Zaï or Tassa is a farming technique to dig pits (20-30 cm long and deep and 90 cm apart) in the soil during the preseason to catch water and concentrate compost. The technique is traditionally used in western Sahel (Burkina Faso, Niger, Mali) to restore degraded drylands and increase soil fertility.
Zaï holes were reintroduced since the 1980s by Yacouba Sawadogo, a farmer from Burkina Faso, who introduced the innovation of filling them with manure and compost to provide plant nutrients. The manure attracts termites, whose tunnels help further break up the soil. He also slightly increased the size of the holes over the traditional models. Zaï holes help by improving the yields of trees, sorghum, and millet by up to 500 percent.
- "Sourcebook of Alternative Technologies for Freshwater Augumentation in Africa". United Nations Environment Programme. Retrieved 11 December 2016.
- Kaboré, Daniel; Reij, Chris (2004). "The emergence and spreading of an improved traditional soil and water conservation practice in Burkina Faso". International Food Policy Research Institute. Archived from the original on 8 January 2013.
- Bass, Hans-Heinrich; von Freyhold, Klaus; Weisskoeppel, Cordula (2013). "Wasser ernten, Bäume schützen: Ernährungssicherung im Sahel" (PDF) (in German). pp. 46–48. Retrieved 11 December 2016.