A zai pit is a planting pit dug before the rainy season and filled with compost or manure, used across dry regions to concentrate scarce rainfall and fertility at the planting point.1 Pits are typically spaced about 90 cm apart, 15-20 cm deep, with a mound rim about 30 cm across.1 The technique is traditional to the Sahel, where it is often combined with contour stone bunds and tree planting to rehabilitate degraded cropland.2