Urban farming needs a radical change not only in the way it is valued but also in the way it is done. Indeed, because of the fierce competition over resources and their precarious land tenure, Dakar Region’s farmers have less and less land and water to farm and therefore feel time is running out for them.
They consequently seek to improve productivity to meet the soaring demand and mobilise low capital investments by using wastewater, pesticides, organic manure or sewage sludge. These practices inevitably have strong negative impacts on human and environmental health (Fall, 2001).
In Patte d’Oie and Malika areas, the increased use of grey water, pesticides and sewage sludge contributes to crops, soil and groundwater (main source of water for agriculture) pollution which affects all the Niayes zone. In Dakar’s area, soil organochlorine contamination due to pesticides is, on average, higher than the WHO standard (Ba et al., 2016).
Besides, wastewater and sewage sludge would be viable alternative sources of irrigation only if they were treated and cleaned of their pathogens and toxic elements before use since they contain nutrients (nitrogen, phosphorus, potassium) which are particularly efficient to fertilise crops (Ndiaye et al., 2010).
Recognising the risk and potential of wastewater, the WHO has developed treatment guidelines for safe reuse. But these complex treatment systems may be impossible to finance and maintain for poor communities that could only deal with cheap and natural systems. The one developed by local researchers in Rufisque and supported by the IDRC which uses aquatic lettuce could do (Redwood, 2003). Rainwater retention as well could partially answer the great need for water in a more sustainable way but, as the region is pretty dry, it would be a very limited solution.
As for the widespread use of organic fertiliser in Dakar Region, that can appear as a sustainable way to farm, it is in fact a source of adverse effects. Organic manure, such as poultry manure, actually involves risks of pathogens and trace metals contamination for groundwater and thus for the population.
To improve the sustainability of farming activities, organic waste use should be more diversified and focused on the least dangerous organic matter (such as horse dung), while inputs should be adjusted according to specific crops (Hodomihou et al., 2016).
However, farmers in Dakar Region are not only concerned about income and environment but also about the fragile stability of local agricultural organisation (Zelem, 2011). They often fear to disturb interconnections between different actors by introducing new types of inputs and rationally prefer to ensure the preservation of subsistance agriculture allowing local communities to survive (Moyo et al., 2015).
In front of all these numerous issues, especially the reduction of available arable land, many Dakar residents developed an other kind of urban agriculture by creating micro-gardens in the remaining spaces of the city. This “outside the ground” way to produce vegetables in small spaces can be implemented almost everywhere and usually exploits recycled materials (FAO, 2010).
Some gardens are cultivated for home consumption, others for sale and frequently both. This farming practice seems to be a cheap way to produce food with high nutritional values and without health dangers since no pesticides are used.
Micro-gardening in Dakar typically consists of gardening directly on the market tables and allows vulnerable people (women, elderly, etc.) to empower themselves since it requires little physical effort (MUFPP, 2018).
This practice uses very little water, while the surplus is recovered and reused. Micro-gardening therefore appears as an example of circular economy through which healthy food is sustainably produced while waste is recycled.
In a nutshell, though risks and challenges exist, well-managed urban farming enables to tackle several socioeconomic issues but also environmental ones. Micro-gardening can substantially contribute to waste recycling (which is of particular relevance regarding the key challenge of city waste management), increased biodiversity, carbon sequestration and thus climate change mitigation (Lwasa et al., 2015). Moreover, urban greening is also known to boost human well-being at both physical (pollution reduction) and psychological levels (Ackerman, 2006). Everything indicates that the micro-gardens model deserves serious attention and investment.