The name Zai pits refers to small basins in which seed of annual or perennial crops are planted. They are beneficial for soil conditions because they increase termite activity that leads to a higher water infiltration when it rains. This intervention is most suitable for flat or gently sloped terrains (0-5%) with a precipitation range of 350-600 mm/y.
Pits usually are 20-30 cm both wide and deep, placed 60 cm – 1 m apart from each other and dug by hand. The excavated soil is placed downslope on the border of the pit to form a small ridge that further improve rainfall and runoff capture. When available, crop residue, mulch or manure is added to every pit to help vegetation grow in the first phases. In order to optimize the efficiency of Zai pits intervention, pits can be constructed in combination with stone lines , especially on degraded and crusted lands because the synergy of these two interventions helps land to be suitable again for agricultural purposes. In this case, when planting pits are used in combination with stones lines, growing grass between the stones is recommended because it helps to further increase infiltration and improve the accumulation of fertile sediment.
Under the name planting pits, we might find different indigenous names that refer to this type of intervention: tassa in Niger, zai pits in Burkina Faso, chololo pits in Tanzania, agun pits in Sudan, kofyarpits in Nigeria and yamka in Kyrgyzstan. Katumani pits and tubukiza pits in Kenya are both used for fodder production.
Food and Agriculture Organization of the United Nations, 1991, Chritchley & Siegert, Water harvesting, http://www.fao.org/3/u3160e/u3160e00.htm. Reproduced with permission
WOCAT, 2012, Schwilch, Hessel & Verzandvoort, Desire for Greener Land, https://edepot.wur.nl/212528. Reproduced with permission.