CAN is not acid forming fertiliser, because it contains

CAN is calcium ammonium nitrate, also known as nitro-limestone or nitrochalk. It is a widely used inorganic fertilizer, accounting for 4% of all nitrogen fertilizers used.
It is hygroscopic, and its dissolution in water is endothermic. It accounts for roughly 8% calcium and 21 - 27% nitrogen. It is preferred for use on acidic soil, but it is not acid forming fertilizer as it contains Calcium.