigenous form of agriculture was viewed as being out-of-touch with modernity. Hence, the reuse of waste in an urban area - which was actually a symbol and show-piece of modernity - was considered taboo.

Lately, there has been a resurgence in WRUF. Urban cultivators "mine" abandoned waste dumps for compost to be applied on farms, while garbage farming - involving cultivation on abandoned waste dumps - is now common in African cities. Food waste generated by restaurants and canteens is used extensively to feed pigs, goats, sheep and cattle.

3. Constraints to WRUF

Health

Economic

Official attitude and behaviour

4. Implications and challenges of WRUF for urban planning

Institutional and organizational planning

The current approach is based on the rational planning paradigm, which excludes important actors and stakeholders in the waste management planning process. Rather, the best approach would be to incorporate other integrative and participatory modes involving citizens and other stakeholders. Within this framework, various actors - including the waste management department, the city council, the agriculture department, community-based and neighbourhood organizations, the planning department, urban farmers, households, and generators of organic solid waste - would be involved in the planning for reusing organic solid waste in urban cultivation. Decentralizing certain aspects of waste management planning to the community level, whereby certain functions (like source separation and the composting of waste) could be undertaken locally, is of paramount importance. Africa is a continent that is rich in traditions of self-help and community participation in providing shelter and other services. Every country south of the Sahara has its own variety of mutual aid organizations, many of them based on traditions of shelter construction and environmental clean-up. The presence of several neighbourhood and self-help groups like the Mbati women's group and Undugu society in Kenya, Nima 441 and La Mansaamo Kpee (LMK) in Ghana and Copricol in Burkina Faso - all of which are actively involved in environmental clean up exercises in their communities - should be exploited. These groups could be given the responsibility of organizing household source separation and composting source-separated waste in their neighbourhoods. These activities are fundamental to the concept of reusing organic solid waste in food cultivation in African cities.

Source separation

Composting

It must also be emphasized, however, that community-based composting in African cities as revealed by Asomani-Boateng et al. (1996) is beset with problems. These include: the difficulty of convincing households to source-separate their waste; negative attitudes of waste management officials to the idea of community composting; the lack of space for composting household waste, especially in poor and high-density residential neighbourhoods; and residents' lack of knowledge about the art of composting. Hence, the essential requirements for successful community composting, among other things, depends on strong community support, cooperation between municipal waste management and cleansing authorities, the availability of space for composting, a market for compost, and a continuous supply of household organic solid waste as feedstock for composting.

Land-use planning

Conclusion

Acknowledgments

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