According to the UN, 24% of land globally is degrading and threatened with desrtification. Trends are only getting worse, considering climate change and mismanagement.
The ancient farming technique of zaï is applied to improve degraded bare soils exposed to drought. The farmers dig pits approximately 20 cm across and 15 cm deep in the ground, fill them with manure, crop residues and other forms of organic matter and then add the seeds for their crop. The micro-environment of the pit retains water and makes it readily available to the roots of the plant, along with nutrients. Additionally, and depending on the location, the pit supports biological activity- in semi arid tropics, for example, composting species of termites contribute to organic matter availability to seedlings.
The technique was revisited since the 1980s in the barren, hard-pan soils of Burkina Faso which were impossible to plow. Farmer innovators like Oursseni Zoromé, Ali Ouedraogo and Yacouba Sawadogo promoted and improved the technique.
The latter is widely known as “the man who stopped the desert” after Mark Dodd turned his story in a movie; and he was one of the recipients of Sweden’s “alternative Nobel prize” in 2018 (The Right Livelihood Award). Sawadogo created a diverse 40-hectare forest on abandoned barren land using zaï pits, and he popularized the technique facing skepticism and adversity.
Thanks to the zaï technique, tens of thousands of degraded land have been recovered in sub-Saharan Africa and in some cases water retention by the pits has resulted in increases of 5-17m in the water level of wells. Authorities, NGOs and farmer associations are endorsing the technique and now new ways are explored to reduce the effort required in digging out the pits.