Abstract

In this arid zone, water is crucial for increasing yields, which justifies why zaï, characterized by spherical pits, has become the main soil recovery technique. However, water table level affects the effectiveness of zaï in collecting sufficient water. The present study aimed to give a rectangular shape to the typically spherical zaï pits to measure the straw and grain yield of sorghum in a factorial design: lengths of pits (30-35-40 and 45 cm) of a constant depth of 20 cm, type of amendments (compost, NPK, compost + NPK, and no input) with 4 repetitions. In the Sahelian zone and Sudano-Sahelian zone, straw mass and grain yield were assessed. The results indicated that rectangular zaï significantly improved straw (4941 kg/ha in 2019 and 2490 kg/ha in 2020) and grain (844 kg/ha in 2019; 839 kg/ha in 2020) yields compared to ordinary zaï (3609 kg/ha in 2019; 1596 kg/ha in 2020 for straw and 588 kg/ha in 2019 and 460 kg/ha in 2020 for grain). The application of compost combined with NPK under rectangular zaï in 45 cm long pits significantly increased grain yield more in the Sahelian zone (1890.5 kg/ha in 2019; 2269.0 kg/ha in 2020) than in the Sudano-Sahelian zone (1750.0 kg/ha in 2019; 1634.6 kg/ha in 2020), with a downward trend over time. The good runoff collection capacity and the combination of compost and NPK likely created better water and nutritional conditions, as reflected in these yields. Rectangular zaï thus emerged as the superior technique compared to ordinary zaï and requires high-quality organo-chemical matter, especially in the Sahelian zone.

Key words: Land degraded, soil fertility, rectangular zaï, sorghum.