Effets résiduel et d’apport continu de gypse sur les propriétés chimiques d’un sol alcalinisé et sur les performances du maïs (Zea mays L.)

Residual and repeated gypsum application effects on alkalinized soil chemical properties and maize (Zea mays L.) yields. Irrigation remains the main source of soil alkalization. Gypsum amendment is a solution to this process of degradation and improvement of crop productivity. To prevent the misuse of gypsum in urban agriculture, the impact of gypsum application modes was studied compared to farmer practice (PP) on Lixisol in a split plot design. The treatments consisted of (i) modes of applications of gypsum with two levels: residual effect (GrA); and continuous application (GrC) and (ii) level of soil degradation with two levels: moderately degraded and highly degraded. The results show that the modes of application decreased the pH by 1.36 units and 1.51 units respectively in moderately degraded and highly degraded soils. The highest decrease was observed with GrC. For soil exchangeable sodium concentration, only GrC induced a decrease of 54.8% in moderately degraded soils. In highly degraded soils, it was reduced by 87% and 76% respectively with GrA and GrC compared to PP. In highly degraded soils, the yields obtained with GrA and GrC are 4 to 3.6 times those of PP respectively.