This is doubtless just your standard fertiliser to make daffodils and such bloom even more lovely. It’s just that, for whatever reason, the Department of Justice thinks that the details of what happened between 1978 and 1981 when they explored the manufacturing of fertiliser by getting the army to test it are still not ready to see the light of day, some thirty years later.
Only seeing this now. There’s a rather obvious reason why the army might test any proposed new artificial fertiliser formulas. Fertilisers can be a key component in homemade explosives.