I understand fairly well the process of sweetening acidic soils using
agricultural lime or dolomite, or sometimes more inadvertently with too much
wood ash and mushroom compost.

To acidify alkaline soils I understand aluminium sulphate (which I have
never come across but imagine it is easily available if I search for it)
works and to a lesser extent peat moss and chciken poo will do this over a
period of time.

Is anyone able to confirm the latter case?