From the peanut basin of Senegal to the Seno plains of Mali, to Yatenga, formerly the most degraded region of Burkina Faso, and as far south as Malawi: gaos are thriving in Africa. And over the past three decades, the landscape of southern Niger has been transformed by more than 200m new trees, many of them gaos. They have not been planted but have grown naturally on over 5m hectares of farmland, nurtured by thousands of farmers.
The root system of the gao is nearly as big as its branches, and unusually it draws nitrogen from the air, fertilising the soil. And unlike other trees in the area, gao tree leaves fall in the rainy season, allowing more sunlight through to the crops at a key moment. Used along with mineral fertilisers, crop yields double under gaos, and the gao-nourished soil holds water better, ensuring a better crop in drought years.