Dry, it's dangerous stuff. On what exactly is this statement based?
A book of two 400 pages volumes about explosives only. Put short: if mixed with a fuel, ammonitrate detonates just by ignition. If alone, it takes a detonator. Said detonator can be a portion of an ammonitrate heap that is tainted by a fuel.
Used in non-industrial amounts by fishermen. One handful in a bottle, mixed with Diesel oil, kills all fish in 100m diameter.
Heating explosives is known to ease their transition from deflagration to detonation, even in the absence of a detonator.
Having survived several similar games, I fully approve the claim by old pyrotechnicians: the more you know explosives, the more you distrust them.