1The old pipe gives the sweetest smoke, it is said, and one can draw inspiration from ancestral practices to develop tomorrow’s agricultural techniques. This was the gist of the large-scale fallow programmes implemented in the 1990s by IRD in those Sahelian countries affected by desertification: Côte d’Ivoire, Niger, Senegal, Mali and Burkina Faso. The idea was to identify traditional agricultural practices and optimise them to respond to the needs of growing populations.

Line of stones against erosion, Gabon.

2In Burkina Faso, researchers paid close attention to “zai”, a technique used by farmers to spectacularly revegetate dry land. It consists of criss-crossing the soil with small gullies and only planting at the intersection of these lines, making it possible to till the land in a targeted manner, by bringing water and organic matter to exactly where the plant is growing. Researchers optimised this practice by adding bacteria or fungi capable of breaking down the organic matter and therefore accelerating the release of nutrients beneficial to the plant.

Irrigation channel, Niger.

3An alternative approach was to use termites as biological fertiliser by making them break down crop residues. The resulting powder was used, for example, to grow tomato plants in Burkina Faso. Furthermore, researchers developed assisted natural regeneration techniques to promote the growth of new shrubs on agricultural land, and prevent the ageing of tree populations, which offer havens for biodiversity while providing natural protection against water and wind erosion. These various forms of knowledge were recognised by the French scientific committee on desertification, and included the “Great Green Wall” project initiated in 2008.