Urban agriculture is a topic of growing interest throughout the world (Tornaghi 2014, FAO 2010). Whereas urban agriculture in developed countries may be controversial and seen as lifestyle product rather than relevant for food production, its value to ameliorate the livelihoods of the urban poor in developing countries is undisputed (Aubry & Kebir 2013, Zezza & Tasciotto 2010, Mougeot 2010). Specifically, urban agriculture is an important income generation among urban households in sub-Saharan Africa. Studies conducted in Lusaka, Zambia, and in West African cities showed that urban agriculture contributes significantly to food security of urban people (Simatele & Binns 2008, Cissé et al. 2005). A market study in Kampala, Uganda, indicates the wide range of important urban agriculture products for sale on urban markets and additional products with good market opportunities for Kampala (Nyapendi et al. 2010). The commonest crops produced for urban markets are leafy vegetables. The marketing chains of vegetables display considerably lower price differentials between farmers and consumers than longer chains (De Bon et al. 2010). Likewise, demand studies in Yaounde, Cameroon, showed that vegetables contribute a significant share of essential nutrients for the urban poor. This study identified several production styles: an intensive system within the urban limits as well as a semi intensive and extensive style in the urban periphery. The largest number of producers were women employing an extensive mixed crop system (Gockowski et al. 2003). Urban agriculture therefore makes a significant contribution to the supply of fresh foods in urban areas with varying proportions from city to city. The contribution of vegetables grown in urban and peri-urban areas thus ranges from 20% in Windhoek and Gaborone, 30% in Lilongwe and Blantyre, to 50% in Nampula and 50- 90% (according to the type of vegetables) in Dar es Salaam (Egal et al. 2001).

Currently, African agricultural systems are in a transition with large-scale developments and growing industrialised production technologies whereas the African traditions use a more natural approach. The project will therefore rather build on the best of indigenous technical knowledge, and supplement this with scientific results based on a sustainable approach to climate smart ecological agriculture, rather than advocating expensive technologies which will not be affordable for smallholder farmers. Using organic soil amendments which help improve soil nutrient and water holding capacity, designing appropriate crop rotations in consultation with local leading farmers, building pest and disease management strategies on local best practice supplemented with research findings, and helping to develop appropriate local grass roots structures will all contribute innovatively to sustainable production.

Existing studies are mostly surveys and market studies of urban agriculture. Still missing is an agronomical and a contextualised socio-economic view on the prospects of urban agriculture in tropical and subtropical Africa. Given the very limited space, which intercropping system provides the highest yield? How should crop composition vary with decreasing space? Which cash crops should be mixed with subsistence crops? Which intensity level is appropriate? Problems with current practices pertain to badly adapted crops, use of polluted water, low efficiency (no cascade use), little investment in soil quality, rain water harvesting, terrace building, little adaptation to upcoming climate changes, diminishing contributions to ecosystem services. The proposed project therefore seeks to better understand the causal factors as well as to identify effective and implementable solutions.

One of the most important obstacles for urban agriculture in sub-Saharan Africa is the informal process of land distribution. Most of the urban population live in informal settlements, have limited access to electricity, and relies on local firewood for energy. Environmental problems include poor waste management, flood hazards, over-exploitation of forests resources (firewood, charcoal, building material), conversion of agricultural land, and destruction of habitats for wildlife. Climate change is exacerbating these processes by generating new risks or reinforcing existing ones. Formal urban planning has generally failed to keep up with the rapid urbanisation, and as a result, the conversion of agricultural to urban land is based on informal rights to land for housing, neglecting needs for infrastructure, roads, and home gardens, among others (McLees 2011). In many cities farming activities are either legally ambiguous or even illegal, but widely pursued, often on land that is not designated for urban agriculture (Cissé et al 2005). The social relations between state agencies, community actors and private actors that underpin informal land delivery processes in African cities are complex and often conflictive (Leduka 2006). What this body of literature uniquely concludes is that purely agronomic activities promoting urban agriculture will fail if they do not consider land tenure issues, the institutions governing the distribution of land tenure rights, environmental suitability, land use zoning, density distribution, accessibility to resources, and equitable provision of basic services in ensuring sustainable use of urban land (Magigi 2008). Therefore, ECOSOLA addresses institutional factors as well as planning approaches with the goal to develop practically feasible, integrated small-scale solutions for vast majorities of urban farmers.