As a Ph.D. chemist, I can tell you that ammonium nitrate has been used for both good and evil purposes over the years. On the good side, it is a great fertilizer and has been used for many years with excellent results. On the evil side, ammonium nitrate has been used as an ingredient for explosives for many years. The Oklahoma City bombing used easy-to-make explosives containing ammonium nitrate. It is extremely difficult for the average person to buy most chemicals and any attempt to buy ammonium nitrate or potassium nitrate (another good fertilizer) would send up red flags in a hurry. I'm not sure what is going on, but the numerous recent reports of missing ammonium nitrate make me a bit nervous about what might happen in the near future.