Réponse du maïs ensilage (Zea mays L.) aux époques d’apport du Zinc dans le sol sablonneux du Loukkos (Nord-Ouest du Maroc)

The influence of timing of zinc (Zn) supply to the soil on growth, yield and nutritional status of corn silage in Zn was studied in the sandy soil of Loukkos. Five timings of Zn application to the soil (5 mg/kg) were tested in a field experiment: 1) at emergence, 2) at 5-6 leaf stage, 3) at 8-9 leaf stage, 4) split supply (50% at emergence, 25% at 5-6 leaf stage and 25% at 8-9 leaf stage) and 5) supply of 10% of the total dose every 7 days from emergence to the end of silking (continuous supply). Zn was supplied as a sulfated form (ZnSO4. 7H2O) and a treatment without Zn supply was maintained as control. The results showed that the adequate timing of Zn supply is between 5-6 leaf stage and 8-9 leaf stage. Zn application at 5-6 leaf stage as well as split and continuous applications showed an adequate Zn content in the shoot at harvest (22 mg/kg). Furthermore, they induced the highest increase in growth parameters and in silage yield. Under these Zn applications, shoot dry weight at harvest increased by 23.5% compared to control. This increase was only 11.1% for Zn supplied at 8-9 leaf stage and at emergence