64

An interdisciplinary program (ADURAA) analyzes the sustainability and the urban functions of agriculture inside and around Antananarivo. Its aim is to develop knowledge and to help public decisions about the interest, limits and conditions of the local maintenance of agriculture, compared with other land uses. Six research themes were identified based on a typology of urban farms; they contribute knowledge on three main functions of this agriculture, viz. food supply, land use and risk prevention, and the emerging role of urban waste reuse. A wide diversity of activities systems and agricultural production systems has been identified in relation to distance to the town and water availability. This urban agriculture significantly contributes to the vegetables supply of the district as well as to its rice supply. Flooding in the lowland and erosion in the hills are also efficiently contained by agricultural land use, but anarchic building and the use of agricultural soil for brick making largely counteract this role. Uncontrolled discharge of industrial liquid wastes into the irrigation network greatly reduces rice production and has even led to the desertion of some intra-urban rice-growing areas, while domestic pollution strongly affects the sanitary quality of intra-urban vegetables. However a positive externality could be developed by using some urban solid waste as fertilisers for the growing horticultural sector. Emerging questions such as the quality of urban produce and potential new risks open up new avenues for future research on this agriculture.