I’m wondering if they are suffering from a caliche buildup from irrigation or something like it. If you find out more, please ping me. Thanks!
If the parent rock is dolomite one would think calcium cementation would be an issue, whether from surface water or wells. Italy has strongly partitioned soil systems between the Alpine foothills, the Po Valley, and the peninsula, interspersed with regions of volcanic deposition. Soils can vary from strongly alkaline to acidic.