See comment to Question 6 in Round 4.
I would also quibble about the amount of science in this question. By definition, IEDs aren't made by scientists; they're made by students, protestors and terrorists.
But that's probably just me.
I did find an article about fertiliser bombs on a website called Live Science. (It was top of the list in my Google search.) But it didn't mention sugar.
According to Live Science, the essential component of a fertiliser bomb, besides fertiliser and "a fuel", is "a detonator".
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