IANAEE, but I think you are mixing potasium nitrare and ammonium nitrate.
Looking in Wikipedia, in the danger warning square, in the yellow part potasium nitrare has a 0 and ammonium nitrate has a 3.
Don't try this at home ...
Potasium nitrate has a lot of oxygens but nothing to burn with it. So it's only explosive when mixed with some fuel.
Ammonium nitrate has the oxygen and also the hidrogens that can be combined and release energy. It has also some spare oxygen, it is probably more dangerous mixed with fuel.
Looking in Wikipedia, in the danger warning square, in the yellow part potasium nitrare has a 0 and ammonium nitrate has a 3.
Don't try this at home ...
Potasium nitrate has a lot of oxygens but nothing to burn with it. So it's only explosive when mixed with some fuel.
Ammonium nitrate has the oxygen and also the hidrogens that can be combined and release energy. It has also some spare oxygen, it is probably more dangerous mixed with fuel.