Hello, some time have elapsed since I wrote my question … thanks for all replies. I have opted for the following solution:
– late September 2024, organic fertilizer 8% nitrogen, 40 units of N per hectare;
– begininng of March 2025 organic fertilizer 4-4-4 (poultry manure) 1 t/ha;

here attached you can find the last sap analysis (May 9)

Next season I think to start with sprays of Mg, Fe, Mn. May you give me your opinion about the sap analysis?
stefano